Merge from rustc

src/tools/clippy/clippy_lints/src/default.rs

@@ -5,7 +5,7 @@ use clippy_utils::{contains_name, get_parent_expr, in_automatically_derived, is_
 use rustc_data_structures::fx::FxHashSet;
 use rustc_errors::Applicability;
 use rustc_hir::def::Res;
-use rustc_hir::{Block, Expr, ExprKind, PatKind, QPath, Stmt, StmtKind};
+use rustc_hir::{Block, Expr, ExprKind, PatKind, QPath, Stmt, StmtKind, StructTailExpr};
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_middle::ty;
 use rustc_middle::ty::print::with_forced_trimmed_paths;
@@ -285,7 +285,7 @@ fn field_reassigned_by_stmt<'tcx>(this: &Stmt<'tcx>, binding_name: Symbol) -> Op
 /// Returns whether `expr` is the update syntax base: `Foo { a: 1, .. base }`
 fn is_update_syntax_base<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) -> bool {
     if let Some(parent) = get_parent_expr(cx, expr)
-        && let ExprKind::Struct(_, _, Some(base)) = parent.kind
+        && let ExprKind::Struct(_, _, StructTailExpr::Base(base)) = parent.kind
     {
         base.hir_id == expr.hir_id
     } else {

src/tools/clippy/clippy_lints/src/default_numeric_fallback.rs

@@ -4,7 +4,7 @@ use clippy_utils::source::snippet_opt;
 use rustc_ast::ast::{LitFloatType, LitIntType, LitKind};
 use rustc_errors::Applicability;
 use rustc_hir::intravisit::{Visitor, walk_expr, walk_stmt};
-use rustc_hir::{Block, Body, ConstContext, Expr, ExprKind, FnRetTy, HirId, Lit, Stmt, StmtKind};
+use rustc_hir::{Block, Body, ConstContext, Expr, ExprKind, FnRetTy, HirId, Lit, Stmt, StmtKind, StructTailExpr};
 use rustc_lint::{LateContext, LateLintPass, LintContext};
 use rustc_middle::lint::in_external_macro;
 use rustc_middle::ty::{self, FloatTy, IntTy, PolyFnSig, Ty};
@@ -197,7 +197,7 @@ impl<'tcx> Visitor<'tcx> for NumericFallbackVisitor<'_, 'tcx> {
                     }
 
                     // Visit base with no bound.
-                    if let Some(base) = base {
+                    if let StructTailExpr::Base(base) = base {
                         self.ty_bounds.push(ExplicitTyBound(false));
                         self.visit_expr(base);
                         self.ty_bounds.pop();

src/tools/clippy/clippy_lints/src/dereference.rs

@@ -818,7 +818,6 @@ impl TyCoercionStability {
                 | TyKind::Typeof(..)
                 | TyKind::TraitObject(..)
                 | TyKind::InferDelegation(..)
-                | TyKind::AnonAdt(..)
                 | TyKind::Err(_) => Self::Reborrow,
             };
         }

src/tools/clippy/clippy_lints/src/inconsistent_struct_constructor.rs

@@ -3,7 +3,7 @@ use clippy_utils::fulfill_or_allowed;
 use clippy_utils::source::snippet;
 use rustc_data_structures::fx::FxHashMap;
 use rustc_errors::Applicability;
-use rustc_hir::{self as hir, ExprKind};
+use rustc_hir::{self as hir, ExprKind, StructTailExpr};
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_session::declare_lint_pass;
 use rustc_span::symbol::Symbol;
@@ -95,7 +95,7 @@ impl<'tcx> LateLintPass<'tcx> for InconsistentStructConstructor {
             }
             fields_snippet.push_str(&last_ident.to_string());
 
-            let base_snippet = if let Some(base) = base {
+            let base_snippet = if let StructTailExpr::Base(base) = base {
                 format!(", ..{}", snippet(cx, base.span, ".."))
             } else {
                 String::new()

src/tools/clippy/clippy_lints/src/init_numbered_fields.rs

@@ -2,7 +2,7 @@ use clippy_utils::diagnostics::span_lint_and_then;
 use clippy_utils::source::{snippet_with_applicability, snippet_with_context};
 use rustc_errors::Applicability;
 use rustc_hir::def::{DefKind, Res};
-use rustc_hir::{Expr, ExprKind};
+use rustc_hir::{Expr, ExprKind, StructTailExpr};
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_session::declare_lint_pass;
 use rustc_span::SyntaxContext;
@@ -43,7 +43,7 @@ declare_lint_pass!(NumberedFields => [INIT_NUMBERED_FIELDS]);
 
 impl<'tcx> LateLintPass<'tcx> for NumberedFields {
     fn check_expr(&mut self, cx: &LateContext<'tcx>, e: &'tcx Expr<'_>) {
-        if let ExprKind::Struct(path, fields @ [field, ..], None) = e.kind
+        if let ExprKind::Struct(path, fields @ [field, ..], StructTailExpr::None) = e.kind
             // If the first character of any field is a digit it has to be a tuple.
             && field.ident.as_str().as_bytes().first().is_some_and(u8::is_ascii_digit)
             // Type aliases can't be used as functions.

src/tools/clippy/clippy_lints/src/loops/never_loop.rs

@@ -5,7 +5,7 @@ use clippy_utils::higher::ForLoop;
 use clippy_utils::macros::root_macro_call_first_node;
 use clippy_utils::source::snippet;
 use rustc_errors::Applicability;
-use rustc_hir::{Block, Destination, Expr, ExprKind, HirId, InlineAsmOperand, Pat, Stmt, StmtKind};
+use rustc_hir::{Block, Destination, Expr, ExprKind, HirId, InlineAsmOperand, Pat, Stmt, StmtKind, StructTailExpr};
 use rustc_lint::LateContext;
 use rustc_span::{Span, sym};
 use std::iter::once;
@@ -164,7 +164,7 @@ fn never_loop_expr<'tcx>(
         },
         ExprKind::Struct(_, fields, base) => {
             let fields = never_loop_expr_all(cx, fields.iter().map(|f| f.expr), local_labels, main_loop_id);
-            if let Some(base) = base {
+            if let StructTailExpr::Base(base) = base {
                 combine_seq(fields, || never_loop_expr(cx, base, local_labels, main_loop_id))
             } else {
                 fields

src/tools/clippy/clippy_lints/src/needless_pass_by_value.rs

@@ -200,6 +200,7 @@ impl<'tcx> LateLintPass<'tcx> for NeedlessPassByValue {
                                 cx.param_env,
                                 ty,
                                 traits::ObligationCause::dummy_with_span(span),
+                                rustc_hir::Safety::Safe,
                             )
                             .is_ok()
                             {

src/tools/clippy/clippy_lints/src/needless_update.rs

@@ -1,5 +1,5 @@
 use clippy_utils::diagnostics::span_lint;
-use rustc_hir::{Expr, ExprKind};
+use rustc_hir::{Expr, ExprKind, StructTailExpr};
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_middle::ty;
 use rustc_session::declare_lint_pass;
@@ -51,7 +51,7 @@ declare_lint_pass!(NeedlessUpdate => [NEEDLESS_UPDATE]);
 
 impl<'tcx> LateLintPass<'tcx> for NeedlessUpdate {
     fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
-        if let ExprKind::Struct(_, fields, Some(base)) = expr.kind {
+        if let ExprKind::Struct(_, fields, StructTailExpr::Base(base)) = expr.kind {
             let ty = cx.typeck_results().expr_ty(expr);
             if let ty::Adt(def, _) = ty.kind() {
                 if fields.len() == def.non_enum_variant().fields.len()

src/tools/clippy/clippy_lints/src/no_effect.rs

@@ -8,7 +8,7 @@ use rustc_errors::Applicability;
 use rustc_hir::def::{DefKind, Res};
 use rustc_hir::{
     BinOpKind, BlockCheckMode, Expr, ExprKind, HirId, HirIdMap, ItemKind, LocalSource, Node, PatKind, Stmt, StmtKind,
-    UnsafeSource, is_range_literal,
+    UnsafeSource, StructTailExpr, is_range_literal,
 };
 use rustc_infer::infer::TyCtxtInferExt as _;
 use rustc_lint::{LateContext, LateLintPass, LintContext};
@@ -238,7 +238,10 @@ fn has_no_effect(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
         ExprKind::Struct(_, fields, ref base) => {
             !has_drop(cx, cx.typeck_results().expr_ty(expr))
                 && fields.iter().all(|field| has_no_effect(cx, field.expr))
-                && base.as_ref().is_none_or(|base| has_no_effect(cx, base))
+                && match &base {
+                    StructTailExpr::None | StructTailExpr::DefaultFields(_) => true,
+                    StructTailExpr::Base(base) => has_no_effect(cx, base),
+                }
         },
         ExprKind::Call(callee, args) => {
             if let ExprKind::Path(ref qpath) = callee.kind {
@@ -342,6 +345,10 @@ fn reduce_expression<'a>(cx: &LateContext<'_>, expr: &'a Expr<'a>) -> Option<Vec
             if has_drop(cx, cx.typeck_results().expr_ty(expr)) {
                 None
             } else {
+                let base = match base {
+                    StructTailExpr::Base(base) => Some(base),
+                    StructTailExpr::None | StructTailExpr::DefaultFields(_) => None,
+                };
                 Some(fields.iter().map(|f| &f.expr).chain(base).map(Deref::deref).collect())
             }
         },

src/tools/clippy/clippy_lints/src/non_copy_const.rs

@@ -11,7 +11,7 @@ use rustc_hir::{
     BodyId, Expr, ExprKind, HirId, Impl, ImplItem, ImplItemKind, Item, ItemKind, Node, TraitItem, TraitItemKind, UnOp,
 };
 use rustc_lint::{LateContext, LateLintPass, Lint};
-use rustc_middle::mir::interpret::{ErrorHandled, EvalToValTreeResult, GlobalId};
+use rustc_middle::mir::interpret::{ErrorHandled, EvalToValTreeResult, GlobalId, ReportedErrorInfo};
 use rustc_middle::ty::adjustment::Adjust;
 use rustc_middle::ty::{self, Ty, TyCtxt};
 use rustc_session::impl_lint_pass;
@@ -302,7 +302,10 @@ impl<'tcx> NonCopyConst<'tcx> {
                 tcx.const_eval_global_id_for_typeck(typing_env, cid, span)
             },
             Ok(None) => Err(ErrorHandled::TooGeneric(span)),
-            Err(err) => Err(ErrorHandled::Reported(err.into(), span)),
+            Err(err) => Err(ErrorHandled::Reported(
+                ReportedErrorInfo::non_const_eval_error(err),
+                span,
+            )),
         }
     }
 }

src/tools/clippy/clippy_lints/src/single_range_in_vec_init.rs

@@ -6,7 +6,7 @@ use clippy_utils::source::SpanRangeExt;
 use clippy_utils::ty::implements_trait;
 use rustc_ast::{LitIntType, LitKind, UintTy};
 use rustc_errors::Applicability;
-use rustc_hir::{Expr, ExprKind, LangItem, QPath};
+use rustc_hir::{Expr, ExprKind, LangItem, QPath, StructTailExpr};
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_session::declare_lint_pass;
 use std::fmt::{self, Display, Formatter};
@@ -86,7 +86,7 @@ impl LateLintPass<'_> for SingleRangeInVecInit {
             return;
         };
 
-        let ExprKind::Struct(QPath::LangItem(lang_item, ..), [start, end], None) = inner_expr.kind else {
+        let ExprKind::Struct(QPath::LangItem(lang_item, ..), [start, end], StructTailExpr::None) = inner_expr.kind else {
             return;
         };
 

src/tools/clippy/clippy_lints/src/unnecessary_struct_initialization.rs

@@ -2,7 +2,7 @@ use clippy_utils::diagnostics::span_lint_and_sugg;
 use clippy_utils::source::snippet;
 use clippy_utils::ty::is_copy;
 use clippy_utils::{get_parent_expr, path_to_local};
-use rustc_hir::{BindingMode, Expr, ExprField, ExprKind, Node, PatKind, Path, QPath, UnOp};
+use rustc_hir::{BindingMode, Expr, ExprField, ExprKind, Node, PatKind, Path, QPath, UnOp, StructTailExpr};
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_session::declare_lint_pass;
 
@@ -59,15 +59,15 @@ impl LateLintPass<'_> for UnnecessaryStruct {
         let field_path = same_path_in_all_fields(cx, expr, fields);
 
         let sugg = match (field_path, base) {
-            (Some(&path), None) => {
+            (Some(&path), StructTailExpr::None | StructTailExpr::DefaultFields(_)) => {
                 // all fields match, no base given
                 path.span
             },
-            (Some(path), Some(base)) if base_is_suitable(cx, expr, base) && path_matches_base(path, base) => {
+            (Some(path), StructTailExpr::Base(base)) if base_is_suitable(cx, expr, base) && path_matches_base(path, base) => {
                 // all fields match, has base: ensure that the path of the base matches
                 base.span
             },
-            (None, Some(base)) if fields.is_empty() && base_is_suitable(cx, expr, base) => {
+            (None, StructTailExpr::Base(base)) if fields.is_empty() && base_is_suitable(cx, expr, base) => {
                 // just the base, no explicit fields
                 base.span
             },

src/tools/clippy/clippy_lints/src/utils/author.rs

@@ -4,7 +4,7 @@ use rustc_ast::ast::{LitFloatType, LitKind};
 use rustc_data_structures::fx::FxHashMap;
 use rustc_hir::{
     self as hir, BindingMode, CaptureBy, Closure, ClosureKind, ConstArg, ConstArgKind, CoroutineKind,
-    ExprKind, FnRetTy, HirId, Lit, PatKind, QPath, StmtKind, TyKind,
+    ExprKind, FnRetTy, HirId, Lit, PatKind, QPath, StmtKind, TyKind, StructTailExpr,
 };
 use rustc_lint::{LateContext, LateLintPass, LintContext};
 use rustc_session::declare_lint_pass;
@@ -598,7 +598,10 @@ impl<'a, 'tcx> PrintVisitor<'a, 'tcx> {
             },
             ExprKind::Struct(qpath, fields, base) => {
                 bind!(self, qpath, fields);
-                opt_bind!(self, base);
+                let base = OptionPat::new(match base {
+                    StructTailExpr::Base(base) => Some(self.bind("base", base)),
+                    StructTailExpr::None | StructTailExpr::DefaultFields(_) => None,
+                });
                 kind!("Struct({qpath}, {fields}, {base})");
                 self.qpath(qpath);
                 self.slice(fields, |field| {

src/tools/clippy/clippy_utils/src/higher.rs

@@ -8,7 +8,7 @@ use crate::ty::is_type_diagnostic_item;
 
 use rustc_ast::ast;
 use rustc_hir as hir;
-use rustc_hir::{Arm, Block, Expr, ExprKind, HirId, LoopSource, MatchSource, Node, Pat, QPath};
+use rustc_hir::{Arm, Block, Expr, ExprKind, StructTailExpr, HirId, LoopSource, MatchSource, Node, Pat, QPath};
 use rustc_lint::LateContext;
 use rustc_span::{Span, sym, symbol};
 
@@ -236,7 +236,7 @@ impl<'a> Range<'a> {
                     limits: ast::RangeLimits::Closed,
                 })
             },
-            ExprKind::Struct(path, fields, None) => match (path, fields) {
+            ExprKind::Struct(path, fields, StructTailExpr::None) => match (path, fields) {
                 (QPath::LangItem(hir::LangItem::RangeFull, ..), []) => Some(Range {
                     start: None,
                     end: None,

src/tools/clippy/clippy_utils/src/hir_utils.rs

@@ -10,7 +10,7 @@ use rustc_hir::{
     AssocItemConstraint, BinOpKind, BindingMode, Block, BodyId, Closure, ConstArg, ConstArgKind, Expr,
     ExprField, ExprKind, FnRetTy, GenericArg, GenericArgs, HirId, HirIdMap, InlineAsmOperand, LetExpr, Lifetime,
     LifetimeName, Pat, PatField, PatKind, Path, PathSegment, PrimTy, QPath, Stmt, StmtKind, TraitBoundModifiers, Ty,
-    TyKind,
+    TyKind, StructTailExpr,
 };
 use rustc_lexer::{TokenKind, tokenize};
 use rustc_lint::LateContext;
@@ -380,7 +380,12 @@ impl HirEqInterExpr<'_, '_, '_> {
             (ExprKind::Ret(l), ExprKind::Ret(r)) => both(l.as_ref(), r.as_ref(), |l, r| self.eq_expr(l, r)),
             (&ExprKind::Struct(l_path, lf, ref lo), &ExprKind::Struct(r_path, rf, ref ro)) => {
                 self.eq_qpath(l_path, r_path)
-                    && both(lo.as_ref(), ro.as_ref(), |l, r| self.eq_expr(l, r))
+                    && match (lo, ro) {
+                        (StructTailExpr::Base(l),StructTailExpr::Base(r)) => self.eq_expr(l, r),
+                        (StructTailExpr::None, StructTailExpr::None) => true,
+                        (StructTailExpr::DefaultFields(_), StructTailExpr::DefaultFields(_)) => true,
+                        _ => false,
+                    }
                     && over(lf, rf, |l, r| self.eq_expr_field(l, r))
             },
             (&ExprKind::Tup(l_tup), &ExprKind::Tup(r_tup)) => self.eq_exprs(l_tup, r_tup),
@@ -591,7 +596,6 @@ impl HirEqInterExpr<'_, '_, '_> {
             (TyKind::Path(l), TyKind::Path(r)) => self.eq_qpath(l, r),
             (&TyKind::Tup(l), &TyKind::Tup(r)) => over(l, r, |l, r| self.eq_ty(l, r)),
             (&TyKind::Infer, &TyKind::Infer) => true,
-            (TyKind::AnonAdt(l_item_id), TyKind::AnonAdt(r_item_id)) => l_item_id == r_item_id,
             _ => false,
         }
     }
@@ -1017,7 +1021,7 @@ impl<'a, 'tcx> SpanlessHash<'a, 'tcx> {
                     self.hash_expr(f.expr);
                 }
 
-                if let Some(e) = *expr {
+                if let StructTailExpr::Base(e) = *expr {
                     self.hash_expr(e);
                 }
             },
@@ -1241,8 +1245,7 @@ impl<'a, 'tcx> SpanlessHash<'a, 'tcx> {
             | TyKind::Infer
             | TyKind::Never
             | TyKind::InferDelegation(..)
-            | TyKind::OpaqueDef(_)
-            | TyKind::AnonAdt(_) => {},
+            | TyKind::OpaqueDef(_) => {},
         }
     }
 

src/tools/clippy/clippy_utils/src/visitors.rs

@@ -7,7 +7,7 @@ use rustc_hir::def::{CtorKind, DefKind, Res};
 use rustc_hir::intravisit::{self, Visitor, walk_block, walk_expr};
 use rustc_hir::{
     AnonConst, Arm, Block, BlockCheckMode, Body, BodyId, Expr, ExprKind, HirId, ItemId, ItemKind, LetExpr, Pat, QPath,
-    Safety, Stmt, UnOp, UnsafeSource,
+    Safety, Stmt, UnOp, UnsafeSource, StructTailExpr,
 };
 use rustc_lint::LateContext;
 use rustc_middle::hir::nested_filter;
@@ -663,7 +663,7 @@ pub fn for_each_unconsumed_temporary<'tcx, B>(
                 for field in fields {
                     helper(typeck, true, field.expr, f)?;
                 }
-                if let Some(default) = default {
+                if let StructTailExpr::Base(default) = default {
                     helper(typeck, false, default, f)?;
                 }
             },

src/tools/compiletest/src/compute_diff.rs

@@ -144,7 +144,7 @@ where
     }
 
     if !wrote_data {
-        println!("note: diff is identical to nightly rustdoc");
+        eprintln!("note: diff is identical to nightly rustdoc");
         assert!(diff_output.metadata().unwrap().len() == 0);
         return false;
     } else if verbose {

src/tools/compiletest/src/debuggers.rs

@@ -20,7 +20,7 @@ pub(crate) fn configure_gdb(config: &Config) -> Option<Arc<Config>> {
     }
 
     if config.remote_test_client.is_some() && !config.target.contains("android") {
-        println!(
+        eprintln!(
             "WARNING: debuginfo tests are not available when \
              testing with remote"
         );
@@ -28,7 +28,7 @@ pub(crate) fn configure_gdb(config: &Config) -> Option<Arc<Config>> {
     }
 
     if config.target.contains("android") {
-        println!(
+        eprintln!(
             "{} debug-info test uses tcp 5039 port.\
              please reserve it",
             config.target
@@ -50,7 +50,7 @@ pub(crate) fn configure_lldb(config: &Config) -> Option<Arc<Config>> {
     config.lldb_python_dir.as_ref()?;
 
     if let Some(350) = config.lldb_version {
-        println!(
+        eprintln!(
             "WARNING: The used version of LLDB (350) has a \
              known issue that breaks debuginfo tests. See \
              issue #32520 for more information. Skipping all \

src/tools/compiletest/src/lib.rs

@@ -188,8 +188,8 @@ pub fn parse_config(args: Vec<String>) -> Config {
     let (argv0, args_) = args.split_first().unwrap();
     if args.len() == 1 || args[1] == "-h" || args[1] == "--help" {
         let message = format!("Usage: {} [OPTIONS] [TESTNAME...]", argv0);
-        println!("{}", opts.usage(&message));
-        println!();
+        eprintln!("{}", opts.usage(&message));
+        eprintln!();
         panic!()
     }
 
@@ -200,8 +200,8 @@ pub fn parse_config(args: Vec<String>) -> Config {
 
     if matches.opt_present("h") || matches.opt_present("help") {
         let message = format!("Usage: {} [OPTIONS]  [TESTNAME...]", argv0);
-        println!("{}", opts.usage(&message));
-        println!();
+        eprintln!("{}", opts.usage(&message));
+        eprintln!();
         panic!()
     }
 
@@ -508,7 +508,7 @@ pub fn run_tests(config: Arc<Config>) {
             // easy to miss which tests failed, and as such fail to reproduce
             // the failure locally.
 
-            println!(
+            eprintln!(
                 "Some tests failed in compiletest suite={}{} mode={} host={} target={}",
                 config.suite,
                 config

src/tools/compiletest/src/runtest.rs

@@ -131,7 +131,7 @@ pub fn run(config: Arc<Config>, testpaths: &TestPaths, revision: Option<&str>) {
 
     if config.verbose {
         // We're going to be dumping a lot of info. Start on a new line.
-        print!("\n\n");
+        eprintln!("\n");
     }
     debug!("running {:?}", testpaths.file.display());
     let mut props = TestProps::from_file(&testpaths.file, revision, &config);
@@ -353,7 +353,7 @@ impl<'test> TestCx<'test> {
                 {
                     self.error(&format!("{} test did not emit an error", self.config.mode));
                     if self.config.mode == crate::common::Mode::Ui {
-                        println!("note: by default, ui tests are expected not to compile");
+                        eprintln!("note: by default, ui tests are expected not to compile");
                     }
                     proc_res.fatal(None, || ());
                 };
@@ -774,20 +774,20 @@ impl<'test> TestCx<'test> {
                 unexpected.len(),
                 not_found.len()
             ));
-            println!("status: {}\ncommand: {}\n", proc_res.status, proc_res.cmdline);
+            eprintln!("status: {}\ncommand: {}\n", proc_res.status, proc_res.cmdline);
             if !unexpected.is_empty() {
-                println!("{}", "--- unexpected errors (from JSON output) ---".green());
+                eprintln!("{}", "--- unexpected errors (from JSON output) ---".green());
                 for error in &unexpected {
-                    println!("{}", error.render_for_expected());
+                    eprintln!("{}", error.render_for_expected());
                 }
-                println!("{}", "---".green());
+                eprintln!("{}", "---".green());
             }
             if !not_found.is_empty() {
-                println!("{}", "--- not found errors (from test file) ---".red());
+                eprintln!("{}", "--- not found errors (from test file) ---".red());
                 for error in &not_found {
-                    println!("{}", error.render_for_expected());
+                    eprintln!("{}", error.render_for_expected());
                 }
-                println!("{}", "---\n".red());
+                eprintln!("{}", "---\n".red());
             }
             panic!("errors differ from expected");
         }
@@ -1876,18 +1876,18 @@ impl<'test> TestCx<'test> {
 
     fn maybe_dump_to_stdout(&self, out: &str, err: &str) {
         if self.config.verbose {
-            println!("------stdout------------------------------");
-            println!("{}", out);
-            println!("------stderr------------------------------");
-            println!("{}", err);
-            println!("------------------------------------------");
+            eprintln!("------stdout------------------------------");
+            eprintln!("{}", out);
+            eprintln!("------stderr------------------------------");
+            eprintln!("{}", err);
+            eprintln!("------------------------------------------");
         }
     }
 
     fn error(&self, err: &str) {
         match self.revision {
-            Some(rev) => println!("\nerror in revision `{}`: {}", rev, err),
-            None => println!("\nerror: {}", err),
+            Some(rev) => eprintln!("\nerror in revision `{}`: {}", rev, err),
+            None => eprintln!("\nerror: {}", err),
         }
     }
 
@@ -1972,7 +1972,7 @@ impl<'test> TestCx<'test> {
         if !self.config.has_html_tidy {
             return;
         }
-        println!("info: generating a diff against nightly rustdoc");
+        eprintln!("info: generating a diff against nightly rustdoc");
 
         let suffix =
             self.safe_revision().map_or("nightly".into(), |path| path.to_owned() + "-nightly");
@@ -2082,7 +2082,7 @@ impl<'test> TestCx<'test> {
                 .output()
                 .unwrap();
             assert!(output.status.success());
-            println!("{}", String::from_utf8_lossy(&output.stdout));
+            eprintln!("{}", String::from_utf8_lossy(&output.stdout));
             eprintln!("{}", String::from_utf8_lossy(&output.stderr));
         } else {
             use colored::Colorize;
@@ -2496,7 +2496,7 @@ impl<'test> TestCx<'test> {
                 )"#
             )
             .replace_all(&output, |caps: &Captures<'_>| {
-                println!("{}", &caps[0]);
+                eprintln!("{}", &caps[0]);
                 caps[0].replace(r"\", "/")
             })
             .replace("\r\n", "\n")
@@ -2601,14 +2601,14 @@ impl<'test> TestCx<'test> {
         if let Err(err) = fs::write(&actual_path, &actual) {
             self.fatal(&format!("failed to write {stream} to `{actual_path:?}`: {err}",));
         }
-        println!("Saved the actual {stream} to {actual_path:?}");
+        eprintln!("Saved the actual {stream} to {actual_path:?}");
 
         let expected_path =
             expected_output_path(self.testpaths, self.revision, &self.config.compare_mode, stream);
 
         if !self.config.bless {
             if expected.is_empty() {
-                println!("normalized {}:\n{}\n", stream, actual);
+                eprintln!("normalized {}:\n{}\n", stream, actual);
             } else {
                 self.show_diff(
                     stream,
@@ -2631,10 +2631,10 @@ impl<'test> TestCx<'test> {
             if let Err(err) = fs::write(&expected_path, &actual) {
                 self.fatal(&format!("failed to write {stream} to `{expected_path:?}`: {err}"));
             }
-            println!("Blessing the {stream} of {test_name} in {expected_path:?}");
+            eprintln!("Blessing the {stream} of {test_name} in {expected_path:?}");
         }
 
-        println!("\nThe actual {0} differed from the expected {0}.", stream);
+        eprintln!("\nThe actual {0} differed from the expected {0}.", stream);
 
         if self.config.bless { 0 } else { 1 }
     }
@@ -2783,7 +2783,7 @@ impl<'test> TestCx<'test> {
         fs::create_dir_all(&incremental_dir).unwrap();
 
         if self.config.verbose {
-            println!("init_incremental_test: incremental_dir={}", incremental_dir.display());
+            eprintln!("init_incremental_test: incremental_dir={}", incremental_dir.display());
         }
     }
 
@@ -2841,7 +2841,7 @@ impl ProcRes {
             }
         }
 
-        println!(
+        eprintln!(
             "status: {}\ncommand: {}\n{}\n{}\n",
             self.status,
             self.cmdline,
@@ -2852,7 +2852,7 @@ impl ProcRes {
 
     pub fn fatal(&self, err: Option<&str>, on_failure: impl FnOnce()) -> ! {
         if let Some(e) = err {
-            println!("\nerror: {}", e);
+            eprintln!("\nerror: {}", e);
         }
         self.print_info();
         on_failure();

src/tools/compiletest/src/runtest/codegen_units.rs

@@ -64,13 +64,13 @@ impl TestCx<'_> {
         if !missing.is_empty() {
             missing.sort();
 
-            println!("\nThese items should have been contained but were not:\n");
+            eprintln!("\nThese items should have been contained but were not:\n");
 
             for item in &missing {
-                println!("{}", item);
+                eprintln!("{}", item);
             }
 
-            println!("\n");
+            eprintln!("\n");
         }
 
         if !unexpected.is_empty() {
@@ -80,24 +80,24 @@ impl TestCx<'_> {
                 sorted
             };
 
-            println!("\nThese items were contained but should not have been:\n");
+            eprintln!("\nThese items were contained but should not have been:\n");
 
             for item in sorted {
-                println!("{}", item);
+                eprintln!("{}", item);
             }
 
