Merge pull request #4094 from rust-lang/rustup-2024-12-13

Automatic Rustup

.gitattributes

@@ -4,10 +4,8 @@
 *.cpp rust
 *.h rust
 *.rs rust diff=rust
-*.fixed linguist-language=Rust -merge
-*.mir linguist-language=Rust -merge
-*.stderr -merge
-*.stdout -merge
+*.fixed linguist-language=Rust
+*.mir linguist-language=Rust
 src/etc/installer/gfx/* binary
 src/vendor/** -text
 Cargo.lock linguist-generated=false

compiler/rustc_ast/src/util/comments/tests.rs

@@ -1,3 +1,5 @@
+#![cfg_attr(not(bootstrap), allow(rustc::symbol_intern_string_literal))]
+
 use rustc_span::create_default_session_globals_then;
 
 use super::*;

compiler/rustc_ast_passes/src/feature_gate.rs

@@ -511,11 +511,6 @@ pub fn check_crate(krate: &ast::Crate, sess: &Session, features: &Features) {
         "you can write `if matches!(<expr>, <pattern>)` instead of `if let <pattern> = <expr>`"
     );
     gate_all!(let_chains, "`let` expressions in this position are unstable");
-    gate_all!(
-        async_closure,
-        "async closures are unstable",
-        "to use an async block, remove the `||`: `async {`"
-    );
     gate_all!(
         async_trait_bounds,
         "`async` trait bounds are unstable",

compiler/rustc_codegen_llvm/src/llvm/ffi.rs

@@ -17,7 +17,9 @@ use super::debuginfo::{
     DebugEmissionKind, DebugNameTableKind,
 };
 
-pub type Bool = c_uint;
+/// In the LLVM-C API, boolean values are passed as `typedef int LLVMBool`,
+/// which has a different ABI from Rust or C++ `bool`.
+pub type Bool = c_int;
 
 pub const True: Bool = 1 as Bool;
 pub const False: Bool = 0 as Bool;

compiler/rustc_error_codes/src/error_codes/E0307.md

@@ -65,8 +65,10 @@ impl Trait for Foo {
 ```
 
 The nightly feature [Arbitrary self types][AST] extends the accepted
-set of receiver types to also include any type that can dereference to
-`Self`:
+set of receiver types to also include any type that implements the
+`Receiver` trait and can follow its chain of `Target` types to `Self`.
+There's a blanket implementation of `Receiver` for `T: Deref`, so any
+type which dereferences to `Self` can be used.
 
 ```
 #![feature(arbitrary_self_types)]

compiler/rustc_error_codes/src/error_codes/E0708.md

@@ -5,8 +5,6 @@
 Erroneous code example:
 
 ```edition2018
-#![feature(async_closure)]
-
 fn main() {
     let add_one = async |num: u8| {
         num + 1
@@ -18,8 +16,6 @@ fn main() {
 version, you can use successfully by using move:
 
 ```edition2018
-#![feature(async_closure)]
-
 fn main() {
     let add_one = async move |num: u8| { // ok!
         num + 1

compiler/rustc_errors/src/lib.rs

@@ -94,8 +94,7 @@ mod styled_buffer;
 mod tests;
 pub mod translation;
 
-pub type PErr<'a> = Diag<'a>;
-pub type PResult<'a, T> = Result<T, PErr<'a>>;
+pub type PResult<'a, T> = Result<T, Diag<'a>>;
 
 rustc_fluent_macro::fluent_messages! { "../messages.ftl" }
 
@@ -576,6 +575,10 @@ pub enum StashKey {
     UndeterminedMacroResolution,
     /// Used by `Parser::maybe_recover_trailing_expr`
     ExprInPat,
+    /// If in the parser we detect a field expr with turbofish generic params it's possible that
+    /// it's a method call without parens. If later on in `hir_typeck` we find out that this is
+    /// the case we suppress this message and we give a better suggestion.
+    GenericInFieldExpr,
 }
 
 fn default_track_diagnostic<R>(diag: DiagInner, f: &mut dyn FnMut(DiagInner) -> R) -> R {

compiler/rustc_feature/src/accepted.rs

@@ -72,6 +72,8 @@ declare_features! (
     (accepted, associated_types, "1.0.0", None),
     /// Allows free and inherent `async fn`s, `async` blocks, and `<expr>.await` expressions.
     (accepted, async_await, "1.39.0", Some(50547)),
+    /// Allows `async || body` closures.
+    (accepted, async_closure, "CURRENT_RUSTC_VERSION", Some(62290)),
     /// Allows async functions to be declared, implemented, and used in traits.
     (accepted, async_fn_in_trait, "1.75.0", Some(91611)),
     /// Allows all literals in attribute lists and values of key-value pairs.

compiler/rustc_feature/src/unstable.rs

@@ -388,8 +388,8 @@ declare_features! (
     (unstable, associated_const_equality, "1.58.0", Some(92827)),
     /// Allows associated type defaults.
     (unstable, associated_type_defaults, "1.2.0", Some(29661)),
-    /// Allows `async || body` closures.
-    (unstable, async_closure, "1.37.0", Some(62290)),
+    /// Allows async functions to be called from `dyn Trait`.
+    (incomplete, async_fn_in_dyn_trait, "CURRENT_RUSTC_VERSION", Some(133119)),
     /// Allows `#[track_caller]` on async functions.
     (unstable, async_fn_track_caller, "1.73.0", Some(110011)),
     /// Allows `for await` loops.

compiler/rustc_hir/src/tests.rs

@@ -1,3 +1,5 @@
+#![cfg_attr(not(bootstrap), allow(rustc::symbol_intern_string_literal))]
+
 use rustc_data_structures::stable_hasher::Hash64;
 use rustc_span::def_id::{DefPathHash, StableCrateId};
 use rustc_span::edition::Edition;

compiler/rustc_hir_analysis/messages.ftl

@@ -241,10 +241,10 @@ hir_analysis_invalid_generic_receiver_ty_help =
     use a concrete type such as `self`, `&self`, `&mut self`, `self: Box<Self>`, `self: Rc<Self>`, `self: Arc<Self>`, or `self: Pin<P>` (where P is one of the previous types except `Self`)
 
 hir_analysis_invalid_receiver_ty = invalid `self` parameter type: `{$receiver_ty}`
-    .note = type of `self` must be `Self` or a type that dereferences to it
+    .note = type of `self` must be `Self` or some type implementing `Receiver`
 
 hir_analysis_invalid_receiver_ty_help =
-    consider changing to `self`, `&self`, `&mut self`, `self: Box<Self>`, `self: Rc<Self>`, `self: Arc<Self>`, or `self: Pin<P>` (where P is one of the previous types except `Self`)
+    consider changing to `self`, `&self`, `&mut self`, or a type implementing `Receiver` such as `self: Box<Self>`, `self: Rc<Self>`, or `self: Arc<Self>`
 
 hir_analysis_invalid_union_field =
     field must implement `Copy` or be wrapped in `ManuallyDrop<...>` to be used in a union

compiler/rustc_hir_analysis/src/autoderef.rs

@@ -18,7 +18,6 @@ pub enum AutoderefKind {
     /// A type which must dispatch to a `Deref` implementation.
     Overloaded,
 }
-
 struct AutoderefSnapshot<'tcx> {
     at_start: bool,
     reached_recursion_limit: bool,
@@ -27,6 +26,10 @@ struct AutoderefSnapshot<'tcx> {
     obligations: PredicateObligations<'tcx>,
 }
 
+/// Recursively dereference a type, considering both built-in
+/// dereferences (`*`) and the `Deref` trait.
+/// Although called `Autoderef` it can be configured to use the
+/// `Receiver` trait instead of the `Deref` trait.
 pub struct Autoderef<'a, 'tcx> {
     // Meta infos:
     infcx: &'a InferCtxt<'tcx>,
@@ -39,6 +42,7 @@ pub struct Autoderef<'a, 'tcx> {
 
     // Configurations:
     include_raw_pointers: bool,
+    use_receiver_trait: bool,
     silence_errors: bool,
 }
 
@@ -69,6 +73,10 @@ impl<'a, 'tcx> Iterator for Autoderef<'a, 'tcx> {
         }
 
         // Otherwise, deref if type is derefable:
+        // NOTE: in the case of self.use_receiver_trait = true, you might think it would
+        // be better to skip this clause and use the Overloaded case only, since &T
+        // and &mut T implement Receiver. But built-in derefs apply equally to Receiver
+        // and Deref, and this has benefits for const and the emitted MIR.
         let (kind, new_ty) =
             if let Some(ty) = self.state.cur_ty.builtin_deref(self.include_raw_pointers) {
                 debug_assert_eq!(ty, self.infcx.resolve_vars_if_possible(ty));
@@ -111,7 +119,7 @@ impl<'a, 'tcx> Autoderef<'a, 'tcx> {
         body_def_id: LocalDefId,
         span: Span,
         base_ty: Ty<'tcx>,
-    ) -> Autoderef<'a, 'tcx> {
+    ) -> Self {
         Autoderef {
             infcx,
             span,
@@ -125,6 +133,7 @@ impl<'a, 'tcx> Autoderef<'a, 'tcx> {
                 reached_recursion_limit: false,
             },
             include_raw_pointers: false,
+            use_receiver_trait: false,
             silence_errors: false,
         }
     }
@@ -137,8 +146,13 @@ impl<'a, 'tcx> Autoderef<'a, 'tcx> {
             return None;
         }
 
-        // <ty as Deref>
-        let trait_ref = ty::TraitRef::new(tcx, tcx.lang_items().deref_trait()?, [ty]);
+        // <ty as Deref>, or whatever the equivalent trait is that we've been asked to walk.
+        let (trait_def_id, trait_target_def_id) = if self.use_receiver_trait {
+            (tcx.lang_items().receiver_trait()?, tcx.lang_items().receiver_target()?)
+        } else {
+            (tcx.lang_items().deref_trait()?, tcx.lang_items().deref_target()?)
+        };
+        let trait_ref = ty::TraitRef::new(tcx, trait_def_id, [ty]);
         let cause = traits::ObligationCause::misc(self.span, self.body_id);
         let obligation = traits::Obligation::new(
             tcx,
@@ -151,11 +165,8 @@ impl<'a, 'tcx> Autoderef<'a, 'tcx> {
             return None;
         }
 
-        let (normalized_ty, obligations) = self.structurally_normalize(Ty::new_projection(
-            tcx,
-            tcx.lang_items().deref_target()?,
-            [ty],
-        ))?;
+        let (normalized_ty, obligations) =
+            self.structurally_normalize(Ty::new_projection(tcx, trait_target_def_id, [ty]))?;
         debug!("overloaded_deref_ty({:?}) = ({:?}, {:?})", ty, normalized_ty, obligations);
         self.state.obligations.extend(obligations);
 
@@ -234,6 +245,14 @@ impl<'a, 'tcx> Autoderef<'a, 'tcx> {
         self
     }
 
+    /// Use `core::ops::Receiver` and `core::ops::Receiver::Target` as
+    /// the trait and associated type to iterate, instead of
+    /// `core::ops::Deref` and `core::ops::Deref::Target`
+    pub fn use_receiver_trait(mut self) -> Self {
+        self.use_receiver_trait = true;
+        self
+    }
+
     pub fn silence_errors(mut self) -> Self {
         self.silence_errors = true;
         self

compiler/rustc_hir_analysis/src/check/intrinsicck.rs

@@ -3,6 +3,7 @@ use std::assert_matches::debug_assert_matches;
 use rustc_abi::FieldIdx;
 use rustc_ast::InlineAsmTemplatePiece;
 use rustc_data_structures::fx::FxIndexSet;
+use rustc_hir::def_id::DefId;
 use rustc_hir::{self as hir, LangItem};
 use rustc_middle::bug;
 use rustc_middle::ty::{self, FloatTy, IntTy, Ty, TyCtxt, TypeVisitableExt, UintTy};
@@ -21,6 +22,12 @@ pub struct InlineAsmCtxt<'a, 'tcx> {
     get_operand_ty: Box<dyn Fn(&'tcx hir::Expr<'tcx>) -> Ty<'tcx> + 'a>,
 }
 
+enum NonAsmTypeReason<'tcx> {
+    UnevaluatedSIMDArrayLength(DefId, ty::Const<'tcx>),
+    Invalid(Ty<'tcx>),
+    InvalidElement(DefId, Ty<'tcx>),
+}
+
 impl<'a, 'tcx> InlineAsmCtxt<'a, 'tcx> {
     pub fn new_global_asm(tcx: TyCtxt<'tcx>) -> Self {
         InlineAsmCtxt {
@@ -56,7 +63,7 @@ impl<'a, 'tcx> InlineAsmCtxt<'a, 'tcx> {
         false
     }
 
-    fn get_asm_ty(&self, ty: Ty<'tcx>) -> Option<InlineAsmType> {
+    fn get_asm_ty(&self, ty: Ty<'tcx>) -> Result<InlineAsmType, NonAsmTypeReason<'tcx>> {
         let asm_ty_isize = match self.tcx.sess.target.pointer_width {
             16 => InlineAsmType::I16,
             32 => InlineAsmType::I32,
@@ -65,64 +72,62 @@ impl<'a, 'tcx> InlineAsmCtxt<'a, 'tcx> {
         };
 
         match *ty.kind() {
-            ty::Int(IntTy::I8) | ty::Uint(UintTy::U8) => Some(InlineAsmType::I8),
-            ty::Int(IntTy::I16) | ty::Uint(UintTy::U16) => Some(InlineAsmType::I16),
-            ty::Int(IntTy::I32) | ty::Uint(UintTy::U32) => Some(InlineAsmType::I32),
-            ty::Int(IntTy::I64) | ty::Uint(UintTy::U64) => Some(InlineAsmType::I64),
-            ty::Int(IntTy::I128) | ty::Uint(UintTy::U128) => Some(InlineAsmType::I128),
-            ty::Int(IntTy::Isize) | ty::Uint(UintTy::Usize) => Some(asm_ty_isize),
-            ty::Float(FloatTy::F16) => Some(InlineAsmType::F16),
-            ty::Float(FloatTy::F32) => Some(InlineAsmType::F32),
-            ty::Float(FloatTy::F64) => Some(InlineAsmType::F64),
-            ty::Float(FloatTy::F128) => Some(InlineAsmType::F128),
-            ty::FnPtr(..) => Some(asm_ty_isize),
-            ty::RawPtr(ty, _) if self.is_thin_ptr_ty(ty) => Some(asm_ty_isize),
+            ty::Int(IntTy::I8) | ty::Uint(UintTy::U8) => Ok(InlineAsmType::I8),
+            ty::Int(IntTy::I16) | ty::Uint(UintTy::U16) => Ok(InlineAsmType::I16),
+            ty::Int(IntTy::I32) | ty::Uint(UintTy::U32) => Ok(InlineAsmType::I32),
+            ty::Int(IntTy::I64) | ty::Uint(UintTy::U64) => Ok(InlineAsmType::I64),
+            ty::Int(IntTy::I128) | ty::Uint(UintTy::U128) => Ok(InlineAsmType::I128),
+            ty::Int(IntTy::Isize) | ty::Uint(UintTy::Usize) => Ok(asm_ty_isize),
+            ty::Float(FloatTy::F16) => Ok(InlineAsmType::F16),
+            ty::Float(FloatTy::F32) => Ok(InlineAsmType::F32),
+            ty::Float(FloatTy::F64) => Ok(InlineAsmType::F64),
+            ty::Float(FloatTy::F128) => Ok(InlineAsmType::F128),
+            ty::FnPtr(..) => Ok(asm_ty_isize),
+            ty::RawPtr(ty, _) if self.is_thin_ptr_ty(ty) => Ok(asm_ty_isize),
             ty::Adt(adt, args) if adt.repr().simd() => {
                 let fields = &adt.non_enum_variant().fields;
-                let elem_ty = fields[FieldIdx::ZERO].ty(self.tcx, args);
+                let field = &fields[FieldIdx::ZERO];
+                let elem_ty = field.ty(self.tcx, args);
 
                 let (size, ty) = match elem_ty.kind() {
                     ty::Array(ty, len) => {
+                        let len = self.tcx.normalize_erasing_regions(self.typing_env, *len);
                         if let Some(len) = len.try_to_target_usize(self.tcx) {
                             (len, *ty)
                         } else {
-                            return None;
+                            return Err(NonAsmTypeReason::UnevaluatedSIMDArrayLength(
+                                field.did, len,
+                            ));
                         }
                     }
                     _ => (fields.len() as u64, elem_ty),
                 };
 
                 match ty.kind() {
-                    ty::Int(IntTy::I8) | ty::Uint(UintTy::U8) => Some(InlineAsmType::VecI8(size)),
-                    ty::Int(IntTy::I16) | ty::Uint(UintTy::U16) => {
-                        Some(InlineAsmType::VecI16(size))
-                    }
-                    ty::Int(IntTy::I32) | ty::Uint(UintTy::U32) => {
-                        Some(InlineAsmType::VecI32(size))
-                    }
-                    ty::Int(IntTy::I64) | ty::Uint(UintTy::U64) => {
-                        Some(InlineAsmType::VecI64(size))
-                    }
+                    ty::Int(IntTy::I8) | ty::Uint(UintTy::U8) => Ok(InlineAsmType::VecI8(size)),
+                    ty::Int(IntTy::I16) | ty::Uint(UintTy::U16) => Ok(InlineAsmType::VecI16(size)),
+                    ty::Int(IntTy::I32) | ty::Uint(UintTy::U32) => Ok(InlineAsmType::VecI32(size)),
+                    ty::Int(IntTy::I64) | ty::Uint(UintTy::U64) => Ok(InlineAsmType::VecI64(size)),
                     ty::Int(IntTy::I128) | ty::Uint(UintTy::U128) => {
-                        Some(InlineAsmType::VecI128(size))
+                        Ok(InlineAsmType::VecI128(size))
                     }
                     ty::Int(IntTy::Isize) | ty::Uint(UintTy::Usize) => {
-                        Some(match self.tcx.sess.target.pointer_width {
+                        Ok(match self.tcx.sess.target.pointer_width {
                             16 => InlineAsmType::VecI16(size),
                             32 => InlineAsmType::VecI32(size),
                             64 => InlineAsmType::VecI64(size),
                             width => bug!("unsupported pointer width: {width}"),
                         })
                     }
-                    ty::Float(FloatTy::F16) => Some(InlineAsmType::VecF16(size)),
-                    ty::Float(FloatTy::F32) => Some(InlineAsmType::VecF32(size)),
-                    ty::Float(FloatTy::F64) => Some(InlineAsmType::VecF64(size)),
-                    ty::Float(FloatTy::F128) => Some(InlineAsmType::VecF128(size)),
-                    _ => None,
+                    ty::Float(FloatTy::F16) => Ok(InlineAsmType::VecF16(size)),
+                    ty::Float(FloatTy::F32) => Ok(InlineAsmType::VecF32(size)),
+                    ty::Float(FloatTy::F64) => Ok(InlineAsmType::VecF64(size)),
+                    ty::Float(FloatTy::F128) => Ok(InlineAsmType::VecF128(size)),
+                    _ => Err(NonAsmTypeReason::InvalidElement(field.did, ty)),
                 }
             }
             ty::Infer(_) => bug!("unexpected infer ty in asm operand"),
-            _ => None,
+            _ => Err(NonAsmTypeReason::Invalid(ty)),
         }
     }
 
@@ -163,17 +168,42 @@ impl<'a, 'tcx> InlineAsmCtxt<'a, 'tcx> {
             }
             _ => self.get_asm_ty(ty),
         };
-        let Some(asm_ty) = asm_ty else {
-            let msg = format!("cannot use value of type `{ty}` for inline assembly");
-            self.tcx
-                .dcx()
-                .struct_span_err(expr.span, msg)
-                .with_note(
-                    "only integers, floats, SIMD vectors, pointers and function pointers \
-                     can be used as arguments for inline assembly",
-                )
-                .emit();
-            return None;
+        let asm_ty = match asm_ty {
+            Ok(asm_ty) => asm_ty,
+            Err(reason) => {
+                match reason {
+                    NonAsmTypeReason::UnevaluatedSIMDArrayLength(did, len) => {
+                        let msg = format!("cannot evaluate SIMD vector length `{len}`");
+                        self.tcx
+                            .dcx()
+                            .struct_span_err(self.tcx.def_span(did), msg)
+                            .with_span_note(
+                                expr.span,
+                                "SIMD vector length needs to be known statically for use in `asm!`",
+                            )
+                            .emit();
+                    }
+                    NonAsmTypeReason::Invalid(ty) => {
+                        let msg = format!("cannot use value of type `{ty}` for inline assembly");
+                        self.tcx.dcx().struct_span_err(expr.span, msg).with_note(
+                            "only integers, floats, SIMD vectors, pointers and function pointers \
+                            can be used as arguments for inline assembly",
+                        ).emit();
+                    }
+                    NonAsmTypeReason::InvalidElement(did, ty) => {
+                        let msg = format!(
+                            "cannot use SIMD vector with element type `{ty}` for inline assembly"
+                        );
+                        self.tcx.dcx()
+                        .struct_span_err(self.tcx.def_span(did), msg).with_span_note(
+                            expr.span,
+                            "only integers, floats, SIMD vectors, pointers and function pointers \
+                            can be used as arguments for inline assembly",
+                        ).emit();
+                    }
+                }
+                return None;
+            }
         };
 
         // Check that the type implements Copy. The only case where this can

compiler/rustc_hir_analysis/src/check/wfcheck.rs

@@ -1821,13 +1821,18 @@ fn receiver_is_valid<'tcx>(
 
     let mut autoderef = Autoderef::new(infcx, wfcx.param_env, wfcx.body_def_id, span, receiver_ty);
 
+    // The `arbitrary_self_types` feature allows custom smart pointer
+    // types to be method receivers, as identified by following the Receiver<Target=T>
+    // chain.
+    if arbitrary_self_types_enabled.is_some() {
+        autoderef = autoderef.use_receiver_trait();
+    }
+
     // The `arbitrary_self_types_pointers` feature allows raw pointer receivers like `self: *const Self`.
     if arbitrary_self_types_enabled == Some(ArbitrarySelfTypesLevel::WithPointers) {
         autoderef = autoderef.include_raw_pointers();
     }
 
-    let receiver_trait_def_id = tcx.require_lang_item(LangItem::LegacyReceiver, Some(span));
-
     // Keep dereferencing `receiver_ty` until we get to `self_ty`.
     while let Some((potential_self_ty, _)) = autoderef.next() {
         debug!(
@@ -1849,11 +1854,13 @@ fn receiver_is_valid<'tcx>(
         }
 
