Auto merge of #152321 - Zalathar:rollup-ezxwhfJ, r=Zalathar

Rollup of 5 pull requests

Successful merges:

 - rust-lang/rust#150443 (Support long diff conflict markers)
 - rust-lang/rust#151887 (Remove some unnecessary `try`-related type annotations)
 - rust-lang/rust#152037 (Suppress unused_mut lint if mutation fails due to borrowck error)
 - rust-lang/rust#152067 (Weaken `assert_dep_node_not_yet_allocated_in_current_session` for multiple threads)
 - rust-lang/rust#151227 (Document `-Zcache-proc-macros`)

compiler/rustc_borrowck/src/lib.rs

@@ -1205,6 +1205,17 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, '_, 'tcx> {
                 "access_place: suppressing error place_span=`{:?}` kind=`{:?}`",
                 place_span, kind
             );
+
+            // If the place is being mutated, then mark it as such anyway in order to suppress the
+            // `unused_mut` lint, which is likely incorrect once the access place error has been
+            // resolved.
+            if rw == ReadOrWrite::Write(WriteKind::Mutate)
+                && let Ok(root_place) =
+                    self.is_mutable(place_span.0.as_ref(), is_local_mutation_allowed)
+            {
+                self.add_used_mut(root_place, state);
+            }
+
             return;
         }
 

compiler/rustc_borrowck/src/nll.rs

@@ -231,13 +231,13 @@ pub(super) fn dump_nll_mir<'tcx>(
     dumper.dump_mir(body);
 
     // Also dump the region constraint graph as a graphviz file.
-    let _: io::Result<()> = try {
+    let _ = try {
         let mut file = dumper.create_dump_file("regioncx.all.dot", body)?;
         regioncx.dump_graphviz_raw_constraints(tcx, &mut file)?;
     };
 
     // Also dump the region constraint SCC graph as a graphviz file.
-    let _: io::Result<()> = try {
+    let _ = try {
         let mut file = dumper.create_dump_file("regioncx.scc.dot", body)?;
         regioncx.dump_graphviz_scc_constraints(tcx, &mut file)?;
     };

compiler/rustc_borrowck/src/polonius/dump.rs

@@ -58,7 +58,7 @@ pub(crate) fn dump_polonius_mir<'tcx>(
 
     let dumper = dumper.set_extra_data(extra_data).set_options(options);
 
-    let _: io::Result<()> = try {
+    let _ = try {
         let mut file = dumper.create_dump_file("html", body)?;
         emit_polonius_dump(
             &dumper,

compiler/rustc_codegen_ssa/src/back/linker.rs

@@ -2,7 +2,7 @@ use std::ffi::{OsStr, OsString};
 use std::fs::{self, File};
 use std::io::prelude::*;
 use std::path::{Path, PathBuf};
-use std::{env, io, iter, mem, str};
+use std::{env, iter, mem, str};
 
 use find_msvc_tools;
 use rustc_hir::attrs::WindowsSubsystemKind;
@@ -809,7 +809,7 @@ impl<'a> Linker for GccLinker<'a> {
 
         if self.sess.target.is_like_darwin {
             // Write a plain, newline-separated list of symbols
-            let res: io::Result<()> = try {
+            let res = try {
                 let mut f = File::create_buffered(&path)?;
                 for (sym, _) in symbols {
                     debug!("  _{sym}");
@@ -821,7 +821,7 @@ impl<'a> Linker for GccLinker<'a> {
             }
             self.link_arg("-exported_symbols_list").link_arg(path);
         } else if self.sess.target.is_like_windows {
-            let res: io::Result<()> = try {
+            let res = try {
                 let mut f = File::create_buffered(&path)?;
 