-            println!("\n");
+            eprintln!("\n");
         }
 
         if !wrong_cgus.is_empty() {
             wrong_cgus.sort_by_key(|pair| pair.0.name.clone());
-            println!("\nThe following items were assigned to wrong codegen units:\n");
+            eprintln!("\nThe following items were assigned to wrong codegen units:\n");
 
             for &(ref expected_item, ref actual_item) in &wrong_cgus {
-                println!("{}", expected_item.name);
-                println!("  expected: {}", codegen_units_to_str(&expected_item.codegen_units));
-                println!("  actual:   {}", codegen_units_to_str(&actual_item.codegen_units));
-                println!();
+                eprintln!("{}", expected_item.name);
+                eprintln!("  expected: {}", codegen_units_to_str(&expected_item.codegen_units));
+                eprintln!("  actual:   {}", codegen_units_to_str(&actual_item.codegen_units));
+                eprintln!();
             }
         }
 

src/tools/compiletest/src/runtest/debuginfo.rs

@@ -260,7 +260,7 @@ impl TestCx<'_> {
                 cmdline,
             };
             if adb.kill().is_err() {
-                println!("Adb process is already finished.");
+                eprintln!("Adb process is already finished.");
             }
         } else {
             let rust_src_root =
@@ -275,7 +275,7 @@ impl TestCx<'_> {
 
             match self.config.gdb_version {
                 Some(version) => {
-                    println!("NOTE: compiletest thinks it is using GDB version {}", version);
+                    eprintln!("NOTE: compiletest thinks it is using GDB version {}", version);
 
                     if version > extract_gdb_version("7.4").unwrap() {
                         // Add the directory containing the pretty printers to
@@ -297,7 +297,7 @@ impl TestCx<'_> {
                     }
                 }
                 _ => {
-                    println!(
+                    eprintln!(
                         "NOTE: compiletest does not know which version of \
                          GDB it is using"
                     );
@@ -392,10 +392,10 @@ impl TestCx<'_> {
 
         match self.config.lldb_version {
             Some(ref version) => {
-                println!("NOTE: compiletest thinks it is using LLDB version {}", version);
+                eprintln!("NOTE: compiletest thinks it is using LLDB version {}", version);
             }
             _ => {
-                println!(
+                eprintln!(
                     "NOTE: compiletest does not know which version of \
                      LLDB it is using"
                 );

src/tools/compiletest/src/runtest/incremental.rs

@@ -30,7 +30,7 @@ impl TestCx<'_> {
         assert!(incremental_dir.exists(), "init_incremental_test failed to create incremental dir");
 
         if self.config.verbose {
-            print!("revision={:?} props={:#?}", revision, self.props);
+            eprint!("revision={:?} props={:#?}", revision, self.props);
         }
 
         if revision.starts_with("cpass") {

src/tools/compiletest/src/runtest/mir_opt.rs

@@ -89,7 +89,7 @@ impl TestCx<'_> {
                 }
                 let expected_string = fs::read_to_string(&expected_file).unwrap();
                 if dumped_string != expected_string {
-                    print!("{}", write_diff(&expected_string, &dumped_string, 3));
+                    eprint!("{}", write_diff(&expected_string, &dumped_string, 3));
                     panic!(
                         "Actual MIR output differs from expected MIR output {}",
                         expected_file.display()

src/tools/compiletest/src/runtest/rustdoc_json.rs

@@ -29,7 +29,7 @@ impl TestCx<'_> {
 
         if !res.status.success() {
             self.fatal_proc_rec_with_ctx("jsondocck failed!", &res, |_| {
-                println!("Rustdoc Output:");
+                eprintln!("Rustdoc Output:");
                 proc_res.print_info();
             })
         }

src/tools/compiletest/src/runtest/ui.rs

@@ -109,10 +109,10 @@ impl TestCx<'_> {
         }
 
         if errors > 0 {
-            println!("To update references, rerun the tests and pass the `--bless` flag");
+            eprintln!("To update references, rerun the tests and pass the `--bless` flag");
             let relative_path_to_file =
                 self.testpaths.relative_dir.join(self.testpaths.file.file_name().unwrap());
-            println!(
+            eprintln!(
                 "To only update this specific test, also pass `--test-args {}`",
                 relative_path_to_file.display(),
             );

src/tools/compiletest/src/util.rs

@@ -30,7 +30,7 @@ fn path_div() -> &'static str {
 pub fn logv(config: &Config, s: String) {
     debug!("{}", s);
     if config.verbose {
-        println!("{}", s);
+        eprintln!("{}", s);
     }
 }
 

src/tools/jsondocck/src/cache.rs

@@ -28,7 +28,8 @@ impl Cache {
         }
     }
 
-    pub fn value(&self) -> &Value {
-        &self.value
+    // FIXME: Make this failible, so jsonpath syntax error has line number.
+    pub fn select(&self, path: &str) -> Vec<&Value> {
+        jsonpath_lib::select(&self.value, path).unwrap()
     }
 }

src/tools/jsondocck/src/error.rs

@@ -1,29 +1,7 @@
-use std::error::Error;
-use std::fmt;
-
 use crate::Command;
 
 #[derive(Debug)]
-pub enum CkError {
-    /// A check failed. File didn't exist or failed to match the command
-    FailedCheck(String, Command),
-    /// An error triggered by some other error
-    Induced(Box<dyn Error>),
-}
-
-impl fmt::Display for CkError {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        match self {
-            CkError::FailedCheck(msg, cmd) => {
-                write!(f, "Failed check: {} on line {}", msg, cmd.lineno)
-            }
-            CkError::Induced(err) => write!(f, "Check failed: {}", err),
-        }
-    }
-}
-
-impl<T: Error + 'static> From<T> for CkError {
-    fn from(err: T) -> CkError {
-        CkError::Induced(Box::new(err))
-    }
+pub struct CkError {
+    pub message: String,
+    pub command: Command,
 }

src/tools/jsondocck/src/main.rs

@@ -1,8 +1,8 @@
 use std::borrow::Cow;
+use std::process::ExitCode;
 use std::sync::OnceLock;
-use std::{env, fmt, fs};
+use std::{env, fs};
 
-use jsonpath_lib::select;
 use regex::{Regex, RegexBuilder};
 use serde_json::Value;
 
@@ -14,90 +14,134 @@ use cache::Cache;
 use config::parse_config;
 use error::CkError;
 
-fn main() -> Result<(), String> {
+fn main() -> ExitCode {
     let config = parse_config(env::args().collect());
 
     let mut failed = Vec::new();
     let mut cache = Cache::new(&config);
-    let commands = get_commands(&config.template)
-        .map_err(|_| format!("Jsondocck failed for {}", &config.template))?;
+    let Ok(commands) = get_commands(&config.template) else {
+        eprintln!("Jsondocck failed for {}", &config.template);
+        return ExitCode::FAILURE;
+    };
 
     for command in commands {
-        if let Err(e) = check_command(command, &mut cache) {
-            failed.push(e);
+        if let Err(message) = check_command(&command, &mut cache) {
+            failed.push(CkError { command, message });
         }
     }
 
     if failed.is_empty() {
-        Ok(())
+        ExitCode::SUCCESS
     } else {
         for i in failed {
-            eprintln!("{}", i);
+            eprintln!("{}:{}, command failed", config.template, i.command.lineno);
+            eprintln!("{}", i.message)
         }
-        Err(format!("Jsondocck failed for {}", &config.template))
+        ExitCode::FAILURE
     }
 }
 
 #[derive(Debug)]
 pub struct Command {
-    negated: bool,
     kind: CommandKind,
-    args: Vec<String>,
+    path: String,
     lineno: usize,
 }
 
 #[derive(Debug)]
-pub enum CommandKind {
-    Has,
-    Count,
-    Is,
-    IsMany,
-    Set,
+enum CommandKind {
+    /// `//@ has <path>`
+    ///
+    /// Checks the path exists.
+    HasPath,
+
+    /// `//@ has <path> <value>`
+    ///
+    /// Check one thing at the path  is equal to the value.
+    HasValue { value: String },
+
+    /// `//@ !has <path>`
+    ///
+    /// Checks the path doesn't exist.
+    HasNotPath,
+
+    /// `//@ is <path> <value>`
+    ///
+    /// Check the path is the given value.
+    Is { value: String },
+
+    /// `//@ is <path> <value> <value>...`
+    ///
+    /// Check that the path matches to exactly every given value.
+    IsMany { values: Vec<String> },
+
+    /// `//@ !is <path> <value>`
+    ///
+    /// Check the path isn't the given value.
+    IsNot { value: String },
+
+    /// `//@ count <path> <value>`
+    ///
+    /// Check the path has the expected number of matches.
+    CountIs { expected: usize },
+
+    /// `//@ set <name> = <path>`
+    Set { variable: String },
 }
 
 impl CommandKind {
-    fn validate(&self, args: &[String], lineno: usize) -> bool {
-        // FIXME(adotinthevoid): We should "parse, don't validate" here, so we avoid ad-hoc
-        // indexing in check_command.
-        let count = match self {
-            CommandKind::Has => (1..=2).contains(&args.len()),
-            CommandKind::IsMany => args.len() >= 2,
-            CommandKind::Count | CommandKind::Is => 2 == args.len(),
-            CommandKind::Set => 3 == args.len(),
-        };
-
-        if !count {
-            print_err(&format!("Incorrect number of arguments to `{}`", self), lineno);
-            return false;
-        }
-
-        if let CommandKind::Count = self {
-            if args[1].parse::<usize>().is_err() {
-                print_err(
-                    &format!(
-                        "Second argument to `count` must be a valid usize (got `{}`)",
-                        args[1]
-                    ),
-                    lineno,
-                );
-                return false;
+    /// Returns both the kind and the path.
+    ///
+    /// Returns `None` if the command isn't from jsondocck (e.g. from compiletest).
+    fn parse<'a>(command_name: &str, negated: bool, args: &'a [String]) -> Option<(Self, &'a str)> {
+        let kind = match (command_name, negated) {
+            ("count", false) => {
+                assert_eq!(args.len(), 2);
+                let expected = args[1].parse().expect("invalid number for `count`");
+                Self::CountIs { expected }
             }
-        }
 
-        true
-    }
-}
+            ("ismany", false) => {
+                // FIXME: Make this >= 3, and migrate len(values)==1 cases to @is
+                assert!(args.len() >= 2, "Not enough args to `ismany`");
+                let values = args[1..].to_owned();
+                Self::IsMany { values }
+            }
 
-impl fmt::Display for CommandKind {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        let text = match self {
-            CommandKind::Has => "has",
-            CommandKind::IsMany => "ismany",
-            CommandKind::Count => "count",
-            CommandKind::Is => "is",
-            CommandKind::Set => "set",
+            ("is", false) => {
+                assert_eq!(args.len(), 2);
+                Self::Is { value: args[1].clone() }
+            }
+            ("is", true) => {
+                assert_eq!(args.len(), 2);
+                Self::IsNot { value: args[1].clone() }
+            }
+
+            ("set", false) => {
+                assert_eq!(args.len(), 3);
+                assert_eq!(args[1], "=");
+                return Some((Self::Set { variable: args[0].clone() }, &args[2]));
+            }
+
+            ("has", false) => match args {
+                [_path] => Self::HasPath,
+                [_path, value] => Self::HasValue { value: value.clone() },
+                _ => panic!("`//@ has` must have 2 or 3 arguments, but got {args:?}"),
+            },
+            ("has", true) => {
+                assert_eq!(args.len(), 1, "args={args:?}");
+                Self::HasNotPath
+            }
+
+            (_, false) if KNOWN_DIRECTIVE_NAMES.contains(&command_name) => {
+                return None;
+            }
+            _ => {
+                panic!("Invalid command `//@ {}{command_name}`", if negated { "!" } else { "" })
+            }
         };
-        write!(f, "{}", text)
+
+        Some((kind, &args[0]))
     }
 }
 
@@ -125,8 +169,7 @@ fn print_err(msg: &str, lineno: usize) {
 //        See <https://github.com/rust-lang/rust/issues/125813#issuecomment-2141953780>.
 include!(concat!(env!("CARGO_MANIFEST_DIR"), "/../compiletest/src/directive-list.rs"));
 
-/// Get a list of commands from a file. Does the work of ensuring the commands
-/// are syntactically valid.
+/// Get a list of commands from a file.
 fn get_commands(template: &str) -> Result<Vec<Command>, ()> {
     let mut commands = Vec::new();
     let mut errors = false;
@@ -142,217 +185,102 @@ fn get_commands(template: &str) -> Result<Vec<Command>, ()> {
 
         let negated = cap.name("negated").unwrap().as_str() == "!";
 
-        let cmd = match cap.name("cmd").unwrap().as_str() {
-            "has" => CommandKind::Has,
-            "count" => CommandKind::Count,
-            "is" => CommandKind::Is,
-            "ismany" => CommandKind::IsMany,
-            "set" => CommandKind::Set,
-            // FIXME: See the comment above the `include!(...)`.
-            cmd if KNOWN_DIRECTIVE_NAMES.contains(&cmd) => continue,
-            cmd => {
-                print_err(&format!("Unrecognized command name `{cmd}`"), lineno);
-                errors = true;
-                continue;
-            }
-        };
-
-        let args = cap.name("args").map_or(Some(vec![]), |m| shlex::split(m.as_str()));
-
-        let args = match args {
+        let args_str = &cap["args"];
+        let args = match shlex::split(args_str) {
             Some(args) => args,
             None => {
-                print_err(
-                    &format!(
-                        "Invalid arguments to shlex::split: `{}`",
-                        cap.name("args").unwrap().as_str()
-                    ),
-                    lineno,
-                );
+                print_err(&format!("Invalid arguments to shlex::split: `{args_str}`",), lineno);
                 errors = true;
                 continue;
             }
         };
 
-        if !cmd.validate(&args, lineno) {
-            errors = true;
-            continue;
+        if let Some((kind, path)) = CommandKind::parse(&cap["cmd"], negated, &args) {
+            commands.push(Command { kind, lineno, path: path.to_owned() })
         }
-
-        commands.push(Command { negated, kind: cmd, args, lineno })
     }
 
     if !errors { Ok(commands) } else { Err(()) }
 }
 
-/// Performs the actual work of ensuring a command passes. Generally assumes the command
-/// is syntactically valid.
-fn check_command(command: Command, cache: &mut Cache) -> Result<(), CkError> {
-    // FIXME: Be more granular about why, (e.g. syntax error, count not equal)
-    let result = match command.kind {
-        CommandKind::Has => {
-            match command.args.len() {
-                // `has <jsonpath>`: Check that `jsonpath` exists.
-                1 => {
-                    let val = cache.value();
-                    let results = select(val, &command.args[0]).unwrap();
-                    !results.is_empty()
-                }
-                // `has <jsonpath> <value>`: Check *any* item matched by `jsonpath` equals `value`.
-                2 => {
-                    let val = cache.value().clone();
-                    let results = select(&val, &command.args[0]).unwrap();
-                    let pat = string_to_value(&command.args[1], cache);
-                    let has = results.contains(&pat.as_ref());
-                    // Give better error for when `has` check fails.
-                    if !command.negated && !has {
-                        return Err(CkError::FailedCheck(
-                            format!(
-                                "{} matched to {:?} but didn't have {:?}",
-                                &command.args[0],
-                                results,
-                                pat.as_ref()
-                            ),
-                            command,
-                        ));
-                    } else {
-                        has
-                    }
-                }
-                _ => unreachable!(),
+/// Performs the actual work of ensuring a command passes.
+fn check_command(command: &Command, cache: &mut Cache) -> Result<(), String> {
+    let matches = cache.select(&command.path);
+    match &command.kind {
+        CommandKind::HasPath => {
+            if matches.is_empty() {
+                return Err("matched to no values".to_owned());
+            }
+        }
+        CommandKind::HasNotPath => {
+            if !matches.is_empty() {
+                return Err(format!("matched to {matches:?}, but wanted no matches"));
+            }
+        }
+        CommandKind::HasValue { value } => {
+            let want_value = string_to_value(value, cache);
+            if !matches.contains(&want_value.as_ref()) {
+                return Err(format!("matched to {matches:?}, which didn't contain {want_value:?}"));
+            }
+        }
+        CommandKind::Is { value } => {
+            let want_value = string_to_value(value, cache);
+            let matched = get_one(&matches)?;
+            if matched != want_value.as_ref() {
+                return Err(format!("matched to {matched:?} but want {want_value:?}"));
+            }
+        }
+        CommandKind::IsNot { value } => {
+            let wantnt_value = string_to_value(value, cache);
+            let matched = get_one(&matches)?;
+            if matched == wantnt_value.as_ref() {
+                return Err(format!("got value {wantnt_value:?}, but want anything else"));
             }
         }
-        // `ismany <path> <jsonpath> <value...>`
-        CommandKind::IsMany => {
-            assert!(!command.negated, "`ismany` may not be negated");
-            let (query, values) = if let [query, values @ ..] = &command.args[..] {
-                (query, values)
-            } else {
-                unreachable!("Checked in CommandKind::validate")
-            };
-            let val = cache.value();
-            let got_values = select(val, &query).unwrap();
 
+        CommandKind::IsMany { values } => {
             // Serde json doesn't implement Ord or Hash for Value, so we must
             // use a Vec here. While in theory that makes setwize equality
             // O(n^2), in practice n will never be large enough to matter.
             let expected_values =
                 values.iter().map(|v| string_to_value(v, cache)).collect::<Vec<_>>();
-            if expected_values.len() != got_values.len() {
-                return Err(CkError::FailedCheck(
-                    format!(
-                        "Expected {} values, but `{}` matched to {} values ({:?})",
-                        expected_values.len(),
-                        query,
-                        got_values.len(),
-                        got_values
-                    ),
-                    command,
+            if expected_values.len() != matches.len() {
+                return Err(format!(
+                    "Expected {} values, but matched to {} values ({:?})",
+                    expected_values.len(),
+                    matches.len(),
+                    matches
                 ));
             };
-            for got_value in got_values {
+            for got_value in matches {
                 if !expected_values.iter().any(|exp| &**exp == got_value) {
-                    return Err(CkError::FailedCheck(
-                        format!("`{}` has match {:?}, which was not expected", query, got_value),
-                        command,
-                    ));
+                    return Err(format!("has match {got_value:?}, which was not expected",));
                 }
             }
-            true
         }
-        // `count <jsonpath> <count>`: Check that `jsonpath` matches exactly `count` times.
-        CommandKind::Count => {
-            assert_eq!(command.args.len(), 2);
-            let expected: usize = command.args[1].parse().unwrap();
-            let val = cache.value();
-            let results = select(val, &command.args[0]).unwrap();
-            let eq = results.len() == expected;
-            if !command.negated && !eq {
-                return Err(CkError::FailedCheck(
-                    format!(
-                        "`{}` matched to `{:?}` with length {}, but expected length {}",
-                        &command.args[0],
-                        results,
-                        results.len(),
-                        expected
-                    ),
-                    command,
+        CommandKind::CountIs { expected } => {
+            if *expected != matches.len() {
+                return Err(format!(
+                    "matched to `{matches:?}` with length {}, but expected length {expected}",
+                    matches.len(),
                 ));
-            } else {
-                eq
             }
         }
-        // `has <jsonpath> <value>`: Check` *exactly one* item matched by `jsonpath`, and it equals `value`.
-        CommandKind::Is => {
-            assert_eq!(command.args.len(), 2);
-            let val = cache.value().clone();
-            let results = select(&val, &command.args[0]).unwrap();
-            let pat = string_to_value(&command.args[1], cache);
-            let is = results.len() == 1 && results[0] == pat.as_ref();
-            if !command.negated && !is {
-                return Err(CkError::FailedCheck(
-                    format!(
-                        "{} matched to {:?}, but expected {:?}",
-                        &command.args[0],
-                        results,
-                        pat.as_ref()
-                    ),
-                    command,
-                ));
-            } else {
-                is
-            }
+        CommandKind::Set { variable } => {
+            let value = get_one(&matches)?;
+            let r = cache.variables.insert(variable.to_owned(), value.clone());
+            assert!(r.is_none(), "name collision: {variable:?} is duplicated");
         }
-        // `set <name> = <jsonpath>`
-        CommandKind::Set => {
-            assert!(!command.negated, "`set` may not be negated");
-            assert_eq!(command.args.len(), 3);
-            assert_eq!(command.args[1], "=", "Expected an `=`");
-            let val = cache.value().clone();
-            let results = select(&val, &command.args[2]).unwrap();
-            assert_eq!(
-                results.len(),
-                1,
-                "Expected 1 match for `{}` (because of `set`): matched to {:?}",
-                command.args[2],
-                results
-            );
-            match results.len() {
-                0 => false,
-                1 => {
-                    let r = cache.variables.insert(command.args[0].clone(), results[0].clone());
-                    assert!(r.is_none(), "Name collision: {} is duplicated", command.args[0]);
-                    true
-                }
-                _ => {
-                    panic!(
-                        "Got multiple results in `set` for `{}`: {:?}",
-                        &command.args[2], results,
-                    );
-                }
-            }
-        }
-    };
+    }
 
-    if result == command.negated {
-        if command.negated {
-            Err(CkError::FailedCheck(
-                format!("`!{} {}` matched when it shouldn't", command.kind, command.args.join(" ")),
-                command,
-            ))
-        } else {
-            // FIXME: In the future, try 'peeling back' each step, and see at what level the match failed
-            Err(CkError::FailedCheck(
-                format!(
-                    "`{} {}` didn't match when it should",
-                    command.kind,
-                    command.args.join(" ")
-                ),
-                command,
-            ))
-        }
-    } else {
-        Ok(())
+    Ok(())
+}
+
+fn get_one<'a>(matches: &[&'a Value]) -> Result<&'a Value, String> {
+    match matches {
+        [] => Err("matched to no values".to_owned()),
+        [matched] => Ok(matched),
+        _ => Err(format!("matched to multiple values {matches:?}, but want exactly 1")),
     }
 }
 

src/tools/miri/src/shims/backtrace.rs

@@ -1,5 +1,4 @@
 use rustc_abi::{ExternAbi, Size};
-use rustc_ast::ast::Mutability;
 use rustc_middle::ty::layout::LayoutOf as _;
 use rustc_middle::ty::{self, Instance, Ty};
 use rustc_span::{BytePos, Loc, Symbol, hygiene};
@@ -179,14 +178,7 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
 
         match flags {
             0 => {
-                // These are "mutable" allocations as we consider them to be owned by the callee.
-                let name_alloc =
-                    this.allocate_str(&name, MiriMemoryKind::Rust.into(), Mutability::Mut)?;
-                let filename_alloc =
-                    this.allocate_str(&filename, MiriMemoryKind::Rust.into(), Mutability::Mut)?;
-
-                this.write_immediate(name_alloc.to_ref(this), &this.project_field(dest, 0)?)?;
-                this.write_immediate(filename_alloc.to_ref(this), &this.project_field(dest, 1)?)?;
+                throw_unsup_format!("miri_resolve_frame: v0 is not supported any more");
             }
             1 => {
                 this.write_scalar(

src/tools/miri/src/shims/panic.rs

@@ -12,7 +12,6 @@
 //!   metadata we remembered when pushing said frame.
 
 use rustc_abi::ExternAbi;
-use rustc_ast::Mutability;
 use rustc_middle::{mir, ty};
 use rustc_target::spec::PanicStrategy;
 
@@ -161,7 +160,7 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
         let this = self.eval_context_mut();
 
         // First arg: message.
-        let msg = this.allocate_str(msg, MiriMemoryKind::Machine.into(), Mutability::Not)?;
+        let msg = this.allocate_str_dedup(msg)?;
 
         // Call the lang item.
         let panic = this.tcx.lang_items().panic_fn().unwrap();
@@ -180,7 +179,7 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
         let this = self.eval_context_mut();
 
         // First arg: message.
-        let msg = this.allocate_str(msg, MiriMemoryKind::Machine.into(), Mutability::Not)?;
+        let msg = this.allocate_str_dedup(msg)?;
 
         // Call the lang item.
         let panic = this.tcx.lang_items().panic_nounwind().unwrap();

src/tools/miri/tests/pass/backtrace/backtrace-api-v0.rs

@@ -1,69 +0,0 @@
-//@normalize-stderr-test: "::<.*>" -> ""
-
-#[inline(never)]
-fn func_a() -> Box<[*mut ()]> {
-    func_b::<u8>()
-}
-#[inline(never)]
-fn func_b<T>() -> Box<[*mut ()]> {
-    func_c()
-}
-
-macro_rules! invoke_func_d {
-    () => {
-        func_d()
-    };
-}
-
-#[inline(never)]
-fn func_c() -> Box<[*mut ()]> {
-    invoke_func_d!()
-}
-#[inline(never)]
-fn func_d() -> Box<[*mut ()]> {
-    unsafe { miri_get_backtrace(0) }
-}
-
-fn main() {
-    let mut seen_main = false;
-    let frames = func_a();
-    for frame in frames.iter() {
-        let miri_frame = unsafe { miri_resolve_frame(*frame, 0) };
-        let name = String::from_utf8(miri_frame.name.into()).unwrap();
-        let filename = String::from_utf8(miri_frame.filename.into()).unwrap();
-
-        if name == "func_a" {
-            assert_eq!(func_a as *mut (), miri_frame.fn_ptr);
-        }
-
-        // Print every frame to stderr.
-        let out = format!("{}:{}:{} ({})", filename, miri_frame.lineno, miri_frame.colno, name);
-        eprintln!("{}", out);
-        // Print the 'main' frame (and everything before it) to stdout, skipping
-        // the printing of internal (and possibly fragile) libstd frames.
-        // Stdout is less normalized so we see more, but it also means we can print less
-        // as platform differences would lead to test suite failures.
-        if !seen_main {
-            println!("{}", out);
-            seen_main = name == "main";
-        }
-    }
-}
-
-// This goes at the bottom of the file so that we can change it
-// without disturbing line numbers of the functions in the backtrace.
-
-extern "Rust" {
-    fn miri_get_backtrace(flags: u64) -> Box<[*mut ()]>;
-    fn miri_resolve_frame(ptr: *mut (), flags: u64) -> MiriFrame;
-}
-
-#[derive(Debug)]
-#[repr(C)]
-struct MiriFrame {
-    name: Box<[u8]>,
-    filename: Box<[u8]>,
-    lineno: u32,
-    colno: u32,
-    fn_ptr: *mut (),
-}

src/tools/miri/tests/pass/backtrace/backtrace-api-v0.stderr

@@ -1,18 +0,0 @@
-tests/pass/backtrace/backtrace-api-v0.rs:LL:CC (func_d)
-tests/pass/backtrace/backtrace-api-v0.rs:LL:CC (func_c)
-tests/pass/backtrace/backtrace-api-v0.rs:LL:CC (func_b)
-tests/pass/backtrace/backtrace-api-v0.rs:LL:CC (func_a)
-tests/pass/backtrace/backtrace-api-v0.rs:LL:CC (main)
-RUSTLIB/core/src/ops/function.rs:LL:CC (<fn() as std::ops::FnOnce<()>>::call_once - shim(fn()))
-RUSTLIB/std/src/sys/backtrace.rs:LL:CC (std::sys::backtrace::__rust_begin_short_backtrace)
-RUSTLIB/std/src/rt.rs:LL:CC (std::rt::lang_start::{closure#0})
-RUSTLIB/core/src/ops/function.rs:LL:CC (std::ops::function::impls::call_once)
-RUSTLIB/std/src/panicking.rs:LL:CC (std::panicking::r#try::do_call)
-RUSTLIB/std/src/panicking.rs:LL:CC (std::panicking::r#try)
-RUSTLIB/std/src/panic.rs:LL:CC (std::panic::catch_unwind)
-RUSTLIB/std/src/rt.rs:LL:CC (std::rt::lang_start_internal::{closure#1})
-RUSTLIB/std/src/panicking.rs:LL:CC (std::panicking::r#try::do_call)
-RUSTLIB/std/src/panicking.rs:LL:CC (std::panicking::r#try)
-RUSTLIB/std/src/panic.rs:LL:CC (std::panic::catch_unwind)
-RUSTLIB/std/src/rt.rs:LL:CC (std::rt::lang_start_internal)
-RUSTLIB/std/src/rt.rs:LL:CC (std::rt::lang_start)

src/tools/miri/tests/pass/backtrace/backtrace-api-v0.stdout

@@ -1,5 +0,0 @@
-tests/pass/backtrace/backtrace-api-v0.rs:24:14 (func_d)
-tests/pass/backtrace/backtrace-api-v0.rs:14:9 (func_c)
-tests/pass/backtrace/backtrace-api-v0.rs:9:5 (func_b::<u8>)
-tests/pass/backtrace/backtrace-api-v0.rs:5:5 (func_a)
-tests/pass/backtrace/backtrace-api-v0.rs:29:18 (main)

src/tools/nix-dev-shell/envrc-flake

@@ -1,7 +1,7 @@
 # If you want to use this as an .envrc file to create a shell with necessery components 
 # to develop rustc, use the following command in the root of the rusr checkout:
 #	
-# ln -s ./src/tools/nix-dev-shell/envrc-flake ./.envrc && nix flake update --flake ./src/tools/nix-dev-shell && echo .envrc >> .git/info/exclude
+# ln -s ./src/tools/nix-dev-shell/envrc-flake ./.envrc && nix flake update --flake ./src/tools/nix-dev-shell
 
 if nix flake show path:./src/tools/nix-dev-shell &> /dev/null; then
   use flake path:./src/tools/nix-dev-shell

src/tools/nix-dev-shell/envrc-shell

@@ -1,7 +1,7 @@
 # If you want to use this as an .envrc file to create a shell with necessery components 
 # to develop rustc, use the following command in the root of the rusr checkout:
 #	
-# ln -s ./src/tools/nix-dev-shell/envrc-shell ./.envrc && echo .envrc >> .git/info/exclude
+# ln -s ./src/tools/nix-dev-shell/envrc-shell ./.envrc
 
 use nix ./src/tools/nix-dev-shell/shell.nix
   

src/tools/nix-dev-shell/flake.nix

@@ -24,9 +24,8 @@
           # Avoid creating text files for ICEs.
           RUSTC_ICE = "0";
           # Provide `libstdc++.so.6` for the self-contained lld.
-          LD_LIBRARY_PATH = "${with pkgs; lib.makeLibraryPath [
-            stdenv.cc.cc.lib
-          ]}";
+          # Provide `libz.so.1`.
+          LD_LIBRARY_PATH = "${with pkgs; lib.makeLibraryPath [stdenv.cc.cc.lib zlib]}";
         };
       }
     );

src/tools/nix-dev-shell/shell.nix

@@ -13,7 +13,6 @@ pkgs.mkShell {
   # Avoid creating text files for ICEs.
   RUSTC_ICE = "0";
   # Provide `libstdc++.so.6` for the self-contained lld.
-  LD_LIBRARY_PATH = "${with pkgs; lib.makeLibraryPath [
-    stdenv.cc.cc.lib
-  ]}";
+  # Provide `libz.so.1`
+  LD_LIBRARY_PATH = "${with pkgs; lib.makeLibraryPath [stdenv.cc.cc.lib zlib]}";
 }

src/tools/run-make-support/Cargo.toml

@@ -7,7 +7,7 @@ edition = "2021"
 bstr = "1.6.0"
 object = "0.36.2"
 similar = "2.5.0"
-wasmparser = { version = "0.216", default-features = false, features = ["std"] }
+wasmparser = { version = "0.219", default-features = false, features = ["std"] }
 regex = "1.8" # 1.8 to avoid memchr 2.6.0, as 2.5.0 is pinned in the workspace
 gimli = "0.31.0"
 build_helper = { path = "../../build_helper" }

src/tools/run-make-support/src/command.rs

@@ -329,7 +329,7 @@ impl CompletedProcess {
     /// Checks that `stderr` does not contain the regex pattern `unexpected`.
     #[track_caller]
     pub fn assert_stderr_not_contains_regex<S: AsRef<str>>(&self, unexpected: S) -> &Self {
-        assert_not_contains_regex(&self.stdout_utf8(), unexpected);
+        assert_not_contains_regex(&self.stderr_utf8(), unexpected);
         self
     }
 

src/tools/run-make-support/src/external_deps/rustc.rs

@@ -325,6 +325,12 @@ impl Rustc {
         self
     }
 
+    /// Pass the `--verbose` flag.
+    pub fn verbose(&mut self) -> &mut Self {
+        self.cmd.arg("--verbose");
+        self
+    }
+
     /// `EXTRARSCXXFLAGS`
     pub fn extra_rs_cxx_flags(&mut self) -> &mut Self {
         // Adapted from tools.mk (trimmed):

src/tools/rust-analyzer/Cargo.lock

@@ -84,6 +84,12 @@ dependencies = [
  "vfs",
 ]
 