         // Without `feature(arbitrary_self_types)`, we require that each step in the
-        // deref chain implement `receiver`.
+        // deref chain implement `LegacyReceiver`.
         if arbitrary_self_types_enabled.is_none() {
-            if !receiver_is_implemented(
+            let legacy_receiver_trait_def_id =
+                tcx.require_lang_item(LangItem::LegacyReceiver, Some(span));
+            if !legacy_receiver_is_implemented(
                 wfcx,
-                receiver_trait_def_id,
+                legacy_receiver_trait_def_id,
                 cause.clone(),
                 potential_self_ty,
             ) {
@@ -1866,7 +1873,7 @@ fn receiver_is_valid<'tcx>(
                 cause.clone(),
                 wfcx.param_env,
                 potential_self_ty,
-                receiver_trait_def_id,
+                legacy_receiver_trait_def_id,
             );
         }
     }
@@ -1875,14 +1882,14 @@ fn receiver_is_valid<'tcx>(
     Err(ReceiverValidityError::DoesNotDeref)
 }
 
-fn receiver_is_implemented<'tcx>(
+fn legacy_receiver_is_implemented<'tcx>(
     wfcx: &WfCheckingCtxt<'_, 'tcx>,
-    receiver_trait_def_id: DefId,
+    legacy_receiver_trait_def_id: DefId,
     cause: ObligationCause<'tcx>,
     receiver_ty: Ty<'tcx>,
 ) -> bool {
     let tcx = wfcx.tcx();
-    let trait_ref = ty::TraitRef::new(tcx, receiver_trait_def_id, [receiver_ty]);
+    let trait_ref = ty::TraitRef::new(tcx, legacy_receiver_trait_def_id, [receiver_ty]);
 
     let obligation = Obligation::new(tcx, cause, wfcx.param_env, trait_ref);
 
@@ -1890,7 +1897,7 @@ fn receiver_is_implemented<'tcx>(
         true
     } else {
         debug!(
-            "receiver_is_implemented: type `{:?}` does not implement `Receiver` trait",
+            "receiver_is_implemented: type `{:?}` does not implement `LegacyReceiver` trait",
             receiver_ty
         );
         false

compiler/rustc_hir_typeck/src/demand.rs

@@ -917,7 +917,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             [candidate] => format!(
                 "the method of the same name on {} `{}`",
                 match candidate.kind {
-                    probe::CandidateKind::InherentImplCandidate(_) => "the inherent impl for",
+                    probe::CandidateKind::InherentImplCandidate { .. } => "the inherent impl for",
                     _ => "trait",
                 },
                 self.tcx.def_path_str(candidate.item.container_id(self.tcx))

compiler/rustc_hir_typeck/src/expr.rs

@@ -3076,7 +3076,8 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             err.help("methods are immutable and cannot be assigned to");
         }
 
-        err.emit()
+        // See `StashKey::GenericInFieldExpr` for more info
+        self.dcx().try_steal_replace_and_emit_err(field.span, StashKey::GenericInFieldExpr, err)
     }
 
     fn point_at_param_definition(&self, err: &mut Diag<'_>, param: ty::ParamTy) {

compiler/rustc_hir_typeck/src/fallback.rs

@@ -613,19 +613,16 @@ impl<'tcx> AnnotateUnitFallbackVisitor<'_, 'tcx> {
         if arg_segment.args.is_none()
             && let Some(all_args) = self.fcx.typeck_results.borrow().node_args_opt(id)
             && let generics = self.fcx.tcx.generics_of(def_id)
-            && let args = &all_args[generics.parent_count..]
+            && let args = all_args[generics.parent_count..].iter().zip(&generics.own_params)
             // We can't turbofish consts :(
-            && args.iter().all(|arg| matches!(arg.unpack(), ty::GenericArgKind::Type(_) | ty::GenericArgKind::Lifetime(_)))
+            && args.clone().all(|(_, param)| matches!(param.kind, ty::GenericParamDefKind::Type { .. } | ty::GenericParamDefKind::Lifetime))
         {
-            let n_tys = args
-                .iter()
-                .filter(|arg| matches!(arg.unpack(), ty::GenericArgKind::Type(_)))
-                .count();
-            for (idx, arg) in args
-                .iter()
-                .filter(|arg| matches!(arg.unpack(), ty::GenericArgKind::Type(_)))
-                .enumerate()
-            {
+            // We filter out APITs, which are not turbofished.
+            let non_apit_type_args = args.filter(|(_, param)| {
+                matches!(param.kind, ty::GenericParamDefKind::Type { synthetic: false, .. })
+            });
+            let n_tys = non_apit_type_args.clone().count();
+            for (idx, (arg, _)) in non_apit_type_args.enumerate() {
                 if let Some(ty) = arg.as_type()
                     && let Some(vid) = self.fcx.root_vid(ty)
                     && self.reachable_vids.contains(&vid)

compiler/rustc_hir_typeck/src/method/probe.rs

@@ -79,12 +79,6 @@ pub(crate) struct ProbeContext<'a, 'tcx> {
     /// used for error reporting
     static_candidates: RefCell<Vec<CandidateSource>>,
 
-    /// Collects near misses when trait bounds for type parameters are unsatisfied and is only used
-    /// for error reporting
-    unsatisfied_predicates: RefCell<
-        Vec<(ty::Predicate<'tcx>, Option<ty::Predicate<'tcx>>, Option<ObligationCause<'tcx>>)>,
-    >,
-
     scope_expr_id: HirId,
 
     /// Is this probe being done for a diagnostic? This will skip some error reporting
@@ -109,7 +103,7 @@ pub(crate) struct Candidate<'tcx> {
 
 #[derive(Debug, Clone)]
 pub(crate) enum CandidateKind<'tcx> {
-    InherentImplCandidate(DefId),
+    InherentImplCandidate { impl_def_id: DefId, receiver_steps: usize },
     ObjectCandidate(ty::PolyTraitRef<'tcx>),
     TraitCandidate(ty::PolyTraitRef<'tcx>),
     WhereClauseCandidate(ty::PolyTraitRef<'tcx>),
@@ -162,6 +156,52 @@ impl AutorefOrPtrAdjustment {
     }
 }
 
+/// Extra information required only for error reporting.
+#[derive(Debug)]
+struct PickDiagHints<'a, 'tcx> {
+    /// Unstable candidates alongside the stable ones.
+    unstable_candidates: Option<Vec<(Candidate<'tcx>, Symbol)>>,
+
+    /// Collects near misses when trait bounds for type parameters are unsatisfied and is only used
+    /// for error reporting
+    unsatisfied_predicates: &'a mut Vec<(
+        ty::Predicate<'tcx>,
+        Option<ty::Predicate<'tcx>>,
+        Option<ObligationCause<'tcx>>,
+    )>,
+}
+
+/// Criteria to apply when searching for a given Pick. This is used during
+/// the search for potentially shadowed methods to ensure we don't search
+/// more candidates than strictly necessary.
+#[derive(Debug)]
+struct PickConstraintsForShadowed {
+    autoderefs: usize,
+    receiver_steps: Option<usize>,
+    def_id: DefId,
+}
+
+impl PickConstraintsForShadowed {
+    fn may_shadow_based_on_autoderefs(&self, autoderefs: usize) -> bool {
+        autoderefs == self.autoderefs
+    }
+
+    fn candidate_may_shadow(&self, candidate: &Candidate<'_>) -> bool {
+        // An item never shadows itself
+        candidate.item.def_id != self.def_id
+            // and we're only concerned about inherent impls doing the shadowing.
+            // Shadowing can only occur if the shadowed is further along
+            // the Receiver dereferencing chain than the shadowed.
+            && match candidate.kind {
+                CandidateKind::InherentImplCandidate { receiver_steps, .. } => match self.receiver_steps {
+                    Some(shadowed_receiver_steps) => receiver_steps > shadowed_receiver_steps,
+                    _ => false
+                },
+                _ => false
+            }
+    }
+}
+
 #[derive(Debug, Clone)]
 pub(crate) struct Pick<'tcx> {
     pub item: ty::AssocItem,
@@ -181,6 +221,11 @@ pub(crate) struct Pick<'tcx> {
 
     /// Unstable candidates alongside the stable ones.
     unstable_candidates: Vec<(Candidate<'tcx>, Symbol)>,
+
+    /// Number of jumps along the `Receiver::Target` chain we followed
+    /// to identify this method. Used only for deshadowing errors.
+    /// Only applies for inherent impls.
+    pub receiver_steps: Option<usize>,
 }
 
 #[derive(Clone, Debug, PartialEq, Eq)]
@@ -366,6 +411,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                         autoderefs: 0,
                         from_unsafe_deref: false,
                         unsize: false,
+                        reachable_via_deref: true,
                     }]),
                     opt_bad_ty: None,
                     reached_recursion_limit: false,
@@ -516,47 +562,93 @@ fn method_autoderef_steps<'tcx>(
     let (ref infcx, goal, inference_vars) = tcx.infer_ctxt().build_with_canonical(DUMMY_SP, &goal);
     let ParamEnvAnd { param_env, value: self_ty } = goal;
 
-    let mut autoderef =
+    // If arbitrary self types is not enabled, we follow the chain of
+    // `Deref<Target=T>`. If arbitrary self types is enabled, we instead
+    // follow the chain of `Receiver<Target=T>`, but we also record whether
+    // such types are reachable by following the (potentially shorter)
+    // chain of `Deref<Target=T>`. We will use the first list when finding
+    // potentially relevant function implementations (e.g. relevant impl blocks)
+    // but the second list when determining types that the receiver may be
+    // converted to, in order to find out which of those methods might actually
+    // be callable.
+    let mut autoderef_via_deref =
         Autoderef::new(infcx, param_env, hir::def_id::CRATE_DEF_ID, DUMMY_SP, self_ty)
             .include_raw_pointers()
             .silence_errors();
-    let mut reached_raw_pointer = false;
-    let mut steps: Vec<_> = autoderef
-        .by_ref()
-        .map(|(ty, d)| {
-            let step = CandidateStep {
-                self_ty: infcx.make_query_response_ignoring_pending_obligations(inference_vars, ty),
-                autoderefs: d,
-                from_unsafe_deref: reached_raw_pointer,
-                unsize: false,
-            };
-            if let ty::RawPtr(_, _) = ty.kind() {
-                // all the subsequent steps will be from_unsafe_deref
-                reached_raw_pointer = true;
-            }
-            step
-        })
-        .collect();
 
-    let final_ty = autoderef.final_ty(true);
+    let mut reached_raw_pointer = false;
+    let arbitrary_self_types_enabled =
+        tcx.features().arbitrary_self_types() || tcx.features().arbitrary_self_types_pointers();
+    let (mut steps, reached_recursion_limit): (Vec<_>, bool) = if arbitrary_self_types_enabled {
+        let reachable_via_deref =
+            autoderef_via_deref.by_ref().map(|_| true).chain(std::iter::repeat(false));
+
+        let mut autoderef_via_receiver =
+            Autoderef::new(infcx, param_env, hir::def_id::CRATE_DEF_ID, DUMMY_SP, self_ty)
+                .include_raw_pointers()
+                .use_receiver_trait()
+                .silence_errors();
+        let steps = autoderef_via_receiver
+            .by_ref()
+            .zip(reachable_via_deref)
+            .map(|((ty, d), reachable_via_deref)| {
+                let step = CandidateStep {
+                    self_ty: infcx
+                        .make_query_response_ignoring_pending_obligations(inference_vars, ty),
+                    autoderefs: d,
+                    from_unsafe_deref: reached_raw_pointer,
+                    unsize: false,
+                    reachable_via_deref,
+                };
+                if ty.is_unsafe_ptr() {
+                    // all the subsequent steps will be from_unsafe_deref
+                    reached_raw_pointer = true;
+                }
+                step
+            })
+            .collect();
+        (steps, autoderef_via_receiver.reached_recursion_limit())
+    } else {
+        let steps = autoderef_via_deref
+            .by_ref()
+            .map(|(ty, d)| {
+                let step = CandidateStep {
+                    self_ty: infcx
+                        .make_query_response_ignoring_pending_obligations(inference_vars, ty),
+                    autoderefs: d,
+                    from_unsafe_deref: reached_raw_pointer,
+                    unsize: false,
+                    reachable_via_deref: true,
+                };
+                if ty.is_unsafe_ptr() {
+                    // all the subsequent steps will be from_unsafe_deref
+                    reached_raw_pointer = true;
+                }
+                step
+            })
+            .collect();
+        (steps, autoderef_via_deref.reached_recursion_limit())
+    };
+    let final_ty = autoderef_via_deref.final_ty(true);
     let opt_bad_ty = match final_ty.kind() {
         ty::Infer(ty::TyVar(_)) | ty::Error(_) => Some(MethodAutoderefBadTy {
             reached_raw_pointer,
             ty: infcx.make_query_response_ignoring_pending_obligations(inference_vars, final_ty),
         }),
         ty::Array(elem_ty, _) => {
-            let dereferences = steps.len() - 1;
-
+            let autoderefs = steps.iter().filter(|s| s.reachable_via_deref).count() - 1;
             steps.push(CandidateStep {
                 self_ty: infcx.make_query_response_ignoring_pending_obligations(
                     inference_vars,
                     Ty::new_slice(infcx.tcx, *elem_ty),
                 ),
-                autoderefs: dereferences,
+                autoderefs,
                 // this could be from an unsafe deref if we had
                 // a *mut/const [T; N]
                 from_unsafe_deref: reached_raw_pointer,
                 unsize: true,
+                reachable_via_deref: true, // this is always the final type from
+                                           // autoderef_via_deref
             });
 
             None
@@ -569,7 +661,7 @@ fn method_autoderef_steps<'tcx>(
     MethodAutoderefStepsResult {
         steps: tcx.arena.alloc_from_iter(steps),
         opt_bad_ty: opt_bad_ty.map(|ty| &*tcx.arena.alloc(ty)),
-        reached_recursion_limit: autoderef.reached_recursion_limit(),
+        reached_recursion_limit,
     }
 }
 
@@ -600,7 +692,6 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
             private_candidates: Vec::new(),
             private_candidate: Cell::new(None),
             static_candidates: RefCell::new(Vec::new()),
-            unsatisfied_predicates: RefCell::new(Vec::new()),
             scope_expr_id,
             is_suggestion,
         }
@@ -613,7 +704,6 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
         self.private_candidates.clear();
         self.private_candidate.set(None);
         self.static_candidates.borrow_mut().clear();
-        self.unsatisfied_predicates.borrow_mut().clear();
     }
 
     /// When we're looking up a method by path (UFCS), we relate the receiver
@@ -652,12 +742,16 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
 
     fn assemble_inherent_candidates(&mut self) {
         for step in self.steps.iter() {
-            self.assemble_probe(&step.self_ty);
+            self.assemble_probe(&step.self_ty, step.autoderefs);
         }
     }
 
     #[instrument(level = "debug", skip(self))]
-    fn assemble_probe(&mut self, self_ty: &Canonical<'tcx, QueryResponse<'tcx, Ty<'tcx>>>) {
+    fn assemble_probe(
+        &mut self,
+        self_ty: &Canonical<'tcx, QueryResponse<'tcx, Ty<'tcx>>>,
+        receiver_steps: usize,
+    ) {
         let raw_self_ty = self_ty.value.value;
         match *raw_self_ty.kind() {
             ty::Dynamic(data, ..) if let Some(p) = data.principal() => {
@@ -682,22 +776,31 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
                     self.fcx.instantiate_canonical(self.span, self_ty);
 
                 self.assemble_inherent_candidates_from_object(generalized_self_ty);
-                self.assemble_inherent_impl_candidates_for_type(p.def_id());
+                self.assemble_inherent_impl_candidates_for_type(p.def_id(), receiver_steps);
                 if self.tcx.has_attr(p.def_id(), sym::rustc_has_incoherent_inherent_impls) {
-                    self.assemble_inherent_candidates_for_incoherent_ty(raw_self_ty);
+                    self.assemble_inherent_candidates_for_incoherent_ty(
+                        raw_self_ty,
+                        receiver_steps,
+                    );
                 }
             }
             ty::Adt(def, _) => {
                 let def_id = def.did();
-                self.assemble_inherent_impl_candidates_for_type(def_id);
+                self.assemble_inherent_impl_candidates_for_type(def_id, receiver_steps);
                 if self.tcx.has_attr(def_id, sym::rustc_has_incoherent_inherent_impls) {
-                    self.assemble_inherent_candidates_for_incoherent_ty(raw_self_ty);
+                    self.assemble_inherent_candidates_for_incoherent_ty(
+                        raw_self_ty,
+                        receiver_steps,
+                    );
                 }
             }
             ty::Foreign(did) => {
-                self.assemble_inherent_impl_candidates_for_type(did);
+                self.assemble_inherent_impl_candidates_for_type(did, receiver_steps);
                 if self.tcx.has_attr(did, sym::rustc_has_incoherent_inherent_impls) {
-                    self.assemble_inherent_candidates_for_incoherent_ty(raw_self_ty);
+                    self.assemble_inherent_candidates_for_incoherent_ty(
+                        raw_self_ty,
+                        receiver_steps,
+                    );
                 }
             }
             ty::Param(p) => {
@@ -714,29 +817,35 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
             | ty::RawPtr(_, _)
             | ty::Ref(..)
             | ty::Never
-            | ty::Tuple(..) => self.assemble_inherent_candidates_for_incoherent_ty(raw_self_ty),
+            | ty::Tuple(..) => {
+                self.assemble_inherent_candidates_for_incoherent_ty(raw_self_ty, receiver_steps)
+            }
             _ => {}
         }
     }
 
-    fn assemble_inherent_candidates_for_incoherent_ty(&mut self, self_ty: Ty<'tcx>) {
+    fn assemble_inherent_candidates_for_incoherent_ty(
+        &mut self,
+        self_ty: Ty<'tcx>,
+        receiver_steps: usize,
+    ) {
         let Some(simp) = simplify_type(self.tcx, self_ty, TreatParams::InstantiateWithInfer) else {
             bug!("unexpected incoherent type: {:?}", self_ty)
         };
         for &impl_def_id in self.tcx.incoherent_impls(simp).into_iter() {
-            self.assemble_inherent_impl_probe(impl_def_id);
+            self.assemble_inherent_impl_probe(impl_def_id, receiver_steps);
         }
     }
 
-    fn assemble_inherent_impl_candidates_for_type(&mut self, def_id: DefId) {
+    fn assemble_inherent_impl_candidates_for_type(&mut self, def_id: DefId, receiver_steps: usize) {
         let impl_def_ids = self.tcx.at(self.span).inherent_impls(def_id).into_iter();
         for &impl_def_id in impl_def_ids {
-            self.assemble_inherent_impl_probe(impl_def_id);
+            self.assemble_inherent_impl_probe(impl_def_id, receiver_steps);
         }
     }
 
     #[instrument(level = "debug", skip(self))]
-    fn assemble_inherent_impl_probe(&mut self, impl_def_id: DefId) {
+    fn assemble_inherent_impl_probe(&mut self, impl_def_id: DefId, receiver_steps: usize) {
         if !self.impl_dups.insert(impl_def_id) {
             return; // already visited
         }
@@ -750,7 +859,7 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
             self.push_candidate(
                 Candidate {
                     item,
-                    kind: InherentImplCandidate(impl_def_id),
+                    kind: InherentImplCandidate { impl_def_id, receiver_steps },
                     import_ids: smallvec![],
                 },
                 true,
@@ -989,7 +1098,9 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
     fn pick(mut self) -> PickResult<'tcx> {
         assert!(self.method_name.is_some());
 
-        if let Some(r) = self.pick_core() {
+        let mut unsatisfied_predicates = Vec::new();
+
+        if let Some(r) = self.pick_core(&mut unsatisfied_predicates) {
             return r;
         }
 
@@ -1009,7 +1120,6 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
 
         let static_candidates = std::mem::take(self.static_candidates.get_mut());
         let private_candidate = self.private_candidate.take();
-        let unsatisfied_predicates = std::mem::take(self.unsatisfied_predicates.get_mut());
 
         // things failed, so lets look at all traits, for diagnostic purposes now:
         self.reset();
@@ -1019,7 +1129,7 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
 
         self.assemble_extension_candidates_for_all_traits();
 
-        let out_of_scope_traits = match self.pick_core() {
+        let out_of_scope_traits = match self.pick_core(&mut Vec::new()) {
             Some(Ok(p)) => vec![p.item.container_id(self.tcx)],
             Some(Err(MethodError::Ambiguity(v))) => v
                 .into_iter()
@@ -1054,17 +1164,48 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
         }))
     }
 
-    fn pick_core(&self) -> Option<PickResult<'tcx>> {
+    fn pick_core(
+        &self,
+        unsatisfied_predicates: &mut Vec<(
+            ty::Predicate<'tcx>,
+            Option<ty::Predicate<'tcx>>,
+            Option<ObligationCause<'tcx>>,
+        )>,
+    ) -> Option<PickResult<'tcx>> {
         // Pick stable methods only first, and consider unstable candidates if not found.
-        self.pick_all_method(Some(&mut vec![])).or_else(|| self.pick_all_method(None))
+        self.pick_all_method(&mut PickDiagHints {
+            // This first cycle, maintain a list of unstable candidates which
+            // we encounter. This will end up in the Pick for diagnostics.
+            unstable_candidates: Some(Vec::new()),
+            // Contribute to the list of unsatisfied predicates which may
+            // also be used for diagnostics.
+            unsatisfied_predicates,
+        })
+        .or_else(|| {
+            self.pick_all_method(&mut PickDiagHints {
+                // On the second search, don't provide a special list of unstable
+                // candidates. This indicates to the picking code that it should
+                // in fact include such unstable candidates in the actual
+                // search.
+                unstable_candidates: None,
+                // And there's no need to duplicate ourselves in the
+                // unsatisifed predicates list. Provide a throwaway list.
+                unsatisfied_predicates: &mut Vec::new(),
+            })
+        })
     }
 