                 // .def file similar to MSVC one but without LIBRARY section
@@ -845,7 +845,7 @@ impl<'a> Linker for GccLinker<'a> {
                 self.link_arg("--export").link_arg(sym);
             }
         } else if crate_type == CrateType::Executable && !self.sess.target.is_like_solaris {
-            let res: io::Result<()> = try {
+            let res = try {
                 let mut f = File::create_buffered(&path)?;
                 writeln!(f, "{{")?;
                 for (sym, _) in symbols {
@@ -860,7 +860,7 @@ impl<'a> Linker for GccLinker<'a> {
             self.link_arg("--dynamic-list").link_arg(path);
         } else {
             // Write an LD version script
-            let res: io::Result<()> = try {
+            let res = try {
                 let mut f = File::create_buffered(&path)?;
                 writeln!(f, "{{")?;
                 if !symbols.is_empty() {
@@ -1139,7 +1139,7 @@ impl<'a> Linker for MsvcLinker<'a> {
         }
 
         let path = tmpdir.join("lib.def");
-        let res: io::Result<()> = try {
+        let res = try {
             let mut f = File::create_buffered(&path)?;
 
             // Start off with the standard module name header and then go
@@ -1735,7 +1735,7 @@ impl<'a> Linker for AixLinker<'a> {
         symbols: &[(String, SymbolExportKind)],
     ) {
         let path = tmpdir.join("list.exp");
-        let res: io::Result<()> = try {
+        let res = try {
             let mut f = File::create_buffered(&path)?;
             // FIXME: use llvm-nm to generate export list.
             for (symbol, _) in symbols {
@@ -2135,7 +2135,7 @@ impl<'a> Linker for BpfLinker<'a> {
         symbols: &[(String, SymbolExportKind)],
     ) {
         let path = tmpdir.join("symbols");
-        let res: io::Result<()> = try {
+        let res = try {
             let mut f = File::create_buffered(&path)?;
             for (sym, _) in symbols {
                 writeln!(f, "{sym}")?;

compiler/rustc_codegen_ssa/src/base.rs

@@ -1111,7 +1111,7 @@ pub fn determine_cgu_reuse<'tcx>(tcx: TyCtxt<'tcx>, cgu: &CodegenUnit<'tcx>) ->
     // know that later). If we are not doing LTO, there is only one optimized
     // version of each module, so we re-use that.
     let dep_node = cgu.codegen_dep_node(tcx);
-    tcx.dep_graph.assert_dep_node_not_yet_allocated_in_current_session(&dep_node, || {
+    tcx.dep_graph.assert_dep_node_not_yet_allocated_in_current_session(tcx.sess, &dep_node, || {
         format!(
             "CompileCodegenUnit dep-node for CGU `{}` already exists before marking.",
             cgu.name()

compiler/rustc_driver_impl/src/lib.rs

@@ -503,7 +503,7 @@ fn show_md_content_with_pager(content: &str, color: ColorConfig) {
     };
 
     // Try to print via the pager, pretty output if possible.
-    let pager_res: Option<()> = try {
+    let pager_res = try {
         let mut pager = cmd.stdin(Stdio::piped()).spawn().ok()?;
 
         let pager_stdin = pager.stdin.as_mut()?;

compiler/rustc_expand/src/proc_macro_server.rs

@@ -7,7 +7,7 @@ use rustc_ast::tokenstream::{self, DelimSpacing, Spacing, TokenStream};
 use rustc_ast::util::literal::escape_byte_str_symbol;
 use rustc_ast_pretty::pprust;
 use rustc_data_structures::fx::FxHashMap;
-use rustc_errors::{Diag, ErrorGuaranteed, MultiSpan, PResult};
+use rustc_errors::{Diag, ErrorGuaranteed, MultiSpan};
 use rustc_parse::lexer::{StripTokens, nfc_normalize};
 use rustc_parse::parser::Parser;
 use rustc_parse::{exp, new_parser_from_source_str, source_str_to_stream, unwrap_or_emit_fatal};
@@ -591,7 +591,7 @@ impl server::Server for Rustc<'_, '_> {
 
     fn ts_expand_expr(&mut self, stream: &Self::TokenStream) -> Result<Self::TokenStream, ()> {
         // Parse the expression from our tokenstream.
-        let expr: PResult<'_, _> = try {
+        let expr = try {
             let mut p = Parser::new(self.psess(), stream.clone(), Some("proc_macro expand expr"));
             let expr = p.parse_expr()?;
             if p.token != token::Eof {