+[[package]]
+name = "base64"
+version = "0.22.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "72b3254f16251a8381aa12e40e3c4d2f0199f8c6508fbecb9d91f575e0fbb8c6"
+
 [[package]]
 name = "bitflags"
 version = "1.3.2"
@@ -509,6 +515,7 @@ dependencies = [
  "base-db",
  "cfg",
  "either",
+ "expect-test",
  "hir-def",
  "hir-expand",
  "hir-ty",
@@ -519,6 +526,9 @@ dependencies = [
  "span",
  "stdx",
  "syntax",
+ "syntax-bridge",
+ "test-fixture",
+ "test-utils",
  "tracing",
  "triomphe",
  "tt",
@@ -1492,9 +1502,9 @@ dependencies = [
 
 [[package]]
 name = "ra-ap-rustc_abi"
-version = "0.80.0"
+version = "0.85.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "613760a3071b25a67a8d7bc97b37c7fd4722562e9479137b83ae9cf8f8c1601a"
+checksum = "af462c3a2d524b84a51b6848b439787f01b35c6c1086d3e3086a5f5eea92ed9a"
 dependencies = [
  "bitflags 2.6.0",
  "ra-ap-rustc_index",
@@ -1503,20 +1513,19 @@ dependencies = [
 
 [[package]]
 name = "ra-ap-rustc_index"
-version = "0.80.0"
+version = "0.85.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5b2bc6b4ecede8ff28295041e22c2e66853f8e0125990c05135bad3c30bad12c"
+checksum = "be6bb8cb0ab78d94a222f1ffd3e87254cdfb57413382b8d6ebe26a85482f99d1"
 dependencies = [
- "arrayvec",
  "ra-ap-rustc_index_macros",
  "smallvec",
 ]
 
 [[package]]
 name = "ra-ap-rustc_index_macros"
-version = "0.80.0"
+version = "0.85.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "2374a39fb2d92d0509178c2b442eadca3cc10e403ef9729a040c1855b08ff261"
+checksum = "c24b1641455b46e87435b7321219672077066e678963d239a4a2904732979b16"
 dependencies = [
  "proc-macro2",
  "quote",
@@ -1525,9 +1534,9 @@ dependencies = [
 
 [[package]]
 name = "ra-ap-rustc_lexer"
-version = "0.80.0"
+version = "0.85.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5a2cf8e48b69af3ecc29ed3449892e8a999111d2f75212a78aa242e117cf1711"
+checksum = "94daa86974417981fed2f12bd8fb00158dfa6fee561152bed689278c846d0272"
 dependencies = [
  "unicode-properties",
  "unicode-xid",
@@ -1535,9 +1544,9 @@ dependencies = [
 
 [[package]]
 name = "ra-ap-rustc_parse_format"
-version = "0.80.0"
+version = "0.85.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "8d6f59a22b559263c5c42747ae362cf5d4fb272293fa119a4623f8ec288f9656"
+checksum = "fc07f6bd581746f358e39c4b6bfe8d455b3d6ad1a857821016d0d42eeb5e1e3e"
 dependencies = [
  "ra-ap-rustc_index",
  "ra-ap-rustc_lexer",
@@ -1545,9 +1554,9 @@ dependencies = [
 
 [[package]]
 name = "ra-ap-rustc_pattern_analysis"
-version = "0.80.0"
+version = "0.85.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a7d0575b54ffe09bc5d2f158454bc05f0c30c01d9992310965f854be50ae22b8"
+checksum = "2f49b86e1276c1c3c72898410def29b699415f4e7d1dfb3531daf79794694372"
 dependencies = [
  "ra-ap-rustc_index",
  "rustc-hash 2.0.0",
@@ -1645,6 +1654,7 @@ version = "0.0.0"
 dependencies = [
  "always-assert",
  "anyhow",
+ "base64",
  "cargo_metadata",
  "cfg",
  "crossbeam-channel",
@@ -1655,6 +1665,7 @@ dependencies = [
  "hir-def",
  "hir-ty",
  "ide",
+ "ide-completion",
  "ide-db",
  "ide-ssr",
  "intern",
@@ -1683,6 +1694,7 @@ dependencies = [
  "stdx",
  "syntax",
  "syntax-bridge",
+ "tenthash",
  "test-fixture",
  "test-utils",
  "tikv-jemallocator",
@@ -1986,6 +1998,12 @@ dependencies = [
  "tt",
 ]
 
+[[package]]
+name = "tenthash"
+version = "0.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d67f9f3cf70e0852941d7bc3cb884b49b24b8ee956baf91ad0abae31f5ef11fb"
+
 [[package]]
 name = "test-fixture"
 version = "0.0.0"

src/tools/rust-analyzer/Cargo.toml

@@ -84,11 +84,11 @@ tt = { path = "./crates/tt", version = "0.0.0" }
 vfs-notify = { path = "./crates/vfs-notify", version = "0.0.0" }
 vfs = { path = "./crates/vfs", version = "0.0.0" }
 
-ra-ap-rustc_lexer = { version = "0.80", default-features = false }
-ra-ap-rustc_parse_format = { version = "0.80", default-features = false }
-ra-ap-rustc_index = { version = "0.80", default-features = false }
-ra-ap-rustc_abi = { version = "0.80", default-features = false }
-ra-ap-rustc_pattern_analysis = { version = "0.80", default-features = false }
+ra-ap-rustc_lexer = { version = "0.85", default-features = false }
+ra-ap-rustc_parse_format = { version = "0.85", default-features = false }
+ra-ap-rustc_index = { version = "0.85", default-features = false }
+ra-ap-rustc_abi = { version = "0.85", default-features = false }
+ra-ap-rustc_pattern_analysis = { version = "0.85", default-features = false }
 
 # local crates that aren't published to crates.io. These should not have versions.
 test-fixture = { path = "./crates/test-fixture" }

src/tools/rust-analyzer/crates/base-db/src/input.rs

@@ -547,29 +547,6 @@ impl CrateGraph {
         None
     }
 
-    // Work around for https://github.com/rust-lang/rust-analyzer/issues/6038.
-    // As hacky as it gets.
-    pub fn patch_cfg_if(&mut self) -> bool {
-        // we stupidly max by version in an attempt to have all duplicated std's depend on the same cfg_if so that deduplication still works
-        let cfg_if =
-            self.hacky_find_crate("cfg_if").max_by_key(|&it| self.arena[it].version.clone());
-        let std = self.hacky_find_crate("std").next();
-        match (cfg_if, std) {
-            (Some(cfg_if), Some(std)) => {
-                self.arena[cfg_if].dependencies.clear();
-                self.arena[std]
-                    .dependencies
-                    .push(Dependency::new(CrateName::new("cfg_if").unwrap(), cfg_if));
-                true
-            }
-            _ => false,
-        }
-    }
-
-    fn hacky_find_crate<'a>(&'a self, display_name: &'a str) -> impl Iterator<Item = CrateId> + 'a {
-        self.iter().filter(move |it| self[*it].display_name.as_deref() == Some(display_name))
-    }
-
     /// Removes all crates from this crate graph except for the ones in `to_keep` and fixes up the dependencies.
     /// Returns a mapping from old crate ids to new crate ids.
     pub fn remove_crates_except(&mut self, to_keep: &[CrateId]) -> Vec<Option<CrateId>> {

src/tools/rust-analyzer/crates/hir-def/src/body.rs

@@ -31,7 +31,7 @@ use crate::{
     path::{ModPath, Path},
     src::HasSource,
     type_ref::{TypeRef, TypeRefId, TypesMap, TypesSourceMap},
-    BlockId, DefWithBodyId, HasModule, Lookup,
+    BlockId, DefWithBodyId, HasModule, Lookup, SyntheticSyntax,
 };
 
 /// A wrapper around [`span::SyntaxContextId`] that is intended only for comparisons.
@@ -141,7 +141,7 @@ pub struct BodySourceMap {
     field_map_back: FxHashMap<ExprId, FieldSource>,
     pat_field_map_back: FxHashMap<PatId, PatFieldSource>,
 
-    types: TypesSourceMap,
+    pub types: TypesSourceMap,
 
     // FIXME: Make this a sane struct.
     template_map: Option<
@@ -160,9 +160,6 @@ pub struct BodySourceMap {
     diagnostics: Vec<BodyDiagnostic>,
 }
 
-#[derive(Default, Debug, Eq, PartialEq, Clone, Copy)]
-pub struct SyntheticSyntax;
-
 #[derive(Debug, Eq, PartialEq)]
 pub enum BodyDiagnostic {
     InactiveCode { node: InFile<SyntaxNodePtr>, cfg: CfgExpr, opts: CfgOptions },
@@ -408,7 +405,8 @@ impl Body {
                     f(else_branch);
                 }
             }
-            Expr::Let { expr, .. } => {
+            Expr::Let { expr, pat } => {
+                self.walk_exprs_in_pat(*pat, &mut f);
                 f(*expr);
             }
             Expr::Block { statements, tail, .. }
@@ -442,6 +440,137 @@ impl Body {
                 f(*receiver);
                 args.iter().copied().for_each(f);
             }
+            Expr::Match { expr, arms } => {
+                f(*expr);
+                arms.iter().for_each(|arm| {
+                    f(arm.expr);
+                    self.walk_exprs_in_pat(arm.pat, &mut f);
+                });
+            }
+            Expr::Break { expr, .. }
+            | Expr::Return { expr }
+            | Expr::Yield { expr }
+            | Expr::Yeet { expr } => {
+                if let &Some(expr) = expr {
+                    f(expr);
+                }
+            }
+            Expr::Become { expr } => f(*expr),
+            Expr::RecordLit { fields, spread, .. } => {
+                for field in fields.iter() {
+                    f(field.expr);
+                }
+                if let &Some(expr) = spread {
+                    f(expr);
+                }
+            }
+            Expr::Closure { body, .. } => {
+                f(*body);
+            }
+            Expr::BinaryOp { lhs, rhs, .. } => {
+                f(*lhs);
+                f(*rhs);
+            }
+            Expr::Range { lhs, rhs, .. } => {
+                if let &Some(lhs) = rhs {
+                    f(lhs);
+                }
+                if let &Some(rhs) = lhs {
+                    f(rhs);
+                }
+            }
+            Expr::Index { base, index, .. } => {
+                f(*base);
+                f(*index);
+            }
+            Expr::Field { expr, .. }
+            | Expr::Await { expr }
+            | Expr::Cast { expr, .. }
+            | Expr::Ref { expr, .. }
+            | Expr::UnaryOp { expr, .. }
+            | Expr::Box { expr } => {
+                f(*expr);
+            }
+            Expr::Tuple { exprs, .. } => exprs.iter().copied().for_each(f),
+            Expr::Array(a) => match a {
+                Array::ElementList { elements, .. } => elements.iter().copied().for_each(f),
+                Array::Repeat { initializer, repeat } => {
+                    f(*initializer);
+                    f(*repeat)
+                }
+            },
+            &Expr::Assignment { target, value } => {
+                self.walk_exprs_in_pat(target, &mut f);
+                f(value);
+            }
+        }
+    }
+
+    pub fn walk_child_exprs_without_pats(&self, expr_id: ExprId, mut f: impl FnMut(ExprId)) {
+        let expr = &self[expr_id];
+        match expr {
+            Expr::Continue { .. }
+            | Expr::Const(_)
+            | Expr::Missing
+            | Expr::Path(_)
+            | Expr::OffsetOf(_)
+            | Expr::Literal(_)
+            | Expr::Underscore => {}
+            Expr::InlineAsm(it) => it.operands.iter().for_each(|(_, op)| match op {
+                AsmOperand::In { expr, .. }
+                | AsmOperand::Out { expr: Some(expr), .. }
+                | AsmOperand::InOut { expr, .. } => f(*expr),
+                AsmOperand::SplitInOut { in_expr, out_expr, .. } => {
+                    f(*in_expr);
+                    if let Some(out_expr) = out_expr {
+                        f(*out_expr);
+                    }
+                }
+                AsmOperand::Out { expr: None, .. }
+                | AsmOperand::Const(_)
+                | AsmOperand::Label(_)
+                | AsmOperand::Sym(_) => (),
+            }),
+            Expr::If { condition, then_branch, else_branch } => {
+                f(*condition);
+                f(*then_branch);
+                if let &Some(else_branch) = else_branch {
+                    f(else_branch);
+                }
+            }
+            Expr::Let { expr, .. } => {
+                f(*expr);
+            }
+            Expr::Block { statements, tail, .. }
+            | Expr::Unsafe { statements, tail, .. }
+            | Expr::Async { statements, tail, .. } => {
+                for stmt in statements.iter() {
+                    match stmt {
+                        Statement::Let { initializer, else_branch, .. } => {
+                            if let &Some(expr) = initializer {
+                                f(expr);
+                            }
+                            if let &Some(expr) = else_branch {
+                                f(expr);
+                            }
+                        }
+                        Statement::Expr { expr: expression, .. } => f(*expression),
+                        Statement::Item(_) => (),
+                    }
+                }
+                if let &Some(expr) = tail {
+                    f(expr);
+                }
+            }
+            Expr::Loop { body, .. } => f(*body),
+            Expr::Call { callee, args, .. } => {
+                f(*callee);
+                args.iter().copied().for_each(f);
+            }
+            Expr::MethodCall { receiver, args, .. } => {
+                f(*receiver);
+                args.iter().copied().for_each(f);
+            }
             Expr::Match { expr, arms } => {
                 f(*expr);
                 arms.iter().map(|arm| arm.expr).for_each(f);
@@ -498,10 +627,7 @@ impl Body {
                     f(*repeat)
                 }
             },
-            &Expr::Assignment { target, value } => {
-                self.walk_exprs_in_pat(target, &mut f);
-                f(value);
-            }
+            &Expr::Assignment { target: _, value } => f(value),
         }
     }
 

src/tools/rust-analyzer/crates/hir-def/src/body/lower.rs

@@ -1510,20 +1510,20 @@ impl ExprCollector<'_> {
                         BuiltinShadowMode::Other,
                         None,
                     );
+                    // Funnily enough, record structs/variants *can* be shadowed
+                    // by pattern bindings (but unit or tuple structs/variants
+                    // can't).
                     match resolved.take_values() {
                         Some(ModuleDefId::ConstId(_)) => (None, Pat::Path(name.into())),
-                        Some(ModuleDefId::EnumVariantId(_)) => {
-                            // this is only really valid for unit variants, but
-                            // shadowing other enum variants with a pattern is
-                            // an error anyway
+                        Some(ModuleDefId::EnumVariantId(variant))
+                            if self.db.variant_data(variant.into()).kind()
+                                != StructKind::Record =>
+                        {
                             (None, Pat::Path(name.into()))
                         }
                         Some(ModuleDefId::AdtId(AdtId::StructId(s)))
                             if self.db.struct_data(s).variant_data.kind() != StructKind::Record =>
                         {
-                            // Funnily enough, record structs *can* be shadowed
-                            // by pattern bindings (but unit or tuple structs
-                            // can't).
                             (None, Pat::Path(name.into()))
                         }
                         // shadowing statics is an error as well, so we just ignore that case here

src/tools/rust-analyzer/crates/hir-def/src/body/tests.rs

@@ -1,6 +1,5 @@
 mod block;
 
-use base_db::SourceDatabase;
 use expect_test::{expect, Expect};
 use test_fixture::WithFixture;
 
@@ -11,7 +10,7 @@ use super::*;
 fn lower(ra_fixture: &str) -> (TestDB, Arc<Body>, DefWithBodyId) {
     let db = TestDB::with_files(ra_fixture);
 
-    let krate = db.crate_graph().iter().next().unwrap();
+    let krate = db.fetch_test_crate();
     let def_map = db.crate_def_map(krate);
     let mut fn_def = None;
     'outer: for (_, module) in def_map.modules() {
@@ -404,3 +403,26 @@ fn foo() {
         }"#]]
     .assert_eq(&body.pretty_print(&db, def, Edition::CURRENT))
 }
+
+#[test]
+fn shadowing_record_variant() {
+    let (_, body, _) = lower(
+        r#"
+enum A {
+    B { field: i32 },
+}
+fn f() {
+    use A::*;
+    match () {
+        B => {}
+    };
+}
+    "#,
+    );
+    assert_eq!(body.bindings.len(), 1, "should have a binding for `B`");
+    assert_eq!(
+        body.bindings[BindingId::from_raw(RawIdx::from_u32(0))].name.as_str(),
+        "B",
+        "should have a binding for `B`",
+    );
+}

src/tools/rust-analyzer/crates/hir-def/src/data.rs

@@ -369,7 +369,7 @@ impl ImplData {
 
         let item_tree = tree_id.item_tree(db);
         let impl_def = &item_tree[tree_id.value];
-        let target_trait = impl_def.target_trait.clone();
+        let target_trait = impl_def.target_trait;
         let self_ty = impl_def.self_ty;
         let is_negative = impl_def.is_negative;
         let is_unsafe = impl_def.is_unsafe;

src/tools/rust-analyzer/crates/hir-def/src/generics.rs

@@ -26,8 +26,8 @@ use crate::{
     nameres::{DefMap, MacroSubNs},
     path::{AssociatedTypeBinding, GenericArg, GenericArgs, NormalPath, Path},
     type_ref::{
-        ArrayType, ConstRef, FnType, LifetimeRef, RefType, TypeBound, TypeRef, TypeRefId, TypesMap,
-        TypesSourceMap,
+        ArrayType, ConstRef, FnType, LifetimeRef, PathId, RefType, TypeBound, TypeRef, TypeRefId,
+        TypesMap, TypesSourceMap,
     },
     AdtId, ConstParamId, GenericDefId, HasModule, ItemTreeLoc, LifetimeParamId,
     LocalLifetimeParamId, LocalTypeOrConstParamId, Lookup, TypeOrConstParamId, TypeParamId,
@@ -224,6 +224,11 @@ impl GenericParams {
         self.len() == 0
     }
 
+    #[inline]
+    pub fn no_predicates(&self) -> bool {
+        self.where_predicates.is_empty()
+    }
+
     #[inline]
     pub fn where_predicates(&self) -> std::slice::Iter<'_, WherePredicate> {
         self.where_predicates.iter()
@@ -874,14 +879,20 @@ fn copy_type_bound(
     to: &mut TypesMap,
     to_source_map: &mut TypesSourceMap,
 ) -> TypeBound {
-    match bound {
-        TypeBound::Path(path, modifier) => {
-            TypeBound::Path(copy_path(path, from, from_source_map, to, to_source_map), *modifier)
+    let mut copy_path_id = |path: PathId| {
+        let new_path = copy_path(&from[path], from, from_source_map, to, to_source_map);
+        let new_path_id = to.types.alloc(TypeRef::Path(new_path));
+        if let Some(&ptr) = from_source_map.types_map_back.get(path.type_ref()) {
+            to_source_map.types_map_back.insert(new_path_id, ptr);
+        }
+        PathId::from_type_ref_unchecked(new_path_id)
+    };
+
+    match bound {
+        &TypeBound::Path(path, modifier) => TypeBound::Path(copy_path_id(path), modifier),
+        TypeBound::ForLifetime(lifetimes, path) => {
+            TypeBound::ForLifetime(lifetimes.clone(), copy_path_id(*path))
         }
-        TypeBound::ForLifetime(lifetimes, path) => TypeBound::ForLifetime(
-            lifetimes.clone(),
-            copy_path(path, from, from_source_map, to, to_source_map),
-        ),
         TypeBound::Lifetime(lifetime) => TypeBound::Lifetime(lifetime.clone()),
         TypeBound::Use(use_args) => TypeBound::Use(use_args.clone()),
         TypeBound::Error => TypeBound::Error,

src/tools/rust-analyzer/crates/hir-def/src/hir/type_ref.rs

@@ -23,6 +23,7 @@ use crate::{
     hir::Literal,
     lower::LowerCtx,
     path::{GenericArg, Path},
+    SyntheticSyntax,
 };
 
 #[derive(Copy, Clone, PartialEq, Eq, Hash, Debug)]
@@ -91,19 +92,37 @@ impl Rawness {
     }
 }
 
-#[derive(Clone, PartialEq, Eq, Hash, Debug)]
+#[derive(Clone, Copy, PartialEq, Eq, Hash, Debug)]
+/// A `TypeRefId` that is guaranteed to always be `TypeRef::Path`. We use this for things like
+/// impl's trait, that are always paths but need to be traced back to source code.
+pub struct PathId(TypeRefId);
+
+impl PathId {
+    #[inline]
+    pub fn from_type_ref_unchecked(type_ref: TypeRefId) -> Self {
+        Self(type_ref)
+    }
+
+    #[inline]
+    pub fn type_ref(self) -> TypeRefId {
+        self.0
+    }
+}
+
+#[derive(Clone, Copy, PartialEq, Eq, Hash, Debug)]
 pub struct TraitRef {
-    pub path: Path,
+    pub path: PathId,
 }
 
 impl TraitRef {
     /// Converts an `ast::PathType` to a `hir::TraitRef`.
     pub(crate) fn from_ast(ctx: &mut LowerCtx<'_>, node: ast::Type) -> Option<Self> {
         // FIXME: Use `Path::from_src`
-        match node {
-            ast::Type::PathType(path) => {
-                path.path().and_then(|it| ctx.lower_path(it)).map(|path| TraitRef { path })
-            }
+        match &node {
+            ast::Type::PathType(path) => path
+                .path()
+                .and_then(|it| ctx.lower_path(it))
+                .map(|path| TraitRef { path: ctx.alloc_path(path, AstPtr::new(&node)) }),
             _ => None,
         }
     }
@@ -173,11 +192,24 @@ impl TypesMap {
 impl Index<TypeRefId> for TypesMap {
     type Output = TypeRef;
 
+    #[inline]
     fn index(&self, index: TypeRefId) -> &Self::Output {
         &self.types[index]
     }
 }
 
+impl Index<PathId> for TypesMap {
+    type Output = Path;
+
+    #[inline]
+    fn index(&self, index: PathId) -> &Self::Output {
+        let TypeRef::Path(path) = &self[index.type_ref()] else {
+            unreachable!("`PathId` always points to `TypeRef::Path`");
+        };
+        path
+    }
+}
+
 pub type TypePtr = AstPtr<ast::Type>;
 pub type TypeSource = InFile<TypePtr>;
 
@@ -187,6 +219,12 @@ pub struct TypesSourceMap {
 }
 
 impl TypesSourceMap {
+    pub const EMPTY: Self = Self { types_map_back: ArenaMap::new() };
+
+    pub fn type_syntax(&self, id: TypeRefId) -> Result<TypeSource, SyntheticSyntax> {
+        self.types_map_back.get(id).cloned().ok_or(SyntheticSyntax)
+    }
+
     pub(crate) fn shrink_to_fit(&mut self) {
         let TypesSourceMap { types_map_back } = self;
         types_map_back.shrink_to_fit();
@@ -214,15 +252,15 @@ impl LifetimeRef {
 
 #[derive(Clone, PartialEq, Eq, Hash, Debug)]
 pub enum TypeBound {
-    Path(Path, TraitBoundModifier),
-    ForLifetime(Box<[Name]>, Path),
+    Path(PathId, TraitBoundModifier),
+    ForLifetime(Box<[Name]>, PathId),
     Lifetime(LifetimeRef),
     Use(Box<[UseArgRef]>),
     Error,
 }
 
 #[cfg(target_pointer_width = "64")]
-const _: [(); 32] = [(); ::std::mem::size_of::<TypeBound>()];
+const _: [(); 24] = [(); ::std::mem::size_of::<TypeBound>()];
 
 #[derive(Clone, PartialEq, Eq, Hash, Debug)]
 pub enum UseArgRef {
@@ -365,8 +403,8 @@ impl TypeRef {
                 TypeRef::ImplTrait(bounds) | TypeRef::DynTrait(bounds) => {
                     for bound in bounds {
                         match bound {
-                            TypeBound::Path(path, _) | TypeBound::ForLifetime(_, path) => {
-                                go_path(path, f, map)
+                            &TypeBound::Path(path, _) | &TypeBound::ForLifetime(_, path) => {
+                                go_path(&map[path], f, map)
                             }
                             TypeBound::Lifetime(_) | TypeBound::Error | TypeBound::Use(_) => (),
                         }
@@ -397,8 +435,8 @@ impl TypeRef {
                         }
                         for bound in binding.bounds.iter() {
                             match bound {
-                                TypeBound::Path(path, _) | TypeBound::ForLifetime(_, path) => {
-                                    go_path(path, f, map)
+                                &TypeBound::Path(path, _) | &TypeBound::ForLifetime(_, path) => {
+                                    go_path(&map[path], f, map)
                                 }
                                 TypeBound::Lifetime(_) | TypeBound::Error | TypeBound::Use(_) => (),
                             }
@@ -425,7 +463,7 @@ pub(crate) fn type_bounds_from_ast(
 
 impl TypeBound {
     pub(crate) fn from_ast(ctx: &mut LowerCtx<'_>, node: ast::TypeBound) -> Self {
-        let mut lower_path_type = |path_type: ast::PathType| ctx.lower_path(path_type.path()?);
+        let mut lower_path_type = |path_type: &ast::PathType| ctx.lower_path(path_type.path()?);
 
         match node.kind() {
             ast::TypeBoundKind::PathType(path_type) => {
@@ -433,8 +471,10 @@ impl TypeBound {
                     Some(_) => TraitBoundModifier::Maybe,
                     None => TraitBoundModifier::None,
                 };
-                lower_path_type(path_type)
-                    .map(|p| TypeBound::Path(p, m))
+                lower_path_type(&path_type)
+                    .map(|p| {
+                        TypeBound::Path(ctx.alloc_path(p, AstPtr::new(&path_type).upcast()), m)
+                    })
                     .unwrap_or(TypeBound::Error)
             }
             ast::TypeBoundKind::ForType(for_type) => {
@@ -445,12 +485,14 @@ impl TypeBound {
                         .collect(),
                     None => Box::default(),
                 };
-                let path = for_type.ty().and_then(|ty| match ty {
-                    ast::Type::PathType(path_type) => lower_path_type(path_type),
+                let path = for_type.ty().and_then(|ty| match &ty {
+                    ast::Type::PathType(path_type) => lower_path_type(path_type).map(|p| (p, ty)),
                     _ => None,
                 });
                 match path {
-                    Some(p) => TypeBound::ForLifetime(lt_refs, p),
+                    Some((p, ty)) => {
+                        TypeBound::ForLifetime(lt_refs, ctx.alloc_path(p, AstPtr::new(&ty)))
+                    }
                     None => TypeBound::Error,
                 }
             }
@@ -470,10 +512,10 @@ impl TypeBound {
         }
     }
 
-    pub fn as_path(&self) -> Option<(&Path, &TraitBoundModifier)> {
+    pub fn as_path<'a>(&self, map: &'a TypesMap) -> Option<(&'a Path, TraitBoundModifier)> {
         match self {
-            TypeBound::Path(p, m) => Some((p, m)),
-            TypeBound::ForLifetime(_, p) => Some((p, &TraitBoundModifier::None)),
+            &TypeBound::Path(p, m) => Some((&map[p], m)),
+            &TypeBound::ForLifetime(_, p) => Some((&map[p], TraitBoundModifier::None)),
             TypeBound::Lifetime(_) | TypeBound::Error | TypeBound::Use(_) => None,
         }
     }

src/tools/rust-analyzer/crates/hir-def/src/item_tree/lower.rs

@@ -34,7 +34,7 @@ use crate::{
     lower::LowerCtx,
     path::AssociatedTypeBinding,
     type_ref::{
-        LifetimeRef, RefType, TraitBoundModifier, TraitRef, TypeBound, TypeRef, TypeRefId,
+        LifetimeRef, PathId, RefType, TraitBoundModifier, TraitRef, TypeBound, TypeRef, TypeRefId,
         TypesMap, TypesSourceMap,
     },
     visibility::RawVisibility,
@@ -514,7 +514,7 @@ impl<'a> Ctx<'a> {
         };
 
         let ret_type = if func.async_token().is_some() {
-            let future_impl = desugar_future_path(ret_type);
+            let future_impl = desugar_future_path(&mut body_ctx, ret_type);
             let ty_bound = TypeBound::Path(future_impl, TraitBoundModifier::None);
             body_ctx.alloc_type_ref_desugared(TypeRef::ImplTrait(ThinVec::from_iter([ty_bound])))
         } else {
@@ -936,7 +936,7 @@ impl<'a> Ctx<'a> {
     }
 }
 
-fn desugar_future_path(orig: TypeRefId) -> Path {
+fn desugar_future_path(ctx: &mut LowerCtx<'_>, orig: TypeRefId) -> PathId {
     let path = path![core::future::Future];
     let mut generic_args: Vec<_> =
         std::iter::repeat(None).take(path.segments().len() - 1).collect();
@@ -948,7 +948,8 @@ fn desugar_future_path(orig: TypeRefId) -> Path {
     };
     generic_args.push(Some(GenericArgs { bindings: Box::new([binding]), ..GenericArgs::empty() }));
 
-    Path::from_known_path(path, generic_args)
+    let path = Path::from_known_path(path, generic_args);
+    PathId::from_type_ref_unchecked(ctx.alloc_type_ref_desugared(TypeRef::Path(path)))
 }
 
 enum HasImplicitSelf {

src/tools/rust-analyzer/crates/hir-def/src/item_tree/pretty.rs

@@ -484,7 +484,7 @@ impl Printer<'_> {
                     w!(self, "!");
                 }
                 if let Some(tr) = target_trait {
-                    self.print_path(&tr.path, types_map);
+                    self.print_path(&types_map[tr.path], types_map);
                     w!(self, " for ");
                 }
                 self.print_type_ref(*self_ty, types_map);
@@ -648,9 +648,9 @@ impl Printer<'_> {
                 let (target, bound) = match pred {
                     WherePredicate::TypeBound { target, bound } => (target, bound),
                     WherePredicate::Lifetime { target, bound } => {
-                        wln!(
+                        w!(
                             this,
-                            "{}: {},",
+                            "{}: {}",
                             target.name.display(self.db.upcast(), edition),
                             bound.name.display(self.db.upcast(), edition)
                         );

src/tools/rust-analyzer/crates/hir-def/src/item_tree/tests.rs

@@ -351,7 +351,8 @@ trait Tr<'a, T: 'a>: Super where Self: for<'a> Tr<'a, T> {}
             where
                 T: Copy,
                 T: 'a,
-                T: 'b
+                T: 'b,
+                'b: 'a
             {
                 pub(self) field: &'a &'b T,
             }
@@ -370,7 +371,8 @@ trait Tr<'a, T: 'a>: Super where Self: for<'a> Tr<'a, T> {}
             where
                 T: Copy,
                 T: 'a,
-                T: 'b
+                T: 'b,
+                'b: 'a
             {
                 // AstId: 9
                 pub(self) fn f<G>(

src/tools/rust-analyzer/crates/hir-def/src/lang_item.rs

@@ -376,6 +376,9 @@ language_item_table! {
     Fn,                      sym::fn_,                 fn_trait,                   Target::Trait,          GenericRequirement::Exact(1);
     FnMut,                   sym::fn_mut,              fn_mut_trait,               Target::Trait,          GenericRequirement::Exact(1);
     FnOnce,                  sym::fn_once,             fn_once_trait,              Target::Trait,          GenericRequirement::Exact(1);
+    AsyncFn,                 sym::async_fn,            async_fn_trait,             Target::Trait,          GenericRequirement::Exact(1);
+    AsyncFnMut,              sym::async_fn_mut,        async_fn_mut_trait,         Target::Trait,          GenericRequirement::Exact(1);
+    AsyncFnOnce,             sym::async_fn_once,       async_fn_once_trait,        Target::Trait,          GenericRequirement::Exact(1);
 