-    fn pick_all_method(
+    fn pick_all_method<'b>(
         &self,
-        mut unstable_candidates: Option<&mut Vec<(Candidate<'tcx>, Symbol)>>,
+        pick_diag_hints: &mut PickDiagHints<'b, 'tcx>,
     ) -> Option<PickResult<'tcx>> {
+        let track_unstable_candidates = pick_diag_hints.unstable_candidates.is_some();
         self.steps
             .iter()
+            // At this point we're considering the types to which the receiver can be converted,
+            // so we want to follow the `Deref` chain not the `Receiver` chain. Filter out
+            // steps which can only be reached by following the (longer) `Receiver` chain.
+            .filter(|step| step.reachable_via_deref)
             .filter(|step| {
                 debug!("pick_all_method: step={:?}", step);
                 // skip types that are from a type error or that would require dereferencing
@@ -1082,40 +1223,188 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
                     .unwrap_or_else(|_| {
                         span_bug!(self.span, "{:?} was applicable but now isn't?", step.self_ty)
                     });
-                self.pick_by_value_method(step, self_ty, unstable_candidates.as_deref_mut())
-                    .or_else(|| {
-                        self.pick_autorefd_method(
-                            step,
-                            self_ty,
-                            hir::Mutability::Not,
-                            unstable_candidates.as_deref_mut(),
-                        )
-                        .or_else(|| {
-                            self.pick_autorefd_method(
+
+                let by_value_pick = self.pick_by_value_method(step, self_ty, pick_diag_hints);
+
+                // Check for shadowing of a by-reference method by a by-value method (see comments on check_for_shadowing)
+                if let Some(by_value_pick) = by_value_pick {
+                    if let Ok(by_value_pick) = by_value_pick.as_ref() {
+                        if by_value_pick.kind == PickKind::InherentImplPick {
+                            if let Err(e) = self.check_for_shadowed_autorefd_method(
+                                by_value_pick,
+                                step,
+                                self_ty,
+                                hir::Mutability::Not,
+                                track_unstable_candidates,
+                            ) {
+                                return Some(Err(e));
+                            }
+                            if let Err(e) = self.check_for_shadowed_autorefd_method(
+                                by_value_pick,
                                 step,
                                 self_ty,
                                 hir::Mutability::Mut,
-                                unstable_candidates.as_deref_mut(),
-                            )
-                        })
-                        .or_else(|| {
-                            self.pick_const_ptr_method(
+                                track_unstable_candidates,
+                            ) {
+                                return Some(Err(e));
+                            }
+                        }
+                    }
+                    return Some(by_value_pick);
+                }
+
+                let autoref_pick = self.pick_autorefd_method(
+                    step,
+                    self_ty,
+                    hir::Mutability::Not,
+                    pick_diag_hints,
+                    None,
+                );
+                // Check for shadowing of a by-mut-ref method by a by-reference method (see comments on check_for_shadowing)
+                if let Some(autoref_pick) = autoref_pick {
+                    if let Ok(autoref_pick) = autoref_pick.as_ref() {
+                        // Check we're not shadowing others
+                        if autoref_pick.kind == PickKind::InherentImplPick {
+                            if let Err(e) = self.check_for_shadowed_autorefd_method(
+                                autoref_pick,
                                 step,
                                 self_ty,
-                                unstable_candidates.as_deref_mut(),
-                            )
-                        })
-                        .or_else(|| {
-                            self.pick_reborrow_pin_method(
-                                step,
-                                self_ty,
-                                unstable_candidates.as_deref_mut(),
-                            )
-                        })
-                    })
+                                hir::Mutability::Mut,
+                                track_unstable_candidates,
+                            ) {
+                                return Some(Err(e));
+                            }
+                        }
+                    }
+                    return Some(autoref_pick);
+                }
+
+                // Note that no shadowing errors are produced from here on,
+                // as we consider const ptr methods.
+                // We allow new methods that take *mut T to shadow
+                // methods which took *const T, so there is no entry in
+                // this list for the results of `pick_const_ptr_method`.
+                // The reason is that the standard pointer cast method
+                // (on a mutable pointer) always already shadows the
+                // cast method (on a const pointer). So, if we added
+                // `pick_const_ptr_method` to this method, the anti-
+                // shadowing algorithm would always complain about
+                // the conflict between *const::cast and *mut::cast.
+                // In practice therefore this does constrain us:
+                // we cannot add new
+                //   self: *mut Self
+                // methods to types such as NonNull or anything else
+                // which implements Receiver, because this might in future
+                // shadow existing methods taking
+                //   self: *const NonNull<Self>
+                // in the pointee. In practice, methods taking raw pointers
+                // are rare, and it seems that it should be easily possible
+                // to avoid such compatibility breaks.
+                // We also don't check for reborrowed pin methods which
+                // may be shadowed; these also seem unlikely to occur.
+                self.pick_autorefd_method(
+                    step,
+                    self_ty,
+                    hir::Mutability::Mut,
+                    pick_diag_hints,
+                    None,
+                )
+                .or_else(|| self.pick_const_ptr_method(step, self_ty, pick_diag_hints))
+                .or_else(|| self.pick_reborrow_pin_method(step, self_ty, pick_diag_hints))
             })
     }
 
+    /// Check for cases where arbitrary self types allows shadowing
+    /// of methods that might be a compatibility break. Specifically,
+    /// we have something like:
+    /// ```ignore (illustrative)
+    /// struct A;
+    /// impl A {
+    ///   fn foo(self: &NonNull<A>) {}
+    ///      // note this is by reference
+    /// }
+    /// ```
+    /// then we've come along and added this method to `NonNull`:
+    /// ```ignore (illustrative)
+    ///   fn foo(self)  // note this is by value
+    /// ```
+    /// Report an error in this case.
+    fn check_for_shadowed_autorefd_method(
+        &self,
+        possible_shadower: &Pick<'tcx>,
+        step: &CandidateStep<'tcx>,
+        self_ty: Ty<'tcx>,
+        mutbl: hir::Mutability,
+        track_unstable_candidates: bool,
+    ) -> Result<(), MethodError<'tcx>> {
+        // We don't want to remember any of the diagnostic hints from this
+        // shadow search, but we do need to provide Some/None for the
+        // unstable_candidates in order to reflect the behavior of the
+        // main search.
+        let mut pick_diag_hints = PickDiagHints {
+            unstable_candidates: if track_unstable_candidates { Some(Vec::new()) } else { None },
+            unsatisfied_predicates: &mut Vec::new(),
+        };
+        // Set criteria for how we find methods possibly shadowed by 'possible_shadower'
+        let pick_constraints = PickConstraintsForShadowed {
+            // It's the same `self` type...
+            autoderefs: possible_shadower.autoderefs,
+            // ... but the method was found in an impl block determined
+            // by searching further along the Receiver chain than the other,
+            // showing that it's a smart pointer type causing the problem...
+            receiver_steps: possible_shadower.receiver_steps,
+            // ... and they don't end up pointing to the same item in the
+            // first place (could happen with things like blanket impls for T)
+            def_id: possible_shadower.item.def_id,
+        };
+        // A note on the autoderefs above. Within pick_by_value_method, an extra
+        // autoderef may be applied in order to reborrow a reference with
+        // a different lifetime. That seems as though it would break the
+        // logic of these constraints, since the number of autoderefs could
+        // no longer be used to identify the fundamental type of the receiver.
+        // However, this extra autoderef is applied only to by-value calls
+        // where the receiver is already a reference. So this situation would
+        // only occur in cases where the shadowing looks like this:
+        // ```
+        // struct A;
+        // impl A {
+        //   fn foo(self: &&NonNull<A>) {}
+        //      // note this is by DOUBLE reference
+        // }
+        // ```
+        // then we've come along and added this method to `NonNull`:
+        // ```
+        //   fn foo(&self)  // note this is by single reference
+        // ```
+        // and the call is:
+        // ```
+        // let bar = NonNull<Foo>;
+        // let bar = &foo;
+        // bar.foo();
+        // ```
+        // In these circumstances, the logic is wrong, and we wouldn't spot
+        // the shadowing, because the autoderef-based maths wouldn't line up.
+        // This is a niche case and we can live without generating an error
+        // in the case of such shadowing.
+        let potentially_shadowed_pick = self.pick_autorefd_method(
+            step,
+            self_ty,
+            mutbl,
+            &mut pick_diag_hints,
+            Some(&pick_constraints),
+        );
+        // Look for actual pairs of shadower/shadowed which are
+        // the sort of shadowing case we want to avoid. Specifically...
+        if let Some(Ok(possible_shadowed)) = potentially_shadowed_pick.as_ref() {
+            let sources = [possible_shadower, possible_shadowed]
+                .into_iter()
+                .map(|p| self.candidate_source_from_pick(p))
+                .collect();
+            return Err(MethodError::Ambiguity(sources));
+        }
+        Ok(())
+    }
+
     /// For each type `T` in the step list, this attempts to find a method where
     /// the (transformed) self type is exactly `T`. We do however do one
     /// transformation on the adjustment: if we are passing a region pointer in,
@@ -1126,13 +1415,13 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
         &self,
         step: &CandidateStep<'tcx>,
         self_ty: Ty<'tcx>,
-        unstable_candidates: Option<&mut Vec<(Candidate<'tcx>, Symbol)>>,
+        pick_diag_hints: &mut PickDiagHints<'_, 'tcx>,
     ) -> Option<PickResult<'tcx>> {
         if step.unsize {
             return None;
         }
 
-        self.pick_method(self_ty, unstable_candidates).map(|r| {
+        self.pick_method(self_ty, pick_diag_hints, None).map(|r| {
             r.map(|mut pick| {
                 pick.autoderefs = step.autoderefs;
 
@@ -1170,15 +1459,22 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
         step: &CandidateStep<'tcx>,
         self_ty: Ty<'tcx>,
         mutbl: hir::Mutability,
-        unstable_candidates: Option<&mut Vec<(Candidate<'tcx>, Symbol)>>,
+        pick_diag_hints: &mut PickDiagHints<'_, 'tcx>,
+        pick_constraints: Option<&PickConstraintsForShadowed>,
     ) -> Option<PickResult<'tcx>> {
         let tcx = self.tcx;
 
+        if let Some(pick_constraints) = pick_constraints {
+            if !pick_constraints.may_shadow_based_on_autoderefs(step.autoderefs) {
+                return None;
+            }
+        }
+
         // In general, during probing we erase regions.
         let region = tcx.lifetimes.re_erased;
 
         let autoref_ty = Ty::new_ref(tcx, region, self_ty, mutbl);
-        self.pick_method(autoref_ty, unstable_candidates).map(|r| {
+        self.pick_method(autoref_ty, pick_diag_hints, pick_constraints).map(|r| {
             r.map(|mut pick| {
                 pick.autoderefs = step.autoderefs;
                 pick.autoref_or_ptr_adjustment =
@@ -1189,12 +1485,12 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
     }
 
     /// Looks for applicable methods if we reborrow a `Pin<&mut T>` as a `Pin<&T>`.
-    #[instrument(level = "debug", skip(self, step, unstable_candidates))]
+    #[instrument(level = "debug", skip(self, step, pick_diag_hints))]
     fn pick_reborrow_pin_method(
         &self,
         step: &CandidateStep<'tcx>,
         self_ty: Ty<'tcx>,
-        unstable_candidates: Option<&mut Vec<(Candidate<'tcx>, Symbol)>>,
+        pick_diag_hints: &mut PickDiagHints<'_, 'tcx>,
     ) -> Option<PickResult<'tcx>> {
         if !self.tcx.features().pin_ergonomics() {
             return None;
@@ -1215,7 +1511,7 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
 
         let region = self.tcx.lifetimes.re_erased;
         let autopin_ty = Ty::new_pinned_ref(self.tcx, region, inner_ty, hir::Mutability::Not);
-        self.pick_method(autopin_ty, unstable_candidates).map(|r| {
+        self.pick_method(autopin_ty, pick_diag_hints, None).map(|r| {
             r.map(|mut pick| {
                 pick.autoderefs = step.autoderefs;
                 pick.autoref_or_ptr_adjustment =
@@ -1232,7 +1528,7 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
         &self,
         step: &CandidateStep<'tcx>,
         self_ty: Ty<'tcx>,
-        unstable_candidates: Option<&mut Vec<(Candidate<'tcx>, Symbol)>>,
+        pick_diag_hints: &mut PickDiagHints<'_, 'tcx>,
     ) -> Option<PickResult<'tcx>> {
         // Don't convert an unsized reference to ptr
         if step.unsize {
@@ -1244,7 +1540,7 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
         };
 
         let const_ptr_ty = Ty::new_imm_ptr(self.tcx, ty);
-        self.pick_method(const_ptr_ty, unstable_candidates).map(|r| {
+        self.pick_method(const_ptr_ty, pick_diag_hints, None).map(|r| {
             r.map(|mut pick| {
                 pick.autoderefs = step.autoderefs;
                 pick.autoref_or_ptr_adjustment = Some(AutorefOrPtrAdjustment::ToConstPtr);
@@ -1256,40 +1552,35 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
     fn pick_method(
         &self,
         self_ty: Ty<'tcx>,
-        mut unstable_candidates: Option<&mut Vec<(Candidate<'tcx>, Symbol)>>,
+        pick_diag_hints: &mut PickDiagHints<'_, 'tcx>,
+        pick_constraints: Option<&PickConstraintsForShadowed>,
     ) -> Option<PickResult<'tcx>> {
         debug!("pick_method(self_ty={})", self.ty_to_string(self_ty));
 
-        let mut possibly_unsatisfied_predicates = Vec::new();
-
         for (kind, candidates) in
             [("inherent", &self.inherent_candidates), ("extension", &self.extension_candidates)]
         {
             debug!("searching {} candidates", kind);
-            let res = self.consider_candidates(
-                self_ty,
-                candidates,
-                &mut possibly_unsatisfied_predicates,
-                unstable_candidates.as_deref_mut(),
-            );
+            let res =
+                self.consider_candidates(self_ty, candidates, pick_diag_hints, pick_constraints);
             if let Some(pick) = res {
                 return Some(pick);
             }
         }
 
         if self.private_candidate.get().is_none() {
-            if let Some(Ok(pick)) =
-                self.consider_candidates(self_ty, &self.private_candidates, &mut vec![], None)
-            {
+            if let Some(Ok(pick)) = self.consider_candidates(
+                self_ty,
+                &self.private_candidates,
+                &mut PickDiagHints {
+                    unstable_candidates: None,
+                    unsatisfied_predicates: &mut vec![],
+                },
+                None,
+            ) {
                 self.private_candidate.set(Some((pick.item.kind.as_def_kind(), pick.item.def_id)));
             }
         }
-
-        // `pick_method` may be called twice for the same self_ty if no stable methods
-        // match. Only extend once.
-        if unstable_candidates.is_some() {
-            self.unsatisfied_predicates.borrow_mut().extend(possibly_unsatisfied_predicates);
-        }
         None
     }
 
@@ -1297,17 +1588,25 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
         &self,
         self_ty: Ty<'tcx>,
         candidates: &[Candidate<'tcx>],
-        possibly_unsatisfied_predicates: &mut Vec<(
-            ty::Predicate<'tcx>,
-            Option<ty::Predicate<'tcx>>,
-            Option<ObligationCause<'tcx>>,
-        )>,
-        mut unstable_candidates: Option<&mut Vec<(Candidate<'tcx>, Symbol)>>,
+        pick_diag_hints: &mut PickDiagHints<'_, 'tcx>,
+        pick_constraints: Option<&PickConstraintsForShadowed>,
     ) -> Option<PickResult<'tcx>> {
         let mut applicable_candidates: Vec<_> = candidates
             .iter()
+            .filter(|candidate| {
+                pick_constraints
+                    .map(|pick_constraints| pick_constraints.candidate_may_shadow(&candidate))
+                    .unwrap_or(true)
+            })
             .map(|probe| {
-                (probe, self.consider_probe(self_ty, probe, possibly_unsatisfied_predicates))
+                (
+                    probe,
+                    self.consider_probe(
+                        self_ty,
+                        probe,
+                        &mut pick_diag_hints.unsatisfied_predicates,
+                    ),
+                )
             })
             .filter(|&(_, status)| status != ProbeResult::NoMatch)
             .collect();
@@ -1322,7 +1621,7 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
             }
         }
 
-        if let Some(uc) = &mut unstable_candidates {
+        if let Some(uc) = &mut pick_diag_hints.unstable_candidates {
             applicable_candidates.retain(|&(candidate, _)| {
                 if let stability::EvalResult::Deny { feature, .. } =
                     self.tcx.eval_stability(candidate.item.def_id, None, self.span, None)
@@ -1340,10 +1639,10 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
         }
 
         applicable_candidates.pop().map(|(probe, status)| match status {
-            ProbeResult::Match => {
-                Ok(probe
-                    .to_unadjusted_pick(self_ty, unstable_candidates.cloned().unwrap_or_default()))
-            }
+            ProbeResult::Match => Ok(probe.to_unadjusted_pick(
+                self_ty,
+                pick_diag_hints.unstable_candidates.clone().unwrap_or_default(),
+            )),
             ProbeResult::NoMatch | ProbeResult::BadReturnType => Err(MethodError::BadReturnType),
         })
     }
@@ -1372,6 +1671,7 @@ impl<'tcx> Pick<'tcx> {
             autoref_or_ptr_adjustment: _,
             self_ty,
             unstable_candidates: _,
+            receiver_steps: _,
         } = *self;
         self_ty != other.self_ty || def_id != other.item.def_id
     }
@@ -1447,7 +1747,7 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
     /// so do not use to make a decision that may lead to a successful compilation.
     fn candidate_source(&self, candidate: &Candidate<'tcx>, self_ty: Ty<'tcx>) -> CandidateSource {
         match candidate.kind {
-            InherentImplCandidate(_) => {
+            InherentImplCandidate { .. } => {
                 CandidateSource::Impl(candidate.item.container_id(self.tcx))
             }
             ObjectCandidate(_) | WhereClauseCandidate(_) => {
@@ -1477,6 +1777,15 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
         }
     }
 
+    fn candidate_source_from_pick(&self, pick: &Pick<'tcx>) -> CandidateSource {
+        match pick.kind {
+            InherentImplPick => CandidateSource::Impl(pick.item.container_id(self.tcx)),
+            ObjectPick | WhereClausePick(_) | TraitPick => {
+                CandidateSource::Trait(pick.item.container_id(self.tcx))
+            }
+        }
+    }
+
     #[instrument(level = "trace", skip(self, possibly_unsatisfied_predicates), ret)]
     fn consider_probe(
         &self,
@@ -1501,7 +1810,7 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
             let (mut xform_self_ty, mut xform_ret_ty);
 
             match probe.kind {
-                InherentImplCandidate(impl_def_id) => {
+                InherentImplCandidate { impl_def_id, .. } => {
                     let impl_args = self.fresh_args_for_item(self.span, impl_def_id);
                     let impl_ty = self.tcx.type_of(impl_def_id).instantiate(self.tcx, impl_args);
                     (xform_self_ty, xform_ret_ty) =
@@ -1693,7 +2002,7 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
                 // We don't normalize the other candidates for perf/backwards-compat reasons...
                 // but `self.return_type` is only set on the diagnostic-path, so we
                 // should be okay doing it here.
-                if !matches!(probe.kind, InherentImplCandidate(_)) {
+                if !matches!(probe.kind, InherentImplCandidate { .. }) {
                     xform_ret_ty = ocx.normalize(&cause, self.param_env, xform_ret_ty);
                 }
 
@@ -1771,6 +2080,7 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
             autoref_or_ptr_adjustment: None,
             self_ty,
             unstable_candidates: vec![],
+            receiver_steps: None,
         })
     }
 
@@ -1808,7 +2118,7 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
                     pcx.method_name = Some(method_name);
                     pcx.assemble_inherent_candidates();
                     pcx.assemble_extension_candidates_for_all_traits();
-                    pcx.pick_core().and_then(|pick| pick.ok()).map(|pick| pick.item)
+                    pcx.pick_core(&mut Vec::new()).and_then(|pick| pick.ok()).map(|pick| pick.item)
                 })
                 .collect();
 
@@ -2042,7 +2352,7 @@ impl<'tcx> Candidate<'tcx> {
         Pick {
             item: self.item,
             kind: match self.kind {
-                InherentImplCandidate(_) => InherentImplPick,
+                InherentImplCandidate { .. } => InherentImplPick,
                 ObjectCandidate(_) => ObjectPick,
                 TraitCandidate(_) => TraitPick,
                 WhereClauseCandidate(trait_ref) => {
@@ -2064,6 +2374,10 @@ impl<'tcx> Candidate<'tcx> {
             autoref_or_ptr_adjustment: None,
             self_ty,
             unstable_candidates,
+            receiver_steps: match self.kind {
+                InherentImplCandidate { receiver_steps, .. } => Some(receiver_steps),
+                _ => None,
+            },
         }
     }
 }

compiler/rustc_hir_typeck/src/upvar.rs

@@ -1840,7 +1840,6 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
 /// captured by move.
 ///
 /// ```rust
-/// #![feature(async_closure)]
 /// let x = &1i32; // Let's call this lifetime `'1`.
 /// let c = async move || {
 ///     println!("{:?}", *x);
@@ -1855,7 +1854,6 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
 /// child capture with the lifetime of the parent coroutine-closure's env.
 ///
 /// ```rust
-/// #![feature(async_closure)]
 /// let mut x = 1i32;
 /// let c = async || {
 ///     x = 1;

compiler/rustc_lint/src/async_closures.rs

@@ -12,7 +12,6 @@ declare_lint! {
     /// ### Example
     ///
     /// ```rust
-    /// #![feature(async_closure)]
     /// #![warn(closure_returning_async_block)]
     /// let c = |x: &str| async {};
     /// ```
@@ -40,8 +39,6 @@ declare_lint! {
     /// But it does work with async closures:
     ///
     /// ```rust
-    /// #![feature(async_closure)]
-    ///
     /// async fn callback(x: &str) {}
     ///
     /// let captured_str = String::new();
@@ -52,7 +49,6 @@ declare_lint! {
     pub CLOSURE_RETURNING_ASYNC_BLOCK,
     Allow,
     "closure that returns `async {}` could be rewritten as an async closure",
-    @feature_gate = async_closure;
 }
 
 declare_lint_pass!(

compiler/rustc_lint/src/tests.rs

@@ -1,3 +1,5 @@
+#![cfg_attr(not(bootstrap), allow(rustc::symbol_intern_string_literal))]
+
 use rustc_span::{Symbol, create_default_session_globals_then};
 
 use crate::levels::parse_lint_and_tool_name;

compiler/rustc_middle/src/traits/query.rs

@@ -149,11 +149,21 @@ pub struct CandidateStep<'tcx> {
     /// `foo.by_raw_ptr()` will work and `foo.by_ref()` won't.
     pub from_unsafe_deref: bool,
     pub unsize: bool,
+    /// We will generate CandidateSteps which are reachable via a chain
+    /// of following `Receiver`. The first 'n' of those will be reachable
+    /// by following a chain of 'Deref' instead (since there's a blanket
+    /// implementation of Receiver for Deref).
+    /// We use the entire set of steps when identifying method candidates
+    /// (e.g. identifying relevant `impl` blocks) but only those that are
+    /// reachable via Deref when examining what the receiver type can
+    /// be converted into by autodereffing.
+    pub reachable_via_deref: bool,
 }
 