compiler/rustc_hir_analysis/src/check/compare_impl_item.rs

@@ -1844,7 +1844,7 @@ fn compare_synthetic_generics<'tcx>(
                 // The case where the impl method uses `impl Trait` but the trait method uses
                 // explicit generics
                 err.span_label(impl_span, "expected generic parameter, found `impl Trait`");
-                let _: Option<_> = try {
+                try {
                     // try taking the name from the trait impl
                     // FIXME: this is obviously suboptimal since the name can already be used
                     // as another generic argument
@@ -1881,7 +1881,7 @@ fn compare_synthetic_generics<'tcx>(
                 // The case where the trait method uses `impl Trait`, but the impl method uses
                 // explicit generics.
                 err.span_label(impl_span, "expected `impl Trait`, found generic parameter");
-                let _: Option<_> = try {
+                try {
                     let impl_m = impl_m.def_id.as_local()?;
                     let impl_m = tcx.hir_expect_impl_item(impl_m);
                     let (sig, _) = impl_m.expect_fn();

compiler/rustc_interface/src/passes.rs

@@ -582,7 +582,7 @@ fn write_out_deps(tcx: TyCtxt<'_>, outputs: &OutputFilenames, out_filenames: &[P
     let deps_output = outputs.path(OutputType::DepInfo);
     let deps_filename = deps_output.as_path();
 
-    let result: io::Result<()> = try {
+    let result = try {
         // Build a list of files used to compile the output and
         // write Makefile-compatible dependency rules
         let mut files: IndexMap<String, (u64, Option<SourceFileHash>)> = sess

compiler/rustc_lint/src/types.rs

@@ -746,24 +746,23 @@ fn pat_ty_is_known_nonnull<'tcx>(
     typing_env: ty::TypingEnv<'tcx>,
     pat: ty::Pattern<'tcx>,
 ) -> bool {
-    Option::unwrap_or_default(
-        try {
-            match *pat {
-                ty::PatternKind::Range { start, end } => {
-                    let start = start.try_to_value()?.try_to_bits(tcx, typing_env)?;
-                    let end = end.try_to_value()?.try_to_bits(tcx, typing_env)?;
+    try {
+        match *pat {
+            ty::PatternKind::Range { start, end } => {
+                let start = start.try_to_value()?.try_to_bits(tcx, typing_env)?;
+                let end = end.try_to_value()?.try_to_bits(tcx, typing_env)?;
 
-                    // This also works for negative numbers, as we just need
-                    // to ensure we aren't wrapping over zero.
-                    start > 0 && end >= start
-                }
-                ty::PatternKind::NotNull => true,
-                ty::PatternKind::Or(patterns) => {
-                    patterns.iter().all(|pat| pat_ty_is_known_nonnull(tcx, typing_env, pat))
-                }
+                // This also works for negative numbers, as we just need
+                // to ensure we aren't wrapping over zero.
+                start > 0 && end >= start
             }
-        },
-    )
+            ty::PatternKind::NotNull => true,
+            ty::PatternKind::Or(patterns) => {
+                patterns.iter().all(|pat| pat_ty_is_known_nonnull(tcx, typing_env, pat))
+            }
+        }
+    }
+    .unwrap_or_default()
 }
 
 /// Given a non-null scalar (or transparent) type `ty`, return the nullable version of that type.

compiler/rustc_middle/src/mir/pretty.rs

@@ -157,13 +157,13 @@ impl<'dis, 'de, 'tcx> MirDumper<'dis, 'de, 'tcx> {
     /// - `foo & nll | bar & typeck` == match if `foo` and `nll` both appear in the name
     ///   or `typeck` and `bar` both appear in the name.
     pub fn dump_mir(&self, body: &Body<'tcx>) {
-        let _: io::Result<()> = try {
+        let _ = try {
             let mut file = self.create_dump_file("mir", body)?;
             self.dump_mir_to_writer(body, &mut file)?;
         };
 
         if self.tcx().sess.opts.unstable_opts.dump_mir_graphviz {
-            let _: io::Result<()> = try {
+            let _ = try {
                 let mut file = self.create_dump_file("dot", body)?;
                 write_mir_fn_graphviz(self.tcx(), body, false, &mut file)?;
             };

compiler/rustc_mir_build/src/builder/custom/mod.rs

@@ -85,7 +85,7 @@ pub(super) fn build_custom_mir<'tcx>(
         block_map: FxHashMap::default(),
     };
 