     FnOnceOutput,            sym::fn_once_output,      fn_once_output,             Target::AssocTy,        GenericRequirement::None;
 

src/tools/rust-analyzer/crates/hir-def/src/lib.rs

@@ -1535,3 +1535,6 @@ fn macro_call_as_call_id_with_eager(
 pub struct UnresolvedMacro {
     pub path: hir_expand::mod_path::ModPath,
 }
+
+#[derive(Default, Debug, Eq, PartialEq, Clone, Copy)]
+pub struct SyntheticSyntax;

src/tools/rust-analyzer/crates/hir-def/src/lower.rs

@@ -2,7 +2,7 @@
 use std::{cell::OnceCell, mem};
 
 use hir_expand::{span_map::SpanMap, AstId, HirFileId, InFile};
-use span::{AstIdMap, AstIdNode};
+use span::{AstIdMap, AstIdNode, Edition, EditionedFileId, FileId, RealSpanMap};
 use stdx::thin_vec::ThinVec;
 use syntax::ast;
 use triomphe::Arc;
@@ -10,7 +10,7 @@ use triomphe::Arc;
 use crate::{
     db::DefDatabase,
     path::Path,
-    type_ref::{TypeBound, TypePtr, TypeRef, TypeRefId, TypesMap, TypesSourceMap},
+    type_ref::{PathId, TypeBound, TypePtr, TypeRef, TypeRefId, TypesMap, TypesSourceMap},
 };
 
 pub struct LowerCtx<'a> {
@@ -63,6 +63,30 @@ impl<'a> LowerCtx<'a> {
         }
     }
 
+    /// Prepares a `LowerCtx` for synthetic AST that needs to be lowered. This is intended for IDE things.
+    pub fn for_synthetic_ast(
+        db: &'a dyn DefDatabase,
+        ast_id_map: Arc<AstIdMap>,
+        types_map: &'a mut TypesMap,
+        types_source_map: &'a mut TypesSourceMap,
+    ) -> Self {
+        let file_id = EditionedFileId::new(
+            FileId::from_raw(EditionedFileId::MAX_FILE_ID),
+            Edition::Edition2015,
+        );
+        LowerCtx {
+            db,
+            // Make up an invalid file id, so that if we will try to actually access it salsa will panic.
+            file_id: file_id.into(),
+            span_map: SpanMap::RealSpanMap(Arc::new(RealSpanMap::absolute(file_id))).into(),
+            ast_id_map: ast_id_map.into(),
+            impl_trait_bounds: Vec::new(),
+            outer_impl_trait: false,
+            types_map,
+            types_source_map,
+        }
+    }
+
     pub(crate) fn span_map(&self) -> &SpanMap {
         self.span_map.get_or_init(|| self.db.span_map(self.file_id))
     }
@@ -118,4 +142,8 @@ impl<'a> LowerCtx<'a> {
     pub(crate) fn alloc_error_type(&mut self) -> TypeRefId {
         self.types_map.types.alloc(TypeRef::Error)
     }
+
+    pub(crate) fn alloc_path(&mut self, path: Path, node: TypePtr) -> PathId {
+        PathId::from_type_ref_unchecked(self.alloc_type_ref(TypeRef::Path(path), node))
+    }
 }

src/tools/rust-analyzer/crates/hir-def/src/macro_expansion_tests/mbe.rs

@@ -1733,7 +1733,7 @@ m!(C("0"));
 macro_rules! m {
     ($k:expr) => { fn f() { K::$k; } }
 }
-/* parse error: expected identifier */
+/* parse error: expected identifier, `self`, `super`, `crate`, or `Self` */
 /* parse error: expected SEMICOLON */
 /* parse error: expected SEMICOLON */
 /* parse error: expected expression, item or let statement */
@@ -1759,8 +1759,9 @@ fn f() {
 //                   NAME_REF@6..7
 //                     IDENT@6..7 "K"
 //               COLON2@7..9 "::"
-//               ERROR@9..10
-//                 L_PAREN@9..10 "("
+//               PATH_SEGMENT@9..10
+//                 ERROR@9..10
+//                   L_PAREN@9..10 "("
 //         EXPR_STMT@10..16
 //           CALL_EXPR@10..16
 //             PATH_EXPR@10..11

src/tools/rust-analyzer/crates/hir-def/src/macro_expansion_tests/mbe/matching.rs

@@ -184,3 +184,31 @@ fn test() {
 "#]],
     );
 }
+
+#[test]
+fn meta_variable_raw_name_equals_non_raw() {
+    check(
+        r#"
+macro_rules! m {
+    ($r#name:tt) => {
+        $name
+    }
+}
+
+fn test() {
+    m!(1234)
+}
+"#,
+        expect![[r#"
+macro_rules! m {
+    ($r#name:tt) => {
+        $name
+    }
+}
+
+fn test() {
+    1234
+}
+"#]],
+    );
+}

src/tools/rust-analyzer/crates/hir-def/src/macro_expansion_tests/mod.rs

@@ -16,7 +16,6 @@ mod proc_macros;
 
 use std::{iter, ops::Range, sync};
 
-use base_db::SourceDatabase;
 use expect_test::Expect;
 use hir_expand::{
     db::ExpandDatabase,
@@ -63,7 +62,7 @@ pub fn identity_when_valid(_attr: TokenStream, item: TokenStream) -> TokenStream
         },
     )];
     let db = TestDB::with_files_extra_proc_macros(ra_fixture, extra_proc_macros);
-    let krate = db.crate_graph().iter().next().unwrap();
+    let krate = db.fetch_test_crate();
     let def_map = db.crate_def_map(krate);
     let local_id = DefMap::ROOT;
     let module = def_map.module_id(local_id);

src/tools/rust-analyzer/crates/hir-def/src/nameres/collector.rs

@@ -910,8 +910,13 @@ impl DefCollector<'_> {
                             self.update(module_id, &items, vis, Some(ImportType::Glob(id)));
                             // record the glob import in case we add further items
                             let glob = self.glob_imports.entry(m.local_id).or_default();
-                            if !glob.iter().any(|(mid, _, _)| *mid == module_id) {
-                                glob.push((module_id, vis, id));
+                            match glob.iter_mut().find(|(mid, _, _)| *mid == module_id) {
+                                None => glob.push((module_id, vis, id)),
+                                Some((_, old_vis, _)) => {
+                                    if let Some(new_vis) = old_vis.max(vis, &self.def_map) {
+                                        *old_vis = new_vis;
+                                    }
+                                }
                             }
                         }
                     }

src/tools/rust-analyzer/crates/hir-def/src/nameres/tests.rs

@@ -13,13 +13,13 @@ use crate::{db::DefDatabase, nameres::DefMap, test_db::TestDB};
 
 fn compute_crate_def_map(ra_fixture: &str) -> Arc<DefMap> {
     let db = TestDB::with_files(ra_fixture);
-    let krate = db.crate_graph().iter().next().unwrap();
+    let krate = db.fetch_test_crate();
     db.crate_def_map(krate)
 }
 
 fn render_crate_def_map(ra_fixture: &str) -> String {
     let db = TestDB::with_files(ra_fixture);
-    let krate = db.crate_graph().iter().next().unwrap();
+    let krate = db.fetch_test_crate();
     db.crate_def_map(krate).dump(&db)
 }
 

src/tools/rust-analyzer/crates/hir-def/src/nameres/tests/globs.rs

@@ -451,3 +451,42 @@ mod glob_target {
         "#]],
     );
 }
+
+#[test]
+fn regression_18580() {
+    check(
+        r#"
+pub mod libs {
+    pub struct Placeholder;
+}
+
+pub mod reexport_2 {
+    use reexport_1::*;
+    pub use reexport_1::*;
+
+    pub mod reexport_1 {
+        pub use crate::libs::*;
+    }
+}
+
+use reexport_2::*;
+"#,
+        expect![[r#"
+            crate
+            Placeholder: t v
+            libs: t
+            reexport_1: t
+            reexport_2: t
+
+            crate::libs
+            Placeholder: t v
+
+            crate::reexport_2
+            Placeholder: t v
+            reexport_1: t
+
+            crate::reexport_2::reexport_1
+            Placeholder: t v
+        "#]],
+    );
+}

src/tools/rust-analyzer/crates/hir-def/src/nameres/tests/incremental.rs

@@ -1,15 +1,11 @@
-use base_db::{SourceDatabase, SourceDatabaseFileInputExt as _};
+use base_db::SourceDatabaseFileInputExt as _;
 use test_fixture::WithFixture;
 
 use crate::{db::DefDatabase, nameres::tests::TestDB, AdtId, ModuleDefId};
 
 fn check_def_map_is_not_recomputed(ra_fixture_initial: &str, ra_fixture_change: &str) {
     let (mut db, pos) = TestDB::with_position(ra_fixture_initial);
-    let krate = {
-        let crate_graph = db.crate_graph();
-        // Some of these tests use minicore/proc-macros which will be injected as the first crate
-        crate_graph.iter().last().unwrap()
-    };
+    let krate = db.fetch_test_crate();
     {
         let events = db.log_executed(|| {
             db.crate_def_map(krate);
@@ -120,28 +116,31 @@ fn f() { foo }
     );
 }
 
-#[test]
-fn typing_inside_an_attribute_arg_should_not_invalidate_def_map() {
-    check_def_map_is_not_recomputed(
-        r"
-//- proc_macros: identity
-//- /lib.rs
-mod foo;
+// Would be nice if this was the case, but as attribute inputs are stored in the item tree, this is
+// not currently the case.
+// #[test]
+// fn typing_inside_an_attribute_arg_should_not_invalidate_def_map() {
+//     check_def_map_is_not_recomputed(
+//         r"
+// //- proc_macros: identity
+// //- /lib.rs
+// mod foo;
 
-//- /foo/mod.rs
-pub mod bar;
+// //- /foo/mod.rs
+// pub mod bar;
+
+// //- /foo/bar.rs
+// $0
+// #[proc_macros::identity]
+// fn f() {}
+// ",
+//         r"
+// #[proc_macros::identity(foo)]
+// fn f() {}
+// ",
+//     );
+// }
 
-//- /foo/bar.rs
-$0
-#[proc_macros::identity]
-fn f() {}
-",
-        r"
-#[proc_macros::identity(foo)]
-fn f() {}
-",
-    );
-}
 #[test]
 fn typing_inside_macro_heavy_file_should_not_invalidate_def_map() {
     check_def_map_is_not_recomputed(
@@ -198,31 +197,33 @@ pub struct S {}
     );
 }
 
-#[test]
-fn typing_inside_a_derive_should_not_invalidate_def_map() {
-    check_def_map_is_not_recomputed(
-        r"
-//- proc_macros: derive_identity
-//- minicore:derive
-//- /lib.rs
-mod foo;
+// Would be nice if this was the case, but as attribute inputs are stored in the item tree, this is
+// not currently the case.
+// #[test]
+// fn typing_inside_a_derive_should_not_invalidate_def_map() {
+//     check_def_map_is_not_recomputed(
+//         r"
+// //- proc_macros: derive_identity
+// //- minicore:derive
+// //- /lib.rs
+// mod foo;
 
-//- /foo/mod.rs
-pub mod bar;
+// //- /foo/mod.rs
+// pub mod bar;
 
-//- /foo/bar.rs
-$0
-#[derive(proc_macros::DeriveIdentity)]
-#[allow()]
-struct S;
-",
-        r"
-#[derive(proc_macros::DeriveIdentity)]
-#[allow(dead_code)]
-struct S;
-",
-    );
-}
+// //- /foo/bar.rs
+// $0
+// #[derive(proc_macros::DeriveIdentity)]
+// #[allow()]
+// struct S;
+// ",
+//         r"
+// #[derive(proc_macros::DeriveIdentity)]
+// #[allow(dead_code)]
+// struct S;
+// ",
+//     );
+// }
 
 #[test]
 fn typing_inside_a_function_should_not_invalidate_item_expansions() {

src/tools/rust-analyzer/crates/hir-def/src/path.rs

@@ -1,5 +1,7 @@
 //! A desugared representation of paths like `crate::foo` or `<Type as Trait>::bar`.
 mod lower;
+#[cfg(test)]
+mod tests;
 
 use std::{
     fmt::{self, Display},
@@ -19,6 +21,8 @@ use syntax::ast;
 
 pub use hir_expand::mod_path::{path, ModPath, PathKind};
 
+pub use lower::hir_segment_to_ast_segment;
+
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub enum ImportAlias {
     /// Unnamed alias, as in `use Foo as _;`
@@ -230,7 +234,7 @@ impl Path {
     }
 }
 
-#[derive(Debug, Clone, PartialEq, Eq, Hash)]
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
 pub struct PathSegment<'a> {
     pub name: &'a Name,
     pub args_and_bindings: Option<&'a GenericArgs>,
@@ -274,6 +278,12 @@ impl<'a> PathSegments<'a> {
             generic_args: self.generic_args.map(|it| it.get(..len).unwrap_or(it)),
         }
     }
+    pub fn strip_last(&self) -> PathSegments<'a> {
+        PathSegments {
+            segments: self.segments.split_last().map_or(&[], |it| it.1),
+            generic_args: self.generic_args.map(|it| it.split_last().map_or(&[][..], |it| it.1)),
+        }
+    }
     pub fn iter(&self) -> impl Iterator<Item = PathSegment<'a>> {
         self.segments
             .iter()

src/tools/rust-analyzer/crates/hir-def/src/path/lower.rs

@@ -17,13 +17,31 @@ use crate::{
     type_ref::{LifetimeRef, TypeBound, TypeRef},
 };
 
+#[cfg(test)]
+thread_local! {
+    /// This is used to test `hir_segment_to_ast_segment()`. It's a hack, but it makes testing much easier.
+    pub(super) static SEGMENT_LOWERING_MAP: std::cell::RefCell<rustc_hash::FxHashMap<ast::PathSegment, usize>> = std::cell::RefCell::default();
+}
+
 /// Converts an `ast::Path` to `Path`. Works with use trees.
 /// It correctly handles `$crate` based path from macro call.
+// If you modify the logic of the lowering, make sure to check if `hir_segment_to_ast_segment()`
+// also needs an update.
 pub(super) fn lower_path(ctx: &mut LowerCtx<'_>, mut path: ast::Path) -> Option<Path> {
     let mut kind = PathKind::Plain;
     let mut type_anchor = None;
     let mut segments = Vec::new();
     let mut generic_args = Vec::new();
+    #[cfg(test)]
+    let mut ast_segments = Vec::new();
+    #[cfg(test)]
+    let mut ast_segments_offset = 0;
+    #[allow(unused_mut)]
+    let mut push_segment = |_segment: &ast::PathSegment, segments: &mut Vec<Name>, name| {
+        #[cfg(test)]
+        ast_segments.push(_segment.clone());
+        segments.push(name);
+    };
     loop {
         let segment = path.segment()?;
 
@@ -34,6 +52,10 @@ pub(super) fn lower_path(ctx: &mut LowerCtx<'_>, mut path: ast::Path) -> Option<
         match segment.kind()? {
             ast::PathSegmentKind::Name(name_ref) => {
                 if name_ref.text() == "$crate" {
+                    if path.qualifier().is_some() {
+                        // FIXME: Report an error.
+                        return None;
+                    }
                     break kind = resolve_crate_root(
                         ctx.db.upcast(),
                         ctx.span_map().span_for_range(name_ref.syntax().text_range()).ctx,
@@ -48,7 +70,7 @@ pub(super) fn lower_path(ctx: &mut LowerCtx<'_>, mut path: ast::Path) -> Option<
                     .or_else(|| {
                         lower_generic_args_from_fn_path(
                             ctx,
-                            segment.param_list(),
+                            segment.parenthesized_arg_list(),
                             segment.ret_type(),
                         )
                     });
@@ -56,10 +78,10 @@ pub(super) fn lower_path(ctx: &mut LowerCtx<'_>, mut path: ast::Path) -> Option<
                     generic_args.resize(segments.len(), None);
                     generic_args.push(args);
                 }
-                segments.push(name);
+                push_segment(&segment, &mut segments, name);
             }
             ast::PathSegmentKind::SelfTypeKw => {
-                segments.push(Name::new_symbol_root(sym::Self_.clone()));
+                push_segment(&segment, &mut segments, Name::new_symbol_root(sym::Self_.clone()));
             }
             ast::PathSegmentKind::Type { type_ref, trait_ref } => {
                 assert!(path.qualifier().is_none()); // this can only occur at the first segment
@@ -81,6 +103,10 @@ pub(super) fn lower_path(ctx: &mut LowerCtx<'_>, mut path: ast::Path) -> Option<
                         kind = mod_path.kind;
 
                         segments.extend(mod_path.segments().iter().cloned().rev());
+                        #[cfg(test)]
+                        {
+                            ast_segments_offset = mod_path.segments().len();
+                        }
                         if let Some(path_generic_args) = path_generic_args {
                             generic_args.resize(segments.len() - num_segments, None);
                             generic_args.extend(Vec::from(path_generic_args).into_iter().rev());
@@ -112,10 +138,18 @@ pub(super) fn lower_path(ctx: &mut LowerCtx<'_>, mut path: ast::Path) -> Option<
                 }
             }
             ast::PathSegmentKind::CrateKw => {
+                if path.qualifier().is_some() {
+                    // FIXME: Report an error.
+                    return None;
+                }
                 kind = PathKind::Crate;
                 break;
             }
             ast::PathSegmentKind::SelfKw => {
+                if path.qualifier().is_some() {
+                    // FIXME: Report an error.
+                    return None;
+                }
                 // don't break out if `self` is the last segment of a path, this mean we got a
                 // use tree like `foo::{self}` which we want to resolve as `foo`
                 if !segments.is_empty() {
@@ -162,6 +196,13 @@ pub(super) fn lower_path(ctx: &mut LowerCtx<'_>, mut path: ast::Path) -> Option<
         }
     }
 
+    #[cfg(test)]
+    {
+        ast_segments.reverse();
+        SEGMENT_LOWERING_MAP
+            .with_borrow_mut(|map| map.extend(ast_segments.into_iter().zip(ast_segments_offset..)));
+    }
+
     let mod_path = Interned::new(ModPath::from_segments(kind, segments));
     if type_anchor.is_none() && generic_args.is_empty() {
         return Some(Path::BarePath(mod_path));
@@ -181,6 +222,41 @@ pub(super) fn lower_path(ctx: &mut LowerCtx<'_>, mut path: ast::Path) -> Option<
     }
 }
 
+/// This function finds the AST segment that corresponds to the HIR segment
+/// with index `segment_idx` on the path that is lowered from `path`.
+pub fn hir_segment_to_ast_segment(path: &ast::Path, segment_idx: u32) -> Option<ast::PathSegment> {
+    // Too tightly coupled to `lower_path()`, but unfortunately we cannot decouple them,
+    // as keeping source maps for all paths segments will have a severe impact on memory usage.
+
+    let mut segments = path.segments();
+    if let Some(ast::PathSegmentKind::Type { trait_ref: Some(trait_ref), .. }) =
+        segments.clone().next().and_then(|it| it.kind())
+    {
+        segments.next();
+        return find_segment(trait_ref.path()?.segments().chain(segments), segment_idx);
+    }
+    return find_segment(segments, segment_idx);
+
+    fn find_segment(
+        segments: impl Iterator<Item = ast::PathSegment>,
+        segment_idx: u32,
+    ) -> Option<ast::PathSegment> {
+        segments
+            .filter(|segment| match segment.kind() {
+                Some(
+                    ast::PathSegmentKind::CrateKw
+                    | ast::PathSegmentKind::SelfKw
+                    | ast::PathSegmentKind::SuperKw
+                    | ast::PathSegmentKind::Type { .. },
+                )
+                | None => false,
+                Some(ast::PathSegmentKind::Name(name)) => name.text() != "$crate",
+                Some(ast::PathSegmentKind::SelfTypeKw) => true,
+            })
+            .nth(segment_idx as usize)
+    }
+}
+
 pub(super) fn lower_generic_args(
     lower_ctx: &mut LowerCtx<'_>,
     node: ast::GenericArgList,
@@ -247,12 +323,12 @@ pub(super) fn lower_generic_args(
 /// -> Z` (which desugars to `Fn<(X, Y), Output=Z>`).
 fn lower_generic_args_from_fn_path(
     ctx: &mut LowerCtx<'_>,
-    params: Option<ast::ParamList>,
+    args: Option<ast::ParenthesizedArgList>,
     ret_type: Option<ast::RetType>,
 ) -> Option<GenericArgs> {
-    let params = params?;
+    let params = args?;
     let mut param_types = Vec::new();
-    for param in params.params() {
+    for param in params.type_args() {
         let type_ref = TypeRef::from_ast_opt(ctx, param.ty());
         param_types.push(type_ref);
     }

src/tools/rust-analyzer/crates/hir-def/src/path/tests.rs

@@ -0,0 +1,126 @@
+use expect_test::{expect, Expect};
+use span::Edition;
+use syntax::ast::{self, make};
+use test_fixture::WithFixture;
+
+use crate::{
+    lower::LowerCtx,
+    path::{
+        lower::{hir_segment_to_ast_segment, SEGMENT_LOWERING_MAP},
+        Path,
+    },
+    pretty,
+    test_db::TestDB,
+    type_ref::{TypesMap, TypesSourceMap},
+};
+
+fn lower_path(path: ast::Path) -> (TestDB, TypesMap, Option<Path>) {
+    let (db, file_id) = TestDB::with_single_file("");
+    let mut types_map = TypesMap::default();
+    let mut types_source_map = TypesSourceMap::default();
+    let mut ctx = LowerCtx::new(&db, file_id.into(), &mut types_map, &mut types_source_map);
+    let lowered_path = ctx.lower_path(path);
+    (db, types_map, lowered_path)
+}
+
+#[track_caller]
+fn check_hir_to_ast(path: &str, ignore_segments: &[&str]) {
+    let path = make::path_from_text(path);
+    SEGMENT_LOWERING_MAP.with_borrow_mut(|map| map.clear());
+    let _ = lower_path(path.clone()).2.expect("failed to lower path");
+    SEGMENT_LOWERING_MAP.with_borrow(|map| {
+        for (segment, segment_idx) in map {
+            if ignore_segments.contains(&&*segment.to_string()) {
+                continue;
+            }
+
+            let restored_segment = hir_segment_to_ast_segment(&path, *segment_idx as u32)
+                .unwrap_or_else(|| {
+                    panic!(
+                        "failed to map back segment `{segment}` \
+                        numbered {segment_idx} in HIR from path `{path}`"
+                    )
+                });
+            assert_eq!(
+                segment, &restored_segment,
+                "mapping back `{segment}` numbered {segment_idx} in HIR \
+                from path `{path}` produced incorrect segment `{restored_segment}`"
+            );
+        }
+    });
+}
+
+#[test]
+fn hir_to_ast_trait_ref() {
+    check_hir_to_ast("<A as B::C::D>::E::F", &["A"]);
+}
+
+#[test]
+fn hir_to_ast_plain_path() {
+    check_hir_to_ast("A::B::C::D::E::F", &[]);
+}
+
+#[test]
+fn hir_to_ast_crate_path() {
+    check_hir_to_ast("crate::A::B::C", &[]);
+    check_hir_to_ast("crate::super::super::A::B::C", &[]);
+}
+
+#[test]
+fn hir_to_ast_self_path() {
+    check_hir_to_ast("self::A::B::C", &[]);
+    check_hir_to_ast("self::super::super::A::B::C", &[]);
+}
+
+#[test]
+fn hir_to_ast_super_path() {
+    check_hir_to_ast("super::A::B::C", &[]);
+    check_hir_to_ast("super::super::super::A::B::C", &[]);
+}
+
+#[test]
+fn hir_to_ast_type_anchor_path() {
+    check_hir_to_ast("<A::B>::C::D", &["A", "B"]);
+}
+
+#[test]
+fn hir_to_ast_path_super_in_middle() {
+    check_hir_to_ast("A::super::B::super::super::C::D", &[]);
+}
+
+#[track_caller]
+fn check_fail_lowering(path: &str) {
+    let (_, _, lowered_path) = lower_path(make::path_from_text(path));
+    assert!(lowered_path.is_none(), "path `{path}` should fail lowering");
+}
+
+#[test]
+fn keywords_in_middle_fail_lowering1() {
+    check_fail_lowering("self::A::self::B::super::C::crate::D");
+}
+
+#[test]
+fn keywords_in_middle_fail_lowering2() {
+    check_fail_lowering("A::super::self::C::D");
+}
+
+#[test]
+fn keywords_in_middle_fail_lowering3() {
+    check_fail_lowering("A::crate::B::C::D");
+}
+
+#[track_caller]
+fn check_path_lowering(path: &str, expected: Expect) {
+    let (db, types_map, lowered_path) = lower_path(make::path_from_text(path));
+    let lowered_path = lowered_path.expect("failed to lower path");
+    let mut buf = String::new();
+    pretty::print_path(&db, &lowered_path, &types_map, &mut buf, Edition::CURRENT)
+        .expect("failed to pretty-print path");
+    expected.assert_eq(&buf);
+}
+
+#[test]
+fn fn_like_path_with_coloncolon() {
+    check_path_lowering("Fn::(A, B) -> C", expect![[r#"Fn::<(A, B), Output = C>"#]]);
+    check_path_lowering("Fn::(A, B)", expect![[r#"Fn::<(A, B), Output = ()>"#]]);
+}

src/tools/rust-analyzer/crates/hir-def/src/pretty.rs

@@ -271,7 +271,7 @@ pub(crate) fn print_type_bounds(
                     TraitBoundModifier::None => (),
                     TraitBoundModifier::Maybe => write!(buf, "?")?,
                 }
-                print_path(db, path, map, buf, edition)?;
+                print_path(db, &map[*path], map, buf, edition)?;
             }
             TypeBound::ForLifetime(lifetimes, path) => {
                 write!(
@@ -279,7 +279,7 @@ pub(crate) fn print_type_bounds(
                     "for<{}> ",
                     lifetimes.iter().map(|it| it.display(db.upcast(), edition)).format(", ")
                 )?;
-                print_path(db, path, map, buf, edition)?;
+                print_path(db, &map[*path], map, buf, edition)?;
             }
             TypeBound::Lifetime(lt) => write!(buf, "{}", lt.name.display(db.upcast(), edition))?,
             TypeBound::Use(args) => {

src/tools/rust-analyzer/crates/hir-def/src/resolver.rs

@@ -576,10 +576,12 @@ impl Resolver {
             match scope {
                 Scope::BlockScope(m) => traits.extend(m.def_map[m.module_id].scope.traits()),
                 &Scope::ImplDefScope(impl_) => {
-                    if let Some(target_trait) = &db.impl_data(impl_).target_trait {
-                        if let Some(TypeNs::TraitId(trait_)) =
-                            self.resolve_path_in_type_ns_fully(db, &target_trait.path)
-                        {
+                    let impl_data = db.impl_data(impl_);
+                    if let Some(target_trait) = impl_data.target_trait {
+                        if let Some(TypeNs::TraitId(trait_)) = self.resolve_path_in_type_ns_fully(
+                            db,
+                            &impl_data.types_map[target_trait.path],
+                        ) {
                             traits.insert(trait_);
                         }
                     }
@@ -640,9 +642,9 @@ impl Resolver {
         })
     }
 
-    pub fn generic_params(&self) -> Option<&Arc<GenericParams>> {
+    pub fn generic_params(&self) -> Option<&GenericParams> {
         self.scopes().find_map(|scope| match scope {
-            Scope::GenericParams { params, .. } => Some(params),
+            Scope::GenericParams { params, .. } => Some(&**params),
             _ => None,
         })
     }

src/tools/rust-analyzer/crates/hir-def/src/test_db.rs

@@ -78,6 +78,19 @@ impl FileLoader for TestDB {
 }
 
 impl TestDB {
+    pub(crate) fn fetch_test_crate(&self) -> CrateId {
+        let crate_graph = self.crate_graph();
+        let it = crate_graph
+            .iter()
+            .find(|&idx| {
+                crate_graph[idx].display_name.as_ref().map(|it| it.canonical_name().as_str())
+                    == Some("ra_test_fixture")
+            })
+            .or_else(|| crate_graph.iter().next())
+            .unwrap();
+        it
+    }
+
     pub(crate) fn module_for_file(&self, file_id: FileId) -> ModuleId {
         for &krate in self.relevant_crates(file_id).iter() {
             let crate_def_map = self.crate_def_map(krate);

src/tools/rust-analyzer/crates/hir-expand/src/files.rs

@@ -180,6 +180,13 @@ impl<FileId: FileIdToSyntax, T> InFileWrapper<FileId, T> {
     }
 }
 
+#[allow(private_bounds)]
+impl<FileId: FileIdToSyntax, N: AstNode> InFileWrapper<FileId, AstPtr<N>> {
+    pub fn to_node(&self, db: &dyn ExpandDatabase) -> N {
+        self.value.to_node(&self.file_syntax(db))
+    }
+}
+
 impl<FileId: Copy, N: AstNode> InFileWrapper<FileId, N> {
     pub fn syntax(&self) -> InFileWrapper<FileId, &SyntaxNode> {
         self.with_value(self.value.syntax())

src/tools/rust-analyzer/crates/hir-expand/src/fixup.rs

@@ -110,7 +110,8 @@ pub(crate) fn fixup_syntax(
                     }
                 },
                 ast::ExprStmt(it) => {
-                    if it.semicolon_token().is_none() {
+                    let needs_semi = it.semicolon_token().is_none() && it.expr().map_or(false, |e| e.syntax().kind() != SyntaxKind::BLOCK_EXPR);
+                    if needs_semi {
                         append.insert(node.clone().into(), vec![
                             Leaf::Punct(Punct {
                                 char: ';',
@@ -905,6 +906,21 @@ fn foo() {
 "#,
             expect![[r#"
 fn foo () {|| __ra_fixup}
+"#]],
+        );
+    }
+
+    #[test]
+    fn fixup_regression_() {
+        check(
+            r#"
+fn foo() {
+    {}
+    {}
+}
+"#,
+            expect![[r#"
+fn foo () {{} {}}
 "#]],
         );
     }

src/tools/rust-analyzer/crates/hir-expand/src/lib.rs

@@ -269,6 +269,13 @@ pub enum MacroDefKind {
     ProcMacro(AstId<ast::Fn>, CustomProcMacroExpander, ProcMacroKind),
 }
 
+impl MacroDefKind {
+    #[inline]
+    pub fn is_declarative(&self) -> bool {
+        matches!(self, MacroDefKind::Declarative(..))
+    }
+}
+
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
 pub struct EagerCallInfo {
     /// The expanded argument of the eager macro.