 #[derive(Copy, Clone, Debug, HashStable)]
 pub struct MethodAutoderefStepsResult<'tcx> {
-    /// The valid autoderef steps that could be found.
+    /// The valid autoderef steps that could be found by following a chain
+    /// of `Receiver<Target=T>` or `Deref<Target=T>` trait implementations.
     pub steps: &'tcx [CandidateStep<'tcx>],
     /// If Some(T), a type autoderef reported an error on.
     pub opt_bad_ty: Option<&'tcx MethodAutoderefBadTy<'tcx>>,

compiler/rustc_middle/src/ty/instance.rs

@@ -677,23 +677,26 @@ impl<'tcx> Instance<'tcx> {
                 //
                 // 1) The underlying method expects a caller location parameter
                 // in the ABI
-                if resolved.def.requires_caller_location(tcx)
-                        // 2) The caller location parameter comes from having `#[track_caller]`
-                        // on the implementation, and *not* on the trait method.
-                        && !tcx.should_inherit_track_caller(def)
-                        // If the method implementation comes from the trait definition itself
-                        // (e.g. `trait Foo { #[track_caller] my_fn() { /* impl */ } }`),
-                        // then we don't need to generate a shim. This check is needed because
-                        // `should_inherit_track_caller` returns `false` if our method
-                        // implementation comes from the trait block, and not an impl block
-                        && !matches!(
-                            tcx.opt_associated_item(def),
-                            Some(ty::AssocItem {
-                                container: ty::AssocItemContainer::Trait,
-                                ..
-                            })
-                        )
-                {
+                let needs_track_caller_shim = resolved.def.requires_caller_location(tcx)
+                    // 2) The caller location parameter comes from having `#[track_caller]`
+                    // on the implementation, and *not* on the trait method.
+                    && !tcx.should_inherit_track_caller(def)
+                    // If the method implementation comes from the trait definition itself
+                    // (e.g. `trait Foo { #[track_caller] my_fn() { /* impl */ } }`),
+                    // then we don't need to generate a shim. This check is needed because
+                    // `should_inherit_track_caller` returns `false` if our method
+                    // implementation comes from the trait block, and not an impl block
+                    && !matches!(
+                        tcx.opt_associated_item(def),
+                        Some(ty::AssocItem {
+                            container: ty::AssocItemContainer::Trait,
+                            ..
+                        })
+                    );
+                // We also need to generate a shim if this is an AFIT.
+                let needs_rpitit_shim =
+                    tcx.return_position_impl_trait_in_trait_shim_data(def).is_some();
+                if needs_track_caller_shim || needs_rpitit_shim {
                     if tcx.is_closure_like(def) {
                         debug!(
                             " => vtable fn pointer created for closure with #[track_caller]: {:?} for method {:?} {:?}",

compiler/rustc_middle/src/ty/mod.rs

@@ -146,6 +146,7 @@ mod opaque_types;
 mod parameterized;
 mod predicate;
 mod region;
+mod return_position_impl_trait_in_trait;
 mod rvalue_scopes;
 mod structural_impls;
 #[allow(hidden_glob_reexports)]

compiler/rustc_middle/src/ty/return_position_impl_trait_in_trait.rs

@@ -0,0 +1,95 @@
+use rustc_hir::def_id::DefId;
+
+use crate::ty::{self, ExistentialPredicateStableCmpExt, TyCtxt};
+
+impl<'tcx> TyCtxt<'tcx> {
+    /// Given a `def_id` of a trait or impl method, compute whether that method needs to
+    /// have an RPITIT shim applied to it for it to be object safe. If so, return the
+    /// `def_id` of the RPITIT, and also the args of trait method that returns the RPITIT.
+    ///
+    /// NOTE that these args are not, in general, the same as than the RPITIT's args. They
+    /// are a subset of those args,  since they do not include the late-bound lifetimes of
+    /// the RPITIT. Depending on the context, these will need to be dealt with in different
+    /// ways -- in codegen, it's okay to fill them with ReErased.
+    pub fn return_position_impl_trait_in_trait_shim_data(
+        self,
+        def_id: DefId,
+    ) -> Option<(DefId, ty::EarlyBinder<'tcx, ty::GenericArgsRef<'tcx>>)> {
+        let assoc_item = self.opt_associated_item(def_id)?;
+
+        let (trait_item_def_id, opt_impl_def_id) = match assoc_item.container {
+            ty::AssocItemContainer::Impl => {
+                (assoc_item.trait_item_def_id?, Some(self.parent(def_id)))
+            }
+            ty::AssocItemContainer::Trait => (def_id, None),
+        };
+
+        let sig = self.fn_sig(trait_item_def_id);
+
+        // Check if the trait returns an RPITIT.
+        let ty::Alias(ty::Projection, ty::AliasTy { def_id, .. }) =
+            *sig.skip_binder().skip_binder().output().kind()
+        else {
+            return None;
+        };
+        if !self.is_impl_trait_in_trait(def_id) {
+            return None;
+        }
+
+        let args = if let Some(impl_def_id) = opt_impl_def_id {
+            // Rebase the args from the RPITIT onto the impl trait ref, so we can later
+            // substitute them with the method args of the *impl* method, since that's
+            // the instance we're building a vtable shim for.
+            ty::GenericArgs::identity_for_item(self, trait_item_def_id).rebase_onto(
+                self,
+                self.parent(trait_item_def_id),
+                self.impl_trait_ref(impl_def_id)
+                    .expect("expected impl trait ref from parent of impl item")
+                    .instantiate_identity()
+                    .args,
+            )
+        } else {
+            // This is when we have a default trait implementation.
+            ty::GenericArgs::identity_for_item(self, trait_item_def_id)
+        };
+
+        Some((def_id, ty::EarlyBinder::bind(args)))
+    }
+
+    /// Given a `DefId` of an RPITIT and its args, return the existential predicates
+    /// that corresponds to the RPITIT's bounds with the self type erased.
+    pub fn item_bounds_to_existential_predicates(
+        self,
+        def_id: DefId,
+        args: ty::GenericArgsRef<'tcx>,
+    ) -> &'tcx ty::List<ty::PolyExistentialPredicate<'tcx>> {
+        let mut bounds: Vec<_> = self
+            .item_super_predicates(def_id)
+            .iter_instantiated(self, args)
+            .filter_map(|clause| {
+                clause
+                    .kind()
+                    .map_bound(|clause| match clause {
+                        ty::ClauseKind::Trait(trait_pred) => Some(ty::ExistentialPredicate::Trait(
+                            ty::ExistentialTraitRef::erase_self_ty(self, trait_pred.trait_ref),
+                        )),
+                        ty::ClauseKind::Projection(projection_pred) => {
+                            Some(ty::ExistentialPredicate::Projection(
+                                ty::ExistentialProjection::erase_self_ty(self, projection_pred),
+                            ))
+                        }
+                        ty::ClauseKind::TypeOutlives(_) => {
+                            // Type outlives bounds don't really turn into anything,
+                            // since we must use an intersection region for the `dyn*`'s
+                            // region anyways.
+                            None
+                        }
+                        _ => unreachable!("unexpected clause in item bounds: {clause:?}"),
+                    })
+                    .transpose()
+            })
+            .collect();
+        bounds.sort_by(|a, b| a.skip_binder().stable_cmp(self, &b.skip_binder()));
+        self.mk_poly_existential_predicates(&bounds)
+    }
+}

compiler/rustc_mir_dataflow/src/move_paths/abs_domain.rs

@@ -4,52 +4,26 @@
 //! field-deref on a local variable, `x.field`, has the same meaning
 //! in both domains). Indexed projections are the exception: `a[x]`
 //! needs to be treated as mapping to the same move path as `a[y]` as
-//! well as `a[13]`, etc.
+//! well as `a[13]`, etc. So we map these `x`/`y` values to `()`.
 //!
 //! (In theory, the analysis could be extended to work with sets of
 //! paths, so that `a[0]` and `a[13]` could be kept distinct, while
 //! `a[x]` would still overlap them both. But that is not this
 //! representation does today.)
 
-use rustc_middle::mir::{Local, Operand, PlaceElem, ProjectionElem};
-use rustc_middle::ty::Ty;
-
-#[derive(Copy, Clone, PartialEq, Eq, Hash, Debug)]
-pub(crate) struct AbstractOperand;
-#[derive(Copy, Clone, PartialEq, Eq, Hash, Debug)]
-pub(crate) struct AbstractType;
-pub(crate) type AbstractElem = ProjectionElem<AbstractOperand, AbstractType>;
+use rustc_middle::mir::{PlaceElem, ProjectionElem, ProjectionKind};
 
 pub(crate) trait Lift {
-    type Abstract;
-    fn lift(&self) -> Self::Abstract;
-}
-impl<'tcx> Lift for Operand<'tcx> {
-    type Abstract = AbstractOperand;
-    fn lift(&self) -> Self::Abstract {
-        AbstractOperand
-    }
-}
-impl Lift for Local {
-    type Abstract = AbstractOperand;
-    fn lift(&self) -> Self::Abstract {
-        AbstractOperand
-    }
-}
-impl<'tcx> Lift for Ty<'tcx> {
-    type Abstract = AbstractType;
-    fn lift(&self) -> Self::Abstract {
-        AbstractType
-    }
+    fn lift(&self) -> ProjectionKind;
 }
+
 impl<'tcx> Lift for PlaceElem<'tcx> {
-    type Abstract = AbstractElem;
-    fn lift(&self) -> Self::Abstract {
+    fn lift(&self) -> ProjectionKind {
         match *self {
             ProjectionElem::Deref => ProjectionElem::Deref,
-            ProjectionElem::Field(f, ty) => ProjectionElem::Field(f, ty.lift()),
-            ProjectionElem::OpaqueCast(ty) => ProjectionElem::OpaqueCast(ty.lift()),
-            ProjectionElem::Index(ref i) => ProjectionElem::Index(i.lift()),
+            ProjectionElem::Field(f, _ty) => ProjectionElem::Field(f, ()),
+            ProjectionElem::OpaqueCast(_ty) => ProjectionElem::OpaqueCast(()),
+            ProjectionElem::Index(_i) => ProjectionElem::Index(()),
             ProjectionElem::Subslice { from, to, from_end } => {
                 ProjectionElem::Subslice { from, to, from_end }
             }
@@ -57,7 +31,7 @@ impl<'tcx> Lift for PlaceElem<'tcx> {
                 ProjectionElem::ConstantIndex { offset, min_length, from_end }
             }
             ProjectionElem::Downcast(a, u) => ProjectionElem::Downcast(a, u),
-            ProjectionElem::Subtype(ty) => ProjectionElem::Subtype(ty.lift()),
+            ProjectionElem::Subtype(_ty) => ProjectionElem::Subtype(()),
         }
     }
 }

compiler/rustc_mir_dataflow/src/move_paths/mod.rs

@@ -8,7 +8,7 @@ use rustc_middle::ty::{Ty, TyCtxt};
 use rustc_span::Span;
 use smallvec::SmallVec;
 
-use self::abs_domain::{AbstractElem, Lift};
+use self::abs_domain::Lift;
 use crate::un_derefer::UnDerefer;
 
 mod abs_domain;
@@ -300,7 +300,7 @@ pub struct MovePathLookup<'tcx> {
     /// subsequent search so that it is solely relative to that
     /// base-place). For the remaining lookup, we map the projection
     /// elem to the associated MovePathIndex.
-    projections: FxHashMap<(MovePathIndex, AbstractElem), MovePathIndex>,
+    projections: FxHashMap<(MovePathIndex, ProjectionKind), MovePathIndex>,
 
     un_derefer: UnDerefer<'tcx>,
 }

compiler/rustc_mir_transform/src/coroutine/by_move_body.rs

@@ -3,8 +3,6 @@
 //!
 //! Consider an async closure like:
 //! ```rust
-//! #![feature(async_closure)]
-//!
 //! let x = vec![1, 2, 3];
 //!
 //! let closure = async move || {

compiler/rustc_mir_transform/src/shim.rs

@@ -9,6 +9,7 @@ use rustc_index::{Idx, IndexVec};
 use rustc_middle::mir::patch::MirPatch;
 use rustc_middle::mir::*;
 use rustc_middle::query::Providers;
+use rustc_middle::ty::adjustment::PointerCoercion;
 use rustc_middle::ty::{
     self, CoroutineArgs, CoroutineArgsExt, EarlyBinder, GenericArgs, Ty, TyCtxt,
 };
@@ -710,6 +711,13 @@ fn build_call_shim<'tcx>(
     };
 
     let def_id = instance.def_id();
+
+    let rpitit_shim = if let ty::InstanceKind::ReifyShim(..) = instance {
+        tcx.return_position_impl_trait_in_trait_shim_data(def_id)
+    } else {
+        None
+    };
+
     let sig = tcx.fn_sig(def_id);
     let sig = sig.map_bound(|sig| tcx.instantiate_bound_regions_with_erased(sig));
 
@@ -765,9 +773,34 @@ fn build_call_shim<'tcx>(
     let mut local_decls = local_decls_for_sig(&sig, span);
     let source_info = SourceInfo::outermost(span);
 
+    let mut destination = Place::return_place();
+    if let Some((rpitit_def_id, fn_args)) = rpitit_shim {
+        let rpitit_args =
+            fn_args.instantiate_identity().extend_to(tcx, rpitit_def_id, |param, _| {
+                match param.kind {
+                    ty::GenericParamDefKind::Lifetime => tcx.lifetimes.re_erased.into(),
+                    ty::GenericParamDefKind::Type { .. }
+                    | ty::GenericParamDefKind::Const { .. } => {
+                        unreachable!("rpitit should have no addition ty/ct")
+                    }
+                }
+            });
+        let dyn_star_ty = Ty::new_dynamic(
+            tcx,
+            tcx.item_bounds_to_existential_predicates(rpitit_def_id, rpitit_args),
+            tcx.lifetimes.re_erased,
+            ty::DynStar,
+        );
+        destination = local_decls.push(local_decls[RETURN_PLACE].clone()).into();
+        local_decls[RETURN_PLACE].ty = dyn_star_ty;
+        let mut inputs_and_output = sig.inputs_and_output.to_vec();
+        *inputs_and_output.last_mut().unwrap() = dyn_star_ty;
+        sig.inputs_and_output = tcx.mk_type_list(&inputs_and_output);
+    }
+
     let rcvr_place = || {
         assert!(rcvr_adjustment.is_some());
-        Place::from(Local::new(1 + 0))
+        Place::from(Local::new(1))
     };
     let mut statements = vec![];
 
@@ -854,7 +887,7 @@ fn build_call_shim<'tcx>(
         TerminatorKind::Call {
             func: callee,
             args,
-            destination: Place::return_place(),
+            destination,
             target: Some(BasicBlock::new(1)),
             unwind: if let Some(Adjustment::RefMut) = rcvr_adjustment {
                 UnwindAction::Cleanup(BasicBlock::new(3))
@@ -882,7 +915,24 @@ fn build_call_shim<'tcx>(
         );
     }
     // BB #1/#2 - return
-    block(&mut blocks, vec![], TerminatorKind::Return, false);
+    // NOTE: If this is an RPITIT in dyn, we also want to coerce
+    // the return type of the function into a `dyn*`.
+    let stmts = if rpitit_shim.is_some() {
+        vec![Statement {
+            source_info,
+            kind: StatementKind::Assign(Box::new((
+                Place::return_place(),
+                Rvalue::Cast(
+                    CastKind::PointerCoercion(PointerCoercion::DynStar, CoercionSource::Implicit),
+                    Operand::Move(destination),
+                    sig.output(),
+                ),
+            ))),
+        }]
+    } else {
+        vec![]
+    };
+    block(&mut blocks, stmts, TerminatorKind::Return, false);
     if let Some(Adjustment::RefMut) = rcvr_adjustment {
         // BB #3 - drop if closure panics
         block(

compiler/rustc_monomorphize/src/lib.rs

@@ -42,7 +42,10 @@ fn custom_coerce_unsize_info<'tcx>(
             ..
         })) => Ok(tcx.coerce_unsized_info(impl_def_id)?.custom_kind.unwrap()),
         impl_source => {
-            bug!("invalid `CoerceUnsized` impl_source: {:?}", impl_source);
+            bug!(
+                "invalid `CoerceUnsized` from {source_ty} to {target_ty}: impl_source: {:?}",
+                impl_source
+            );
         }
     }
 }

compiler/rustc_parse/src/lexer/tokentrees.rs

@@ -1,7 +1,7 @@
 use rustc_ast::token::{self, Delimiter, Token};
 use rustc_ast::tokenstream::{DelimSpacing, DelimSpan, Spacing, TokenStream, TokenTree};
 use rustc_ast_pretty::pprust::token_to_string;
-use rustc_errors::{Applicability, PErr};
+use rustc_errors::{Applicability, Diag};
 use rustc_span::symbol::kw;
 
 use super::diagnostics::{report_suspicious_mismatch_block, same_indentation_level};
@@ -14,7 +14,7 @@ impl<'psess, 'src> Lexer<'psess, 'src> {
     pub(super) fn lex_token_trees(
         &mut self,
         is_delimited: bool,
-    ) -> (Spacing, TokenStream, Result<(), Vec<PErr<'psess>>>) {
+    ) -> (Spacing, TokenStream, Result<(), Vec<Diag<'psess>>>) {
         // Move past the opening delimiter.
         let open_spacing = self.bump_minimal();
 
@@ -56,7 +56,7 @@ impl<'psess, 'src> Lexer<'psess, 'src> {
         }
     }
 
-    fn eof_err(&mut self) -> PErr<'psess> {
+    fn eof_err(&mut self) -> Diag<'psess> {
         let msg = "this file contains an unclosed delimiter";
         let mut err = self.dcx().struct_span_err(self.token.span, msg);
 
@@ -98,7 +98,7 @@ impl<'psess, 'src> Lexer<'psess, 'src> {
     fn lex_token_tree_open_delim(
         &mut self,
         open_delim: Delimiter,
-    ) -> Result<TokenTree, Vec<PErr<'psess>>> {
+    ) -> Result<TokenTree, Vec<Diag<'psess>>> {
         // The span for beginning of the delimited section.
         let pre_span = self.token.span;
 
@@ -250,8 +250,8 @@ impl<'psess, 'src> Lexer<'psess, 'src> {
     fn unclosed_delim_err(
         &mut self,
         tts: TokenStream,
-        mut errs: Vec<PErr<'psess>>,
-    ) -> Vec<PErr<'psess>> {
+        mut errs: Vec<Diag<'psess>>,
+    ) -> Vec<Diag<'psess>> {
         // If there are unclosed delims, see if there are diff markers and if so, point them
         // out instead of complaining about the unclosed delims.
         let mut parser = Parser::new(self.psess, tts, None);
@@ -308,7 +308,7 @@ impl<'psess, 'src> Lexer<'psess, 'src> {
         errs
     }
 
-    fn close_delim_err(&mut self, delim: Delimiter) -> PErr<'psess> {
+    fn close_delim_err(&mut self, delim: Delimiter) -> Diag<'psess> {
         // An unexpected closing delimiter (i.e., there is no matching opening delimiter).
         let token_str = token_to_string(&self.token);
         let msg = format!("unexpected closing delimiter: `{token_str}`");

compiler/rustc_parse/src/parser/diagnostics.rs

@@ -16,7 +16,7 @@ use rustc_ast_pretty::pprust;
 use rustc_data_structures::fx::FxHashSet;
 use rustc_data_structures::sync::Lrc;
 use rustc_errors::{
-    Applicability, Diag, DiagCtxtHandle, ErrorGuaranteed, FatalError, PErr, PResult, Subdiagnostic,
+    Applicability, Diag, DiagCtxtHandle, ErrorGuaranteed, FatalError, PResult, Subdiagnostic,
     Suggestions, pluralize,
 };
 use rustc_session::errors::ExprParenthesesNeeded;
@@ -2132,7 +2132,7 @@ impl<'a> Parser<'a> {
         &mut self,
         delim: Delimiter,
         lo: Span,
-        err: PErr<'a>,
+        err: Diag<'a>,
     ) -> P<Expr> {
         let guar = err.emit();
         // Recover from parse error, callers expect the closing delim to be consumed.
@@ -3014,7 +3014,7 @@ impl<'a> Parser<'a> {
     }
 
     /// Check for exclusive ranges written as `..<`
-    pub(crate) fn maybe_err_dotdotlt_syntax(&self, maybe_lt: Token, mut err: PErr<'a>) -> PErr<'a> {
+    pub(crate) fn maybe_err_dotdotlt_syntax(&self, maybe_lt: Token, mut err: Diag<'a>) -> Diag<'a> {
         if maybe_lt == token::Lt
             && (self.expected_tokens.contains(&TokenType::Token(token::Gt))
                 || matches!(self.token.kind, token::Literal(..)))

compiler/rustc_parse/src/parser/expr.rs

@@ -1369,11 +1369,14 @@ impl<'a> Parser<'a> {
             ))
         } else {
             // Field access `expr.f`
+            let span = lo.to(self.prev_token.span);
             if let Some(args) = seg.args {
-                self.dcx().emit_err(errors::FieldExpressionWithGeneric(args.span()));
+                // See `StashKey::GenericInFieldExpr` for more info on why we stash this.
+                self.dcx()
+                    .create_err(errors::FieldExpressionWithGeneric(args.span()))
+                    .stash(seg.ident.span, StashKey::GenericInFieldExpr);
             }
 
-            let span = lo.to(self.prev_token.span);
             Ok(self.mk_expr(span, ExprKind::Field(self_arg, seg.ident)))
         }
     }
@@ -2363,10 +2366,7 @@ impl<'a> Parser<'a> {
         };
 
         match coroutine_kind {
-            Some(CoroutineKind::Async { span, .. }) => {
-                // Feature-gate `async ||` closures.
-                self.psess.gated_spans.gate(sym::async_closure, span);
-            }
+            Some(CoroutineKind::Async { .. }) => {}
             Some(CoroutineKind::Gen { span, .. }) | Some(CoroutineKind::AsyncGen { span, .. }) => {
                 // Feature-gate `gen ||` and `async gen ||` closures.
                 // FIXME(gen_blocks): This perhaps should be a different gate.

compiler/rustc_parse/src/parser/tests.rs

@@ -1,3 +1,5 @@
+#![cfg_attr(not(bootstrap), allow(rustc::symbol_intern_string_literal))]
+
 use std::assert_matches::assert_matches;
 use std::io::prelude::*;
 use std::iter::Peekable;

compiler/rustc_parse/src/parser/tokenstream/tests.rs

@@ -1,3 +1,5 @@
+#![cfg_attr(not(bootstrap), allow(rustc::symbol_intern_string_literal))]
+
 use rustc_ast::token::{self, IdentIsRaw};
 use rustc_ast::tokenstream::{TokenStream, TokenTree};
 use rustc_span::{BytePos, Span, Symbol, create_default_session_globals_then};

compiler/rustc_span/src/edit_distance/tests.rs

@@ -1,3 +1,5 @@
+#![cfg_attr(not(bootstrap), allow(rustc::symbol_intern_string_literal))]
+
 use super::*;
 