-    let res: PResult<_> = try {
+    let res = try {
         pctxt.parse_args(params)?;
         pctxt.parse_body(expr)?;
     };

compiler/rustc_parse/src/parser/diagnostics.rs

@@ -3023,27 +3023,53 @@ impl<'a> Parser<'a> {
         long_kind: &TokenKind,
         short_kind: &TokenKind,
     ) -> bool {
-        (0..3).all(|i| self.look_ahead(i, |tok| tok == long_kind))
-            && self.look_ahead(3, |tok| tok == short_kind)
+        if long_kind == short_kind {
+            // For conflict marker chars like `%` and `\`.
+            (0..7).all(|i| self.look_ahead(i, |tok| tok == long_kind))
+        } else {
+            // For conflict marker chars like `<` and `|`.
+            (0..3).all(|i| self.look_ahead(i, |tok| tok == long_kind))
+                && self.look_ahead(3, |tok| tok == short_kind || tok == long_kind)
+        }
     }
 
-    fn conflict_marker(&mut self, long_kind: &TokenKind, short_kind: &TokenKind) -> Option<Span> {
+    fn conflict_marker(
+        &mut self,
+        long_kind: &TokenKind,
+        short_kind: &TokenKind,
+        expected: Option<usize>,
+    ) -> Option<(Span, usize)> {
         if self.is_vcs_conflict_marker(long_kind, short_kind) {
             let lo = self.token.span;
-            for _ in 0..4 {
-                self.bump();
+            if self.psess.source_map().span_to_margin(lo) != Some(0) {
+                return None;
             }
-            return Some(lo.to(self.prev_token.span));
+            let mut len = 0;
+            while self.token.kind == *long_kind || self.token.kind == *short_kind {
+                if self.token.kind.break_two_token_op(1).is_some() {
+                    len += 2;
+                } else {
+                    len += 1;
+                }
+                self.bump();
+                if expected == Some(len) {
+                    break;
+                }
+            }
+            if expected.is_some() && expected != Some(len) {
+                return None;
+            }
+            return Some((lo.to(self.prev_token.span), len));
         }
         None
     }
 
     pub(super) fn recover_vcs_conflict_marker(&mut self) {
         // <<<<<<<
-        let Some(start) = self.conflict_marker(&TokenKind::Shl, &TokenKind::Lt) else {
+        let Some((start, len)) = self.conflict_marker(&TokenKind::Shl, &TokenKind::Lt, None) else {
             return;
         };
-        let mut spans = Vec::with_capacity(3);
+        let mut spans = Vec::with_capacity(2);
         spans.push(start);
         // |||||||
         let mut middlediff3 = None;
@@ -3055,13 +3081,19 @@ impl<'a> Parser<'a> {
             if self.token == TokenKind::Eof {
                 break;
             }
-            if let Some(span) = self.conflict_marker(&TokenKind::OrOr, &TokenKind::Or) {
+            if let Some((span, _)) =
+                self.conflict_marker(&TokenKind::OrOr, &TokenKind::Or, Some(len))
+            {
                 middlediff3 = Some(span);
             }
-            if let Some(span) = self.conflict_marker(&TokenKind::EqEq, &TokenKind::Eq) {
+            if let Some((span, _)) =
+                self.conflict_marker(&TokenKind::EqEq, &TokenKind::Eq, Some(len))
+            {
                 middle = Some(span);
             }
-            if let Some(span) = self.conflict_marker(&TokenKind::Shr, &TokenKind::Gt) {
+            if let Some((span, _)) =
+                self.conflict_marker(&TokenKind::Shr, &TokenKind::Gt, Some(len))
+            {
                 spans.push(span);
                 end = Some(span);
                 break;