src/tools/rust-analyzer/crates/hir-ty/src/db.rs

@@ -22,7 +22,7 @@ use crate::{
     consteval::ConstEvalError,
     dyn_compatibility::DynCompatibilityViolation,
     layout::{Layout, LayoutError},
-    lower::{GenericDefaults, GenericPredicates},
+    lower::{Diagnostics, GenericDefaults, GenericPredicates},
     method_resolution::{InherentImpls, TraitImpls, TyFingerprint},
     mir::{BorrowckResult, MirBody, MirLowerError},
     Binders, ClosureId, Const, FnDefId, ImplTraitId, ImplTraits, InferenceResult, Interner,
@@ -115,21 +115,35 @@ pub trait HirDatabase: DefDatabase + Upcast<dyn DefDatabase> {
     #[ra_salsa::cycle(crate::lower::ty_recover)]
     fn ty(&self, def: TyDefId) -> Binders<Ty>;
 
+    #[ra_salsa::invoke(crate::lower::type_for_type_alias_with_diagnostics_query)]
+    fn type_for_type_alias_with_diagnostics(&self, def: TypeAliasId) -> (Binders<Ty>, Diagnostics);
+
     /// Returns the type of the value of the given constant, or `None` if the `ValueTyDefId` is
     /// a `StructId` or `EnumVariantId` with a record constructor.
     #[ra_salsa::invoke(crate::lower::value_ty_query)]
     fn value_ty(&self, def: ValueTyDefId) -> Option<Binders<Ty>>;
 
+    #[ra_salsa::invoke(crate::lower::impl_self_ty_with_diagnostics_query)]
+    #[ra_salsa::cycle(crate::lower::impl_self_ty_with_diagnostics_recover)]
+    fn impl_self_ty_with_diagnostics(&self, def: ImplId) -> (Binders<Ty>, Diagnostics);
     #[ra_salsa::invoke(crate::lower::impl_self_ty_query)]
-    #[ra_salsa::cycle(crate::lower::impl_self_ty_recover)]
     fn impl_self_ty(&self, def: ImplId) -> Binders<Ty>;
 
+    #[ra_salsa::invoke(crate::lower::const_param_ty_with_diagnostics_query)]
+    fn const_param_ty_with_diagnostics(&self, def: ConstParamId) -> (Ty, Diagnostics);
     #[ra_salsa::invoke(crate::lower::const_param_ty_query)]
     fn const_param_ty(&self, def: ConstParamId) -> Ty;
 
+    #[ra_salsa::invoke(crate::lower::impl_trait_with_diagnostics_query)]
+    fn impl_trait_with_diagnostics(&self, def: ImplId) -> Option<(Binders<TraitRef>, Diagnostics)>;
     #[ra_salsa::invoke(crate::lower::impl_trait_query)]
     fn impl_trait(&self, def: ImplId) -> Option<Binders<TraitRef>>;
 
+    #[ra_salsa::invoke(crate::lower::field_types_with_diagnostics_query)]
+    fn field_types_with_diagnostics(
+        &self,
+        var: VariantId,
+    ) -> (Arc<ArenaMap<LocalFieldId, Binders<Ty>>>, Diagnostics);
     #[ra_salsa::invoke(crate::lower::field_types_query)]
     fn field_types(&self, var: VariantId) -> Arc<ArenaMap<LocalFieldId, Binders<Ty>>>;
 
@@ -154,6 +168,11 @@ pub trait HirDatabase: DefDatabase + Upcast<dyn DefDatabase> {
     #[ra_salsa::invoke(crate::lower::generic_predicates_query)]
     fn generic_predicates(&self, def: GenericDefId) -> GenericPredicates;
 
+    #[ra_salsa::invoke(crate::lower::generic_predicates_without_parent_with_diagnostics_query)]
+    fn generic_predicates_without_parent_with_diagnostics(
+        &self,
+        def: GenericDefId,
+    ) -> (GenericPredicates, Diagnostics);
     #[ra_salsa::invoke(crate::lower::generic_predicates_without_parent_query)]
     fn generic_predicates_without_parent(&self, def: GenericDefId) -> GenericPredicates;
 
@@ -164,8 +183,13 @@ pub trait HirDatabase: DefDatabase + Upcast<dyn DefDatabase> {
     #[ra_salsa::invoke(crate::lower::trait_environment_query)]
     fn trait_environment(&self, def: GenericDefId) -> Arc<TraitEnvironment>;
 
+    #[ra_salsa::invoke(crate::lower::generic_defaults_with_diagnostics_query)]
+    #[ra_salsa::cycle(crate::lower::generic_defaults_with_diagnostics_recover)]
+    fn generic_defaults_with_diagnostics(
+        &self,
+        def: GenericDefId,
+    ) -> (GenericDefaults, Diagnostics);
     #[ra_salsa::invoke(crate::lower::generic_defaults_query)]
-    #[ra_salsa::cycle(crate::lower::generic_defaults_recover)]
     fn generic_defaults(&self, def: GenericDefId) -> GenericDefaults;
 
     #[ra_salsa::invoke(InherentImpls::inherent_impls_in_crate_query)]

src/tools/rust-analyzer/crates/hir-ty/src/diagnostics.rs

@@ -9,5 +9,5 @@ pub use crate::diagnostics::{
     expr::{
         record_literal_missing_fields, record_pattern_missing_fields, BodyValidationDiagnostic,
     },
-    unsafe_check::{missing_unsafe, unsafe_expressions, UnsafeExpr},
+    unsafe_check::{missing_unsafe, unsafe_expressions, InsideUnsafeBlock, UnsafetyReason},
 };

src/tools/rust-analyzer/crates/hir-ty/src/diagnostics/match_check/pat_analysis.rs

@@ -383,9 +383,6 @@ impl<'db> PatCx for MatchCheckCtx<'db> {
                     } else {
                         let variant = Self::variant_id_for_adt(self.db, ctor, adt).unwrap();
 
-                        // Whether we must not match the fields of this variant exhaustively.
-                        let is_non_exhaustive =
-                            LazyCell::new(|| self.is_foreign_non_exhaustive(adt));
                         let visibilities = LazyCell::new(|| self.db.field_visibilities(variant));
 
                         self.list_variant_fields(ty, variant)
@@ -396,8 +393,7 @@ impl<'db> PatCx for MatchCheckCtx<'db> {
                                             .is_visible_from(self.db.upcast(), self.module)
                                 };
                                 let is_uninhabited = self.is_uninhabited(&ty);
-                                let private_uninhabited =
-                                    is_uninhabited && (!is_visible() || *is_non_exhaustive);
+                                let private_uninhabited = is_uninhabited && !is_visible();
                                 (ty, PrivateUninhabitedField(private_uninhabited))
                             })
                             .collect()

src/tools/rust-analyzer/crates/hir-ty/src/diagnostics/unsafe_check.rs

@@ -1,12 +1,16 @@
 //! Provides validations for unsafe code. Currently checks if unsafe functions are missing
 //! unsafe blocks.
 
+use std::mem;
+
+use either::Either;
 use hir_def::{
     body::Body,
-    hir::{Expr, ExprId, ExprOrPatId, Pat, UnaryOp},
-    resolver::{resolver_for_expr, ResolveValueResult, Resolver, ValueNs},
+    hir::{Expr, ExprId, ExprOrPatId, Pat, PatId, Statement, UnaryOp},
+    path::Path,
+    resolver::{HasResolver, ResolveValueResult, Resolver, ValueNs},
     type_ref::Rawness,
-    DefWithBodyId,
+    AdtId, DefWithBodyId, FieldId, VariantId,
 };
 
 use crate::{
@@ -16,7 +20,10 @@ use crate::{
 /// Returns `(unsafe_exprs, fn_is_unsafe)`.
 ///
 /// If `fn_is_unsafe` is false, `unsafe_exprs` are hard errors. If true, they're `unsafe_op_in_unsafe_fn`.
-pub fn missing_unsafe(db: &dyn HirDatabase, def: DefWithBodyId) -> (Vec<ExprOrPatId>, bool) {
+pub fn missing_unsafe(
+    db: &dyn HirDatabase,
+    def: DefWithBodyId,
+) -> (Vec<(ExprOrPatId, UnsafetyReason)>, bool) {
     let _p = tracing::info_span!("missing_unsafe").entered();
 
     let mut res = Vec::new();
@@ -30,111 +37,243 @@ pub fn missing_unsafe(db: &dyn HirDatabase, def: DefWithBodyId) -> (Vec<ExprOrPa
 
     let body = db.body(def);
     let infer = db.infer(def);
-    unsafe_expressions(db, &infer, def, &body, body.body_expr, &mut |expr| {
-        if !expr.inside_unsafe_block {
-            res.push(expr.node);
+    let mut callback = |node, inside_unsafe_block, reason| {
+        if inside_unsafe_block == InsideUnsafeBlock::No {
+            res.push((node, reason));
         }
-    });
+    };
+    let mut visitor = UnsafeVisitor::new(db, &infer, &body, def, &mut callback);
+    visitor.walk_expr(body.body_expr);
+
+    if !is_unsafe {
+        // Unsafety in function parameter patterns (that can only be union destructuring)
+        // cannot be inserted into an unsafe block, so even with `unsafe_op_in_unsafe_fn`
+        // it is turned off for unsafe functions.
+        for &param in &body.params {
+            visitor.walk_pat(param);
+        }
+    }
 
     (res, is_unsafe)
 }
 
-pub struct UnsafeExpr {
-    pub node: ExprOrPatId,
-    pub inside_unsafe_block: bool,
+#[derive(Debug, Clone, Copy)]
+pub enum UnsafetyReason {
+    UnionField,
+    UnsafeFnCall,
+    InlineAsm,
+    RawPtrDeref,
+    MutableStatic,
+    ExternStatic,
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum InsideUnsafeBlock {
+    No,
+    Yes,
 }
 
-// FIXME: Move this out, its not a diagnostic only thing anymore, and handle unsafe pattern accesses as well
 pub fn unsafe_expressions(
     db: &dyn HirDatabase,
     infer: &InferenceResult,
     def: DefWithBodyId,
     body: &Body,
     current: ExprId,
-    unsafe_expr_cb: &mut dyn FnMut(UnsafeExpr),
+    unsafe_expr_cb: &mut dyn FnMut(ExprOrPatId, InsideUnsafeBlock, UnsafetyReason),
 ) {
-    walk_unsafe(
-        db,
-        infer,
-        body,
-        &mut resolver_for_expr(db.upcast(), def, current),
-        def,
-        current,
-        false,
-        unsafe_expr_cb,
-    )
+    let mut visitor = UnsafeVisitor::new(db, infer, body, def, unsafe_expr_cb);
+    _ = visitor.resolver.update_to_inner_scope(db.upcast(), def, current);
+    visitor.walk_expr(current);
 }
 
-fn walk_unsafe(
-    db: &dyn HirDatabase,
-    infer: &InferenceResult,
-    body: &Body,
-    resolver: &mut Resolver,
+struct UnsafeVisitor<'a> {
+    db: &'a dyn HirDatabase,
+    infer: &'a InferenceResult,
+    body: &'a Body,
+    resolver: Resolver,
     def: DefWithBodyId,
-    current: ExprId,
-    inside_unsafe_block: bool,
-    unsafe_expr_cb: &mut dyn FnMut(UnsafeExpr),
-) {
-    let mut mark_unsafe_path = |path, node| {
-        let g = resolver.update_to_inner_scope(db.upcast(), def, current);
-        let hygiene = body.expr_or_pat_path_hygiene(node);
-        let value_or_partial = resolver.resolve_path_in_value_ns(db.upcast(), path, hygiene);
-        if let Some(ResolveValueResult::ValueNs(ValueNs::StaticId(id), _)) = value_or_partial {
-            let static_data = db.static_data(id);
-            if static_data.mutable || (static_data.is_extern && !static_data.has_safe_kw) {
-                unsafe_expr_cb(UnsafeExpr { node, inside_unsafe_block });
-            }
-        }
-        resolver.reset_to_guard(g);
-    };
+    inside_unsafe_block: InsideUnsafeBlock,
+    inside_assignment: bool,
+    inside_union_destructure: bool,
+    unsafe_expr_cb: &'a mut dyn FnMut(ExprOrPatId, InsideUnsafeBlock, UnsafetyReason),
+}
 
-    let expr = &body.exprs[current];
-    match expr {
-        &Expr::Call { callee, .. } => {
-            if let Some(func) = infer[callee].as_fn_def(db) {
-                if is_fn_unsafe_to_call(db, func) {
-                    unsafe_expr_cb(UnsafeExpr { node: current.into(), inside_unsafe_block });
-                }
-            }
+impl<'a> UnsafeVisitor<'a> {
+    fn new(
+        db: &'a dyn HirDatabase,
+        infer: &'a InferenceResult,
+        body: &'a Body,
+        def: DefWithBodyId,
+        unsafe_expr_cb: &'a mut dyn FnMut(ExprOrPatId, InsideUnsafeBlock, UnsafetyReason),
+    ) -> Self {
+        let resolver = def.resolver(db.upcast());
+        Self {
+            db,
+            infer,
+            body,
+            resolver,
+            def,
+            inside_unsafe_block: InsideUnsafeBlock::No,
+            inside_assignment: false,
+            inside_union_destructure: false,
+            unsafe_expr_cb,
         }
-        Expr::Path(path) => mark_unsafe_path(path, current.into()),
-        Expr::Ref { expr, rawness: Rawness::RawPtr, mutability: _ } => {
-            if let Expr::Path(_) = body.exprs[*expr] {
-                // Do not report unsafe for `addr_of[_mut]!(EXTERN_OR_MUT_STATIC)`,
-                // see https://github.com/rust-lang/rust/pull/125834.
-                return;
-            }
-        }
-        Expr::MethodCall { .. } => {
-            if infer
-                .method_resolution(current)
-                .map(|(func, _)| is_fn_unsafe_to_call(db, func))
-                .unwrap_or(false)
-            {
-                unsafe_expr_cb(UnsafeExpr { node: current.into(), inside_unsafe_block });
-            }
-        }
-        Expr::UnaryOp { expr, op: UnaryOp::Deref } => {
-            if let TyKind::Raw(..) = &infer[*expr].kind(Interner) {
-                unsafe_expr_cb(UnsafeExpr { node: current.into(), inside_unsafe_block });
-            }
-        }
-        Expr::Unsafe { .. } => {
-            return body.walk_child_exprs(current, |child| {
-                walk_unsafe(db, infer, body, resolver, def, child, true, unsafe_expr_cb);
-            });
-        }
-        &Expr::Assignment { target, value: _ } => {
-            body.walk_pats(target, &mut |pat| {
-                if let Pat::Path(path) = &body[pat] {
-                    mark_unsafe_path(path, pat.into());
-                }
-            });
-        }
-        _ => {}
     }
 
-    body.walk_child_exprs(current, |child| {
-        walk_unsafe(db, infer, body, resolver, def, child, inside_unsafe_block, unsafe_expr_cb);
-    });
+    fn call_cb(&mut self, node: ExprOrPatId, reason: UnsafetyReason) {
+        (self.unsafe_expr_cb)(node, self.inside_unsafe_block, reason);
+    }
+
+    fn walk_pats_top(&mut self, pats: impl Iterator<Item = PatId>, parent_expr: ExprId) {
+        let guard = self.resolver.update_to_inner_scope(self.db.upcast(), self.def, parent_expr);
+        pats.for_each(|pat| self.walk_pat(pat));
+        self.resolver.reset_to_guard(guard);
+    }
+
+    fn walk_pat(&mut self, current: PatId) {
+        let pat = &self.body.pats[current];
+
+        if self.inside_union_destructure {
+            match pat {
+                Pat::Tuple { .. }
+                | Pat::Record { .. }
+                | Pat::Range { .. }
+                | Pat::Slice { .. }
+                | Pat::Path(..)
+                | Pat::Lit(..)
+                | Pat::Bind { .. }
+                | Pat::TupleStruct { .. }
+                | Pat::Ref { .. }
+                | Pat::Box { .. }
+                | Pat::Expr(..)
+                | Pat::ConstBlock(..) => self.call_cb(current.into(), UnsafetyReason::UnionField),
+                // `Or` only wraps other patterns, and `Missing`/`Wild` do not constitute a read.
+                Pat::Missing | Pat::Wild | Pat::Or(_) => {}
+            }
+        }
+
+        match pat {
+            Pat::Record { .. } => {
+                if let Some((AdtId::UnionId(_), _)) = self.infer[current].as_adt() {
+                    let old_inside_union_destructure =
+                        mem::replace(&mut self.inside_union_destructure, true);
+                    self.body.walk_pats_shallow(current, |pat| self.walk_pat(pat));
+                    self.inside_union_destructure = old_inside_union_destructure;
+                    return;
+                }
+            }
+            Pat::Path(path) => self.mark_unsafe_path(current.into(), path),
+            &Pat::ConstBlock(expr) => {
+                let old_inside_assignment = mem::replace(&mut self.inside_assignment, false);
+                self.walk_expr(expr);
+                self.inside_assignment = old_inside_assignment;
+            }
+            &Pat::Expr(expr) => self.walk_expr(expr),
+            _ => {}
+        }
+
+        self.body.walk_pats_shallow(current, |pat| self.walk_pat(pat));
+    }
+
+    fn walk_expr(&mut self, current: ExprId) {
+        let expr = &self.body.exprs[current];
+        let inside_assignment = mem::replace(&mut self.inside_assignment, false);
+        match expr {
+            &Expr::Call { callee, .. } => {
+                if let Some(func) = self.infer[callee].as_fn_def(self.db) {
+                    if is_fn_unsafe_to_call(self.db, func) {
+                        self.call_cb(current.into(), UnsafetyReason::UnsafeFnCall);
+                    }
+                }
+            }
+            Expr::Path(path) => {
+                let guard =
+                    self.resolver.update_to_inner_scope(self.db.upcast(), self.def, current);
+                self.mark_unsafe_path(current.into(), path);
+                self.resolver.reset_to_guard(guard);
+            }
+            Expr::Ref { expr, rawness: Rawness::RawPtr, mutability: _ } => {
+                if let Expr::Path(_) = self.body.exprs[*expr] {
+                    // Do not report unsafe for `addr_of[_mut]!(EXTERN_OR_MUT_STATIC)`,
+                    // see https://github.com/rust-lang/rust/pull/125834.
+                    return;
+                }
+            }
+            Expr::MethodCall { .. } => {
+                if self
+                    .infer
+                    .method_resolution(current)
+                    .map(|(func, _)| is_fn_unsafe_to_call(self.db, func))
+                    .unwrap_or(false)
+                {
+                    self.call_cb(current.into(), UnsafetyReason::UnsafeFnCall);
+                }
+            }
+            Expr::UnaryOp { expr, op: UnaryOp::Deref } => {
+                if let TyKind::Raw(..) = &self.infer[*expr].kind(Interner) {
+                    self.call_cb(current.into(), UnsafetyReason::RawPtrDeref);
+                }
+            }
+            Expr::Unsafe { .. } => {
+                let old_inside_unsafe_block =
+                    mem::replace(&mut self.inside_unsafe_block, InsideUnsafeBlock::Yes);
+                self.body.walk_child_exprs_without_pats(current, |child| self.walk_expr(child));
+                self.inside_unsafe_block = old_inside_unsafe_block;
+                return;
+            }
+            &Expr::Assignment { target, value: _ } => {
+                let old_inside_assignment = mem::replace(&mut self.inside_assignment, true);
+                self.walk_pats_top(std::iter::once(target), current);
+                self.inside_assignment = old_inside_assignment;
+            }
+            Expr::InlineAsm(_) => self.call_cb(current.into(), UnsafetyReason::InlineAsm),
+            // rustc allows union assignment to propagate through field accesses and casts.
+            Expr::Cast { .. } => self.inside_assignment = inside_assignment,
+            Expr::Field { .. } => {
+                self.inside_assignment = inside_assignment;
+                if !inside_assignment {
+                    if let Some(Either::Left(FieldId { parent: VariantId::UnionId(_), .. })) =
+                        self.infer.field_resolution(current)
+                    {
+                        self.call_cb(current.into(), UnsafetyReason::UnionField);
+                    }
+                }
+            }
+            Expr::Block { statements, .. } | Expr::Async { statements, .. } => {
+                self.walk_pats_top(
+                    statements.iter().filter_map(|statement| match statement {
+                        &Statement::Let { pat, .. } => Some(pat),
+                        _ => None,
+                    }),
+                    current,
+                );
+            }
+            Expr::Match { arms, .. } => {
+                self.walk_pats_top(arms.iter().map(|arm| arm.pat), current);
+            }
+            &Expr::Let { pat, .. } => {
+                self.walk_pats_top(std::iter::once(pat), current);
+            }
+            Expr::Closure { args, .. } => {
+                self.walk_pats_top(args.iter().copied(), current);
+            }
+            _ => {}
+        }
+
+        self.body.walk_child_exprs_without_pats(current, |child| self.walk_expr(child));
+    }
+
+    fn mark_unsafe_path(&mut self, node: ExprOrPatId, path: &Path) {
+        let hygiene = self.body.expr_or_pat_path_hygiene(node);
+        let value_or_partial =
+            self.resolver.resolve_path_in_value_ns(self.db.upcast(), path, hygiene);
+        if let Some(ResolveValueResult::ValueNs(ValueNs::StaticId(id), _)) = value_or_partial {
+            let static_data = self.db.static_data(id);
+            if static_data.mutable {
+                self.call_cb(node, UnsafetyReason::MutableStatic);
+            } else if static_data.is_extern && !static_data.has_safe_kw {
+                self.call_cb(node, UnsafetyReason::ExternStatic);
+            }
+        }
+    }
 }

src/tools/rust-analyzer/crates/hir-ty/src/display.rs

@@ -1047,10 +1047,14 @@ impl HirDisplay for Ty {
                     );
                     // We print all params except implicit impl Trait params. Still a bit weird; should we leave out parent and self?
                     if parameters.len() - impl_ > 0 {
+                        let params_len = parameters.len();
                         // `parameters` are in the order of fn's params (including impl traits), fn's lifetimes
                         let parameters =
                             generic_args_sans_defaults(f, Some(generic_def_id), parameters);
-                        let without_impl = self_param as usize + type_ + const_ + lifetime;
+                        assert!(params_len >= parameters.len());
+                        let defaults = params_len - parameters.len();
+                        let without_impl =
+                            self_param as usize + type_ + const_ + lifetime - defaults;
                         // parent's params (those from enclosing impl or trait, if any).
                         let (fn_params, parent_params) = parameters.split_at(without_impl + impl_);
 
@@ -2062,12 +2066,12 @@ impl HirDisplayWithTypesMap for TypeBound {
         types_map: &TypesMap,
     ) -> Result<(), HirDisplayError> {
         match self {
-            TypeBound::Path(path, modifier) => {
+            &TypeBound::Path(path, modifier) => {
                 match modifier {
                     TraitBoundModifier::None => (),
                     TraitBoundModifier::Maybe => write!(f, "?")?,
                 }
-                path.hir_fmt(f, types_map)
+                types_map[path].hir_fmt(f, types_map)
             }
             TypeBound::Lifetime(lifetime) => {
                 write!(f, "{}", lifetime.name.display(f.db.upcast(), f.edition()))
@@ -2079,7 +2083,7 @@ impl HirDisplayWithTypesMap for TypeBound {
                     "for<{}> ",
                     lifetimes.iter().map(|it| it.display(f.db.upcast(), edition)).format(", ")
                 )?;
-                path.hir_fmt(f, types_map)
+                types_map[*path].hir_fmt(f, types_map)
             }
             TypeBound::Use(args) => {
                 let edition = f.edition();

src/tools/rust-analyzer/crates/hir-ty/src/generics.rs

@@ -55,6 +55,10 @@ impl Generics {
         self.def
     }
 
+    pub(crate) fn self_types_map(&self) -> &TypesMap {
+        &self.params.types_map
+    }
+
     pub(crate) fn iter_id(&self) -> impl Iterator<Item = GenericParamId> + '_ {
         self.iter_self_id().chain(self.iter_parent_id())
     }
@@ -86,15 +90,13 @@ impl Generics {
         self.iter_self().chain(self.iter_parent())
     }
 
-    pub(crate) fn iter_with_types_map(
+    pub(crate) fn iter_parents_with_types_map(
         &self,
     ) -> impl Iterator<Item = ((GenericParamId, GenericParamDataRef<'_>), &TypesMap)> + '_ {
-        self.iter_self().zip(std::iter::repeat(&self.params.types_map)).chain(
-            self.iter_parent().zip(
-                self.parent_generics()
-                    .into_iter()
-                    .flat_map(|it| std::iter::repeat(&it.params.types_map)),
-            ),
+        self.iter_parent().zip(
+            self.parent_generics()
+                .into_iter()
+                .flat_map(|it| std::iter::repeat(&it.params.types_map)),
         )
     }
 

src/tools/rust-analyzer/crates/hir-ty/src/infer.rs

@@ -58,7 +58,7 @@ use crate::{
     fold_tys,
     generics::Generics,
     infer::{coerce::CoerceMany, expr::ExprIsRead, unify::InferenceTable},
-    lower::ImplTraitLoweringMode,
+    lower::{ImplTraitLoweringMode, TyLoweringDiagnostic},
     mir::MirSpan,
     to_assoc_type_id,
     traits::FnTrait,
@@ -191,6 +191,14 @@ impl<T> InferOk<T> {
     }
 }
 
+#[derive(Debug, PartialEq, Eq, Clone, Copy)]
+pub enum InferenceTyDiagnosticSource {
+    /// Diagnostics that come from types in the body.
+    Body,
+    /// Diagnostics that come from types in fn parameters/return type, or static & const types.
+    Signature,
+}
+
 #[derive(Debug)]
 pub(crate) struct TypeError;
 pub(crate) type InferResult<T> = Result<InferOk<T>, TypeError>;
@@ -264,6 +272,10 @@ pub enum InferenceDiagnostic {
         expr_ty: Ty,
         cast_ty: Ty,
     },
+    TyDiagnostic {
+        source: InferenceTyDiagnosticSource,
+        diag: TyLoweringDiagnostic,
+    },
 }
 
 /// A mismatch between an expected and an inferred type.
@@ -858,7 +870,8 @@ impl<'a> InferenceContext<'a> {
     }
 
     fn collect_const(&mut self, data: &ConstData) {
-        let return_ty = self.make_ty(data.type_ref, &data.types_map);
+        let return_ty =
+            self.make_ty(data.type_ref, &data.types_map, InferenceTyDiagnosticSource::Signature);
 
         // Constants might be defining usage sites of TAITs.
         self.make_tait_coercion_table(iter::once(&return_ty));
@@ -867,7 +880,8 @@ impl<'a> InferenceContext<'a> {
     }
 
     fn collect_static(&mut self, data: &StaticData) {
-        let return_ty = self.make_ty(data.type_ref, &data.types_map);
+        let return_ty =
+            self.make_ty(data.type_ref, &data.types_map, InferenceTyDiagnosticSource::Signature);
 
         // Statics might be defining usage sites of TAITs.
         self.make_tait_coercion_table(iter::once(&return_ty));
@@ -877,11 +891,12 @@ impl<'a> InferenceContext<'a> {
 
     fn collect_fn(&mut self, func: FunctionId) {
         let data = self.db.function_data(func);
-        let mut param_tys = self.with_ty_lowering(&data.types_map, |ctx| {
-            ctx.type_param_mode(ParamLoweringMode::Placeholder)
-                .impl_trait_mode(ImplTraitLoweringMode::Param);
-            data.params.iter().map(|&type_ref| ctx.lower_ty(type_ref)).collect::<Vec<_>>()
-        });
+        let mut param_tys =
+            self.with_ty_lowering(&data.types_map, InferenceTyDiagnosticSource::Signature, |ctx| {
+                ctx.type_param_mode(ParamLoweringMode::Placeholder)
+                    .impl_trait_mode(ImplTraitLoweringMode::Param);
+                data.params.iter().map(|&type_ref| ctx.lower_ty(type_ref)).collect::<Vec<_>>()
+            });
         // Check if function contains a va_list, if it does then we append it to the parameter types
         // that are collected from the function data
         if data.is_varargs() {
@@ -918,11 +933,12 @@ impl<'a> InferenceContext<'a> {
         }
         let return_ty = data.ret_type;
 
-        let return_ty = self.with_ty_lowering(&data.types_map, |ctx| {
-            ctx.type_param_mode(ParamLoweringMode::Placeholder)
-                .impl_trait_mode(ImplTraitLoweringMode::Opaque)
-                .lower_ty(return_ty)
-        });
+        let return_ty =
+            self.with_ty_lowering(&data.types_map, InferenceTyDiagnosticSource::Signature, |ctx| {
+                ctx.type_param_mode(ParamLoweringMode::Placeholder)
+                    .impl_trait_mode(ImplTraitLoweringMode::Opaque)
+                    .lower_ty(return_ty)
+            });
         let return_ty = self.insert_type_vars(return_ty);
 
         let return_ty = if let Some(rpits) = self.db.return_type_impl_traits(func) {
@@ -1226,9 +1242,20 @@ impl<'a> InferenceContext<'a> {
         self.result.diagnostics.push(diagnostic);
     }
 
+    fn push_ty_diagnostics(
+        &mut self,
+        source: InferenceTyDiagnosticSource,
+        diagnostics: Vec<TyLoweringDiagnostic>,
+    ) {
+        self.result.diagnostics.extend(
+            diagnostics.into_iter().map(|diag| InferenceDiagnostic::TyDiagnostic { source, diag }),
+        );
+    }
+
     fn with_ty_lowering<R>(
-        &self,
+        &mut self,
         types_map: &TypesMap,
+        types_source: InferenceTyDiagnosticSource,
         f: impl FnOnce(&mut crate::lower::TyLoweringContext<'_>) -> R,
     ) -> R {
         let mut ctx = crate::lower::TyLoweringContext::new(
@@ -1237,32 +1264,41 @@ impl<'a> InferenceContext<'a> {
             types_map,
             self.owner.into(),
         );
-        f(&mut ctx)
+        let result = f(&mut ctx);
+        self.push_ty_diagnostics(types_source, ctx.diagnostics);
+        result
     }
 
     fn with_body_ty_lowering<R>(
-        &self,
+        &mut self,
         f: impl FnOnce(&mut crate::lower::TyLoweringContext<'_>) -> R,
     ) -> R {
-        self.with_ty_lowering(&self.body.types, f)
+        self.with_ty_lowering(&self.body.types, InferenceTyDiagnosticSource::Body, f)
     }
 
-    fn make_ty(&mut self, type_ref: TypeRefId, types_map: &TypesMap) -> Ty {
-        let ty = self.with_ty_lowering(types_map, |ctx| ctx.lower_ty(type_ref));
+    fn make_ty(
+        &mut self,
+        type_ref: TypeRefId,
+        types_map: &TypesMap,
+        type_source: InferenceTyDiagnosticSource,
+    ) -> Ty {
+        let ty = self.with_ty_lowering(types_map, type_source, |ctx| ctx.lower_ty(type_ref));
         let ty = self.insert_type_vars(ty);
         self.normalize_associated_types_in(ty)
     }
 
     fn make_body_ty(&mut self, type_ref: TypeRefId) -> Ty {
-        self.make_ty(type_ref, &self.body.types)
+        self.make_ty(type_ref, &self.body.types, InferenceTyDiagnosticSource::Body)
     }
 
     fn err_ty(&self) -> Ty {
         self.result.standard_types.unknown.clone()
     }
 