 #[test]

compiler/rustc_span/src/symbol.rs

@@ -461,6 +461,7 @@ symbols! {
         async_drop_slice,
         async_drop_surface_drop_in_place,
         async_fn,
+        async_fn_in_dyn_trait,
         async_fn_in_trait,
         async_fn_kind_helper,
         async_fn_kind_upvars,

compiler/rustc_target/src/spec/base/windows_gnullvm.rs

@@ -42,6 +42,8 @@ pub(crate) fn opts() -> TargetOptions {
         eh_frame_header: false,
         no_default_libraries: false,
         has_thread_local: true,
+        crt_static_allows_dylibs: true,
+        crt_static_respected: true,
         // FIXME(davidtwco): Support Split DWARF on Windows GNU - may require LLVM changes to
         // output DWO, despite using DWARF, doesn't use ELF..
         debuginfo_kind: DebuginfoKind::Pdb,

compiler/rustc_target/src/target_features.rs

@@ -611,6 +611,8 @@ const HEXAGON_FEATURES_FOR_CORRECT_VECTOR_ABI: &'static [(u64, &'static str)] =
     &[/*(512, "hvx-length64b"),*/ (1024, "hvx-length128b")];
 const MIPS_FEATURES_FOR_CORRECT_VECTOR_ABI: &'static [(u64, &'static str)] = &[(128, "msa")];
 const CSKY_FEATURES_FOR_CORRECT_VECTOR_ABI: &'static [(u64, &'static str)] = &[(128, "vdspv1")];
+const LOONGARCH_FEATURES_FOR_CORRECT_VECTOR_ABI: &'static [(u64, &'static str)] =
+    &[(128, "lsx"), (256, "lasx")];
 
 impl super::spec::Target {
     pub fn rust_target_features(&self) -> &'static [(&'static str, Stability, ImpliedFeatures)] {
@@ -638,7 +640,7 @@ impl super::spec::Target {
             "aarch64" | "arm64ec" => AARCH64_FEATURES_FOR_CORRECT_VECTOR_ABI,
             "arm" => ARM_FEATURES_FOR_CORRECT_VECTOR_ABI,
             "powerpc" | "powerpc64" => POWERPC_FEATURES_FOR_CORRECT_VECTOR_ABI,
-            "loongarch64" => &[], // on-stack ABI, so we complain about all by-val vectors
+            "loongarch64" => LOONGARCH_FEATURES_FOR_CORRECT_VECTOR_ABI,
             "riscv32" | "riscv64" => RISCV_FEATURES_FOR_CORRECT_VECTOR_ABI,
             "wasm32" | "wasm64" => WASM_FEATURES_FOR_CORRECT_VECTOR_ABI,
             "s390x" => S390X_FEATURES_FOR_CORRECT_VECTOR_ABI,

compiler/rustc_trait_selection/src/traits/dyn_compatibility.rs

@@ -11,6 +11,7 @@ use rustc_abi::BackendRepr;
 use rustc_errors::FatalError;
 use rustc_hir as hir;
 use rustc_hir::def_id::DefId;
+use rustc_middle::bug;
 use rustc_middle::query::Providers;
 use rustc_middle::ty::{
     self, EarlyBinder, ExistentialPredicateStableCmpExt as _, GenericArgs, Ty, TyCtxt,
@@ -901,23 +902,59 @@ fn contains_illegal_impl_trait_in_trait<'tcx>(
     fn_def_id: DefId,
     ty: ty::Binder<'tcx, Ty<'tcx>>,
 ) -> Option<MethodViolationCode> {
-    // This would be caught below, but rendering the error as a separate
-    // `async-specific` message is better.
-    if tcx.asyncness(fn_def_id).is_async() {
-        return Some(MethodViolationCode::AsyncFn);
-    }
+    let ty = tcx.liberate_late_bound_regions(fn_def_id, ty);
+
+    if tcx.asyncness(fn_def_id).is_async() {
+        // FIXME(async_fn_in_dyn_trait): Think of a better way to unify these code paths
+        // to issue an appropriate feature suggestion when users try to use AFIDT.
+        // Obviously we must only do this once AFIDT is finished enough to actually be usable.
+        if tcx.features().async_fn_in_dyn_trait() {
+            let ty::Alias(ty::Projection, proj) = *ty.kind() else {
+                bug!("expected async fn in trait to return an RPITIT");
+            };
+            assert!(tcx.is_impl_trait_in_trait(proj.def_id));
+
+            // FIXME(async_fn_in_dyn_trait): We should check that this bound is legal too,
+            // and stop relying on `async fn` in the definition.
+            for bound in tcx.item_bounds(proj.def_id).instantiate(tcx, proj.args) {
+                if let Some(violation) = bound
+                    .visit_with(&mut IllegalRpititVisitor { tcx, allowed: Some(proj) })
+                    .break_value()
+                {
+                    return Some(violation);
+                }
+            }
 
-    // FIXME(RPITIT): Perhaps we should use a visitor here?
-    ty.skip_binder().walk().find_map(|arg| {
-        if let ty::GenericArgKind::Type(ty) = arg.unpack()
-            && let ty::Alias(ty::Projection, proj) = ty.kind()
-            && tcx.is_impl_trait_in_trait(proj.def_id)
-        {
-            Some(MethodViolationCode::ReferencesImplTraitInTrait(tcx.def_span(proj.def_id)))
-        } else {
             None
+        } else {
+            // Rendering the error as a separate `async-specific` message is better.
+            Some(MethodViolationCode::AsyncFn)
         }
-    })
+    } else {
+        ty.visit_with(&mut IllegalRpititVisitor { tcx, allowed: None }).break_value()
+    }
+}
+
+struct IllegalRpititVisitor<'tcx> {
+    tcx: TyCtxt<'tcx>,
+    allowed: Option<ty::AliasTy<'tcx>>,
+}
+
+impl<'tcx> TypeVisitor<TyCtxt<'tcx>> for IllegalRpititVisitor<'tcx> {
+    type Result = ControlFlow<MethodViolationCode>;
+
+    fn visit_ty(&mut self, ty: Ty<'tcx>) -> Self::Result {
+        if let ty::Alias(ty::Projection, proj) = *ty.kind()
+            && Some(proj) != self.allowed
+            && self.tcx.is_impl_trait_in_trait(proj.def_id)
+        {
+            ControlFlow::Break(MethodViolationCode::ReferencesImplTraitInTrait(
+                self.tcx.def_span(proj.def_id),
+            ))
+        } else {
+            ty.super_visit_with(self)
+        }
+    }
 }
 
 pub(crate) fn provide(providers: &mut Providers) {

compiler/rustc_trait_selection/src/traits/project.rs

@@ -7,8 +7,8 @@ use rustc_data_structures::stack::ensure_sufficient_stack;
 use rustc_errors::ErrorGuaranteed;
 use rustc_hir::def::DefKind;
 use rustc_hir::lang_items::LangItem;
-use rustc_infer::infer::DefineOpaqueTypes;
 use rustc_infer::infer::resolve::OpportunisticRegionResolver;
+use rustc_infer::infer::{DefineOpaqueTypes, RegionVariableOrigin};
 use rustc_infer::traits::{ObligationCauseCode, PredicateObligations};
 use rustc_middle::traits::select::OverflowError;
 use rustc_middle::traits::{BuiltinImplSource, ImplSource, ImplSourceUserDefinedData};
@@ -18,6 +18,7 @@ use rustc_middle::ty::visit::TypeVisitableExt;
 use rustc_middle::ty::{self, Term, Ty, TyCtxt, TypingMode, Upcast};
 use rustc_middle::{bug, span_bug};
 use rustc_span::symbol::sym;
+use thin_vec::thin_vec;
 use tracing::{debug, instrument};
 
 use super::{
@@ -61,6 +62,9 @@ enum ProjectionCandidate<'tcx> {
     /// Bounds specified on an object type
     Object(ty::PolyProjectionPredicate<'tcx>),
 
+    /// Built-in bound for a dyn async fn in trait
+    ObjectRpitit,
+
     /// From an "impl" (or a "pseudo-impl" returned by select)
     Select(Selection<'tcx>),
 }
@@ -827,6 +831,17 @@ fn assemble_candidates_from_object_ty<'cx, 'tcx>(
         env_predicates,
         false,
     );
+
+    // `dyn Trait` automagically project their AFITs to `dyn* Future`.
+    if tcx.is_impl_trait_in_trait(obligation.predicate.def_id)
+        && let Some(out_trait_def_id) = data.principal_def_id()
+        && let rpitit_trait_def_id = tcx.parent(obligation.predicate.def_id)
+        && tcx
+            .supertrait_def_ids(out_trait_def_id)
+            .any(|trait_def_id| trait_def_id == rpitit_trait_def_id)
+    {
+        candidate_set.push_candidate(ProjectionCandidate::ObjectRpitit);
+    }
 }
 
 #[instrument(
@@ -1247,6 +1262,8 @@ fn confirm_candidate<'cx, 'tcx>(
         ProjectionCandidate::Select(impl_source) => {
             confirm_select_candidate(selcx, obligation, impl_source)
         }
+
+        ProjectionCandidate::ObjectRpitit => confirm_object_rpitit_candidate(selcx, obligation),
     };
 
     // When checking for cycle during evaluation, we compare predicates with
@@ -2034,6 +2051,45 @@ fn confirm_impl_candidate<'cx, 'tcx>(
     }
 }
 
+fn confirm_object_rpitit_candidate<'cx, 'tcx>(
+    selcx: &mut SelectionContext<'cx, 'tcx>,
+    obligation: &ProjectionTermObligation<'tcx>,
+) -> Progress<'tcx> {
+    let tcx = selcx.tcx();
+    let mut obligations = thin_vec![];
+
+    // Compute an intersection lifetime for all the input components of this GAT.
+    let intersection =
+        selcx.infcx.next_region_var(RegionVariableOrigin::MiscVariable(obligation.cause.span));
+    for component in obligation.predicate.args {
+        match component.unpack() {
+            ty::GenericArgKind::Lifetime(lt) => {
+                obligations.push(obligation.with(tcx, ty::OutlivesPredicate(lt, intersection)));
+            }
+            ty::GenericArgKind::Type(ty) => {
+                obligations.push(obligation.with(tcx, ty::OutlivesPredicate(ty, intersection)));
+            }
+            ty::GenericArgKind::Const(_ct) => {
+                // Consts have no outlives...
+            }
+        }
+    }
+
+    Progress {
+        term: Ty::new_dynamic(
+            tcx,
+            tcx.item_bounds_to_existential_predicates(
+                obligation.predicate.def_id,
+                obligation.predicate.args,
+            ),
+            intersection,
+            ty::DynStar,
+        )
+        .into(),
+        obligations,
+    }
+}
+
 // Get obligations corresponding to the predicates from the where-clause of the
 // associated type itself.
 fn assoc_ty_own_obligations<'cx, 'tcx>(

compiler/rustc_trait_selection/src/traits/select/confirmation.rs

@@ -19,6 +19,7 @@ use rustc_middle::traits::{BuiltinImplSource, SignatureMismatchData};
 use rustc_middle::ty::{self, GenericArgsRef, ToPolyTraitRef, Ty, TyCtxt, Upcast};
 use rustc_middle::{bug, span_bug};
 use rustc_span::def_id::DefId;
+use rustc_type_ir::elaborate;
 use tracing::{debug, instrument};
 
 use super::SelectionCandidate::{self, *};
@@ -624,6 +625,12 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
         for assoc_type in assoc_types {
             let defs: &ty::Generics = tcx.generics_of(assoc_type);
 
+            // When `async_fn_in_dyn_trait` is enabled, we don't need to check the
+            // RPITIT for compatibility, since it's not provided by the user.
+            if tcx.features().async_fn_in_dyn_trait() && tcx.is_impl_trait_in_trait(assoc_type) {
+                continue;
+            }
+
             if !defs.own_params.is_empty() {
                 tcx.dcx().span_delayed_bug(
                     obligation.cause.span,
@@ -1175,6 +1182,38 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
                     ty::ClauseKind::TypeOutlives(outlives).upcast(tcx),
                 ));
 
+                // Require that all AFIT will return something that can be coerced into `dyn*`
+                // -- a shim will be responsible for doing the actual coercion to `dyn*`.
+                if let Some(principal) = data.principal() {
+                    for supertrait in
+                        elaborate::supertraits(tcx, principal.with_self_ty(tcx, source))
+                    {
+                        if tcx.is_trait_alias(supertrait.def_id()) {
+                            continue;
+                        }
+
+                        for &assoc_item in tcx.associated_item_def_ids(supertrait.def_id()) {
+                            if !tcx.is_impl_trait_in_trait(assoc_item) {
+                                continue;
+                            }
+
+                            // RPITITs with `Self: Sized` don't need to be checked.
+                            if tcx.generics_require_sized_self(assoc_item) {
+                                continue;
+                            }
+
+                            let pointer_like_goal = pointer_like_goal_for_rpitit(
+                                tcx,
+                                supertrait,
+                                assoc_item,
+                                &obligation.cause,
+                            );
+
+                            nested.push(predicate_to_obligation(pointer_like_goal.upcast(tcx)));
+                        }
+                    }
+                }
+
                 ImplSource::Builtin(BuiltinImplSource::Misc, nested)
             }
 
@@ -1280,3 +1319,43 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
         })
     }
 }
+
+/// Compute a goal that some RPITIT (right now, only RPITITs corresponding to Futures)
+/// implements the `PointerLike` trait, which is a requirement for the RPITIT to be
+/// coercible to `dyn* Future`, which is itself a requirement for the RPITIT's parent
+/// trait to be coercible to `dyn Trait`.
+///
+/// We do this given a supertrait's substitutions, and then augment the substitutions
+/// with bound variables to compute the goal universally. Given that `PointerLike` has
+/// no region requirements (at least for the built-in pointer types), this shouldn't
+/// *really* matter, but it is the best choice for soundness.
+fn pointer_like_goal_for_rpitit<'tcx>(
+    tcx: TyCtxt<'tcx>,
+    supertrait: ty::PolyTraitRef<'tcx>,
+    rpitit_item: DefId,
+    cause: &ObligationCause<'tcx>,
+) -> ty::PolyTraitRef<'tcx> {
+    let mut bound_vars = supertrait.bound_vars().to_vec();
+
+    let args = supertrait.skip_binder().args.extend_to(tcx, rpitit_item, |arg, _| match arg.kind {
+        ty::GenericParamDefKind::Lifetime => {
+            let kind = ty::BoundRegionKind::Named(arg.def_id, tcx.item_name(arg.def_id));
+            bound_vars.push(ty::BoundVariableKind::Region(kind));
+            ty::Region::new_bound(tcx, ty::INNERMOST, ty::BoundRegion {
+                var: ty::BoundVar::from_usize(bound_vars.len() - 1),
+                kind,
+            })
+            .into()
+        }
+        ty::GenericParamDefKind::Type { .. } | ty::GenericParamDefKind::Const { .. } => {
+            unreachable!()
+        }
+    });
+
+    ty::Binder::bind_with_vars(
+        ty::TraitRef::new(tcx, tcx.require_lang_item(LangItem::PointerLike, Some(cause.span)), [
+            Ty::new_projection_from_args(tcx, rpitit_item, args),
+        ]),
+        tcx.mk_bound_variable_kinds(&bound_vars),
+    )
+}

compiler/rustc_ty_utils/src/abi.rs

@@ -48,12 +48,38 @@ fn fn_sig_for_fn_abi<'tcx>(
             let mut sig = tcx
                 .instantiate_bound_regions_with_erased(tcx.fn_sig(def_id).instantiate(tcx, args));
 
+            // Modify `fn(self, ...)` to `fn(self: *mut Self, ...)`.
             if let ty::InstanceKind::VTableShim(..) = instance.def {
                 let mut inputs_and_output = sig.inputs_and_output.to_vec();
                 inputs_and_output[0] = Ty::new_mut_ptr(tcx, inputs_and_output[0]);
                 sig.inputs_and_output = tcx.mk_type_list(&inputs_and_output);
             }
 
+            // Modify `fn() -> impl Future` to `fn() -> dyn* Future`.
+            if let ty::InstanceKind::ReifyShim(def_id, _) = instance.def
+                && let Some((rpitit_def_id, fn_args)) =
+                    tcx.return_position_impl_trait_in_trait_shim_data(def_id)
+            {
+                let fn_args = fn_args.instantiate(tcx, args);
+                let rpitit_args =
+                    fn_args.extend_to(tcx, rpitit_def_id, |param, _| match param.kind {
+                        ty::GenericParamDefKind::Lifetime => tcx.lifetimes.re_erased.into(),
+                        ty::GenericParamDefKind::Type { .. }
+                        | ty::GenericParamDefKind::Const { .. } => {
+                            unreachable!("rpitit should have no addition ty/ct")
+                        }
+                    });
+                let dyn_star_ty = Ty::new_dynamic(
+                    tcx,
+                    tcx.item_bounds_to_existential_predicates(rpitit_def_id, rpitit_args),
+                    tcx.lifetimes.re_erased,
+                    ty::DynStar,
+                );
+                let mut inputs_and_output = sig.inputs_and_output.to_vec();
+                *inputs_and_output.last_mut().unwrap() = dyn_star_ty;
+                sig.inputs_and_output = tcx.mk_type_list(&inputs_and_output);
+            }
+
             sig
         }
         ty::Closure(def_id, args) => {

library/alloc/src/alloc.rs

@@ -10,9 +10,6 @@ use core::hint;
 #[cfg(not(test))]
 use core::ptr::{self, NonNull};
 
-#[cfg(test)]
-mod tests;
-
 extern "Rust" {
     // These are the magic symbols to call the global allocator. rustc generates
     // them to call `__rg_alloc` etc. if there is a `#[global_allocator]` attribute

library/alloc/src/boxed.rs

@@ -1985,7 +1985,8 @@ impl<Args: Tuple, F: Fn<Args> + ?Sized, A: Allocator> Fn<Args> for Box<F, A> {
     }
 }
 
-#[unstable(feature = "async_fn_traits", issue = "none")]
+#[cfg_attr(bootstrap, unstable(feature = "async_closure", issue = "62290"))]
+#[cfg_attr(not(bootstrap), stable(feature = "async_closure", since = "CURRENT_RUSTC_VERSION"))]
 impl<Args: Tuple, F: AsyncFnOnce<Args> + ?Sized, A: Allocator> AsyncFnOnce<Args> for Box<F, A> {
     type Output = F::Output;
     type CallOnceFuture = F::CallOnceFuture;
@@ -1995,7 +1996,8 @@ impl<Args: Tuple, F: AsyncFnOnce<Args> + ?Sized, A: Allocator> AsyncFnOnce<Args>
     }
 }
 
-#[unstable(feature = "async_fn_traits", issue = "none")]
+#[cfg_attr(bootstrap, unstable(feature = "async_closure", issue = "62290"))]
+#[cfg_attr(not(bootstrap), stable(feature = "async_closure", since = "CURRENT_RUSTC_VERSION"))]
 impl<Args: Tuple, F: AsyncFnMut<Args> + ?Sized, A: Allocator> AsyncFnMut<Args> for Box<F, A> {
     type CallRefFuture<'a>
         = F::CallRefFuture<'a>
@@ -2007,7 +2009,8 @@ impl<Args: Tuple, F: AsyncFnMut<Args> + ?Sized, A: Allocator> AsyncFnMut<Args> f
     }
 }
 
-#[unstable(feature = "async_fn_traits", issue = "none")]
+#[cfg_attr(bootstrap, unstable(feature = "async_closure", issue = "62290"))]
+#[cfg_attr(not(bootstrap), stable(feature = "async_closure", since = "CURRENT_RUSTC_VERSION"))]
 impl<Args: Tuple, F: AsyncFn<Args> + ?Sized, A: Allocator> AsyncFn<Args> for Box<F, A> {
     extern "rust-call" fn async_call(&self, args: Args) -> Self::CallRefFuture<'_> {
         F::async_call(self, args)

library/alloc/src/collections/binary_heap/mod.rs

@@ -155,9 +155,6 @@ use crate::collections::TryReserveError;
 use crate::slice;
 use crate::vec::{self, AsVecIntoIter, Vec};
 
-#[cfg(test)]
-mod tests;
-
 /// A priority queue implemented with a binary heap.
 ///
 /// This will be a max-heap.

library/alloc/src/ffi/c_str.rs

@@ -1,8 +1,5 @@
 //! [`CString`] and its related types.
 
-#[cfg(test)]
-mod tests;
-
 use core::borrow::Borrow;
 use core::ffi::{CStr, c_char};
 use core::num::NonZero;

library/alloc/src/lib.rs

@@ -91,6 +91,7 @@
 //
 // Library features:
 // tidy-alphabetical-start
+#![cfg_attr(bootstrap, feature(async_closure))]
 #![cfg_attr(test, feature(str_as_str))]
 #![feature(alloc_layout_extra)]
 #![feature(allocator_api)]
@@ -99,7 +100,6 @@
 #![feature(array_windows)]
 #![feature(ascii_char)]
 #![feature(assert_matches)]
-#![feature(async_closure)]
 #![feature(async_fn_traits)]
 #![feature(async_iterator)]
 #![feature(box_uninit_write)]
@@ -239,8 +239,6 @@ pub mod string;
 pub mod sync;
 #[cfg(all(not(no_global_oom_handling), not(no_rc), not(no_sync)))]
 pub mod task;
-#[cfg(test)]
-mod tests;
 pub mod vec;
 
 #[doc(hidden)]

library/alloc/src/sync.rs

@@ -39,9 +39,6 @@ use crate::string::String;
 #[cfg(not(no_global_oom_handling))]
 use crate::vec::Vec;
 
-#[cfg(test)]
-mod tests;
-
 /// A soft limit on the amount of references that may be made to an `Arc`.
 ///
 /// Going above this limit will abort your program (although not

library/alloc/tests/alloc.rs

@@ -1,10 +1,9 @@
-use super::*;
+use alloc::alloc::*;
+use alloc::boxed::Box;
 
 extern crate test;
 use test::Bencher;
 
-use crate::boxed::Box;
-
 #[test]
 fn allocate_zeroed() {
     unsafe {

library/alloc/tests/c_str2.rs

@@ -1,11 +1,12 @@
+use alloc::ffi::CString;
+use alloc::rc::Rc;
+use alloc::sync::Arc;
 use core::assert_matches::assert_matches;
-use core::ffi::FromBytesUntilNulError;
+use core::ffi::{CStr, FromBytesUntilNulError, c_char};
 #[allow(deprecated)]
 use core::hash::SipHasher13 as DefaultHasher;
 use core::hash::{Hash, Hasher};
 
-use super::*;
-
 #[test]
 fn c_to_rust() {
     let data = b"123\0";

library/alloc/tests/collections/binary_heap.rs

@@ -1,7 +1,9 @@
+use alloc::boxed::Box;
+use alloc::collections::binary_heap::*;
+use std::iter::TrustedLen;
+use std::mem;
 use std::panic::{AssertUnwindSafe, catch_unwind};
 
-use super::*;
-use crate::boxed::Box;
 use crate::testing::crash_test::{CrashTestDummy, Panic};
 
 #[test]
@@ -531,7 +533,7 @@ fn panic_safe() {
             self.0.partial_cmp(&other.0)
         }
     }
-    let mut rng = crate::test_helpers::test_rng();
+    let mut rng = crate::test_rng();
     const DATASZ: usize = 32;
     // Miri is too slow
     let ntest = if cfg!(miri) { 1 } else { 10 };

library/alloc/tests/collections/mod.rs

@@ -0,0 +1 @@
+mod binary_heap;

library/alloc/tests/lib.rs

@@ -5,8 +5,10 @@
 #![feature(btree_extract_if)]
 #![feature(cow_is_borrowed)]
 #![feature(core_intrinsics)]
+#![feature(downcast_unchecked)]
 #![feature(extract_if)]
 #![feature(exact_size_is_empty)]
+#![feature(hashmap_internals)]
 #![feature(linked_list_cursors)]
 #![feature(map_try_insert)]
 #![feature(pattern)]
@@ -29,9 +31,11 @@
 #![feature(const_str_from_utf8)]
 #![feature(panic_update_hook)]
 #![feature(pointer_is_aligned_to)]
+#![feature(test)]
 #![feature(thin_box)]
 #![feature(drain_keep_rest)]
 #![feature(local_waker)]
+#![feature(str_as_str)]
 #![feature(strict_provenance_lints)]
 #![feature(vec_pop_if)]
 #![feature(unique_rc_arc)]
@@ -40,25 +44,33 @@
 #![deny(fuzzy_provenance_casts)]
 #![deny(unsafe_op_in_unsafe_fn)]
 