compiler/rustc_privacy/src/lib.rs

@@ -1157,14 +1157,14 @@ impl<'tcx> TypePrivacyVisitor<'tcx> {
         let typeck_results = self
             .maybe_typeck_results
             .unwrap_or_else(|| span_bug!(span, "`hir::Expr` or `hir::Pat` outside of a body"));
-        let result: ControlFlow<()> = try {
+        try {
             self.visit(typeck_results.node_type(id))?;
             self.visit(typeck_results.node_args(id))?;
             if let Some(adjustments) = typeck_results.adjustments().get(id) {
                 adjustments.iter().try_for_each(|adjustment| self.visit(adjustment.target))?;
             }
-        };
-        result.is_break()
+        }
+        .is_break()
     }
 
     fn check_def_id(&self, def_id: DefId, kind: &str, descr: &dyn fmt::Display) -> bool {

compiler/rustc_query_system/src/dep_graph/graph.rs

@@ -336,13 +336,17 @@ impl<D: Deps> DepGraphData<D> {
         //    in `DepGraph::try_mark_green()`.
         // 2. Two distinct query keys get mapped to the same `DepNode`
         //    (see for example #48923).
-        self.assert_dep_node_not_yet_allocated_in_current_session(&key, || {
-            format!(
-                "forcing query with already existing `DepNode`\n\
+        self.assert_dep_node_not_yet_allocated_in_current_session(
+            cx.dep_context().sess(),
+            &key,
+            || {
+                format!(
+                    "forcing query with already existing `DepNode`\n\
                  - query-key: {arg:?}\n\
                  - dep-node: {key:?}"
-            )
-        });
+                )
+            },
+        );
 
         let with_deps = |task_deps| D::with_deps(task_deps, || task(cx, arg));
         let (result, edges) = if cx.dep_context().is_eval_always(key.kind) {
@@ -627,12 +631,20 @@ impl<D: Deps> DepGraph<D> {
 impl<D: Deps> DepGraphData<D> {
     fn assert_dep_node_not_yet_allocated_in_current_session<S: std::fmt::Display>(
         &self,
+        sess: &Session,
         dep_node: &DepNode,
         msg: impl FnOnce() -> S,
     ) {
         if let Some(prev_index) = self.previous.node_to_index_opt(dep_node) {
-            let current = self.colors.get(prev_index);
-            assert_matches!(current, DepNodeColor::Unknown, "{}", msg())
+            let color = self.colors.get(prev_index);
+            let ok = match color {
+                DepNodeColor::Unknown => true,
+                DepNodeColor::Red => false,
+                DepNodeColor::Green(..) => sess.threads() > 1, // Other threads may mark this green
+            };
+            if !ok {
+                panic!("{}", msg())
+            }
         } else if let Some(nodes_in_current_session) = &self.current.nodes_in_current_session {
             outline(|| {
                 let seen = nodes_in_current_session.lock().contains_key(dep_node);
@@ -1035,11 +1047,12 @@ impl<D: Deps> DepGraph<D> {
 
     pub fn assert_dep_node_not_yet_allocated_in_current_session<S: std::fmt::Display>(
         &self,
+        sess: &Session,
         dep_node: &DepNode,
         msg: impl FnOnce() -> S,
     ) {
         if let Some(data) = &self.data {
-            data.assert_dep_node_not_yet_allocated_in_current_session(dep_node, msg)
+            data.assert_dep_node_not_yet_allocated_in_current_session(sess, dep_node, msg)
         }
     }
 

compiler/rustc_trait_selection/src/error_reporting/infer/need_type_info.rs

@@ -1023,7 +1023,7 @@ impl<'a, 'tcx> FindInferSourceVisitor<'a, 'tcx> {
             hir::ExprKind::MethodCall(segment, ..) => {
                 if let Some(def_id) = self.typeck_results.type_dependent_def_id(expr.hir_id) {
                     let generics = tcx.generics_of(def_id);
-                    let insertable: Option<_> = try {
+                    let insertable = try {
                         if generics.has_impl_trait() {
                             None?
                         }
@@ -1061,7 +1061,7 @@ impl<'a, 'tcx> FindInferSourceVisitor<'a, 'tcx> {
         //
         // FIXME: We deal with that one separately for now,
         // would be good to remove this special case.
-        let last_segment_using_path_data: Option<_> = try {
+        let last_segment_using_path_data = try {
             let generics_def_id = tcx.res_generics_def_id(path.res)?;
             let generics = tcx.generics_of(generics_def_id);
             if generics.has_impl_trait() {
@@ -1117,19 +1117,18 @@ impl<'a, 'tcx> FindInferSourceVisitor<'a, 'tcx> {
                 };
 