-    fn make_lifetime(&mut self, lifetime_ref: &LifetimeRef) -> Lifetime {
-        let lt = self.with_ty_lowering(TypesMap::EMPTY, |ctx| ctx.lower_lifetime(lifetime_ref));
+    fn make_body_lifetime(&mut self, lifetime_ref: &LifetimeRef) -> Lifetime {
+        let lt = self.with_ty_lowering(TypesMap::EMPTY, InferenceTyDiagnosticSource::Body, |ctx| {
+            ctx.lower_lifetime(lifetime_ref)
+        });
         self.insert_type_vars(lt)
     }
 
@@ -1431,12 +1467,20 @@ impl<'a> InferenceContext<'a> {
                 Some(ResolveValueResult::ValueNs(value, _)) => match value {
                     ValueNs::EnumVariantId(var) => {
                         let substs = ctx.substs_from_path(path, var.into(), true);
+                        self.push_ty_diagnostics(
+                            InferenceTyDiagnosticSource::Body,
+                            ctx.diagnostics,
+                        );
                         let ty = self.db.ty(var.lookup(self.db.upcast()).parent.into());
                         let ty = self.insert_type_vars(ty.substitute(Interner, &substs));
                         return (ty, Some(var.into()));
                     }
                     ValueNs::StructId(strukt) => {
                         let substs = ctx.substs_from_path(path, strukt.into(), true);
+                        self.push_ty_diagnostics(
+                            InferenceTyDiagnosticSource::Body,
+                            ctx.diagnostics,
+                        );
                         let ty = self.db.ty(strukt.into());
                         let ty = self.insert_type_vars(ty.substitute(Interner, &substs));
                         return (ty, Some(strukt.into()));
@@ -1462,18 +1506,21 @@ impl<'a> InferenceContext<'a> {
         return match resolution {
             TypeNs::AdtId(AdtId::StructId(strukt)) => {
                 let substs = ctx.substs_from_path(path, strukt.into(), true);
+                self.push_ty_diagnostics(InferenceTyDiagnosticSource::Body, ctx.diagnostics);
                 let ty = self.db.ty(strukt.into());
                 let ty = self.insert_type_vars(ty.substitute(Interner, &substs));
                 forbid_unresolved_segments((ty, Some(strukt.into())), unresolved)
             }
             TypeNs::AdtId(AdtId::UnionId(u)) => {
                 let substs = ctx.substs_from_path(path, u.into(), true);
+                self.push_ty_diagnostics(InferenceTyDiagnosticSource::Body, ctx.diagnostics);
                 let ty = self.db.ty(u.into());
                 let ty = self.insert_type_vars(ty.substitute(Interner, &substs));
                 forbid_unresolved_segments((ty, Some(u.into())), unresolved)
             }
             TypeNs::EnumVariantId(var) => {
                 let substs = ctx.substs_from_path(path, var.into(), true);
+                self.push_ty_diagnostics(InferenceTyDiagnosticSource::Body, ctx.diagnostics);
                 let ty = self.db.ty(var.lookup(self.db.upcast()).parent.into());
                 let ty = self.insert_type_vars(ty.substitute(Interner, &substs));
                 forbid_unresolved_segments((ty, Some(var.into())), unresolved)
@@ -1519,6 +1566,9 @@ impl<'a> InferenceContext<'a> {
                         resolved_segment,
                         current_segment,
                         false,
+                        &mut |_, _reason| {
+                            // FIXME: Report an error.
+                        },
                     );
 
                     ty = self.table.insert_type_vars(ty);
@@ -1532,6 +1582,7 @@ impl<'a> InferenceContext<'a> {
                     remaining_idx += 1;
                     remaining_segments = remaining_segments.skip(1);
                 }
+                self.push_ty_diagnostics(InferenceTyDiagnosticSource::Body, ctx.diagnostics);
 
                 let variant = ty.as_adt().and_then(|(id, _)| match id {
                     AdtId::StructId(s) => Some(VariantId::StructId(s)),
@@ -1550,6 +1601,7 @@ impl<'a> InferenceContext<'a> {
                 };
                 let substs =
                     ctx.substs_from_path_segment(resolved_seg, Some(it.into()), true, None);
+                self.push_ty_diagnostics(InferenceTyDiagnosticSource::Body, ctx.diagnostics);
                 let ty = self.db.ty(it.into());
                 let ty = self.insert_type_vars(ty.substitute(Interner, &substs));
 

src/tools/rust-analyzer/crates/hir-ty/src/infer/coerce.rs

@@ -125,7 +125,11 @@ impl CoerceMany {
         // pointers to have a chance at getting a match. See
         // https://github.com/rust-lang/rust/blob/7b805396bf46dce972692a6846ce2ad8481c5f85/src/librustc_typeck/check/coercion.rs#L877-L916
         let sig = match (self.merged_ty().kind(Interner), expr_ty.kind(Interner)) {
-            (TyKind::FnDef(x, _), TyKind::FnDef(y, _)) if x == y => None,
+            (TyKind::FnDef(x, _), TyKind::FnDef(y, _))
+                if x == y && ctx.table.unify(&self.merged_ty(), &expr_ty) =>
+            {
+                None
+            }
             (TyKind::Closure(x, _), TyKind::Closure(y, _)) if x == y => None,
             (TyKind::FnDef(..) | TyKind::Closure(..), TyKind::FnDef(..) | TyKind::Closure(..)) => {
                 // FIXME: we're ignoring safety here. To be more correct, if we have one FnDef and one Closure,

src/tools/rust-analyzer/crates/hir-ty/src/infer/expr.rs

@@ -1287,8 +1287,8 @@ impl InferenceContext<'_> {
         tgt_expr: ExprId,
     ) {
         match fn_x {
-            FnTrait::FnOnce => (),
-            FnTrait::FnMut => {
+            FnTrait::FnOnce | FnTrait::AsyncFnOnce => (),
+            FnTrait::FnMut | FnTrait::AsyncFnMut => {
                 if let TyKind::Ref(Mutability::Mut, lt, inner) = derefed_callee.kind(Interner) {
                     if adjustments
                         .last()
@@ -1312,7 +1312,7 @@ impl InferenceContext<'_> {
                     ));
                 }
             }
-            FnTrait::Fn => {
+            FnTrait::Fn | FnTrait::AsyncFn => {
                 if !matches!(derefed_callee.kind(Interner), TyKind::Ref(Mutability::Not, _, _)) {
                     adjustments.push(Adjustment::borrow(
                         Mutability::Not,
@@ -2155,7 +2155,7 @@ impl InferenceContext<'_> {
                                 DebruijnIndex::INNERMOST,
                             )
                         },
-                        |this, lt_ref| this.make_lifetime(lt_ref),
+                        |this, lt_ref| this.make_body_lifetime(lt_ref),
                     ),
                 };
 

src/tools/rust-analyzer/crates/hir-ty/src/infer/path.rs

@@ -19,7 +19,7 @@ use crate::{
     TyBuilder, TyExt, TyKind, ValueTyDefId,
 };
 
-use super::{ExprOrPatId, InferenceContext};
+use super::{ExprOrPatId, InferenceContext, InferenceTyDiagnosticSource};
 
 impl InferenceContext<'_> {
     pub(super) fn infer_path(&mut self, path: &Path, id: ExprOrPatId) -> Option<Ty> {
@@ -163,6 +163,7 @@ impl InferenceContext<'_> {
 
             let remaining_segments_for_ty = path.segments().take(path.segments().len() - 1);
             let (ty, _) = ctx.lower_ty_relative_path(ty, orig_ns, remaining_segments_for_ty);
+            self.push_ty_diagnostics(InferenceTyDiagnosticSource::Body, ctx.diagnostics);
             let ty = self.table.insert_type_vars(ty);
             let ty = self.table.normalize_associated_types_in(ty);
             self.resolve_ty_assoc_item(ty, last.name, id).map(|(it, substs)| (it, Some(substs)))?
@@ -265,6 +266,9 @@ impl InferenceContext<'_> {
                         resolved_segment,
                         remaining_segments_for_ty,
                         true,
+                        &mut |_, _reason| {
+                            // FIXME: Report an error.
+                        },
                     )
                 });
                 if ty.is_unknown() {

src/tools/rust-analyzer/crates/hir-ty/src/infer/unify.rs

@@ -666,7 +666,7 @@ impl<'a> InferenceTable<'a> {
             highest_known_var: InferenceVar,
         }
         impl TypeFolder<Interner> for VarFudger<'_, '_> {
-            fn as_dyn(&mut self) -> &mut dyn TypeFolder<Interner, Error = Self::Error> {
+            fn as_dyn(&mut self) -> &mut dyn TypeFolder<Interner> {
                 self
             }
 
@@ -794,69 +794,75 @@ impl<'a> InferenceTable<'a> {
         ty: &Ty,
         num_args: usize,
     ) -> Option<(FnTrait, Vec<Ty>, Ty)> {
-        let krate = self.trait_env.krate;
-        let fn_once_trait = FnTrait::FnOnce.get_id(self.db, krate)?;
-        let trait_data = self.db.trait_data(fn_once_trait);
-        let output_assoc_type =
-            trait_data.associated_type_by_name(&Name::new_symbol_root(sym::Output.clone()))?;
+        for (fn_trait_name, output_assoc_name, subtraits) in [
+            (FnTrait::FnOnce, sym::Output.clone(), &[FnTrait::Fn, FnTrait::FnMut][..]),
+            (FnTrait::AsyncFnMut, sym::CallRefFuture.clone(), &[FnTrait::AsyncFn]),
+            (FnTrait::AsyncFnOnce, sym::CallOnceFuture.clone(), &[]),
+        ] {
+            let krate = self.trait_env.krate;
+            let fn_trait = fn_trait_name.get_id(self.db, krate)?;
+            let trait_data = self.db.trait_data(fn_trait);
+            let output_assoc_type =
+                trait_data.associated_type_by_name(&Name::new_symbol_root(output_assoc_name))?;
 
-        let mut arg_tys = Vec::with_capacity(num_args);
-        let arg_ty = TyBuilder::tuple(num_args)
-            .fill(|it| {
-                let arg = match it {
-                    ParamKind::Type => self.new_type_var(),
-                    ParamKind::Lifetime => unreachable!("Tuple with lifetime parameter"),
-                    ParamKind::Const(_) => unreachable!("Tuple with const parameter"),
-                };
-                arg_tys.push(arg.clone());
-                arg.cast(Interner)
-            })
-            .build();
+            let mut arg_tys = Vec::with_capacity(num_args);
+            let arg_ty = TyBuilder::tuple(num_args)
+                .fill(|it| {
+                    let arg = match it {
+                        ParamKind::Type => self.new_type_var(),
+                        ParamKind::Lifetime => unreachable!("Tuple with lifetime parameter"),
+                        ParamKind::Const(_) => unreachable!("Tuple with const parameter"),
+                    };
+                    arg_tys.push(arg.clone());
+                    arg.cast(Interner)
+                })
+                .build();
 
-        let b = TyBuilder::trait_ref(self.db, fn_once_trait);
-        if b.remaining() != 2 {
-            return None;
-        }
-        let mut trait_ref = b.push(ty.clone()).push(arg_ty).build();
+            let b = TyBuilder::trait_ref(self.db, fn_trait);
+            if b.remaining() != 2 {
+                return None;
+            }
+            let mut trait_ref = b.push(ty.clone()).push(arg_ty).build();
 
-        let projection = {
-            TyBuilder::assoc_type_projection(
+            let projection = TyBuilder::assoc_type_projection(
                 self.db,
                 output_assoc_type,
                 Some(trait_ref.substitution.clone()),
             )
-            .build()
-        };
+            .fill_with_unknown()
+            .build();
 
-        let trait_env = self.trait_env.env.clone();
-        let obligation = InEnvironment {
-            goal: trait_ref.clone().cast(Interner),
-            environment: trait_env.clone(),
-        };
-        let canonical = self.canonicalize(obligation.clone());
-        if self.db.trait_solve(krate, self.trait_env.block, canonical.cast(Interner)).is_some() {
-            self.register_obligation(obligation.goal);
-            let return_ty = self.normalize_projection_ty(projection);
-            for fn_x in [FnTrait::Fn, FnTrait::FnMut, FnTrait::FnOnce] {
-                let fn_x_trait = fn_x.get_id(self.db, krate)?;
-                trait_ref.trait_id = to_chalk_trait_id(fn_x_trait);
-                let obligation: chalk_ir::InEnvironment<chalk_ir::Goal<Interner>> = InEnvironment {
-                    goal: trait_ref.clone().cast(Interner),
-                    environment: trait_env.clone(),
-                };
-                let canonical = self.canonicalize(obligation.clone());
-                if self
-                    .db
-                    .trait_solve(krate, self.trait_env.block, canonical.cast(Interner))
-                    .is_some()
-                {
-                    return Some((fn_x, arg_tys, return_ty));
+            let trait_env = self.trait_env.env.clone();
+            let obligation = InEnvironment {
+                goal: trait_ref.clone().cast(Interner),
+                environment: trait_env.clone(),
+            };
+            let canonical = self.canonicalize(obligation.clone());
+            if self.db.trait_solve(krate, self.trait_env.block, canonical.cast(Interner)).is_some()
+            {
+                self.register_obligation(obligation.goal);
+                let return_ty = self.normalize_projection_ty(projection);
+                for &fn_x in subtraits {
+                    let fn_x_trait = fn_x.get_id(self.db, krate)?;
+                    trait_ref.trait_id = to_chalk_trait_id(fn_x_trait);
+                    let obligation: chalk_ir::InEnvironment<chalk_ir::Goal<Interner>> =
+                        InEnvironment {
+                            goal: trait_ref.clone().cast(Interner),
+                            environment: trait_env.clone(),
+                        };
+                    let canonical = self.canonicalize(obligation.clone());
+                    if self
+                        .db
+                        .trait_solve(krate, self.trait_env.block, canonical.cast(Interner))
+                        .is_some()
+                    {
+                        return Some((fn_x, arg_tys, return_ty));
+                    }
                 }
+                return Some((fn_trait_name, arg_tys, return_ty));
             }
-            unreachable!("It should at least implement FnOnce at this point");
-        } else {
-            None
         }
+        None
     }
 
     pub(super) fn insert_type_vars<T>(&mut self, ty: T) -> T
@@ -1004,7 +1010,7 @@ mod resolve {
     where
         F: Fn(InferenceVar, VariableKind, GenericArg, DebruijnIndex) -> GenericArg,
     {
-        fn as_dyn(&mut self) -> &mut dyn TypeFolder<Interner, Error = Self::Error> {
+        fn as_dyn(&mut self) -> &mut dyn TypeFolder<Interner> {
             self
         }
 

src/tools/rust-analyzer/crates/hir-ty/src/inhabitedness.rs

@@ -5,8 +5,7 @@ use chalk_ir::{
     visit::{TypeSuperVisitable, TypeVisitable, TypeVisitor},
     DebruijnIndex,
 };
-use hir_def::{visibility::Visibility, AdtId, EnumVariantId, HasModule, ModuleId, VariantId};
-use intern::sym;
+use hir_def::{visibility::Visibility, AdtId, EnumVariantId, ModuleId, VariantId};
 use rustc_hash::FxHashSet;
 
 use crate::{
@@ -118,11 +117,6 @@ impl UninhabitedFrom<'_> {
         variant: VariantId,
         subst: &Substitution,
     ) -> ControlFlow<VisiblyUninhabited> {
-        let is_local = variant.krate(self.db.upcast()) == self.target_mod.krate();
-        if !is_local && self.db.attrs(variant.into()).by_key(&sym::non_exhaustive).exists() {
-            return CONTINUE_OPAQUELY_INHABITED;
-        }
-
         let variant_data = self.db.variant_data(variant);
         let fields = variant_data.fields();
         if fields.is_empty() {

src/tools/rust-analyzer/crates/hir-ty/src/lib.rs

@@ -84,12 +84,14 @@ pub use infer::{
     cast::CastError,
     closure::{CaptureKind, CapturedItem},
     could_coerce, could_unify, could_unify_deeply, Adjust, Adjustment, AutoBorrow, BindingMode,
-    InferenceDiagnostic, InferenceResult, OverloadedDeref, PointerCast,
+    InferenceDiagnostic, InferenceResult, InferenceTyDiagnosticSource, OverloadedDeref,
+    PointerCast,
 };
 pub use interner::Interner;
 pub use lower::{
-    associated_type_shorthand_candidates, ImplTraitLoweringMode, ParamLoweringMode, TyDefId,
-    TyLoweringContext, ValueTyDefId,
+    associated_type_shorthand_candidates, GenericArgsProhibitedReason, ImplTraitLoweringMode,
+    ParamLoweringMode, TyDefId, TyLoweringContext, TyLoweringDiagnostic, TyLoweringDiagnosticKind,
+    ValueTyDefId,
 };
 pub use mapping::{
     from_assoc_type_id, from_chalk_trait_id, from_foreign_def_id, from_placeholder_idx,
@@ -385,7 +387,6 @@ pub enum FnAbi {
     Fastcall,
     FastcallUnwind,
     Msp430Interrupt,
-    PlatformIntrinsic,
     PtxKernel,
     RiscvInterruptM,
     RiscvInterruptS,
@@ -444,7 +445,6 @@ impl FnAbi {
             s if *s == sym::fastcall_dash_unwind => FnAbi::FastcallUnwind,
             s if *s == sym::fastcall => FnAbi::Fastcall,
             s if *s == sym::msp430_dash_interrupt => FnAbi::Msp430Interrupt,
-            s if *s == sym::platform_dash_intrinsic => FnAbi::PlatformIntrinsic,
             s if *s == sym::ptx_dash_kernel => FnAbi::PtxKernel,
             s if *s == sym::riscv_dash_interrupt_dash_m => FnAbi::RiscvInterruptM,
             s if *s == sym::riscv_dash_interrupt_dash_s => FnAbi::RiscvInterruptS,
@@ -487,7 +487,6 @@ impl FnAbi {
             FnAbi::Fastcall => "fastcall",
             FnAbi::FastcallUnwind => "fastcall-unwind",
             FnAbi::Msp430Interrupt => "msp430-interrupt",
-            FnAbi::PlatformIntrinsic => "platform-intrinsic",
             FnAbi::PtxKernel => "ptx-kernel",
             FnAbi::RiscvInterruptM => "riscv-interrupt-m",
             FnAbi::RiscvInterruptS => "riscv-interrupt-s",
@@ -646,7 +645,7 @@ pub(crate) fn fold_free_vars<T: HasInterner<Interner = Interner> + TypeFoldable<
             F2: FnMut(Ty, BoundVar, DebruijnIndex) -> Const,
         > TypeFolder<Interner> for FreeVarFolder<F1, F2>
     {
-        fn as_dyn(&mut self) -> &mut dyn TypeFolder<Interner, Error = Self::Error> {
+        fn as_dyn(&mut self) -> &mut dyn TypeFolder<Interner> {
             self
         }
 
@@ -697,7 +696,7 @@ pub(crate) fn fold_tys_and_consts<T: HasInterner<Interner = Interner> + TypeFold
     impl<F: FnMut(Either<Ty, Const>, DebruijnIndex) -> Either<Ty, Const>> TypeFolder<Interner>
         for TyFolder<F>
     {
-        fn as_dyn(&mut self) -> &mut dyn TypeFolder<Interner, Error = Self::Error> {
+        fn as_dyn(&mut self) -> &mut dyn TypeFolder<Interner> {
             self
         }
 

src/tools/rust-analyzer/crates/hir-ty/src/lower.rs

@@ -33,8 +33,8 @@ use hir_def::{
     path::{GenericArg, GenericArgs, ModPath, Path, PathKind, PathSegment, PathSegments},
     resolver::{HasResolver, LifetimeNs, Resolver, TypeNs},
     type_ref::{
-        ConstRef, LifetimeRef, TraitBoundModifier, TraitRef as HirTraitRef, TypeBound, TypeRef,
-        TypeRefId, TypesMap, TypesSourceMap,
+        ConstRef, LifetimeRef, PathId, TraitBoundModifier, TraitRef as HirTraitRef, TypeBound,
+        TypeRef, TypeRefId, TypesMap, TypesSourceMap,
     },
     AdtId, AssocItemId, CallableDefId, ConstId, ConstParamId, DefWithBodyId, EnumId, EnumVariantId,
     FunctionId, GenericDefId, GenericParamId, HasModule, ImplId, InTypeConstLoc, ItemContainerId,
@@ -48,7 +48,7 @@ use rustc_pattern_analysis::Captures;
 use smallvec::SmallVec;
 use stdx::{impl_from, never};
 use syntax::ast;
-use triomphe::Arc;
+use triomphe::{Arc, ThinArc};
 
 use crate::{
     all_super_traits,
@@ -102,6 +102,31 @@ impl ImplTraitLoweringState {
     }
 }
 
+type TypeSource = Either<TypeRefId, hir_def::type_ref::TypeSource>;
+
+#[derive(Debug, PartialEq, Eq, Clone)]
+pub struct TyLoweringDiagnostic {
+    pub source: TypeSource,
+    pub kind: TyLoweringDiagnosticKind,
+}
+
+#[derive(Debug, PartialEq, Eq, Clone)]
+pub enum TyLoweringDiagnosticKind {
+    GenericArgsProhibited { segment: u32, reason: GenericArgsProhibitedReason },
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum GenericArgsProhibitedReason {
+    Module,
+    TyParam,
+    SelfTy,
+    PrimitiveTy,
+    /// When there is a generic enum, within the expression `Enum::Variant`,
+    /// either `Enum` or `Variant` are allowed to have generic arguments, but not both.
+    // FIXME: This is not used now but it should be.
+    EnumVariant,
+}
+
 #[derive(Debug)]
 pub struct TyLoweringContext<'a> {
     pub db: &'a dyn HirDatabase,
@@ -125,6 +150,7 @@ pub struct TyLoweringContext<'a> {
     expander: Option<Expander>,
     /// Tracks types with explicit `?Sized` bounds.
     pub(crate) unsized_types: FxHashSet<Ty>,
+    pub(crate) diagnostics: Vec<TyLoweringDiagnostic>,
 }
 
 impl<'a> TyLoweringContext<'a> {
@@ -159,6 +185,7 @@ impl<'a> TyLoweringContext<'a> {
             type_param_mode,
             expander: None,
             unsized_types: FxHashSet::default(),
+            diagnostics: Vec::new(),
         }
     }
 
@@ -198,6 +225,20 @@ impl<'a> TyLoweringContext<'a> {
         self.type_param_mode = type_param_mode;
         self
     }
+
+    pub fn push_diagnostic(&mut self, type_ref: TypeRefId, kind: TyLoweringDiagnosticKind) {
+        let source = match self.types_source_map {
+            Some(source_map) => {
+                let Ok(source) = source_map.type_syntax(type_ref) else {
+                    stdx::never!("error in synthetic type");
+                    return;
+                };
+                Either::Right(source)
+            }
+            None => Either::Left(type_ref),
+        };
+        self.diagnostics.push(TyLoweringDiagnostic { source, kind });
+    }
 }
 
 #[derive(Copy, Clone, Debug, PartialEq, Eq, Default)]
@@ -264,7 +305,8 @@ impl<'a> TyLoweringContext<'a> {
                     .intern(Interner)
             }
             TypeRef::Path(path) => {
-                let (ty, res_) = self.lower_path(path);
+                let (ty, res_) =
+                    self.lower_path(path, PathId::from_type_ref_unchecked(type_ref_id));
                 res = res_;
                 ty
             }
@@ -463,6 +505,7 @@ impl<'a> TyLoweringContext<'a> {
                                 impl_trait_mode: mem::take(&mut self.impl_trait_mode),
                                 expander: self.expander.take(),
                                 unsized_types: mem::take(&mut self.unsized_types),
+                                diagnostics: mem::take(&mut self.diagnostics),
                             };
 
                             let ty = inner_ctx.lower_ty(type_ref);
@@ -470,6 +513,7 @@ impl<'a> TyLoweringContext<'a> {
                             self.impl_trait_mode = inner_ctx.impl_trait_mode;
                             self.expander = inner_ctx.expander;
                             self.unsized_types = inner_ctx.unsized_types;
+                            self.diagnostics = inner_ctx.diagnostics;
 
                             self.expander.as_mut().unwrap().exit(mark);
                             Some(ty)
@@ -541,6 +585,10 @@ impl<'a> TyLoweringContext<'a> {
         resolved_segment: PathSegment<'_>,
         remaining_segments: PathSegments<'_>,
         infer_args: bool,
+        on_prohibited_generics_for_resolved_segment: &mut dyn FnMut(
+            &mut Self,
+            GenericArgsProhibitedReason,
+        ),
     ) -> (Ty, Option<TypeNs>) {
         let ty = match resolution {
             TypeNs::TraitId(trait_) => {
@@ -607,28 +655,44 @@ impl<'a> TyLoweringContext<'a> {
                 // FIXME(trait_alias): Implement trait alias.
                 return (TyKind::Error.intern(Interner), None);
             }
-            TypeNs::GenericParam(param_id) => match self.type_param_mode {
-                ParamLoweringMode::Placeholder => {
-                    TyKind::Placeholder(to_placeholder_idx(self.db, param_id.into()))
+            TypeNs::GenericParam(param_id) => {
+                if resolved_segment.args_and_bindings.is_some() {
+                    on_prohibited_generics_for_resolved_segment(
+                        self,
+                        GenericArgsProhibitedReason::TyParam,
+                    );
                 }
-                ParamLoweringMode::Variable => {
-                    let idx = match self
-                        .generics()
-                        .expect("generics in scope")
-                        .type_or_const_param_idx(param_id.into())
-                    {
-                        None => {
-                            never!("no matching generics");
-                            return (TyKind::Error.intern(Interner), None);
-                        }
-                        Some(idx) => idx,
-                    };
 
-                    TyKind::BoundVar(BoundVar::new(self.in_binders, idx))
+                match self.type_param_mode {
+                    ParamLoweringMode::Placeholder => {
+                        TyKind::Placeholder(to_placeholder_idx(self.db, param_id.into()))
+                    }
+                    ParamLoweringMode::Variable => {
+                        let idx = match self
+                            .generics()
+                            .expect("generics in scope")
+                            .type_or_const_param_idx(param_id.into())
+                        {
+                            None => {
+                                never!("no matching generics");
+                                return (TyKind::Error.intern(Interner), None);
+                            }
+                            Some(idx) => idx,
+                        };
+
+                        TyKind::BoundVar(BoundVar::new(self.in_binders, idx))
+                    }
                 }
+                .intern(Interner)
             }
-            .intern(Interner),
             TypeNs::SelfType(impl_id) => {
+                if resolved_segment.args_and_bindings.is_some() {
+                    on_prohibited_generics_for_resolved_segment(
+                        self,
+                        GenericArgsProhibitedReason::SelfTy,
+                    );
+                }
+
                 let generics = self.generics().expect("impl should have generic param scope");
 
                 match self.type_param_mode {
@@ -654,6 +718,13 @@ impl<'a> TyLoweringContext<'a> {
                 }
             }
             TypeNs::AdtSelfType(adt) => {
+                if resolved_segment.args_and_bindings.is_some() {
+                    on_prohibited_generics_for_resolved_segment(
+                        self,
+                        GenericArgsProhibitedReason::SelfTy,
+                    );
+                }
+
                 let generics = generics(self.db.upcast(), adt.into());
                 let substs = match self.type_param_mode {
                     ParamLoweringMode::Placeholder => generics.placeholder_subst(self.db),
@@ -666,6 +737,12 @@ impl<'a> TyLoweringContext<'a> {
 
             TypeNs::AdtId(it) => self.lower_path_inner(resolved_segment, it.into(), infer_args),
             TypeNs::BuiltinType(it) => {
+                if resolved_segment.args_and_bindings.is_some() {
+                    on_prohibited_generics_for_resolved_segment(
+                        self,
+                        GenericArgsProhibitedReason::PrimitiveTy,
+                    );
+                }
                 self.lower_path_inner(resolved_segment, it.into(), infer_args)
             }
             TypeNs::TypeAliasId(it) => {
@@ -677,7 +754,7 @@ impl<'a> TyLoweringContext<'a> {
         self.lower_ty_relative_path(ty, Some(resolution), remaining_segments)
     }
 
-    pub(crate) fn lower_path(&mut self, path: &Path) -> (Ty, Option<TypeNs>) {
+    pub(crate) fn lower_path(&mut self, path: &Path, path_id: PathId) -> (Ty, Option<TypeNs>) {
         // Resolve the path (in type namespace)
         if let Some(type_ref) = path.type_anchor() {
             let (ty, res) = self.lower_ty_ext(type_ref);
@@ -692,19 +769,44 @@ impl<'a> TyLoweringContext<'a> {
 
         if matches!(resolution, TypeNs::TraitId(_)) && remaining_index.is_none() {
             // trait object type without dyn
-            let bound = TypeBound::Path(path.clone(), TraitBoundModifier::None);
+            let bound = TypeBound::Path(path_id, TraitBoundModifier::None);
             let ty = self.lower_dyn_trait(&[bound]);
             return (ty, None);
         }
 
-        let (resolved_segment, remaining_segments) = match remaining_index {
-            None => (
-                path.segments().last().expect("resolved path has at least one element"),
-                PathSegments::EMPTY,
-            ),
-            Some(i) => (path.segments().get(i - 1).unwrap(), path.segments().skip(i)),
-        };
-        self.lower_partly_resolved_path(resolution, resolved_segment, remaining_segments, false)
+        let (module_segments, resolved_segment_idx, resolved_segment, remaining_segments) =
+            match remaining_index {
+                None => (
+                    path.segments().strip_last(),
+                    path.segments().len() - 1,
+                    path.segments().last().expect("resolved path has at least one element"),
+                    PathSegments::EMPTY,
+                ),
+                Some(i) => (
+                    path.segments().take(i - 1),
+                    i - 1,
+                    path.segments().get(i - 1).unwrap(),
+                    path.segments().skip(i),
+                ),
+            };
+
+        self.prohibit_generics(path_id, 0, module_segments, GenericArgsProhibitedReason::Module);
+
+        self.lower_partly_resolved_path(
+            resolution,
+            resolved_segment,
+            remaining_segments,
+            false,
+            &mut |this, reason| {
+                this.push_diagnostic(
+                    path_id.type_ref(),
+                    TyLoweringDiagnosticKind::GenericArgsProhibited {
+                        segment: resolved_segment_idx as u32,
+                        reason,
+                    },
+                )
+            },
+        )
     }
 
     fn select_associated_type(&mut self, res: Option<TypeNs>, segment: PathSegment<'_>) -> Ty {
@@ -741,12 +843,8 @@ impl<'a> TyLoweringContext<'a> {
                 // generic params. It's inefficient to splice the `Substitution`s, so we may want
                 // that method to optionally take parent `Substitution` as we already know them at
                 // this point (`t.substitution`).
-                let substs = self.substs_from_path_segment(
-                    segment.clone(),
-                    Some(associated_ty.into()),
-                    false,
-                    None,
-                );
+                let substs =
+                    self.substs_from_path_segment(segment, Some(associated_ty.into()), false, None);
 
                 let len_self =
                     crate::generics::generics(self.db.upcast(), associated_ty.into()).len_self();
@@ -998,12 +1096,41 @@ impl<'a> TyLoweringContext<'a> {
         TraitRef { trait_id: to_chalk_trait_id(resolved), substitution: substs }
     }
 