+extern crate test;
+
 use std::hash::{DefaultHasher, Hash, Hasher};
 
+mod alloc;
 mod arc;
 mod autotraits;
 mod borrow;
 mod boxed;
 mod btree_set_hash;
 mod c_str;
+mod c_str2;
+mod collections;
 mod const_fns;
 mod cow_str;
 mod fmt;
 mod heap;
 mod linked_list;
+mod misc_tests;
 mod rc;
 mod slice;
 mod sort;
 mod str;
 mod string;
+mod sync;
 mod task;
+mod testing;
 mod thin_box;
 mod vec;
 mod vec_deque;
@@ -69,6 +81,18 @@ fn hash<T: Hash>(t: &T) -> u64 {
     s.finish()
 }
 
+/// Copied from `std::test_helpers::test_rng`, since these tests rely on the
+/// seed not being the same for every RNG invocation too.
+fn test_rng() -> rand_xorshift::XorShiftRng {
+    use std::hash::{BuildHasher, Hash, Hasher};
+    let mut hasher = std::hash::RandomState::new().build_hasher();
+    std::panic::Location::caller().hash(&mut hasher);
+    let hc64 = hasher.finish();
+    let seed_vec = hc64.to_le_bytes().into_iter().chain(0u8..8).collect::<Vec<u8>>();
+    let seed: [u8; 16] = seed_vec.as_slice().try_into().unwrap();
+    rand::SeedableRng::from_seed(seed)
+}
+
 // FIXME: Instantiated functions with i128 in the signature is not supported in Emscripten.
 // See https://github.com/kripken/emscripten-fastcomp/issues/169
 #[cfg(not(target_os = "emscripten"))]

library/alloc/tests/sync.rs

@@ -1,14 +1,16 @@
+use alloc::sync::*;
+use std::alloc::{AllocError, Allocator, Layout};
+use std::any::Any;
 use std::clone::Clone;
 use std::mem::MaybeUninit;
 use std::option::Option::None;
+use std::ptr::NonNull;
 use std::sync::Mutex;
-use std::sync::atomic::AtomicUsize;
-use std::sync::atomic::Ordering::SeqCst;
+use std::sync::atomic::Ordering::*;
+use std::sync::atomic::{self, AtomicUsize};
 use std::sync::mpsc::channel;
 use std::thread;
 
-use super::*;
-
 struct Canary(*mut AtomicUsize);
 
 impl Drop for Canary {

library/alloc/tests/testing/crash_test.rs

@@ -0,0 +1,80 @@
+use std::cmp::Ordering;
+use std::fmt::Debug;
+use std::sync::atomic::AtomicUsize;
+use std::sync::atomic::Ordering::SeqCst;
+
+/// A blueprint for crash test dummy instances that monitor drops.
+/// Some instances may be configured to panic at some point.
+///
+/// Crash test dummies are identified and ordered by an id, so they can be used
+/// as keys in a BTreeMap.
+#[derive(Debug)]
+pub struct CrashTestDummy {
+    pub id: usize,
+    dropped: AtomicUsize,
+}
+
+impl CrashTestDummy {
+    /// Creates a crash test dummy design. The `id` determines order and equality of instances.
+    pub fn new(id: usize) -> CrashTestDummy {
+        CrashTestDummy { id, dropped: AtomicUsize::new(0) }
+    }
+
+    /// Creates an instance of a crash test dummy that records what events it experiences
+    /// and optionally panics.
+    pub fn spawn(&self, panic: Panic) -> Instance<'_> {
+        Instance { origin: self, panic }
+    }
+
+    /// Returns how many times instances of the dummy have been dropped.
+    pub fn dropped(&self) -> usize {
+        self.dropped.load(SeqCst)
+    }
+}
+
+#[derive(Debug)]
+pub struct Instance<'a> {
+    origin: &'a CrashTestDummy,
+    panic: Panic,
+}
+
+#[derive(Copy, Clone, Debug, PartialEq, Eq)]
+pub enum Panic {
+    Never,
+    InDrop,
+}
+
+impl Instance<'_> {
+    pub fn id(&self) -> usize {
+        self.origin.id
+    }
+}
+
+impl Drop for Instance<'_> {
+    fn drop(&mut self) {
+        self.origin.dropped.fetch_add(1, SeqCst);
+        if self.panic == Panic::InDrop {
+            panic!("panic in `drop`");
+        }
+    }
+}
+
+impl PartialOrd for Instance<'_> {
+    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
+        self.id().partial_cmp(&other.id())
+    }
+}
+
+impl Ord for Instance<'_> {
+    fn cmp(&self, other: &Self) -> Ordering {
+        self.id().cmp(&other.id())
+    }
+}
+
+impl PartialEq for Instance<'_> {
+    fn eq(&self, other: &Self) -> bool {
+        self.id().eq(&other.id())
+    }
+}
+
+impl Eq for Instance<'_> {}

library/alloc/tests/testing/mod.rs

@@ -0,0 +1 @@
+pub mod crash_test;

library/core/src/ops/async_function.rs

@@ -4,7 +4,8 @@ use crate::marker::Tuple;
 /// An async-aware version of the [`Fn`](crate::ops::Fn) trait.
 ///
 /// All `async fn` and functions returning futures implement this trait.
-#[unstable(feature = "async_closure", issue = "62290")]
+#[cfg_attr(bootstrap, unstable(feature = "async_closure", issue = "62290"))]
+#[cfg_attr(not(bootstrap), stable(feature = "async_closure", since = "CURRENT_RUSTC_VERSION"))]
 #[rustc_paren_sugar]
 #[fundamental]
 #[must_use = "async closures are lazy and do nothing unless called"]
@@ -18,7 +19,8 @@ pub trait AsyncFn<Args: Tuple>: AsyncFnMut<Args> {
 /// An async-aware version of the [`FnMut`](crate::ops::FnMut) trait.
 ///
 /// All `async fn` and functions returning futures implement this trait.
-#[unstable(feature = "async_closure", issue = "62290")]
+#[cfg_attr(bootstrap, unstable(feature = "async_closure", issue = "62290"))]
+#[cfg_attr(not(bootstrap), stable(feature = "async_closure", since = "CURRENT_RUSTC_VERSION"))]
 #[rustc_paren_sugar]
 #[fundamental]
 #[must_use = "async closures are lazy and do nothing unless called"]
@@ -39,7 +41,8 @@ pub trait AsyncFnMut<Args: Tuple>: AsyncFnOnce<Args> {
 /// An async-aware version of the [`FnOnce`](crate::ops::FnOnce) trait.
 ///
 /// All `async fn` and functions returning futures implement this trait.
-#[unstable(feature = "async_closure", issue = "62290")]
+#[cfg_attr(bootstrap, unstable(feature = "async_closure", issue = "62290"))]
+#[cfg_attr(not(bootstrap), stable(feature = "async_closure", since = "CURRENT_RUSTC_VERSION"))]
 #[rustc_paren_sugar]
 #[fundamental]
 #[must_use = "async closures are lazy and do nothing unless called"]
@@ -64,7 +67,8 @@ mod impls {
     use super::{AsyncFn, AsyncFnMut, AsyncFnOnce};
     use crate::marker::Tuple;
 
-    #[unstable(feature = "async_fn_traits", issue = "none")]
+    #[cfg_attr(bootstrap, unstable(feature = "async_closure", issue = "62290"))]
+    #[cfg_attr(not(bootstrap), stable(feature = "async_closure", since = "CURRENT_RUSTC_VERSION"))]
     impl<A: Tuple, F: ?Sized> AsyncFn<A> for &F
     where
         F: AsyncFn<A>,
@@ -74,7 +78,8 @@ mod impls {
         }
     }
 
-    #[unstable(feature = "async_fn_traits", issue = "none")]
+    #[cfg_attr(bootstrap, unstable(feature = "async_closure", issue = "62290"))]
+    #[cfg_attr(not(bootstrap), stable(feature = "async_closure", since = "CURRENT_RUSTC_VERSION"))]
     impl<A: Tuple, F: ?Sized> AsyncFnMut<A> for &F
     where
         F: AsyncFn<A>,
@@ -89,7 +94,8 @@ mod impls {
         }
     }
 
-    #[unstable(feature = "async_fn_traits", issue = "none")]
+    #[cfg_attr(bootstrap, unstable(feature = "async_closure", issue = "62290"))]
+    #[cfg_attr(not(bootstrap), stable(feature = "async_closure", since = "CURRENT_RUSTC_VERSION"))]
     impl<'a, A: Tuple, F: ?Sized> AsyncFnOnce<A> for &'a F
     where
         F: AsyncFn<A>,
@@ -102,7 +108,8 @@ mod impls {
         }
     }
 
-    #[unstable(feature = "async_fn_traits", issue = "none")]
+    #[cfg_attr(bootstrap, unstable(feature = "async_closure", issue = "62290"))]
+    #[cfg_attr(not(bootstrap), stable(feature = "async_closure", since = "CURRENT_RUSTC_VERSION"))]
     impl<A: Tuple, F: ?Sized> AsyncFnMut<A> for &mut F
     where
         F: AsyncFnMut<A>,
@@ -117,7 +124,8 @@ mod impls {
         }
     }
 
-    #[unstable(feature = "async_fn_traits", issue = "none")]
+    #[cfg_attr(bootstrap, unstable(feature = "async_closure", issue = "62290"))]
+    #[cfg_attr(not(bootstrap), stable(feature = "async_closure", since = "CURRENT_RUSTC_VERSION"))]
     impl<'a, A: Tuple, F: ?Sized> AsyncFnOnce<A> for &'a mut F
     where
         F: AsyncFnMut<A>,

library/core/src/prelude/mod.rs

@@ -71,7 +71,7 @@ pub mod rust_2021 {
 /// The 2024 version of the core prelude.
 ///
 /// See the [module-level documentation](self) for more.
-#[unstable(feature = "prelude_2024", issue = "121042")]
+#[stable(feature = "prelude_2024", since = "CURRENT_RUSTC_VERSION")]
 pub mod rust_2024 {
     #[stable(feature = "rust1", since = "1.0.0")]
     pub use super::common::*;
@@ -84,7 +84,7 @@ pub mod rust_2024 {
     #[doc(no_inline)]
     pub use crate::convert::{TryFrom, TryInto};
 
-    #[unstable(feature = "prelude_2024", issue = "121042")]
+    #[stable(feature = "prelude_2024", since = "CURRENT_RUSTC_VERSION")]
     #[doc(no_inline)]
     pub use crate::future::{Future, IntoFuture};
 }

library/core/src/ptr/mut_ptr.rs

@@ -1587,15 +1587,6 @@ impl<T: ?Sized> *mut T {
     /// beyond the allocation that the pointer points into. It is up to the caller to ensure that
     /// the returned offset is correct in all terms other than alignment.
     ///
-    /// When this is called during compile-time evaluation (which is unstable), the implementation
-    /// may return `usize::MAX` in cases where that can never happen at runtime. This is because the
-    /// actual alignment of pointers is not known yet during compile-time, so an offset with
-    /// guaranteed alignment can sometimes not be computed. For example, a buffer declared as `[u8;
-    /// N]` might be allocated at an odd or an even address, but at compile-time this is not yet
-    /// known, so the execution has to be correct for either choice. It is therefore impossible to
-    /// find an offset that is guaranteed to be 2-aligned. (This behavior is subject to change, as usual
-    /// for unstable APIs.)
-    ///
     /// # Panics
     ///
     /// The function panics if `align` is not a power-of-two.

library/std/src/lib.rs

@@ -348,7 +348,6 @@
 #![feature(pin_coerce_unsized_trait)]
 #![feature(pointer_is_aligned_to)]
 #![feature(portable_simd)]
-#![feature(prelude_2024)]
 #![feature(ptr_as_uninit)]
 #![feature(ptr_mask)]
 #![feature(random)]

library/std/src/os/hurd/mod.rs

@@ -1,6 +1,7 @@
 //! Hurd-specific definitions
 
 #![stable(feature = "raw_ext", since = "1.1.0")]
+#![forbid(unsafe_op_in_unsafe_fn)]
 
 pub mod fs;
 pub mod raw;

library/std/src/prelude/common.rs

@@ -12,7 +12,8 @@ pub use crate::marker::{Send, Sized, Sync, Unpin};
 #[stable(feature = "rust1", since = "1.0.0")]
 #[doc(no_inline)]
 pub use crate::ops::{Drop, Fn, FnMut, FnOnce};
-#[unstable(feature = "async_closure", issue = "62290")]
+#[cfg_attr(bootstrap, unstable(feature = "async_closure", issue = "62290"))]
+#[cfg_attr(not(bootstrap), stable(feature = "async_closure", since = "CURRENT_RUSTC_VERSION"))]
 #[doc(no_inline)]
 pub use crate::ops::{AsyncFn, AsyncFnMut, AsyncFnOnce};
 

library/std/src/prelude/mod.rs

@@ -25,6 +25,7 @@
 //!
 //! # Prelude contents
 //!
+//! The items included in the prelude depend on the edition of the crate.
 //! The first version of the prelude is used in Rust 2015 and Rust 2018,
 //! and lives in [`std::prelude::v1`].
 //! [`std::prelude::rust_2015`] and [`std::prelude::rust_2018`] re-export this prelude.
@@ -32,8 +33,9 @@
 //!
 //! * <code>[std::marker]::{[Copy], [Send], [Sized], [Sync], [Unpin]}</code>,
 //!   marker traits that indicate fundamental properties of types.
-//! * <code>[std::ops]::{[Drop], [Fn], [FnMut], [FnOnce]}</code>, various
-//!   operations for both destructors and overloading `()`.
+//! * <code>[std::ops]::{[Fn], [FnMut], [FnOnce]}</code>, and their analogous
+//!   async traits, <code>[std::ops]::{[AsyncFn], [AsyncFnMut], [AsyncFnOnce]}</code>.
+//! * <code>[std::ops]::[Drop]</code>, for implementing destructors.
 //! * <code>[std::mem]::[drop]</code>, a convenience function for explicitly
 //!   dropping a value.
 //! * <code>[std::mem]::{[size_of], [size_of_val]}</code>, to get the size of
@@ -67,15 +69,21 @@
 //! The prelude used in Rust 2021, [`std::prelude::rust_2021`], includes all of the above,
 //! and in addition re-exports:
 //!
-//! * <code>[std::convert]::{[TryFrom], [TryInto]}</code>,
+//! * <code>[std::convert]::{[TryFrom], [TryInto]}</code>.
 //! * <code>[std::iter]::[FromIterator]</code>.
 //!
+//! The prelude used in Rust 2024, [`std::prelude::rust_2024`], includes all of the above,
+//! and in addition re-exports:
+//!
+//! * <code>[std::future]::{[Future], [IntoFuture]}</code>.
+//!
 //! [std::borrow]: crate::borrow
 //! [std::boxed]: crate::boxed
 //! [std::clone]: crate::clone
 //! [std::cmp]: crate::cmp
 //! [std::convert]: crate::convert
 //! [std::default]: crate::default
+//! [std::future]: crate::future
 //! [std::iter]: crate::iter
 //! [std::marker]: crate::marker
 //! [std::mem]: crate::mem
@@ -85,6 +93,7 @@
 //! [`std::prelude::rust_2015`]: rust_2015
 //! [`std::prelude::rust_2018`]: rust_2018
 //! [`std::prelude::rust_2021`]: rust_2021
+//! [`std::prelude::rust_2024`]: rust_2024
 //! [std::result]: crate::result
 //! [std::slice]: crate::slice
 //! [std::string]: crate::string
@@ -94,6 +103,8 @@
 //! [book-dtor]: ../../book/ch15-03-drop.html
 //! [book-enums]: ../../book/ch06-01-defining-an-enum.html
 //! [book-iter]: ../../book/ch13-02-iterators.html
+//! [Future]: crate::future::Future
+//! [IntoFuture]: crate::future::IntoFuture
 
 // No formatting: this file is nothing but re-exports, and their order is worth preserving.
 #![cfg_attr(rustfmt, rustfmt::skip)]
@@ -158,12 +169,12 @@ pub mod rust_2021 {
 /// The 2024 version of the prelude of The Rust Standard Library.
 ///
 /// See the [module-level documentation](self) for more.
-#[unstable(feature = "prelude_2024", issue = "121042")]
+#[stable(feature = "prelude_2024", since = "CURRENT_RUSTC_VERSION")]
 pub mod rust_2024 {
     #[stable(feature = "rust1", since = "1.0.0")]
     pub use super::common::*;
 
-    #[unstable(feature = "prelude_2024", issue = "121042")]
+    #[stable(feature = "prelude_2024", since = "CURRENT_RUSTC_VERSION")]
     #[doc(no_inline)]
     pub use core::prelude::rust_2024::*;
 }

library/unwind/src/lib.rs

@@ -178,3 +178,8 @@ cfg_if::cfg_if! {
 #[cfg(target_os = "hurd")]
 #[link(name = "gcc_s")]
 extern "C" {}
+
+#[cfg(all(target_os = "windows", target_env = "gnu", target_abi = "llvm"))]
+#[link(name = "unwind", kind = "static", modifiers = "-bundle", cfg(target_feature = "crt-static"))]
+#[link(name = "unwind", cfg(not(target_feature = "crt-static")))]
+extern "C" {}

library/unwind/src/libunwind.rs

@@ -102,12 +102,9 @@ pub type _Unwind_Exception_Cleanup_Fn =
 // rustc_codegen_ssa::src::back::symbol_export, rustc_middle::middle::exported_symbols
 // and RFC 2841
 #[cfg_attr(
-    any(
-        all(
-            feature = "llvm-libunwind",
-            any(target_os = "fuchsia", target_os = "linux", target_os = "xous")
-        ),
-        all(target_os = "windows", target_env = "gnu", target_abi = "llvm")
+    all(
+        feature = "llvm-libunwind",
+        any(target_os = "fuchsia", target_os = "linux", target_os = "xous")
     ),
     link(name = "unwind", kind = "static", modifiers = "-bundle")
 )]

src/bootstrap/src/bin/main.rs

@@ -48,9 +48,9 @@ fn main() {
             err => {
                 drop(err);
                 if let Ok(pid) = pid {
-                    eprintln!("WARNING: build directory locked by process {pid}, waiting for lock");
+                    println!("WARNING: build directory locked by process {pid}, waiting for lock");
                 } else {
-                    eprintln!("WARNING: build directory locked, waiting for lock");
+                    println!("WARNING: build directory locked, waiting for lock");
                 }
                 let mut lock = t!(build_lock.write());
                 t!(lock.write(process::id().to_string().as_ref()));
@@ -70,13 +70,13 @@ fn main() {
     // changelog warning, not the `x.py setup` message.
     let suggest_setup = config.config.is_none() && !matches!(config.cmd, Subcommand::Setup { .. });
     if suggest_setup {
-        eprintln!("WARNING: you have not made a `config.toml`");
-        eprintln!(
+        println!("WARNING: you have not made a `config.toml`");
+        println!(
             "HELP: consider running `./x.py setup` or copying `config.example.toml` by running \
             `cp config.example.toml config.toml`"
         );
     } else if let Some(suggestion) = &changelog_suggestion {
-        eprintln!("{suggestion}");
+        println!("{suggestion}");
     }
 
     let pre_commit = config.src.join(".git").join("hooks").join("pre-commit");
@@ -86,13 +86,13 @@ fn main() {
     Build::new(config).build();
 
     if suggest_setup {
-        eprintln!("WARNING: you have not made a `config.toml`");
-        eprintln!(
+        println!("WARNING: you have not made a `config.toml`");
+        println!(
             "HELP: consider running `./x.py setup` or copying `config.example.toml` by running \
             `cp config.example.toml config.toml`"
         );
     } else if let Some(suggestion) = &changelog_suggestion {
-        eprintln!("{suggestion}");
+        println!("{suggestion}");
     }
 
     // Give a warning if the pre-commit script is in pre-commit and not pre-push.
@@ -102,14 +102,14 @@ fn main() {
     if fs::read_to_string(pre_commit).is_ok_and(|contents| {
         contents.contains("https://github.com/rust-lang/rust/issues/77620#issuecomment-705144570")
     }) {
-        eprintln!(
+        println!(
             "WARNING: You have the pre-push script installed to .git/hooks/pre-commit. \
                   Consider moving it to .git/hooks/pre-push instead, which runs less often."
         );
     }
 
     if suggest_setup || changelog_suggestion.is_some() {
-        eprintln!("NOTE: this message was printed twice to make it more likely to be seen");
+        println!("NOTE: this message was printed twice to make it more likely to be seen");
     }
 
     if dump_bootstrap_shims {

src/bootstrap/src/bin/rustc.rs

@@ -306,7 +306,7 @@ fn main() {
         // should run on success, after this block.
     }
     if verbose > 0 {
-        eprintln!("\nDid not run successfully: {status}\n{cmd:?}\n-------------");
+        println!("\nDid not run successfully: {status}\n{cmd:?}\n-------------");
     }
 
     if let Some(mut on_fail) = on_fail {

src/bootstrap/src/core/build_steps/check.rs

@@ -287,7 +287,7 @@ impl Step for CodegenBackend {
     fn run(self, builder: &Builder<'_>) {
         // FIXME: remove once https://github.com/rust-lang/rust/issues/112393 is resolved
         if builder.build.config.vendor && self.backend == "gcc" {
-            eprintln!("Skipping checking of `rustc_codegen_gcc` with vendoring enabled.");
+            println!("Skipping checking of `rustc_codegen_gcc` with vendoring enabled.");
             return;
         }
 

src/bootstrap/src/core/build_steps/compile.rs

@@ -1611,7 +1611,7 @@ impl Step for Sysroot {
         let sysroot = sysroot_dir(compiler.stage);
 
         builder
-            .verbose(|| eprintln!("Removing sysroot {} to avoid caching bugs", sysroot.display()));
+            .verbose(|| println!("Removing sysroot {} to avoid caching bugs", sysroot.display()));
         let _ = fs::remove_dir_all(&sysroot);
         t!(fs::create_dir_all(&sysroot));
 
@@ -1681,7 +1681,7 @@ impl Step for Sysroot {
                     return true;
                 }
                 if !filtered_files.iter().all(|f| f != path.file_name().unwrap()) {
-                    builder.verbose_than(1, || eprintln!("ignoring {}", path.display()));
+                    builder.verbose_than(1, || println!("ignoring {}", path.display()));
                     false
                 } else {
                     true
@@ -2240,7 +2240,7 @@ pub fn stream_cargo(
         cargo.arg(arg);
     }
 