                 let generics = tcx.generics_of(def_id);
-                let segment: Option<_> = try {
-                    if !segment.infer_args || generics.has_impl_trait() {
-                        do yeet ();
-                    }
+                let segment = if !segment.infer_args || generics.has_impl_trait() {
+                    None
+                } else {
                     let span = tcx.hir_span(segment.hir_id);
                     let insert_span = segment.ident.span.shrink_to_hi().with_hi(span.hi());
-                    InsertableGenericArgs {
+                    Some(InsertableGenericArgs {
                         insert_span,
                         args,
                         generics_def_id: def_id,
                         def_id,
                         have_turbofish: false,
-                    }
+                    })
                 };
 
                 let parent_def_id = generics.parent.unwrap();

src/doc/unstable-book/src/compiler-flags/cache-proc-macros.md

@@ -0,0 +1,9 @@
+## `cache-proc-macros`
+
+The tracking issue for this feature is: [#151364]
+
+[#151364]: https://github.com/rust-lang/rust/issues/151364
+
+------------------------
+
+This option instructs `rustc` to cache (derive) proc-macro invocations using the incremental system. Note that the compiler does not currently check whether the proc-macro is actually "cacheable" or not. If you use this flag when compiling a crate that uses non-pure proc-macros, it can result in stale expansions being compiled.

tests/ui/lint/unused/mut-used-despite-borrowck-error.rs

@@ -0,0 +1,19 @@
+//! Do not fire unused_mut lint when mutation of the bound variable fails due to a borrow-checking
+//! error.
+//!
+//! Regression test for https://github.com/rust-lang/rust/issues/152024
+//@ compile-flags: -W unused_mut
+
+struct Thing;
+impl Drop for Thing {
+    fn drop(&mut self) {}
+}
+
+fn main() {
+    let mut t;
+    let mut b = None;
+    loop {
+        t = Thing; //~ ERROR cannot assign to `t` because it is borrowed
+        b.insert(&t);
+    }
+}

tests/ui/lint/unused/mut-used-despite-borrowck-error.stderr

@@ -0,0 +1,13 @@
+error[E0506]: cannot assign to `t` because it is borrowed
+  --> $DIR/mut-used-despite-borrowck-error.rs:16:9
+   |
+LL |         t = Thing;
+   |         ^ `t` is assigned to here but it was already borrowed
+LL |         b.insert(&t);
+   |         -        -- `t` is borrowed here
+   |         |
+   |         borrow later used here
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0506`.

tests/ui/parser/diff-markers/long-conflict-markers.rs

@@ -0,0 +1,11 @@
+enum E {
+    Foo {
+<<<<<<<<< HEAD //~ ERROR encountered diff marker
+        x: u8,
+|||||||
+        z: (),
+=========
+        y: i8,
+>>>>>>>>> branch
+    }
+}

tests/ui/parser/diff-markers/long-conflict-markers.stderr

@@ -0,0 +1,20 @@
+error: encountered diff marker
+  --> $DIR/long-conflict-markers.rs:3:1
+   |
+LL | <<<<<<<<< HEAD
+   | ^^^^^^^^^ between this marker and `=======` is the code that you are merging into
+...
+LL | =========
+   | --------- between this marker and `>>>>>>>` is the incoming code
+LL |         y: i8,
+LL | >>>>>>>>> branch
+   | ^^^^^^^^^ this marker concludes the conflict region
+   |
+   = note: conflict markers indicate that a merge was started but could not be completed due to merge conflicts
+           to resolve a conflict, keep only the code you want and then delete the lines containing conflict markers
+   = help: if you are in a merge, the top section is the code you already had checked out and the bottom section is the new code
+           if you are in a rebase, the top section is the code being rebased onto and the bottom section is the code you had checked out which is being rebased
+   = note: for an explanation on these markers from the `git` documentation, visit <https://git-scm.com/book/en/v2/Git-Tools-Advanced-Merging#_checking_out_conflicts>
+
+error: aborting due to 1 previous error
+