-    fn lower_trait_ref_from_path(&mut self, path: &Path, explicit_self_ty: Ty) -> Option<TraitRef> {
+    fn prohibit_generics(
+        &mut self,
+        path_id: PathId,
+        idx: u32,
+        segments: PathSegments<'_>,
+        reason: GenericArgsProhibitedReason,
+    ) {
+        segments.iter().zip(idx..).for_each(|(segment, idx)| {
+            if segment.args_and_bindings.is_some() {
+                self.push_diagnostic(
+                    path_id.type_ref(),
+                    TyLoweringDiagnosticKind::GenericArgsProhibited { segment: idx, reason },
+                );
+            }
+        });
+    }
+
+    fn lower_trait_ref_from_path(
+        &mut self,
+        path_id: PathId,
+        explicit_self_ty: Ty,
+    ) -> Option<TraitRef> {
+        let path = &self.types_map[path_id];
         let resolved = match self.resolver.resolve_path_in_type_ns_fully(self.db.upcast(), path)? {
             // FIXME(trait_alias): We need to handle trait alias here.
             TypeNs::TraitId(tr) => tr,
             _ => return None,
         };
+        // Do this after we verify it's indeed a trait to not confuse the user if they're not modules.
+        self.prohibit_generics(
+            path_id,
+            0,
+            path.segments().strip_last(),
+            GenericArgsProhibitedReason::Module,
+        );
         let segment = path.segments().last().expect("path should have at least one segment");
         Some(self.lower_trait_ref_from_resolved_path(resolved, segment, explicit_self_ty))
     }
@@ -1013,7 +1140,7 @@ impl<'a> TyLoweringContext<'a> {
         trait_ref: &HirTraitRef,
         explicit_self_ty: Ty,
     ) -> Option<TraitRef> {
-        self.lower_trait_ref_from_path(&trait_ref.path, explicit_self_ty)
+        self.lower_trait_ref_from_path(trait_ref.path, explicit_self_ty)
     }
 
     fn trait_ref_substs_from_path(
@@ -1072,11 +1199,11 @@ impl<'a> TyLoweringContext<'a> {
     ) -> impl Iterator<Item = QuantifiedWhereClause> + use<'b, 'a> {
         let mut trait_ref = None;
         let clause = match bound {
-            TypeBound::Path(path, TraitBoundModifier::None) => {
+            &TypeBound::Path(path, TraitBoundModifier::None) => {
                 trait_ref = self.lower_trait_ref_from_path(path, self_ty);
                 trait_ref.clone().map(WhereClause::Implemented).map(crate::wrap_empty_binders)
             }
-            TypeBound::Path(path, TraitBoundModifier::Maybe) => {
+            &TypeBound::Path(path, TraitBoundModifier::Maybe) => {
                 let sized_trait = self
                     .db
                     .lang_item(self.resolver.krate(), LangItem::Sized)
@@ -1092,7 +1219,7 @@ impl<'a> TyLoweringContext<'a> {
                 }
                 None
             }
-            TypeBound::ForLifetime(_, path) => {
+            &TypeBound::ForLifetime(_, path) => {
                 // FIXME Don't silently drop the hrtb lifetimes here
                 trait_ref = self.lower_trait_ref_from_path(path, self_ty);
                 trait_ref.clone().map(WhereClause::Implemented).map(crate::wrap_empty_binders)
@@ -1121,8 +1248,8 @@ impl<'a> TyLoweringContext<'a> {
         trait_ref: TraitRef,
     ) -> impl Iterator<Item = QuantifiedWhereClause> + use<'b, 'a> {
         let last_segment = match bound {
-            TypeBound::Path(path, TraitBoundModifier::None) | TypeBound::ForLifetime(_, path) => {
-                path.segments().last()
+            &TypeBound::Path(path, TraitBoundModifier::None) | &TypeBound::ForLifetime(_, path) => {
+                self.types_map[path].segments().last()
             }
             TypeBound::Path(_, TraitBoundModifier::Maybe)
             | TypeBound::Use(_)
@@ -1227,7 +1354,9 @@ impl<'a> TyLoweringContext<'a> {
                                     }
                                     _ => unreachable!(),
                                 }
-                                ext.lower_ty(type_ref)
+                                let ty = ext.lower_ty(type_ref);
+                                self.diagnostics.extend(ext.diagnostics);
+                                ty
                             } else {
                                 self.lower_ty(type_ref)
                             };
@@ -1523,11 +1652,24 @@ fn named_associated_type_shorthand_candidates<R>(
     }
 }
 
-/// Build the type of all specific fields of a struct or enum variant.
+pub(crate) type Diagnostics = Option<ThinArc<(), TyLoweringDiagnostic>>;
+
+fn create_diagnostics(diagnostics: Vec<TyLoweringDiagnostic>) -> Diagnostics {
+    (!diagnostics.is_empty()).then(|| ThinArc::from_header_and_iter((), diagnostics.into_iter()))
+}
+
 pub(crate) fn field_types_query(
     db: &dyn HirDatabase,
     variant_id: VariantId,
 ) -> Arc<ArenaMap<LocalFieldId, Binders<Ty>>> {
+    db.field_types_with_diagnostics(variant_id).0
+}
+
+/// Build the type of all specific fields of a struct or enum variant.
+pub(crate) fn field_types_with_diagnostics_query(
+    db: &dyn HirDatabase,
+    variant_id: VariantId,
+) -> (Arc<ArenaMap<LocalFieldId, Binders<Ty>>>, Diagnostics) {
     let var_data = variant_id.variant_data(db.upcast());
     let (resolver, def): (_, GenericDefId) = match variant_id {
         VariantId::StructId(it) => (it.resolver(db.upcast()), it.into()),
@@ -1543,7 +1685,7 @@ pub(crate) fn field_types_query(
     for (field_id, field_data) in var_data.fields().iter() {
         res.insert(field_id, make_binders(db, &generics, ctx.lower_ty(field_data.type_ref)));
     }
-    Arc::new(res)
+    (Arc::new(res), create_diagnostics(ctx.diagnostics))
 }
 
 /// This query exists only to be used when resolving short-hand associated types
@@ -1593,9 +1735,10 @@ pub(crate) fn generic_predicates_for_param_query(
             }
 
             match bound {
-                TypeBound::ForLifetime(_, path) | TypeBound::Path(path, _) => {
+                &TypeBound::ForLifetime(_, path) | &TypeBound::Path(path, _) => {
                     // Only lower the bound if the trait could possibly define the associated
                     // type we're looking for.
+                    let path = &ctx.types_map[path];
 
                     let Some(assoc_name) = &assoc_name else { return true };
                     let Some(TypeNs::TraitId(tr)) =
@@ -1743,15 +1886,22 @@ pub(crate) fn generic_predicates_query(
     db: &dyn HirDatabase,
     def: GenericDefId,
 ) -> GenericPredicates {
-    generic_predicates_filtered_by(db, def, |_, _| true)
+    generic_predicates_filtered_by(db, def, |_, _| true).0
 }
 
-/// Resolve the where clause(s) of an item with generics,
-/// except the ones inherited from the parent
 pub(crate) fn generic_predicates_without_parent_query(
     db: &dyn HirDatabase,
     def: GenericDefId,
 ) -> GenericPredicates {
+    db.generic_predicates_without_parent_with_diagnostics(def).0
+}
+
+/// Resolve the where clause(s) of an item with generics,
+/// except the ones inherited from the parent
+pub(crate) fn generic_predicates_without_parent_with_diagnostics_query(
+    db: &dyn HirDatabase,
+    def: GenericDefId,
+) -> (GenericPredicates, Diagnostics) {
     generic_predicates_filtered_by(db, def, |_, d| *d == def)
 }
 
@@ -1761,7 +1911,7 @@ fn generic_predicates_filtered_by<F>(
     db: &dyn HirDatabase,
     def: GenericDefId,
     filter: F,
-) -> GenericPredicates
+) -> (GenericPredicates, Diagnostics)
 where
     F: Fn(&WherePredicate, &GenericDefId) -> bool,
 {
@@ -1802,7 +1952,10 @@ where
             );
         };
     }
-    GenericPredicates(predicates.is_empty().not().then(|| predicates.into()))
+    (
+        GenericPredicates(predicates.is_empty().not().then(|| predicates.into())),
+        create_diagnostics(ctx.diagnostics),
+    )
 }
 
 /// Generate implicit `: Sized` predicates for all generics that has no `?Sized` bound.
@@ -1855,75 +2008,110 @@ impl ops::Deref for GenericDefaults {
     }
 }
 
-/// Resolve the default type params from generics
 pub(crate) fn generic_defaults_query(db: &dyn HirDatabase, def: GenericDefId) -> GenericDefaults {
+    db.generic_defaults_with_diagnostics(def).0
+}
+
+/// Resolve the default type params from generics.
+///
+/// Diagnostics are only returned for this `GenericDefId` (returned defaults include parents).
+pub(crate) fn generic_defaults_with_diagnostics_query(
+    db: &dyn HirDatabase,
+    def: GenericDefId,
+) -> (GenericDefaults, Diagnostics) {
     let generic_params = generics(db.upcast(), def);
     if generic_params.len() == 0 {
-        return GenericDefaults(None);
+        return (GenericDefaults(None), None);
     }
     let resolver = def.resolver(db.upcast());
     let parent_start_idx = generic_params.len_self();
 
-    let mut ctx = TyLoweringContext::new(db, &resolver, TypesMap::EMPTY, def.into())
-        .with_impl_trait_mode(ImplTraitLoweringMode::Disallowed)
-        .with_type_param_mode(ParamLoweringMode::Variable);
-    GenericDefaults(Some(Arc::from_iter(generic_params.iter_with_types_map().enumerate().map(
-        |(idx, ((id, p), types_map))| {
-            ctx.types_map = types_map;
-            match p {
-                GenericParamDataRef::TypeParamData(p) => {
-                    let ty = p.default.as_ref().map_or(TyKind::Error.intern(Interner), |ty| {
-                        // Each default can only refer to previous parameters.
-                        // Type variable default referring to parameter coming
-                        // after it is forbidden (FIXME: report diagnostic)
-                        fallback_bound_vars(ctx.lower_ty(*ty), idx, parent_start_idx)
-                    });
-                    crate::make_binders(db, &generic_params, ty.cast(Interner))
-                }
-                GenericParamDataRef::ConstParamData(p) => {
-                    let GenericParamId::ConstParamId(id) = id else {
-                        unreachable!("Unexpected lifetime or type argument")
-                    };
+    let mut ctx =
+        TyLoweringContext::new(db, &resolver, generic_params.self_types_map(), def.into())
+            .with_impl_trait_mode(ImplTraitLoweringMode::Disallowed)
+            .with_type_param_mode(ParamLoweringMode::Variable);
+    let mut idx = 0;
+    let mut defaults = generic_params
+        .iter_self()
+        .map(|(id, p)| {
+            let result =
+                handle_generic_param(&mut ctx, idx, id, p, parent_start_idx, &generic_params);
+            idx += 1;
+            result
+        })
+        .collect::<Vec<_>>();
+    let diagnostics = create_diagnostics(mem::take(&mut ctx.diagnostics));
+    defaults.extend(generic_params.iter_parents_with_types_map().map(|((id, p), types_map)| {
+        ctx.types_map = types_map;
+        let result = handle_generic_param(&mut ctx, idx, id, p, parent_start_idx, &generic_params);
+        idx += 1;
+        result
+    }));
+    let defaults = GenericDefaults(Some(Arc::from_iter(defaults)));
+    return (defaults, diagnostics);
 
-                    let mut val = p.default.as_ref().map_or_else(
-                        || unknown_const_as_generic(db.const_param_ty(id)),
-                        |c| {
-                            let param_ty = ctx.lower_ty(p.ty);
-                            let c = ctx.lower_const(c, param_ty);
-                            c.cast(Interner)
-                        },
-                    );
-                    // Each default can only refer to previous parameters, see above.
-                    val = fallback_bound_vars(val, idx, parent_start_idx);
-                    make_binders(db, &generic_params, val)
-                }
-                GenericParamDataRef::LifetimeParamData(_) => {
-                    make_binders(db, &generic_params, error_lifetime().cast(Interner))
-                }
+    fn handle_generic_param(
+        ctx: &mut TyLoweringContext<'_>,
+        idx: usize,
+        id: GenericParamId,
+        p: GenericParamDataRef<'_>,
+        parent_start_idx: usize,
+        generic_params: &Generics,
+    ) -> Binders<crate::GenericArg> {
+        match p {
+            GenericParamDataRef::TypeParamData(p) => {
+                let ty = p.default.as_ref().map_or(TyKind::Error.intern(Interner), |ty| {
+                    // Each default can only refer to previous parameters.
+                    // Type variable default referring to parameter coming
+                    // after it is forbidden (FIXME: report diagnostic)
+                    fallback_bound_vars(ctx.lower_ty(*ty), idx, parent_start_idx)
+                });
+                crate::make_binders(ctx.db, generic_params, ty.cast(Interner))
             }
-        },
-    ))))
+            GenericParamDataRef::ConstParamData(p) => {
+                let GenericParamId::ConstParamId(id) = id else {
+                    unreachable!("Unexpected lifetime or type argument")
+                };
+
+                let mut val = p.default.as_ref().map_or_else(
+                    || unknown_const_as_generic(ctx.db.const_param_ty(id)),
+                    |c| {
+                        let param_ty = ctx.lower_ty(p.ty);
+                        let c = ctx.lower_const(c, param_ty);
+                        c.cast(Interner)
+                    },
+                );
+                // Each default can only refer to previous parameters, see above.
+                val = fallback_bound_vars(val, idx, parent_start_idx);
+                make_binders(ctx.db, generic_params, val)
+            }
+            GenericParamDataRef::LifetimeParamData(_) => {
+                make_binders(ctx.db, generic_params, error_lifetime().cast(Interner))
+            }
+        }
+    }
 }
 
-pub(crate) fn generic_defaults_recover(
+pub(crate) fn generic_defaults_with_diagnostics_recover(
     db: &dyn HirDatabase,
     _cycle: &Cycle,
     def: &GenericDefId,
-) -> GenericDefaults {
+) -> (GenericDefaults, Diagnostics) {
     let generic_params = generics(db.upcast(), *def);
     if generic_params.len() == 0 {
-        return GenericDefaults(None);
+        return (GenericDefaults(None), None);
     }
     // FIXME: this code is not covered in tests.
     // we still need one default per parameter
-    GenericDefaults(Some(Arc::from_iter(generic_params.iter_id().map(|id| {
+    let defaults = GenericDefaults(Some(Arc::from_iter(generic_params.iter_id().map(|id| {
         let val = match id {
             GenericParamId::TypeParamId(_) => TyKind::Error.intern(Interner).cast(Interner),
             GenericParamId::ConstParamId(id) => unknown_const_as_generic(db.const_param_ty(id)),
             GenericParamId::LifetimeParamId(_) => error_lifetime().cast(Interner),
         };
         crate::make_binders(db, &generic_params, val)
-    }))))
+    }))));
+    (defaults, None)
 }
 
 fn fn_sig_for_fn(db: &dyn HirDatabase, def: FunctionId) -> PolyFnSig {
@@ -2066,7 +2254,10 @@ fn type_for_adt(db: &dyn HirDatabase, adt: AdtId) -> Binders<Ty> {
     make_binders(db, &generics, ty)
 }
 
-fn type_for_type_alias(db: &dyn HirDatabase, t: TypeAliasId) -> Binders<Ty> {
+pub(crate) fn type_for_type_alias_with_diagnostics_query(
+    db: &dyn HirDatabase,
+    t: TypeAliasId,
+) -> (Binders<Ty>, Diagnostics) {
     let generics = generics(db.upcast(), t.into());
     let resolver = t.resolver(db.upcast());
     let type_alias_data = db.type_alias_data(t);
@@ -2081,7 +2272,7 @@ fn type_for_type_alias(db: &dyn HirDatabase, t: TypeAliasId) -> Binders<Ty> {
             .map(|type_ref| ctx.lower_ty(type_ref))
             .unwrap_or_else(|| TyKind::Error.intern(Interner))
     };
-    make_binders(db, &generics, inner)
+    (make_binders(db, &generics, inner), create_diagnostics(ctx.diagnostics))
 }
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
@@ -2124,7 +2315,7 @@ pub(crate) fn ty_query(db: &dyn HirDatabase, def: TyDefId) -> Binders<Ty> {
     match def {
         TyDefId::BuiltinType(it) => Binders::empty(Interner, TyBuilder::builtin(it)),
         TyDefId::AdtId(it) => type_for_adt(db, it),
-        TyDefId::TypeAliasId(it) => type_for_type_alias(db, it),
+        TyDefId::TypeAliasId(it) => db.type_for_type_alias_with_diagnostics(it).0,
     }
 }
 
@@ -2149,47 +2340,73 @@ pub(crate) fn value_ty_query(db: &dyn HirDatabase, def: ValueTyDefId) -> Option<
 }
 
 pub(crate) fn impl_self_ty_query(db: &dyn HirDatabase, impl_id: ImplId) -> Binders<Ty> {
+    db.impl_self_ty_with_diagnostics(impl_id).0
+}
+
+pub(crate) fn impl_self_ty_with_diagnostics_query(
+    db: &dyn HirDatabase,
+    impl_id: ImplId,
+) -> (Binders<Ty>, Diagnostics) {
     let impl_data = db.impl_data(impl_id);
     let resolver = impl_id.resolver(db.upcast());
     let generics = generics(db.upcast(), impl_id.into());
     let mut ctx = TyLoweringContext::new(db, &resolver, &impl_data.types_map, impl_id.into())
         .with_type_param_mode(ParamLoweringMode::Variable);
-    make_binders(db, &generics, ctx.lower_ty(impl_data.self_ty))
+    (
+        make_binders(db, &generics, ctx.lower_ty(impl_data.self_ty)),
+        create_diagnostics(ctx.diagnostics),
+    )
+}
+
+pub(crate) fn const_param_ty_query(db: &dyn HirDatabase, def: ConstParamId) -> Ty {
+    db.const_param_ty_with_diagnostics(def).0
 }
 
 // returns None if def is a type arg
-pub(crate) fn const_param_ty_query(db: &dyn HirDatabase, def: ConstParamId) -> Ty {
+pub(crate) fn const_param_ty_with_diagnostics_query(
+    db: &dyn HirDatabase,
+    def: ConstParamId,
+) -> (Ty, Diagnostics) {
     let parent_data = db.generic_params(def.parent());
     let data = &parent_data[def.local_id()];
     let resolver = def.parent().resolver(db.upcast());
     let mut ctx =
         TyLoweringContext::new(db, &resolver, &parent_data.types_map, def.parent().into());
-    match data {
+    let ty = match data {
         TypeOrConstParamData::TypeParamData(_) => {
             never!();
             Ty::new(Interner, TyKind::Error)
         }
         TypeOrConstParamData::ConstParamData(d) => ctx.lower_ty(d.ty),
-    }
+    };
+    (ty, create_diagnostics(ctx.diagnostics))
 }
 
-pub(crate) fn impl_self_ty_recover(
+pub(crate) fn impl_self_ty_with_diagnostics_recover(
     db: &dyn HirDatabase,
     _cycle: &Cycle,
     impl_id: &ImplId,
-) -> Binders<Ty> {
+) -> (Binders<Ty>, Diagnostics) {
     let generics = generics(db.upcast(), (*impl_id).into());
-    make_binders(db, &generics, TyKind::Error.intern(Interner))
+    (make_binders(db, &generics, TyKind::Error.intern(Interner)), None)
 }
 
 pub(crate) fn impl_trait_query(db: &dyn HirDatabase, impl_id: ImplId) -> Option<Binders<TraitRef>> {
+    db.impl_trait_with_diagnostics(impl_id).map(|it| it.0)
+}
+
+pub(crate) fn impl_trait_with_diagnostics_query(
+    db: &dyn HirDatabase,
+    impl_id: ImplId,
+) -> Option<(Binders<TraitRef>, Diagnostics)> {
     let impl_data = db.impl_data(impl_id);
     let resolver = impl_id.resolver(db.upcast());
     let mut ctx = TyLoweringContext::new(db, &resolver, &impl_data.types_map, impl_id.into())
         .with_type_param_mode(ParamLoweringMode::Variable);
     let (self_ty, binders) = db.impl_self_ty(impl_id).into_value_and_skipped_binders();
     let target_trait = impl_data.target_trait.as_ref()?;
-    Some(Binders::new(binders, ctx.lower_trait_ref(target_trait, self_ty)?))
+    let trait_ref = Binders::new(binders, ctx.lower_trait_ref(target_trait, self_ty)?);
+    Some((trait_ref, create_diagnostics(ctx.diagnostics)))
 }
 
 pub(crate) fn return_type_impl_traits(

src/tools/rust-analyzer/crates/hir-ty/src/mir/lower.rs

@@ -2023,11 +2023,11 @@ pub fn mir_body_for_closure_query(
     ctx.result.locals.alloc(Local { ty: infer[*root].clone() });
     let closure_local = ctx.result.locals.alloc(Local {
         ty: match kind {
-            FnTrait::FnOnce => infer[expr].clone(),
-            FnTrait::FnMut => {
+            FnTrait::FnOnce | FnTrait::AsyncFnOnce => infer[expr].clone(),
+            FnTrait::FnMut | FnTrait::AsyncFnMut => {
                 TyKind::Ref(Mutability::Mut, error_lifetime(), infer[expr].clone()).intern(Interner)
             }
-            FnTrait::Fn => {
+            FnTrait::Fn | FnTrait::AsyncFn => {
                 TyKind::Ref(Mutability::Not, error_lifetime(), infer[expr].clone()).intern(Interner)
             }
         },
@@ -2055,8 +2055,10 @@ pub fn mir_body_for_closure_query(
     let mut err = None;
     let closure_local = ctx.result.locals.iter().nth(1).unwrap().0;
     let closure_projection = match kind {
-        FnTrait::FnOnce => vec![],
-        FnTrait::FnMut | FnTrait::Fn => vec![ProjectionElem::Deref],
+        FnTrait::FnOnce | FnTrait::AsyncFnOnce => vec![],
+        FnTrait::FnMut | FnTrait::Fn | FnTrait::AsyncFnMut | FnTrait::AsyncFn => {
+            vec![ProjectionElem::Deref]
+        }
     };
     ctx.result.walk_places(|p, store| {
         if let Some(it) = upvar_map.get(&p.local) {

src/tools/rust-analyzer/crates/hir-ty/src/tests.rs

@@ -18,13 +18,13 @@ use std::sync::LazyLock;
 use base_db::SourceDatabaseFileInputExt as _;
 use expect_test::Expect;
 use hir_def::{
-    body::{Body, BodySourceMap, SyntheticSyntax},
+    body::{Body, BodySourceMap},
     db::DefDatabase,
     hir::{ExprId, Pat, PatId},
     item_scope::ItemScope,
     nameres::DefMap,
     src::HasSource,
-    AssocItemId, DefWithBodyId, HasModule, LocalModuleId, Lookup, ModuleDefId,
+    AssocItemId, DefWithBodyId, HasModule, LocalModuleId, Lookup, ModuleDefId, SyntheticSyntax,
 };
 use hir_expand::{db::ExpandDatabase, FileRange, InFile};
 use itertools::Itertools;

src/tools/rust-analyzer/crates/hir-ty/src/tests/coercion.rs

@@ -942,3 +942,19 @@ fn main() {
 "#,
     )
 }
+
+#[test]
+fn regression_18626() {
+    check_no_mismatches(
+        r#"
+fn f() {
+    trait T {
+        fn f() {}
+    }
+    impl T for i32 {}
+    impl T for u32 {}
+    &[i32::f, u32::f] as &[fn()];
+}
+    "#,
+    );
+}

src/tools/rust-analyzer/crates/hir-ty/src/tests/traits.rs

@@ -1630,6 +1630,29 @@ fn test<'lifetime>(
     );
 }
 
+#[test]
+fn lifetime_bounds() {
+    check_infer(
+        r#"
+//- minicore: sized, coerce_unsized
+trait Trait<'a>: Sized {
+    fn f(&'a self) {}
+}
+fn test<'a, 'b: 'a>(it: impl Trait<'a>){
+    it.f();
+}
+"#,
+        expect![[r#"
+            38..42 'self': &'a Self
+            44..46 '{}': ()
+            69..71 'it': impl Trait<'a>
+            88..103 '{     it.f(); }': ()
+            94..96 'it': impl Trait<'a>
+            94..100 'it.f()': ()
+        "#]],
+    );
+}
+
 #[test]
 fn error_bound_chalk() {
     check_types(
@@ -4811,3 +4834,53 @@ fn bar(v: *const ()) {
         "#]],
     );
 }
+
+#[test]
+fn async_fn_traits() {
+    check_infer(
+        r#"
+//- minicore: async_fn
+async fn foo<T: AsyncFn(u32) -> i32>(a: T) {
+    let fut1 = a(0);
+    fut1.await;
+}
+async fn bar<T: AsyncFnMut(u32) -> i32>(mut b: T) {
+    let fut2 = b(0);
+    fut2.await;
+}
+async fn baz<T: AsyncFnOnce(u32) -> i32>(c: T) {
+    let fut3 = c(0);
+    fut3.await;
+}
+    "#,
+        expect![[r#"
+            37..38 'a': T
+            43..83 '{     ...ait; }': ()
+            43..83 '{     ...ait; }': impl Future<Output = ()>
+            53..57 'fut1': AsyncFnMut::CallRefFuture<'?, T, (u32,)>
+            60..61 'a': T
+            60..64 'a(0)': AsyncFnMut::CallRefFuture<'?, T, (u32,)>
+            62..63 '0': u32
+            70..74 'fut1': AsyncFnMut::CallRefFuture<'?, T, (u32,)>
+            70..80 'fut1.await': i32
+            124..129 'mut b': T
+            134..174 '{     ...ait; }': ()
+            134..174 '{     ...ait; }': impl Future<Output = ()>
+            144..148 'fut2': AsyncFnMut::CallRefFuture<'?, T, (u32,)>
+            151..152 'b': T
+            151..155 'b(0)': AsyncFnMut::CallRefFuture<'?, T, (u32,)>
+            153..154 '0': u32
+            161..165 'fut2': AsyncFnMut::CallRefFuture<'?, T, (u32,)>
+            161..171 'fut2.await': i32
+            216..217 'c': T
+            222..262 '{     ...ait; }': ()
+            222..262 '{     ...ait; }': impl Future<Output = ()>
+            232..236 'fut3': AsyncFnOnce::CallOnceFuture<T, (u32,)>
+            239..240 'c': T
+            239..243 'c(0)': AsyncFnOnce::CallOnceFuture<T, (u32,)>
+            241..242 '0': u32
+            249..253 'fut3': AsyncFnOnce::CallOnceFuture<T, (u32,)>
+            249..259 'fut3.await': i32
+        "#]],
+    );
+}

src/tools/rust-analyzer/crates/hir-ty/src/traits.rs

@@ -220,6 +220,10 @@ pub enum FnTrait {
     FnOnce,
     FnMut,
     Fn,
+
+    AsyncFnOnce,
+    AsyncFnMut,
+    AsyncFn,
 }
 
 impl fmt::Display for FnTrait {
@@ -228,6 +232,9 @@ impl fmt::Display for FnTrait {
             FnTrait::FnOnce => write!(f, "FnOnce"),
             FnTrait::FnMut => write!(f, "FnMut"),
             FnTrait::Fn => write!(f, "Fn"),
+            FnTrait::AsyncFnOnce => write!(f, "AsyncFnOnce"),
+            FnTrait::AsyncFnMut => write!(f, "AsyncFnMut"),
+            FnTrait::AsyncFn => write!(f, "AsyncFn"),
         }
     }
 }
@@ -238,6 +245,9 @@ impl FnTrait {
             FnTrait::FnOnce => "call_once",
             FnTrait::FnMut => "call_mut",
             FnTrait::Fn => "call",
+            FnTrait::AsyncFnOnce => "async_call_once",
+            FnTrait::AsyncFnMut => "async_call_mut",
+            FnTrait::AsyncFn => "async_call",
         }
     }
 
@@ -246,6 +256,9 @@ impl FnTrait {
             FnTrait::FnOnce => LangItem::FnOnce,
             FnTrait::FnMut => LangItem::FnMut,
             FnTrait::Fn => LangItem::Fn,
+            FnTrait::AsyncFnOnce => LangItem::AsyncFnOnce,
+            FnTrait::AsyncFnMut => LangItem::AsyncFnMut,
+            FnTrait::AsyncFn => LangItem::AsyncFn,
         }
     }
 
@@ -254,15 +267,19 @@ impl FnTrait {
             LangItem::FnOnce => Some(FnTrait::FnOnce),
             LangItem::FnMut => Some(FnTrait::FnMut),
             LangItem::Fn => Some(FnTrait::Fn),
+            LangItem::AsyncFnOnce => Some(FnTrait::AsyncFnOnce),
+            LangItem::AsyncFnMut => Some(FnTrait::AsyncFnMut),
+            LangItem::AsyncFn => Some(FnTrait::AsyncFn),
             _ => None,
         }
     }
 
     pub const fn to_chalk_ir(self) -> rust_ir::ClosureKind {
+        // Chalk doesn't support async fn traits.
         match self {
-            FnTrait::FnOnce => rust_ir::ClosureKind::FnOnce,
-            FnTrait::FnMut => rust_ir::ClosureKind::FnMut,
-            FnTrait::Fn => rust_ir::ClosureKind::Fn,
+            FnTrait::AsyncFnOnce | FnTrait::FnOnce => rust_ir::ClosureKind::FnOnce,
+            FnTrait::AsyncFnMut | FnTrait::FnMut => rust_ir::ClosureKind::FnMut,
+            FnTrait::AsyncFn | FnTrait::Fn => rust_ir::ClosureKind::Fn,
         }
     }
 
@@ -271,6 +288,9 @@ impl FnTrait {
             FnTrait::FnOnce => Name::new_symbol_root(sym::call_once.clone()),
             FnTrait::FnMut => Name::new_symbol_root(sym::call_mut.clone()),
             FnTrait::Fn => Name::new_symbol_root(sym::call.clone()),
+            FnTrait::AsyncFnOnce => Name::new_symbol_root(sym::async_call_once.clone()),
+            FnTrait::AsyncFnMut => Name::new_symbol_root(sym::async_call_mut.clone()),
+            FnTrait::AsyncFn => Name::new_symbol_root(sym::async_call.clone()),
         }
     }
 

src/tools/rust-analyzer/crates/hir-ty/src/utils.rs

@@ -185,7 +185,7 @@ fn direct_super_traits_cb(db: &dyn DefDatabase, trait_: TraitId, cb: impl FnMut(
                     }
                 };
                 match is_trait {
-                    true => bound.as_path(),
+                    true => bound.as_path(&generic_params.types_map),
                     false => None,
                 }
             }

src/tools/rust-analyzer/crates/hir/Cargo.toml

@@ -33,6 +33,14 @@ syntax.workspace = true
 tt.workspace = true
 span.workspace = true
 