-    builder.verbose(|| eprintln!("running: {cargo:?}"));
+    builder.verbose(|| println!("running: {cargo:?}"));
 
     if builder.config.dry_run() {
         return true;
@@ -2266,7 +2266,7 @@ pub fn stream_cargo(
                 cb(msg)
             }
             // If this was informational, just print it out and continue
-            Err(_) => eprintln!("{line}"),
+            Err(_) => println!("{line}"),
         }
     }
 

src/bootstrap/src/core/build_steps/dist.rs

@@ -2080,7 +2080,7 @@ fn maybe_install_llvm(
     {
         let mut cmd = command(llvm_config);
         cmd.arg("--libfiles");
-        builder.verbose(|| eprintln!("running {cmd:?}"));
+        builder.verbose(|| println!("running {cmd:?}"));
         let files = cmd.run_capture_stdout(builder).stdout();
         let build_llvm_out = &builder.llvm_out(builder.config.build);
         let target_llvm_out = &builder.llvm_out(target);

src/bootstrap/src/core/build_steps/format.rs

@@ -107,10 +107,10 @@ fn print_paths(verb: &str, adjective: Option<&str>, paths: &[String]) {
         if let Some(adjective) = adjective { format!("{adjective} ") } else { String::new() };
     if len <= 10 {
         for path in paths {
-            eprintln!("fmt: {verb} {adjective}file {path}");
+            println!("fmt: {verb} {adjective}file {path}");
         }
     } else {
-        eprintln!("fmt: {verb} {len} {adjective}files");
+        println!("fmt: {verb} {len} {adjective}files");
     }
 }
 
@@ -199,7 +199,7 @@ pub fn format(build: &Builder<'_>, check: bool, all: bool, paths: &[PathBuf]) {
                 match get_modified_rs_files(build) {
                     Ok(Some(files)) => {
                         if files.is_empty() {
-                            eprintln!("fmt info: No modified files detected for formatting.");
+                            println!("fmt info: No modified files detected for formatting.");
                             return;
                         }
 

src/bootstrap/src/core/build_steps/setup.rs

@@ -134,7 +134,7 @@ impl Step for Profile {
                     t!(fs::remove_file(path));
                 }
                 _ => {
-                    eprintln!("Exiting.");
+                    println!("Exiting.");
                     crate::exit!(1);
                 }
             }
@@ -184,15 +184,15 @@ pub fn setup(config: &Config, profile: Profile) {
         Profile::Dist => &["dist", "build"],
     };
 
-    eprintln!();
+    println!();
 
-    eprintln!("To get started, try one of the following commands:");
+    println!("To get started, try one of the following commands:");
     for cmd in suggestions {
-        eprintln!("- `x.py {cmd}`");
+        println!("- `x.py {cmd}`");
     }
 
     if profile != Profile::Dist {
-        eprintln!(
+        println!(
             "For more suggestions, see https://rustc-dev-guide.rust-lang.org/building/suggested.html"
         );
     }
@@ -224,7 +224,7 @@ fn setup_config_toml(path: &PathBuf, profile: Profile, config: &Config) {
     t!(fs::write(path, settings));
 
     let include_path = profile.include_path(&config.src);
-    eprintln!("`x.py` will now use the configuration at {}", include_path.display());
+    println!("`x.py` will now use the configuration at {}", include_path.display());
 }
 
 /// Creates a toolchain link for stage1 using `rustup`
@@ -256,7 +256,7 @@ impl Step for Link {
         }
 
         if !rustup_installed(builder) {
-            eprintln!("WARNING: `rustup` is not installed; Skipping `stage1` toolchain linking.");
+            println!("WARNING: `rustup` is not installed; Skipping `stage1` toolchain linking.");
             return;
         }
 
@@ -296,7 +296,7 @@ fn attempt_toolchain_link(builder: &Builder<'_>, stage_path: &str) {
     }
 
     if try_link_toolchain(builder, stage_path) {
-        eprintln!(
+        println!(
             "Added `stage1` rustup toolchain; try `cargo +stage1 build` on a separate rust project to run a newly-built toolchain"
         );
     } else {
@@ -321,14 +321,14 @@ fn toolchain_is_linked(builder: &Builder<'_>) -> bool {
                 return false;
             }
             // The toolchain has already been linked.
-            eprintln!(
+            println!(
                 "`stage1` toolchain already linked; not attempting to link `stage1` toolchain"
             );
         }
         None => {
             // In this case, we don't know if the `stage1` toolchain has been linked;
             // but `rustup` failed, so let's not go any further.
-            eprintln!(
+            println!(
                 "`rustup` failed to list current toolchains; not attempting to link `stage1` toolchain"
             );
         }
@@ -389,12 +389,12 @@ pub fn interactive_path() -> io::Result<Profile> {
         input.parse()
     }
 
-    eprintln!("Welcome to the Rust project! What do you want to do with x.py?");
+    println!("Welcome to the Rust project! What do you want to do with x.py?");
     for ((letter, _), profile) in abbrev_all() {
-        eprintln!("{}) {}: {}", letter, profile, profile.purpose());
+        println!("{}) {}: {}", letter, profile, profile.purpose());
     }
     let template = loop {
-        eprint!(
+        print!(
             "Please choose one ({}): ",
             abbrev_all().map(|((l, _), _)| l).collect::<Vec<_>>().join("/")
         );
@@ -428,7 +428,7 @@ enum PromptResult {
 fn prompt_user(prompt: &str) -> io::Result<Option<PromptResult>> {
     let mut input = String::new();
     loop {
-        eprint!("{prompt} ");
+        print!("{prompt} ");
         io::stdout().flush()?;
         input.clear();
         io::stdin().read_line(&mut input)?;
@@ -490,7 +490,7 @@ fn install_git_hook_maybe(builder: &Builder<'_>, config: &Config) -> io::Result<
         return Ok(());
     }
 
-    eprintln!(
+    println!(
         "\nRust's CI will automatically fail if it doesn't pass `tidy`, the internal tool for ensuring code quality.
 If you'd like, x.py can install a git hook for you that will automatically run `test tidy` before
 pushing your code to ensure your code is up to par. If you decide later that this behavior is
@@ -498,7 +498,7 @@ undesirable, simply delete the `pre-push` file from .git/hooks."
     );
 
     if prompt_user("Would you like to install the git hook?: [y/N]")? != Some(PromptResult::Yes) {
-        eprintln!("Ok, skipping installation!");
+        println!("Ok, skipping installation!");
         return Ok(());
     }
     if !hooks_dir.exists() {
@@ -515,7 +515,7 @@ undesirable, simply delete the `pre-push` file from .git/hooks."
             );
             return Err(e);
         }
-        Ok(_) => eprintln!("Linked `src/etc/pre-push.sh` to `.git/hooks/pre-push`"),
+        Ok(_) => println!("Linked `src/etc/pre-push.sh` to `.git/hooks/pre-push`"),
     };
     Ok(())
 }
@@ -541,7 +541,7 @@ Select which editor you would like to set up [default: None]: ";
 
         let mut input = String::new();
         loop {
-            eprint!("{}", prompt_str);
+            print!("{}", prompt_str);
             io::stdout().flush()?;
             input.clear();
             io::stdin().read_line(&mut input)?;
@@ -656,7 +656,7 @@ impl Step for Editor {
                 if let Some(editor_kind) = editor_kind {
                     while !t!(create_editor_settings_maybe(config, editor_kind.clone())) {}
                 } else {
-                    eprintln!("Ok, skipping editor setup!");
+                    println!("Ok, skipping editor setup!");
                 }
             }
             Err(e) => eprintln!("Could not determine the editor: {e}"),
@@ -689,7 +689,7 @@ fn create_editor_settings_maybe(config: &Config, editor: EditorKind) -> io::Resu
             mismatched_settings = Some(false);
         }
     }
-    eprintln!(
+    println!(
         "\nx.py can automatically install the recommended `{settings_filename}` file for rustc development"
     );
 
@@ -708,7 +708,7 @@ fn create_editor_settings_maybe(config: &Config, editor: EditorKind) -> io::Resu
         Some(PromptResult::Yes) => true,
         Some(PromptResult::Print) => false,
         _ => {
-            eprintln!("Ok, skipping settings!");
+            println!("Ok, skipping settings!");
             return Ok(true);
         }
     };
@@ -735,9 +735,9 @@ fn create_editor_settings_maybe(config: &Config, editor: EditorKind) -> io::Resu
             _ => "Created",
         };
         fs::write(&settings_path, editor.settings_template())?;
-        eprintln!("{verb} `{}`", settings_filename);
+        println!("{verb} `{}`", settings_filename);
     } else {
-        eprintln!("\n{}", editor.settings_template());
+        println!("\n{}", editor.settings_template());
     }
     Ok(should_create)
 }

src/bootstrap/src/core/build_steps/suggest.rs

@@ -66,6 +66,6 @@ pub fn suggest(builder: &Builder<'_>, run: bool) {
             build.build();
         }
     } else {
-        eprintln!("HELP: consider using the `--run` flag to automatically run suggested tests");
+        println!("HELP: consider using the `--run` flag to automatically run suggested tests");
     }
 }

src/bootstrap/src/core/build_steps/test.rs

@@ -471,11 +471,11 @@ impl Miri {
         // We re-use the `cargo` from above.
         cargo.arg("--print-sysroot");
 
-        builder.verbose(|| eprintln!("running: {cargo:?}"));
+        builder.verbose(|| println!("running: {cargo:?}"));
         let stdout = cargo.run_capture_stdout(builder).stdout();
         // Output is "<sysroot>\n".
         let sysroot = stdout.trim_end();
-        builder.verbose(|| eprintln!("`cargo miri setup --print-sysroot` said: {sysroot:?}"));
+        builder.verbose(|| println!("`cargo miri setup --print-sysroot` said: {sysroot:?}"));
         PathBuf::from(sysroot)
     }
 }
@@ -2488,7 +2488,7 @@ fn markdown_test(builder: &Builder<'_>, compiler: Compiler, markdown: &Path) ->
         }
     }
 
-    builder.verbose(|| eprintln!("doc tests for: {}", markdown.display()));
+    builder.verbose(|| println!("doc tests for: {}", markdown.display()));
     let mut cmd = builder.rustdoc_cmd(compiler);
     builder.add_rust_test_threads(&mut cmd);
     // allow for unstable options such as new editions

src/bootstrap/src/core/builder/cargo.rs

@@ -523,7 +523,7 @@ impl Builder<'_> {
 
         let sysroot_str = sysroot.as_os_str().to_str().expect("sysroot should be UTF-8");
         if self.is_verbose() && !matches!(self.config.dry_run, DryRun::SelfCheck) {
-            eprintln!("using sysroot {sysroot_str}");
+            println!("using sysroot {sysroot_str}");
         }
 
         let mut rustflags = Rustflags::new(target);
@@ -1035,12 +1035,7 @@ impl Builder<'_> {
             rustflags.arg("-Wrustc::internal");
             // cfg(bootstrap) - remove this check when lint is in bootstrap compiler
             if stage != 0 {
-                // Lint is allow by default so downstream tools don't get a lit
-                // they can do nothing about
-                // We shouldn't be preinterning symbols used by tests
-                if cmd_kind != Kind::Test {
-                    rustflags.arg("-Drustc::symbol_intern_string_literal");
-                }
+                rustflags.arg("-Drustc::symbol_intern_string_literal");
             }
             // FIXME(edition_2024): Change this to `-Wrust_2024_idioms` when all
             // of the individual lints are satisfied.

src/bootstrap/src/core/builder/mod.rs

@@ -392,14 +392,14 @@ impl StepDescription {
     fn is_excluded(&self, builder: &Builder<'_>, pathset: &PathSet) -> bool {
         if builder.config.skip.iter().any(|e| pathset.has(e, builder.kind)) {
             if !matches!(builder.config.dry_run, DryRun::SelfCheck) {
-                eprintln!("Skipping {pathset:?} because it is excluded");
+                println!("Skipping {pathset:?} because it is excluded");
             }
             return true;
         }
 
         if !builder.config.skip.is_empty() && !matches!(builder.config.dry_run, DryRun::SelfCheck) {
             builder.verbose(|| {
-                eprintln!(
+                println!(
                     "{:?} not skipped for {:?} -- not in {:?}",
                     pathset, self.name, builder.config.skip
                 )
@@ -1437,11 +1437,11 @@ impl<'a> Builder<'a> {
                 panic!("{}", out);
             }
             if let Some(out) = self.cache.get(&step) {
-                self.verbose_than(1, || eprintln!("{}c {:?}", "  ".repeat(stack.len()), step));
+                self.verbose_than(1, || println!("{}c {:?}", "  ".repeat(stack.len()), step));
 
                 return out;
             }
-            self.verbose_than(1, || eprintln!("{}> {:?}", "  ".repeat(stack.len()), step));
+            self.verbose_than(1, || println!("{}> {:?}", "  ".repeat(stack.len()), step));
             stack.push(Box::new(step.clone()));
         }
 
@@ -1462,7 +1462,7 @@ impl<'a> Builder<'a> {
             let step_string = format!("{step:?}");
             let brace_index = step_string.find('{').unwrap_or(0);
             let type_string = type_name::<S>();
-            eprintln!(
+            println!(
                 "[TIMING] {} {} -- {}.{:03}",
                 &type_string.strip_prefix("bootstrap::").unwrap_or(type_string),
                 &step_string[brace_index..],
@@ -1479,9 +1479,7 @@ impl<'a> Builder<'a> {
             let cur_step = stack.pop().expect("step stack empty");
             assert_eq!(cur_step.downcast_ref(), Some(&step));
         }
-        self.verbose_than(1, || {
-            eprintln!("{}< {:?}", "  ".repeat(self.stack.borrow().len()), step)
-        });
+        self.verbose_than(1, || println!("{}< {:?}", "  ".repeat(self.stack.borrow().len()), step));
         self.cache.put(step, out.clone());
         out
     }

src/bootstrap/src/core/config/config.rs

@@ -1299,7 +1299,7 @@ impl Config {
                     .map(|change_id| change_id.inner.map(crate::find_recent_config_change_ids))
                 {
                     if !changes.is_empty() {
-                        eprintln!(
+                        println!(
                             "WARNING: There have been changes to x.py since you last updated:\n{}",
                             crate::human_readable_changes(&changes)
                         );
@@ -1565,7 +1565,7 @@ impl Config {
         }
 
         if cargo_clippy.is_some() && rustc.is_none() {
-            eprintln!(
+            println!(
                 "WARNING: Using `build.cargo-clippy` without `build.rustc` usually fails due to toolchain conflict."
             );
         }
@@ -1852,7 +1852,7 @@ impl Config {
 
             // FIXME: Remove this option at the end of 2024.
             if parallel_compiler.is_some() {
-                eprintln!(
+                println!(
                     "WARNING: The `rust.parallel-compiler` option is deprecated and does nothing. The parallel compiler (with one thread) is now the default"
                 );
             }
@@ -1884,7 +1884,7 @@ impl Config {
                         if available_backends.contains(&backend) {
                             panic!("Invalid value '{s}' for 'rust.codegen-backends'. Instead, please use '{backend}'.");
                         } else {
-                            eprintln!("HELP: '{s}' for 'rust.codegen-backends' might fail. \
+                            println!("HELP: '{s}' for 'rust.codegen-backends' might fail. \
                                 Codegen backends are mostly defined without the '{CODEGEN_BACKEND_PREFIX}' prefix. \
                                 In this case, it would be referred to as '{backend}'.");
                         }
@@ -1913,7 +1913,7 @@ impl Config {
         // tests may fail due to using a different channel than the one used by the compiler during tests.
         if let Some(commit) = &config.download_rustc_commit {
             if is_user_configured_rust_channel {
-                eprintln!(
+                println!(
                     "WARNING: `rust.download-rustc` is enabled. The `rust.channel` option will be overridden by the CI rustc's channel."
                 );
 
@@ -2003,10 +2003,10 @@ impl Config {
 
             if config.llvm_from_ci {
                 let warn = |option: &str| {
-                    eprintln!(
+                    println!(
                         "WARNING: `{option}` will only be used on `compiler/rustc_llvm` build, not for the LLVM build."
                     );
-                    eprintln!(
+                    println!(
                         "HELP: To use `{option}` for LLVM builds, set `download-ci-llvm` option to false."
                     );
                 };
@@ -2025,12 +2025,12 @@ impl Config {
                 // if they've chosen a different value.
 
                 if libzstd.is_some() {
-                    eprintln!(
+                    println!(
                         "WARNING: when using `download-ci-llvm`, the local `llvm.libzstd` option, \
                         like almost all `llvm.*` options, will be ignored and set by the LLVM CI \
                         artifacts builder config."
                     );
-                    eprintln!(
+                    println!(
                         "HELP: To use `llvm.libzstd` for LLVM/LLD builds, set `download-ci-llvm` option to false."
                     );
                 }
@@ -2099,7 +2099,7 @@ impl Config {
                             if available_backends.contains(&backend) {
                                 panic!("Invalid value '{s}' for 'target.{triple}.codegen-backends'. Instead, please use '{backend}'.");
                             } else {
-                                eprintln!("HELP: '{s}' for 'target.{triple}.codegen-backends' might fail. \
+                                println!("HELP: '{s}' for 'target.{triple}.codegen-backends' might fail. \
                                     Codegen backends are mostly defined without the '{CODEGEN_BACKEND_PREFIX}' prefix. \
                                     In this case, it would be referred to as '{backend}'.");
                             }
@@ -2315,7 +2315,7 @@ impl Config {
         if self.dry_run() {
             return Ok(());
         }
-        self.verbose(|| eprintln!("running: {cmd:?}"));
+        self.verbose(|| println!("running: {cmd:?}"));
         build_helper::util::try_run(cmd, self.is_verbose())
     }
 
@@ -2490,7 +2490,7 @@ impl Config {
                         // This happens when LLVM submodule is updated in CI, we should disable ci-rustc without an error
                         // to not break CI. For non-CI environments, we should return an error.
                         if CiEnv::is_ci() {
-                            eprintln!("WARNING: LLVM submodule has changes, `download-rustc` will be disabled.");
+                            println!("WARNING: LLVM submodule has changes, `download-rustc` will be disabled.");
                             return None;
                         } else {
                             panic!("ERROR: LLVM submodule has changes, `download-rustc` can't be used.");
@@ -2501,8 +2501,8 @@ impl Config {
                         let ci_config_toml = match self.get_builder_toml("ci-rustc") {
                             Ok(ci_config_toml) => ci_config_toml,
                             Err(e) if e.to_string().contains("unknown field") => {
-                                eprintln!("WARNING: CI rustc has some fields that are no longer supported in bootstrap; download-rustc will be disabled.");
-                                eprintln!("HELP: Consider rebasing to a newer commit if available.");
+                                println!("WARNING: CI rustc has some fields that are no longer supported in bootstrap; download-rustc will be disabled.");
+                                println!("HELP: Consider rebasing to a newer commit if available.");
                                 return None;
                             },
                             Err(e) => {
@@ -2527,7 +2527,7 @@ impl Config {
                             .is_some_and(|s| s == "1" || s == "true");
 
                         if disable_ci_rustc_if_incompatible && res.is_err() {
-                            eprintln!("WARNING: download-rustc is disabled with `DISABLE_CI_RUSTC_IF_INCOMPATIBLE` env.");
+                            println!("WARNING: download-rustc is disabled with `DISABLE_CI_RUSTC_IF_INCOMPATIBLE` env.");
                             return None;
                         }
 
@@ -2712,7 +2712,7 @@ impl Config {
             return;
         }
 
-        eprintln!("Updating submodule {relative_path}");
+        println!("Updating submodule {relative_path}");
         self.check_run(
             helpers::git(Some(&self.src))
                 .run_always()
@@ -2835,7 +2835,7 @@ impl Config {
             Some(StringOrBool::Bool(true)) => false,
             Some(StringOrBool::String(s)) if s == "if-unchanged" => {
                 if !self.rust_info.is_managed_git_subrepository() {
-                    eprintln!(
+                    println!(
                         "ERROR: `download-rustc=if-unchanged` is only compatible with Git managed sources."
                     );
                     crate::exit!(1);
@@ -2868,10 +2868,10 @@ impl Config {
                 if if_unchanged {
                     return None;
                 }
-                eprintln!("ERROR: could not find commit hash for downloading rustc");
-                eprintln!("HELP: maybe your repository history is too shallow?");
-                eprintln!("HELP: consider setting `rust.download-rustc=false` in config.toml");
-                eprintln!("HELP: or fetch enough history to include one upstream commit");
+                println!("ERROR: could not find commit hash for downloading rustc");
+                println!("HELP: maybe your repository history is too shallow?");
+                println!("HELP: consider setting `rust.download-rustc=false` in config.toml");
+                println!("HELP: or fetch enough history to include one upstream commit");
                 crate::exit!(1);
             }
         };
@@ -2910,7 +2910,7 @@ impl Config {
         let if_unchanged = || {
             if self.rust_info.is_from_tarball() {
                 // Git is needed for running "if-unchanged" logic.
-                eprintln!(
+                println!(
                     "WARNING: 'if-unchanged' has no effect on tarball sources; ignoring `download-ci-llvm`."
                 );
                 return false;
@@ -2959,10 +2959,10 @@ impl Config {
         // Only commits merged by bors will have CI artifacts.
         let commit = get_closest_merge_commit(Some(&self.src), &self.git_config(), &[]).unwrap();
         if commit.is_empty() {
-            eprintln!("error: could not find commit hash for downloading components from CI");
-            eprintln!("help: maybe your repository history is too shallow?");
-            eprintln!("help: consider disabling `{option_name}`");
-            eprintln!("help: or fetch enough history to include one upstream commit");
+            println!("error: could not find commit hash for downloading components from CI");
+            println!("help: maybe your repository history is too shallow?");
+            println!("help: consider disabling `{option_name}`");
+            println!("help: or fetch enough history to include one upstream commit");
             crate::exit!(1);
         }
 