+[dev-dependencies]
+expect-test.workspace = true
+
+# local deps
+test-utils.workspace = true
+test-fixture.workspace = true
+syntax-bridge.workspace = true
+
 [features]
 in-rust-tree = ["hir-expand/in-rust-tree"]
 

src/tools/rust-analyzer/crates/hir/src/diagnostics.rs

@@ -3,21 +3,35 @@
 //!
 //! This probably isn't the best way to do this -- ideally, diagnostics should
 //! be expressed in terms of hir types themselves.
-pub use hir_ty::diagnostics::{CaseType, IncorrectCase};
-use hir_ty::{
-    db::HirDatabase, diagnostics::BodyValidationDiagnostic, CastError, InferenceDiagnostic,
-};
-
 use cfg::{CfgExpr, CfgOptions};
 use either::Either;
-pub use hir_def::VariantId;
-use hir_def::{body::SyntheticSyntax, hir::ExprOrPatId, path::ModPath, AssocItemId, DefWithBodyId};
+use hir_def::{
+    hir::ExprOrPatId,
+    path::{hir_segment_to_ast_segment, ModPath},
+    type_ref::TypesSourceMap,
+    AssocItemId, DefWithBodyId, SyntheticSyntax,
+};
 use hir_expand::{name::Name, HirFileId, InFile};
-use syntax::{ast, AstPtr, SyntaxError, SyntaxNodePtr, TextRange};
+use hir_ty::{
+    db::HirDatabase,
+    diagnostics::{BodyValidationDiagnostic, UnsafetyReason},
+    CastError, InferenceDiagnostic, InferenceTyDiagnosticSource, TyLoweringDiagnostic,
+    TyLoweringDiagnosticKind,
+};
+use syntax::{
+    ast::{self, HasGenericArgs},
+    AstPtr, SyntaxError, SyntaxNodePtr, TextRange,
+};
 use triomphe::Arc;
 
 use crate::{AssocItem, Field, Local, Trait, Type};
 
+pub use hir_def::VariantId;
+pub use hir_ty::{
+    diagnostics::{CaseType, IncorrectCase},
+    GenericArgsProhibitedReason,
+};
+
 macro_rules! diagnostics {
     ($($diag:ident,)*) => {
         #[derive(Debug)]
@@ -96,6 +110,7 @@ diagnostics![
     UnresolvedIdent,
     UnusedMut,
     UnusedVariable,
+    GenericArgsProhibited,
 ];
 
 #[derive(Debug)]
@@ -258,9 +273,10 @@ pub struct PrivateField {
 
 #[derive(Debug)]
 pub struct MissingUnsafe {
-    pub expr: InFile<AstPtr<Either<ast::Expr, ast::Pat>>>,
+    pub node: InFile<AstPtr<Either<ast::Expr, ast::Pat>>>,
     /// If true, the diagnostics is an `unsafe_op_in_unsafe_fn` lint instead of a hard error.
     pub only_lint: bool,
+    pub reason: UnsafetyReason,
 }
 
 #[derive(Debug)]
@@ -385,6 +401,12 @@ pub struct InvalidCast {
     pub cast_ty: Type,
 }
 
+#[derive(Debug)]
+pub struct GenericArgsProhibited {
+    pub args: InFile<AstPtr<Either<ast::GenericArgList, ast::ParenthesizedArgList>>>,
+    pub reason: GenericArgsProhibitedReason,
+}
+
 impl AnyDiagnostic {
     pub(crate) fn body_validation_diagnostic(
         db: &dyn HirDatabase,
@@ -524,6 +546,7 @@ impl AnyDiagnostic {
         db: &dyn HirDatabase,
         def: DefWithBodyId,
         d: &InferenceDiagnostic,
+        outer_types_source_map: &TypesSourceMap,
         source_map: &hir_def::body::BodySourceMap,
     ) -> Option<AnyDiagnostic> {
         let expr_syntax = |expr| {
@@ -637,6 +660,44 @@ impl AnyDiagnostic {
                 let cast_ty = Type::new(db, def, cast_ty.clone());
                 InvalidCast { expr, error: *error, expr_ty, cast_ty }.into()
             }
+            InferenceDiagnostic::TyDiagnostic { source, diag } => {
+                let source_map = match source {
+                    InferenceTyDiagnosticSource::Body => &source_map.types,
+                    InferenceTyDiagnosticSource::Signature => outer_types_source_map,
+                };
+                Self::ty_diagnostic(diag, source_map, db)?
+            }
+        })
+    }
+
+    pub(crate) fn ty_diagnostic(
+        diag: &TyLoweringDiagnostic,
+        source_map: &TypesSourceMap,
+        db: &dyn HirDatabase,
+    ) -> Option<AnyDiagnostic> {
+        let source = match diag.source {
+            Either::Left(type_ref_id) => {
+                let Ok(source) = source_map.type_syntax(type_ref_id) else {
+                    stdx::never!("error on synthetic type syntax");
+                    return None;
+                };
+                source
+            }
+            Either::Right(source) => source,
+        };
+        let syntax = || source.value.to_node(&db.parse_or_expand(source.file_id));
+        Some(match diag.kind {
+            TyLoweringDiagnosticKind::GenericArgsProhibited { segment, reason } => {
+                let ast::Type::PathType(syntax) = syntax() else { return None };
+                let segment = hir_segment_to_ast_segment(&syntax.path()?, segment)?;
+                let args = if let Some(generics) = segment.generic_arg_list() {
+                    AstPtr::new(&generics).wrap_left()
+                } else {
+                    AstPtr::new(&segment.parenthesized_arg_list()?).wrap_right()
+                };
+                let args = source.with_value(args);
+                GenericArgsProhibited { args, reason }.into()
+            }
         })
     }
 }

src/tools/rust-analyzer/crates/hir/src/display.rs

@@ -132,12 +132,18 @@ impl HirDisplay for Function {
         } else {
             match &data.types_map[data.ret_type] {
                 TypeRef::ImplTrait(bounds) => match &bounds[0] {
-                    TypeBound::Path(path, _) => Some(
-                        *path.segments().iter().last().unwrap().args_and_bindings.unwrap().bindings
-                            [0]
-                        .type_ref
-                        .as_ref()
-                        .unwrap(),
+                    &TypeBound::Path(path, _) => Some(
+                        *data.types_map[path]
+                            .segments()
+                            .iter()
+                            .last()
+                            .unwrap()
+                            .args_and_bindings
+                            .unwrap()
+                            .bindings[0]
+                            .type_ref
+                            .as_ref()
+                            .unwrap(),
                     ),
                     _ => None,
                 },

src/tools/rust-analyzer/crates/hir/src/lib.rs

@@ -20,12 +20,11 @@
 #![cfg_attr(feature = "in-rust-tree", feature(rustc_private))]
 #![recursion_limit = "512"]
 
-mod semantics;
-mod source_analyzer;
-
 mod attrs;
 mod from_id;
 mod has_source;
+mod semantics;
+mod source_analyzer;
 
 pub mod db;
 pub mod diagnostics;
@@ -43,7 +42,7 @@ use arrayvec::ArrayVec;
 use base_db::{CrateDisplayName, CrateId, CrateOrigin};
 use either::Either;
 use hir_def::{
-    body::{BodyDiagnostic, SyntheticSyntax},
+    body::BodyDiagnostic,
     data::adt::VariantData,
     generics::{LifetimeParamData, TypeOrConstParamData, TypeParamProvenance},
     hir::{BindingAnnotation, BindingId, ExprId, ExprOrPatId, LabelId, Pat},
@@ -54,11 +53,12 @@ use hir_def::{
     path::ImportAlias,
     per_ns::PerNs,
     resolver::{HasResolver, Resolver},
+    type_ref::TypesSourceMap,
     AssocItemId, AssocItemLoc, AttrDefId, CallableDefId, ConstId, ConstParamId, CrateRootModuleId,
     DefWithBodyId, EnumId, EnumVariantId, ExternCrateId, FunctionId, GenericDefId, GenericParamId,
     HasModule, ImplId, InTypeConstId, ItemContainerId, LifetimeParamId, LocalFieldId, Lookup,
-    MacroExpander, ModuleId, StaticId, StructId, TraitAliasId, TraitId, TupleId, TypeAliasId,
-    TypeOrConstParamId, TypeParamId, UnionId,
+    MacroExpander, ModuleId, StaticId, StructId, SyntheticSyntax, TraitAliasId, TraitId, TupleId,
+    TypeAliasId, TypeOrConstParamId, TypeParamId, UnionId,
 };
 use hir_expand::{
     attrs::collect_attrs, proc_macro::ProcMacroKind, AstId, MacroCallKind, RenderedExpandError,
@@ -76,8 +76,8 @@ use hir_ty::{
     traits::FnTrait,
     AliasTy, CallableSig, Canonical, CanonicalVarKinds, Cast, ClosureId, GenericArg,
     GenericArgData, Interner, ParamKind, QuantifiedWhereClause, Scalar, Substitution,
-    TraitEnvironment, TraitRefExt, Ty, TyBuilder, TyDefId, TyExt, TyKind, ValueTyDefId,
-    WhereClause,
+    TraitEnvironment, TraitRefExt, Ty, TyBuilder, TyDefId, TyExt, TyKind, TyLoweringDiagnostic,
+    ValueTyDefId, WhereClause,
 };
 use itertools::Itertools;
 use nameres::diagnostics::DefDiagnosticKind;
@@ -89,7 +89,7 @@ use syntax::{
     ast::{self, HasAttrs as _, HasGenericParams, HasName},
     format_smolstr, AstNode, AstPtr, SmolStr, SyntaxNode, SyntaxNodePtr, TextRange, ToSmolStr, T,
 };
-use triomphe::Arc;
+use triomphe::{Arc, ThinArc};
 
 use crate::db::{DefDatabase, HirDatabase};
 
@@ -147,6 +147,7 @@ pub use {
     },
     hir_ty::{
         consteval::ConstEvalError,
+        diagnostics::UnsafetyReason,
         display::{ClosureStyle, HirDisplay, HirDisplayError, HirWrite},
         dyn_compatibility::{DynCompatibilityViolation, MethodViolationCode},
         layout::LayoutError,
@@ -410,6 +411,10 @@ impl ModuleDef {
             }
         }
 
+        if let Some(def) = self.as_self_generic_def() {
+            def.diagnostics(db, &mut acc);
+        }
+
         acc
     }
 
@@ -430,6 +435,23 @@ impl ModuleDef {
         }
     }
 
+    /// Returns only defs that have generics from themselves, not their parent.
+    pub fn as_self_generic_def(self) -> Option<GenericDef> {
+        match self {
+            ModuleDef::Function(it) => Some(it.into()),
+            ModuleDef::Adt(it) => Some(it.into()),
+            ModuleDef::Trait(it) => Some(it.into()),
+            ModuleDef::TraitAlias(it) => Some(it.into()),
+            ModuleDef::TypeAlias(it) => Some(it.into()),
+            ModuleDef::Module(_)
+            | ModuleDef::Variant(_)
+            | ModuleDef::Static(_)
+            | ModuleDef::Const(_)
+            | ModuleDef::BuiltinType(_)
+            | ModuleDef::Macro(_) => None,
+        }
+    }
+
     pub fn attrs(&self, db: &dyn HirDatabase) -> Option<AttrsWithOwner> {
         Some(match self {
             ModuleDef::Module(it) => it.attrs(db),
@@ -604,17 +626,42 @@ impl Module {
                 ModuleDef::Adt(adt) => {
                     match adt {
                         Adt::Struct(s) => {
+                            let tree_id = s.id.lookup(db.upcast()).id;
+                            let tree_source_maps = tree_id.item_tree_with_source_map(db.upcast()).1;
+                            push_ty_diagnostics(
+                                db,
+                                acc,
+                                db.field_types_with_diagnostics(s.id.into()).1,
+                                tree_source_maps.strukt(tree_id.value).item(),
+                            );
                             for diag in db.struct_data_with_diagnostics(s.id).1.iter() {
                                 emit_def_diagnostic(db, acc, diag, edition);
                             }
                         }
                         Adt::Union(u) => {
+                            let tree_id = u.id.lookup(db.upcast()).id;
+                            let tree_source_maps = tree_id.item_tree_with_source_map(db.upcast()).1;
+                            push_ty_diagnostics(
+                                db,
+                                acc,
+                                db.field_types_with_diagnostics(u.id.into()).1,
+                                tree_source_maps.union(tree_id.value).item(),
+                            );
                             for diag in db.union_data_with_diagnostics(u.id).1.iter() {
                                 emit_def_diagnostic(db, acc, diag, edition);
                             }
                         }
                         Adt::Enum(e) => {
                             for v in e.variants(db) {
+                                let tree_id = v.id.lookup(db.upcast()).id;
+                                let tree_source_maps =
+                                    tree_id.item_tree_with_source_map(db.upcast()).1;
+                                push_ty_diagnostics(
+                                    db,
+                                    acc,
+                                    db.field_types_with_diagnostics(v.id.into()).1,
+                                    tree_source_maps.variant(tree_id.value),
+                                );
                                 acc.extend(ModuleDef::Variant(v).diagnostics(db, style_lints));
                                 for diag in db.enum_variant_data_with_diagnostics(v.id).1.iter() {
                                     emit_def_diagnostic(db, acc, diag, edition);
@@ -625,6 +672,17 @@ impl Module {
                     acc.extend(def.diagnostics(db, style_lints))
                 }
                 ModuleDef::Macro(m) => emit_macro_def_diagnostics(db, acc, m),
+                ModuleDef::TypeAlias(type_alias) => {
+                    let tree_id = type_alias.id.lookup(db.upcast()).id;
+                    let tree_source_maps = tree_id.item_tree_with_source_map(db.upcast()).1;
+                    push_ty_diagnostics(
+                        db,
+                        acc,
+                        db.type_for_type_alias_with_diagnostics(type_alias.id).1,
+                        tree_source_maps.type_alias(tree_id.value).item(),
+                    );
+                    acc.extend(def.diagnostics(db, style_lints));
+                }
                 _ => acc.extend(def.diagnostics(db, style_lints)),
             }
         }
@@ -634,8 +692,11 @@ impl Module {
 
         let mut impl_assoc_items_scratch = vec![];
         for impl_def in self.impl_defs(db) {
+            GenericDef::Impl(impl_def).diagnostics(db, acc);
+
             let loc = impl_def.id.lookup(db.upcast());
-            let tree = loc.id.item_tree(db.upcast());
+            let (tree, tree_source_maps) = loc.id.item_tree_with_source_map(db.upcast());
+            let source_map = tree_source_maps.impl_(loc.id.value).item();
             let node = &tree[loc.id.value];
             let file_id = loc.id.file_id();
             if file_id.macro_file().map_or(false, |it| it.is_builtin_derive(db.upcast())) {
@@ -770,6 +831,19 @@ impl Module {
                 impl_assoc_items_scratch.clear();
             }
 
+            push_ty_diagnostics(
+                db,
+                acc,
+                db.impl_self_ty_with_diagnostics(impl_def.id).1,
+                source_map,
+            );
+            push_ty_diagnostics(
+                db,
+                acc,
+                db.impl_trait_with_diagnostics(impl_def.id).and_then(|it| it.1),
+                source_map,
+            );
+
             for &item in db.impl_data(impl_def.id).items.iter() {
                 AssocItem::from(item).diagnostics(db, acc, style_lints);
             }
@@ -1801,6 +1875,25 @@ impl DefWithBody {
         let krate = self.module(db).id.krate();
 
         let (body, source_map) = db.body_with_source_map(self.into());
+        let item_tree_source_maps;
+        let outer_types_source_map = match self {
+            DefWithBody::Function(function) => {
+                let function = function.id.lookup(db.upcast()).id;
+                item_tree_source_maps = function.item_tree_with_source_map(db.upcast()).1;
+                item_tree_source_maps.function(function.value).item()
+            }
+            DefWithBody::Static(statik) => {
+                let statik = statik.id.lookup(db.upcast()).id;
+                item_tree_source_maps = statik.item_tree_with_source_map(db.upcast()).1;
+                item_tree_source_maps.statik(statik.value)
+            }
+            DefWithBody::Const(konst) => {
+                let konst = konst.id.lookup(db.upcast()).id;
+                item_tree_source_maps = konst.item_tree_with_source_map(db.upcast()).1;
+                item_tree_source_maps.konst(konst.value)
+            }
+            DefWithBody::Variant(_) | DefWithBody::InTypeConst(_) => &TypesSourceMap::EMPTY,
+        };
 
         for (_, def_map) in body.blocks(db.upcast()) {
             Module { id: def_map.module_id(DefMap::ROOT) }.diagnostics(db, acc, style_lints);
@@ -1860,7 +1953,13 @@ impl DefWithBody {
 
         let infer = db.infer(self.into());
         for d in &infer.diagnostics {
-            acc.extend(AnyDiagnostic::inference_diagnostic(db, self.into(), d, &source_map));
+            acc.extend(AnyDiagnostic::inference_diagnostic(
+                db,
+                self.into(),
+                d,
+                outer_types_source_map,
+                &source_map,
+            ));
         }
 
         for (pat_or_expr, mismatch) in infer.type_mismatches() {
@@ -1890,10 +1989,10 @@ impl DefWithBody {
             );
         }
 
-        let (unafe_exprs, only_lint) = hir_ty::diagnostics::missing_unsafe(db, self.into());
-        for expr in unafe_exprs {
-            match source_map.expr_or_pat_syntax(expr) {
-                Ok(expr) => acc.push(MissingUnsafe { expr, only_lint }.into()),
+        let (unsafe_exprs, only_lint) = hir_ty::diagnostics::missing_unsafe(db, self.into());
+        for (node, reason) in unsafe_exprs {
+            match source_map.expr_or_pat_syntax(node) {
+                Ok(node) => acc.push(MissingUnsafe { node, only_lint, reason }.into()),
                 Err(SyntheticSyntax) => {
                     // FIXME: Here and elsewhere in this file, the `expr` was
                     // desugared, report or assert that this doesn't happen.
@@ -3324,12 +3423,22 @@ impl AssocItem {
     ) {
         match self {
             AssocItem::Function(func) => {
+                GenericDef::Function(func).diagnostics(db, acc);
                 DefWithBody::from(func).diagnostics(db, acc, style_lints);
             }
             AssocItem::Const(const_) => {
                 DefWithBody::from(const_).diagnostics(db, acc, style_lints);
             }
             AssocItem::TypeAlias(type_alias) => {
+                GenericDef::TypeAlias(type_alias).diagnostics(db, acc);
+                let tree_id = type_alias.id.lookup(db.upcast()).id;
+                let tree_source_maps = tree_id.item_tree_with_source_map(db.upcast()).1;
+                push_ty_diagnostics(
+                    db,
+                    acc,
+                    db.type_for_type_alias_with_diagnostics(type_alias.id).1,
+                    tree_source_maps.type_alias(tree_id.value).item(),
+                );
                 for diag in hir_ty::diagnostics::incorrect_case(db, type_alias.id.into()) {
                     acc.push(diag.into());
                 }
@@ -3416,6 +3525,97 @@ impl GenericDef {
             })
             .collect()
     }
+
+    fn id(self) -> GenericDefId {
+        match self {
+            GenericDef::Function(it) => it.id.into(),
+            GenericDef::Adt(it) => it.into(),
+            GenericDef::Trait(it) => it.id.into(),
+            GenericDef::TraitAlias(it) => it.id.into(),
+            GenericDef::TypeAlias(it) => it.id.into(),
+            GenericDef::Impl(it) => it.id.into(),
+            GenericDef::Const(it) => it.id.into(),
+        }
+    }
+
+    pub fn diagnostics(self, db: &dyn HirDatabase, acc: &mut Vec<AnyDiagnostic>) {
+        let def = self.id();
+
+        let item_tree_source_maps;
+        let (generics, generics_source_map) = db.generic_params_with_source_map(def);
+
+        if generics.is_empty() && generics.no_predicates() {
+            return;
+        }
+
+        let source_map = match &generics_source_map {
+            Some(it) => it,
+            None => match def {
+                GenericDefId::FunctionId(it) => {
+                    let id = it.lookup(db.upcast()).id;
+                    item_tree_source_maps = id.item_tree_with_source_map(db.upcast()).1;
+                    item_tree_source_maps.function(id.value).generics()
+                }
+                GenericDefId::AdtId(AdtId::EnumId(it)) => {
+                    let id = it.lookup(db.upcast()).id;
+                    item_tree_source_maps = id.item_tree_with_source_map(db.upcast()).1;
+                    item_tree_source_maps.enum_generic(id.value)
+                }
+                GenericDefId::AdtId(AdtId::StructId(it)) => {
+                    let id = it.lookup(db.upcast()).id;
+                    item_tree_source_maps = id.item_tree_with_source_map(db.upcast()).1;
+                    item_tree_source_maps.strukt(id.value).generics()
+                }
+                GenericDefId::AdtId(AdtId::UnionId(it)) => {
+                    let id = it.lookup(db.upcast()).id;
+                    item_tree_source_maps = id.item_tree_with_source_map(db.upcast()).1;
+                    item_tree_source_maps.union(id.value).generics()
+                }
+                GenericDefId::TraitId(it) => {
+                    let id = it.lookup(db.upcast()).id;
+                    item_tree_source_maps = id.item_tree_with_source_map(db.upcast()).1;
+                    item_tree_source_maps.trait_generic(id.value)
+                }
+                GenericDefId::TraitAliasId(it) => {
+                    let id = it.lookup(db.upcast()).id;
+                    item_tree_source_maps = id.item_tree_with_source_map(db.upcast()).1;
+                    item_tree_source_maps.trait_alias_generic(id.value)
+                }
+                GenericDefId::TypeAliasId(it) => {
+                    let id = it.lookup(db.upcast()).id;
+                    item_tree_source_maps = id.item_tree_with_source_map(db.upcast()).1;
+                    item_tree_source_maps.type_alias(id.value).generics()
+                }
+                GenericDefId::ImplId(it) => {
+                    let id = it.lookup(db.upcast()).id;
+                    item_tree_source_maps = id.item_tree_with_source_map(db.upcast()).1;
+                    item_tree_source_maps.impl_(id.value).generics()
+                }
+                GenericDefId::ConstId(_) => return,
+            },
+        };
+
+        push_ty_diagnostics(db, acc, db.generic_defaults_with_diagnostics(def).1, source_map);
+        push_ty_diagnostics(
+            db,
+            acc,
+            db.generic_predicates_without_parent_with_diagnostics(def).1,
+            source_map,
+        );
+        for (param_id, param) in generics.iter_type_or_consts() {
+            if let TypeOrConstParamData::ConstParamData(_) = param {
+                push_ty_diagnostics(
+                    db,
+                    acc,
+                    db.const_param_ty_with_diagnostics(ConstParamId::from_unchecked(
+                        TypeOrConstParamId { parent: def, local_id: param_id },
+                    ))
+                    .1,
+                    source_map,
+                );
+            }
+        }
+    }
 }
 
 /// A single local definition.
@@ -3581,6 +3781,18 @@ impl Local {
     }
 }
 
+impl PartialOrd for Local {
+    fn partial_cmp(&self, other: &Self) -> Option<std::cmp::Ordering> {
+        Some(self.cmp(other))
+    }
+}
+
+impl Ord for Local {
+    fn cmp(&self, other: &Self) -> std::cmp::Ordering {
+        self.binding_id.cmp(&other.binding_id)
+    }
+}
+
 #[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
 pub struct DeriveHelper {
     pub(crate) derive: MacroId,
@@ -5799,3 +6011,19 @@ pub enum DocLinkDef {
     Field(Field),
     SelfType(Trait),
 }
+
+fn push_ty_diagnostics(
+    db: &dyn HirDatabase,
+    acc: &mut Vec<AnyDiagnostic>,
+    diagnostics: Option<ThinArc<(), TyLoweringDiagnostic>>,
+    source_map: &TypesSourceMap,
+) {
+    if let Some(diagnostics) = diagnostics {
+        acc.extend(
+            diagnostics
+                .slice
+                .iter()
+                .filter_map(|diagnostic| AnyDiagnostic::ty_diagnostic(diagnostic, source_map, db)),
+        );
+    }
+}

src/tools/rust-analyzer/crates/hir/src/semantics.rs

@@ -34,7 +34,7 @@ use intern::Symbol;
 use itertools::Itertools;
 use rustc_hash::{FxHashMap, FxHashSet};
 use smallvec::{smallvec, SmallVec};
-use span::{EditionedFileId, FileId, HirFileIdRepr, SyntaxContextId};
+use span::{AstIdMap, EditionedFileId, FileId, HirFileIdRepr, SyntaxContextId};
 use stdx::TupleExt;
 use syntax::{
     algo::skip_trivia_token,
@@ -42,6 +42,7 @@ use syntax::{
     AstNode, AstToken, Direction, SyntaxKind, SyntaxNode, SyntaxNodePtr, SyntaxToken, TextRange,
     TextSize,
 };
+use triomphe::Arc;
 
 use crate::{
     db::HirDatabase,
@@ -509,6 +510,22 @@ impl<'db> SemanticsImpl<'db> {
         self.with_ctx(|ctx| ctx.has_derives(adt))
     }
 
+    pub fn derive_helpers_in_scope(&self, adt: &ast::Adt) -> Option<Vec<(Symbol, Symbol)>> {
+        let sa = self.analyze_no_infer(adt.syntax())?;
+        let id = self.db.ast_id_map(sa.file_id).ast_id(adt);
+        let result = sa
+            .resolver
+            .def_map()
+            .derive_helpers_in_scope(InFile::new(sa.file_id, id))?
+            .iter()
+            .map(|(name, macro_, _)| {
+                let macro_name = Macro::from(*macro_).name(self.db).symbol().clone();
+                (name.symbol().clone(), macro_name)
+            })
+            .collect();
+        Some(result)
+    }
+
     pub fn derive_helper(&self, attr: &ast::Attr) -> Option<Vec<(Macro, MacroFileId)>> {
         let adt = attr.syntax().ancestors().find_map(ast::Item::cast).and_then(|it| match it {
             ast::Item::Struct(it) => Some(ast::Adt::Struct(it)),
@@ -1500,6 +1517,10 @@ impl<'db> SemanticsImpl<'db> {
         self.analyze(path.syntax())?.resolve_path(self.db, path)
     }
 
+    pub fn resolve_use_type_arg(&self, name: &ast::NameRef) -> Option<TypeParam> {
+        self.analyze(name.syntax())?.resolve_use_type_arg(name)
+    }
+
     pub fn resolve_mod_path(
         &self,
         scope: &SyntaxNode,
@@ -1973,10 +1994,16 @@ impl SemanticsScope<'_> {
     /// Resolve a path as-if it was written at the given scope. This is
     /// necessary a heuristic, as it doesn't take hygiene into account.
     pub fn speculative_resolve(&self, ast_path: &ast::Path) -> Option<PathResolution> {
+        let root = ast_path.syntax().ancestors().last().unwrap();
+        let ast_id_map = Arc::new(AstIdMap::from_source(&root));
         let (mut types_map, mut types_source_map) =
             (TypesMap::default(), TypesSourceMap::default());
-        let mut ctx =
-            LowerCtx::new(self.db.upcast(), self.file_id, &mut types_map, &mut types_source_map);
+        let mut ctx = LowerCtx::for_synthetic_ast(
+            self.db.upcast(),
+            ast_id_map,
+            &mut types_map,
+            &mut types_source_map,
+        );
         let path = Path::from_src(&mut ctx, ast_path.clone())?;
         resolve_hir_path(
             self.db,
@@ -2003,6 +2030,10 @@ impl SemanticsScope<'_> {
         )
     }
 
+    pub fn generic_def(&self) -> Option<crate::GenericDef> {
+        self.resolver.generic_def().map(|id| id.into())
+    }
+
     pub fn extern_crates(&self) -> impl Iterator<Item = (Name, Module)> + '_ {
         self.resolver.extern_crates_in_scope().map(|(name, id)| (name, Module { id }))
     }

src/tools/rust-analyzer/crates/hir/src/source_analyzer.rs

@@ -36,7 +36,7 @@ use hir_expand::{
 use hir_ty::{
     diagnostics::{
         record_literal_missing_fields, record_pattern_missing_fields, unsafe_expressions,
-        UnsafeExpr,
+        InsideUnsafeBlock,
     },
     lang_items::lang_items_for_bin_op,
     method_resolution, Adjustment, InferenceResult, Interner, Substitution, Ty, TyExt, TyKind,
@@ -642,6 +642,14 @@ impl SourceAnalyzer {
         }
     }
 
+    pub(crate) fn resolve_use_type_arg(&self, name: &ast::NameRef) -> Option<crate::TypeParam> {
+        let name = name.as_name();
+        self.resolver
+            .all_generic_params()
+            .find_map(|(params, parent)| params.find_type_by_name(&name, *parent))
+            .map(crate::TypeParam::from)
+    }
+
     pub(crate) fn resolve_path(
         &self,
         db: &dyn HirDatabase,
@@ -939,8 +947,8 @@ impl SourceAnalyzer {
                         *def,
                         body,
                         expr_id,
-                        &mut |UnsafeExpr { inside_unsafe_block, .. }| {
-                            is_unsafe |= !inside_unsafe_block
+                        &mut |_, inside_unsafe_block, _| {
+                            is_unsafe |= inside_unsafe_block == InsideUnsafeBlock::No
                         },
                     )
                 };

src/tools/rust-analyzer/crates/ide-assists/src/handlers/add_missing_impl_members.rs

@@ -2318,4 +2318,49 @@ impl<'a> Test<'a, i32> for bool {
 "#,
         );
     }
+
+    #[test]
+    fn issue_17321() {
+        check_assist(
+            add_missing_impl_members,
+            r#"
+fn main() {}
+
+mod other_file_1 {
+    pub const SOME_CONSTANT: usize = 8;
+}
+
+mod other_file_2 {
+    use crate::other_file_1::SOME_CONSTANT;
+
+    pub trait Trait {
+        type Iter: Iterator<Item = [u8; SOME_CONSTANT]>;
+    }
+}
+
+pub struct MyStruct;
+
+impl other_file_2::Trait for MyStruct$0 {}"#,
+            r#"
+fn main() {}
+
+mod other_file_1 {
+    pub const SOME_CONSTANT: usize = 8;
+}
+
+mod other_file_2 {
+    use crate::other_file_1::SOME_CONSTANT;
+
+    pub trait Trait {
+        type Iter: Iterator<Item = [u8; SOME_CONSTANT]>;
+    }
+}
+
+pub struct MyStruct;
+
+impl other_file_2::Trait for MyStruct {
+    $0type Iter;
+}"#,
+        );
+    }
 }