@@ -2974,14 +2974,14 @@ impl Config {
         if has_changes {
             if if_unchanged {
                 if self.is_verbose() {
-                    eprintln!(
+                    println!(
                         "warning: saw changes to one of {modified_paths:?} since {commit}; \
                             ignoring `{option_name}`"
                     );
                 }
                 return None;
             }
-            eprintln!(
+            println!(
                 "warning: `{option_name}` is enabled, but there are changes to one of {modified_paths:?}"
             );
         }
@@ -3018,7 +3018,7 @@ pub(crate) fn check_incompatible_options_for_ci_llvm(
         ($current:expr, $expected:expr) => {
             if let Some(current) = &$current {
                 if Some(current) != $expected.as_ref() {
-                    eprintln!(
+                    println!(
                         "WARNING: `llvm.{}` has no effect with `llvm.download-ci-llvm`. \
                         Current value: {:?}, Expected value(s): {}{:?}",
                         stringify!($expected).replace("_", "-"),
@@ -3123,7 +3123,7 @@ fn check_incompatible_options_for_ci_rustc(
         ($current:expr, $expected:expr, $config_section:expr) => {
             if let Some(current) = &$current {
                 if Some(current) != $expected.as_ref() {
-                    eprintln!(
+                    println!(
                         "WARNING: `{}` has no effect with `rust.download-rustc`. \
                         Current value: {:?}, Expected value(s): {}{:?}",
                         format!("{}.{}", $config_section, stringify!($expected).replace("_", "-")),

src/bootstrap/src/core/config/flags.rs

@@ -196,12 +196,12 @@ impl Flags {
         if let Ok(HelpVerboseOnly { help: true, verbose: 1.., cmd: subcommand }) =
             HelpVerboseOnly::try_parse_from(normalize_args(args))
         {
-            eprintln!("NOTE: updating submodules before printing available paths");
+            println!("NOTE: updating submodules before printing available paths");
             let config = Config::parse(Self::parse(&[String::from("build")]));
             let build = Build::new(config);
             let paths = Builder::get_help(&build, subcommand);
             if let Some(s) = paths {
-                eprintln!("{s}");
+                println!("{s}");
             } else {
                 panic!("No paths available for subcommand `{}`", subcommand.as_str());
             }

src/bootstrap/src/core/download.rs

@@ -77,7 +77,7 @@ impl Config {
         if self.dry_run() && !cmd.run_always {
             return true;
         }
-        self.verbose(|| eprintln!("running: {cmd:?}"));
+        self.verbose(|| println!("running: {cmd:?}"));
         check_run(cmd, self.is_verbose())
     }
 
@@ -144,7 +144,7 @@ impl Config {
     /// Please see <https://nixos.org/patchelf.html> for more information
     fn fix_bin_or_dylib(&self, fname: &Path) {
         assert_eq!(SHOULD_FIX_BINS_AND_DYLIBS.get(), Some(&true));
-        eprintln!("attempting to patch {}", fname.display());
+        println!("attempting to patch {}", fname.display());
 
         // Only build `.nix-deps` once.
         static NIX_DEPS_DIR: OnceLock<PathBuf> = OnceLock::new();
@@ -206,7 +206,7 @@ impl Config {
     }
 
     fn download_file(&self, url: &str, dest_path: &Path, help_on_error: &str) {
-        self.verbose(|| eprintln!("download {url}"));
+        self.verbose(|| println!("download {url}"));
         // Use a temporary file in case we crash while downloading, to avoid a corrupt download in cache/.
         let tempfile = self.tempdir().join(dest_path.file_name().unwrap());
         // While bootstrap itself only supports http and https downloads, downstream forks might
@@ -226,7 +226,7 @@ impl Config {
     }
 
     fn download_http_with_retries(&self, tempfile: &Path, url: &str, help_on_error: &str) {
-        eprintln!("downloading {url}");
+        println!("downloading {url}");
         // Try curl. If that fails and we are on windows, fallback to PowerShell.
         // options should be kept in sync with
         // src/bootstrap/src/core/download.rs
@@ -341,7 +341,7 @@ impl Config {
             short_path = short_path.strip_prefix(pattern).unwrap_or(short_path);
             let dst_path = dst.join(short_path);
             self.verbose(|| {
-                eprintln!("extracting {} to {}", original_path.display(), dst.display())
+                println!("extracting {} to {}", original_path.display(), dst.display())
             });
             if !t!(member.unpack_in(dst)) {
                 panic!("path traversal attack ??");
@@ -365,7 +365,7 @@ impl Config {
     pub(crate) fn verify(&self, path: &Path, expected: &str) -> bool {
         use sha2::Digest;
 
-        self.verbose(|| eprintln!("verifying {}", path.display()));
+        self.verbose(|| println!("verifying {}", path.display()));
 
         if self.dry_run() {
             return false;
@@ -391,7 +391,7 @@ impl Config {
         let verified = checksum == expected;
 
         if !verified {
-            eprintln!(
+            println!(
                 "invalid checksum: \n\
                 found:    {checksum}\n\
                 expected: {expected}",
@@ -421,7 +421,7 @@ enum DownloadSource {
 /// Functions that are only ever called once, but named for clarify and to avoid thousand-line functions.
 impl Config {
     pub(crate) fn download_clippy(&self) -> PathBuf {
-        self.verbose(|| eprintln!("downloading stage0 clippy artifacts"));
+        self.verbose(|| println!("downloading stage0 clippy artifacts"));
 
         let date = &self.stage0_metadata.compiler.date;
         let version = &self.stage0_metadata.compiler.version;
@@ -518,7 +518,7 @@ impl Config {
     }
 
     pub(crate) fn download_ci_rustc(&self, commit: &str) {
-        self.verbose(|| eprintln!("using downloaded stage2 artifacts from CI (commit {commit})"));
+        self.verbose(|| println!("using downloaded stage2 artifacts from CI (commit {commit})"));
 
         let version = self.artifact_version_part(commit);
         // download-rustc doesn't need its own cargo, it can just use beta's. But it does need the
@@ -539,7 +539,7 @@ impl Config {
 
     #[cfg(not(feature = "bootstrap-self-test"))]
     pub(crate) fn download_beta_toolchain(&self) {
-        self.verbose(|| eprintln!("downloading stage0 beta artifacts"));
+        self.verbose(|| println!("downloading stage0 beta artifacts"));
 
         let date = &self.stage0_metadata.compiler.date;
         let version = &self.stage0_metadata.compiler.version;
@@ -677,7 +677,7 @@ impl Config {
                     return;
                 } else {
                     self.verbose(|| {
-                        eprintln!(
+                        println!(
                             "ignoring cached file {} due to failed verification",
                             tarball.display()
                         )
@@ -776,10 +776,10 @@ download-rustc = false
                     t!(check_incompatible_options_for_ci_llvm(current_config_toml, ci_config_toml));
                 }
                 Err(e) if e.to_string().contains("unknown field") => {
-                    eprintln!(
+                    println!(
                         "WARNING: CI LLVM has some fields that are no longer supported in bootstrap; download-ci-llvm will be disabled."
                     );
-                    eprintln!("HELP: Consider rebasing to a newer commit if available.");
+                    println!("HELP: Consider rebasing to a newer commit if available.");
                 }
                 Err(e) => {
                     eprintln!("ERROR: Failed to parse CI LLVM config.toml: {e}");

src/bootstrap/src/core/sanity.rs

@@ -237,11 +237,11 @@ than building it.
                 stage0_supported_target_list.intersection(&missing_targets_hashset).collect();
 
             if !duplicated_targets.is_empty() {
-                eprintln!(
+                println!(
                     "Following targets supported from the stage0 compiler, please remove them from STAGE0_MISSING_TARGETS list."
                 );
                 for duplicated_target in duplicated_targets {
-                    eprintln!("  {duplicated_target}");
+                    println!("  {duplicated_target}");
                 }
                 std::process::exit(1);
             }

src/bootstrap/src/lib.rs

@@ -406,11 +406,11 @@ impl Build {
             .unwrap()
             .trim();
         if local_release.split('.').take(2).eq(version.split('.').take(2)) {
-            build.verbose(|| eprintln!("auto-detected local-rebuild {local_release}"));
+            build.verbose(|| println!("auto-detected local-rebuild {local_release}"));
             build.local_rebuild = true;
         }
 
-        build.verbose(|| eprintln!("finding compilers"));
+        build.verbose(|| println!("finding compilers"));
         utils::cc_detect::find(&build);
         // When running `setup`, the profile is about to change, so any requirements we have now may
         // be different on the next invocation. Don't check for them until the next time x.py is
@@ -418,7 +418,7 @@ impl Build {
         //
         // Similarly, for `setup` we don't actually need submodules or cargo metadata.
         if !matches!(build.config.cmd, Subcommand::Setup { .. }) {
-            build.verbose(|| eprintln!("running sanity check"));
+            build.verbose(|| println!("running sanity check"));
             crate::core::sanity::check(&mut build);
 
             // Make sure we update these before gathering metadata so we don't get an error about missing
@@ -436,7 +436,7 @@ impl Build {
             // Now, update all existing submodules.
             build.update_existing_submodules();
 
-            build.verbose(|| eprintln!("learning about cargo"));
+            build.verbose(|| println!("learning about cargo"));
             crate::core::metadata::build(&mut build);
         }
 
@@ -605,7 +605,7 @@ impl Build {
         let stamp = dir.join(".stamp");
         let mut cleared = false;
         if mtime(&stamp) < mtime(input) {
-            self.verbose(|| eprintln!("Dirty - {}", dir.display()));
+            self.verbose(|| println!("Dirty - {}", dir.display()));
             let _ = fs::remove_dir_all(dir);
             cleared = true;
         } else if stamp.exists() {
@@ -890,7 +890,7 @@ impl Build {
         let executed_at = std::panic::Location::caller();
 
         self.verbose(|| {
-            eprintln!("running: {command:?} (created at {created_at}, executed at {executed_at})")
+            println!("running: {command:?} (created at {created_at}, executed at {executed_at})")
         });
 
         let cmd = command.as_command_mut();
@@ -947,7 +947,7 @@ Executed at: {executed_at}"#,
 
         let fail = |message: &str, output: CommandOutput| -> ! {
             if self.is_verbose() {
-                eprintln!("{message}");
+                println!("{message}");
             } else {
                 let (stdout, stderr) = (output.stdout_if_present(), output.stderr_if_present());
                 // If the command captures output, the user would not see any indication that
@@ -957,16 +957,16 @@ Executed at: {executed_at}"#,
                     if let Some(stdout) =
                         output.stdout_if_present().take_if(|s| !s.trim().is_empty())
                     {
-                        eprintln!("STDOUT:\n{stdout}\n");
+                        println!("STDOUT:\n{stdout}\n");
                     }
                     if let Some(stderr) =
                         output.stderr_if_present().take_if(|s| !s.trim().is_empty())
                     {
-                        eprintln!("STDERR:\n{stderr}\n");
+                        println!("STDERR:\n{stderr}\n");
                     }
-                    eprintln!("Command {command:?} has failed. Rerun with -v to see more details.");
+                    println!("Command {command:?} has failed. Rerun with -v to see more details.");
                 } else {
-                    eprintln!("Command has failed. Rerun with -v to see more details.");
+                    println!("Command has failed. Rerun with -v to see more details.");
                 }
             }
             exit!(1);
@@ -1011,7 +1011,7 @@ Executed at: {executed_at}"#,
         match self.config.dry_run {
             DryRun::SelfCheck => (),
             DryRun::Disabled | DryRun::UserSelected => {
-                eprintln!("{msg}");
+                println!("{msg}");
             }
         }
     }
@@ -1666,7 +1666,7 @@ Executed at: {executed_at}"#,
         if self.config.dry_run() {
             return;
         }
-        self.verbose_than(1, || eprintln!("Copy/Link {src:?} to {dst:?}"));
+        self.verbose_than(1, || println!("Copy/Link {src:?} to {dst:?}"));
         if src == dst {
             return;
         }
@@ -1775,7 +1775,7 @@ Executed at: {executed_at}"#,
             return;
         }
         let dst = dstdir.join(src.file_name().unwrap());
-        self.verbose_than(1, || eprintln!("Install {src:?} to {dst:?}"));
+        self.verbose_than(1, || println!("Install {src:?} to {dst:?}"));
         t!(fs::create_dir_all(dstdir));
         if !src.exists() {
             panic!("ERROR: File \"{}\" not found!", src.display());

src/bootstrap/src/utils/cc_detect.rs

@@ -155,15 +155,15 @@ pub fn find_target(build: &Build, target: TargetSelection) {
         build.cxx.borrow_mut().insert(target, compiler);
     }
 
-    build.verbose(|| eprintln!("CC_{} = {:?}", target.triple, build.cc(target)));
-    build.verbose(|| eprintln!("CFLAGS_{} = {cflags:?}", target.triple));
+    build.verbose(|| println!("CC_{} = {:?}", target.triple, build.cc(target)));
+    build.verbose(|| println!("CFLAGS_{} = {cflags:?}", target.triple));
     if let Ok(cxx) = build.cxx(target) {
         let cxxflags = build.cflags(target, GitRepo::Rustc, CLang::Cxx);
-        build.verbose(|| eprintln!("CXX_{} = {cxx:?}", target.triple));
-        build.verbose(|| eprintln!("CXXFLAGS_{} = {cxxflags:?}", target.triple));
+        build.verbose(|| println!("CXX_{} = {cxx:?}", target.triple));
+        build.verbose(|| println!("CXXFLAGS_{} = {cxxflags:?}", target.triple));
     }
     if let Some(ar) = ar {
-        build.verbose(|| eprintln!("AR_{} = {ar:?}", target.triple));
+        build.verbose(|| println!("AR_{} = {ar:?}", target.triple));
         build.ar.borrow_mut().insert(target, ar);
     }
 

src/bootstrap/src/utils/helpers.rs

@@ -135,7 +135,7 @@ impl Drop for TimeIt {
     fn drop(&mut self) {
         let time = self.1.elapsed();
         if !self.0 {
-            eprintln!("\tfinished in {}.{:03} seconds", time.as_secs(), time.subsec_millis());
+            println!("\tfinished in {}.{:03} seconds", time.as_secs(), time.subsec_millis());
         }
     }
 }
@@ -267,12 +267,12 @@ pub fn check_run(cmd: &mut BootstrapCommand, print_cmd_on_fail: bool) -> bool {
     let status = match cmd.as_command_mut().status() {
         Ok(status) => status,
         Err(e) => {
-            eprintln!("failed to execute command: {cmd:?}\nERROR: {e}");
+            println!("failed to execute command: {cmd:?}\nERROR: {e}");
             return false;
         }
     };
     if !status.success() && print_cmd_on_fail {
-        eprintln!(
+        println!(
             "\n\ncommand did not execute successfully: {cmd:?}\n\
              expected success, got: {status}\n\n"
         );

src/bootstrap/src/utils/metrics.rs

@@ -185,7 +185,7 @@ impl BuildMetrics {
                 if version.format_version == CURRENT_FORMAT_VERSION {
                     t!(serde_json::from_slice::<JsonRoot>(&contents)).invocations
                 } else {
-                    eprintln!(
+                    println!(
                         "WARNING: overriding existing build/metrics.json, as it's not \
                          compatible with build metrics format version {CURRENT_FORMAT_VERSION}."
                     );

src/bootstrap/src/utils/render_tests.rs

@@ -56,7 +56,7 @@ fn run_tests(builder: &Builder<'_>, cmd: &mut BootstrapCommand, stream: bool) ->
     let cmd = cmd.as_command_mut();
     cmd.stdout(Stdio::piped());
 
-    builder.verbose(|| eprintln!("running: {cmd:?}"));
+    builder.verbose(|| println!("running: {cmd:?}"));
 
     let mut process = cmd.spawn().unwrap();
 
@@ -71,7 +71,7 @@ fn run_tests(builder: &Builder<'_>, cmd: &mut BootstrapCommand, stream: bool) ->
 
     let result = process.wait_with_output().unwrap();
     if !result.status.success() && builder.is_verbose() {
-        eprintln!(
+        println!(
             "\n\ncommand did not execute successfully: {cmd:?}\n\
              expected success, got: {}",
             result.status
@@ -135,9 +135,7 @@ impl<'a> Renderer<'a> {
         if self.up_to_date_tests > 0 {
             let n = self.up_to_date_tests;
             let s = if n > 1 { "s" } else { "" };
-            eprintln!(
-                "help: ignored {n} up-to-date test{s}; use `--force-rerun` to prevent this\n"
-            );
+            println!("help: ignored {n} up-to-date test{s}; use `--force-rerun` to prevent this\n");
         }
     }
 
@@ -187,12 +185,12 @@ impl<'a> Renderer<'a> {
     }
 
     fn render_test_outcome_verbose(&self, outcome: Outcome<'_>, test: &TestOutcome) {
-        eprint!("test {} ... ", test.name);
-        self.builder.colored_stderr(|stdout| outcome.write_long(stdout)).unwrap();
+        print!("test {} ... ", test.name);
+        self.builder.colored_stdout(|stdout| outcome.write_long(stdout)).unwrap();
         if let Some(exec_time) = test.exec_time {
-            eprint!(" ({exec_time:.2?})");
+            print!(" ({exec_time:.2?})");
         }
-        eprintln!();
+        println!();
     }
 
     fn render_test_outcome_terse(&mut self, outcome: Outcome<'_>, test: &TestOutcome) {
@@ -200,45 +198,45 @@ impl<'a> Renderer<'a> {
             if let Some(total) = self.tests_count {
                 let total = total.to_string();
                 let executed = format!("{:>width$}", self.executed_tests - 1, width = total.len());
-                eprint!(" {executed}/{total}");
+                print!(" {executed}/{total}");
             }
-            eprintln!();
+            println!();
             self.terse_tests_in_line = 0;
         }
 
         self.terse_tests_in_line += 1;
-        self.builder.colored_stderr(|stdout| outcome.write_short(stdout, &test.name)).unwrap();
+        self.builder.colored_stdout(|stdout| outcome.write_short(stdout, &test.name)).unwrap();
         let _ = std::io::stdout().flush();
     }
 
     fn render_suite_outcome(&self, outcome: Outcome<'_>, suite: &SuiteOutcome) {
         // The terse output doesn't end with a newline, so we need to add it ourselves.
         if !self.builder.config.verbose_tests {
-            eprintln!();
+            println!();
         }
 
         if !self.failures.is_empty() {
-            eprintln!("\nfailures:\n");
+            println!("\nfailures:\n");
             for failure in &self.failures {
                 if failure.stdout.is_some() || failure.message.is_some() {
-                    eprintln!("---- {} stdout ----", failure.name);
+                    println!("---- {} stdout ----", failure.name);
                     if let Some(stdout) = &failure.stdout {
-                        eprintln!("{stdout}");
+                        println!("{stdout}");
                     }
                     if let Some(message) = &failure.message {
-                        eprintln!("NOTE: {message}");
+                        println!("NOTE: {message}");
                     }
                 }
             }
 
-            eprintln!("\nfailures:");
+            println!("\nfailures:");
             for failure in &self.failures {
-                eprintln!("    {}", failure.name);
+                println!("    {}", failure.name);
             }
         }
 
         if !self.benches.is_empty() {
-            eprintln!("\nbenchmarks:");
+            println!("\nbenchmarks:");
 
             let mut rows = Vec::new();
             for bench in &self.benches {
@@ -253,13 +251,13 @@ impl<'a> Renderer<'a> {
             let max_1 = rows.iter().map(|r| r.1.len()).max().unwrap_or(0);
             let max_2 = rows.iter().map(|r| r.2.len()).max().unwrap_or(0);
             for row in &rows {
-                eprintln!("    {:<max_0$} {:>max_1$} {:>max_2$}", row.0, row.1, row.2);
+                println!("    {:<max_0$} {:>max_1$} {:>max_2$}", row.0, row.1, row.2);
             }
         }
 
-        eprint!("\ntest result: ");
-        self.builder.colored_stderr(|stdout| outcome.write_long(stdout)).unwrap();
-        eprintln!(
+        print!("\ntest result: ");
+        self.builder.colored_stdout(|stdout| outcome.write_long(stdout)).unwrap();
+        println!(
             ". {} passed; {} failed; {} ignored; {} measured; {} filtered out{time}\n",
             suite.passed,
             suite.failed,
@@ -276,7 +274,7 @@ impl<'a> Renderer<'a> {
     fn render_message(&mut self, message: Message) {
         match message {
             Message::Suite(SuiteMessage::Started { test_count }) => {
-                eprintln!("\nrunning {test_count} tests");
+                println!("\nrunning {test_count} tests");
                 self.executed_tests = 0;
                 self.terse_tests_in_line = 0;
                 self.tests_count = Some(test_count);
@@ -316,7 +314,7 @@ impl<'a> Renderer<'a> {
                 self.failures.push(outcome);
             }
             Message::Test(TestMessage::Timeout { name }) => {
-                eprintln!("test {name} has been running for a long time");
+                println!("test {name} has been running for a long time");
             }
             Message::Test(TestMessage::Started) => {} // Not useful
         }

src/bootstrap/src/utils/tarball.rs

@@ -344,7 +344,7 @@ impl<'a> Tarball<'a> {
         // For `x install` tarball files aren't needed, so we can speed up the process by not producing them.
         let compression_profile = if self.builder.kind == Kind::Install {
             self.builder.verbose(|| {
-                eprintln!("Forcing dist.compression-profile = 'no-op' for `x install`.")
+                println!("Forcing dist.compression-profile = 'no-op' for `x install`.")
             });
             // "no-op" indicates that the rust-installer won't produce compressed tarball sources.
             "no-op"

src/ci/docker/host-x86_64/x86_64-fuchsia/build-fuchsia.sh

@@ -35,7 +35,7 @@ PICK_REFS=()
 # commit hash of fuchsia.git and some other repos in the "monorepo" checkout, in
 # addition to versions of prebuilts. It should be bumped regularly by the
 # Fuchsia team – we aim for every 1-2 months.
-INTEGRATION_SHA=9f632bb7446d5a6af2998f1a0ebdb4b8ea2f4511
+INTEGRATION_SHA=bb38af4e3d45e490531b71fc52a460003141d032
 
 checkout=fuchsia
 jiri=.jiri_root/bin/jiri

src/librustdoc/html/render/search_index.rs

@@ -201,7 +201,7 @@ pub(crate) fn build_index(
                             // exported from this same module). It's also likely to Do
                             // What I Mean, since if a re-export changes the name, it might
                             // also be a change in semantic meaning.
-                            .filter(|fqp| fqp.last() == fqp.last());
+                            .filter(|this_fqp| this_fqp.last() == fqp.last());
                         Some(insert_into_map(
                             itemid_to_pathid,
                             ItemId::DefId(defid),

src/tools/clippy/tests/ui/async_yields_async.fixed

@@ -1,4 +1,3 @@
-#![feature(async_closure)]
 #![warn(clippy::async_yields_async)]
 #![allow(clippy::redundant_async_block)]
 

src/tools/clippy/tests/ui/async_yields_async.rs

@@ -1,4 +1,3 @@
-#![feature(async_closure)]
 #![warn(clippy::async_yields_async)]
 #![allow(clippy::redundant_async_block)]
 

src/tools/clippy/tests/ui/async_yields_async.stderr

@@ -1,5 +1,5 @@
 error: an async construct yields a type which is itself awaitable
-  --> tests/ui/async_yields_async.rs:38:9
+  --> tests/ui/async_yields_async.rs:37:9
    |
 LL |        let _h = async {
    |  _____________________-
@@ -20,7 +20,7 @@ LL +         }.await
    |
 
 error: an async construct yields a type which is itself awaitable
-  --> tests/ui/async_yields_async.rs:43:9
+  --> tests/ui/async_yields_async.rs:42:9
    |
 LL |       let _i = async {
    |  ____________________-
@@ -33,7 +33,7 @@ LL | |     };
    | |_____- outer async construct
 
 error: an async construct yields a type which is itself awaitable
-  --> tests/ui/async_yields_async.rs:49:9
+  --> tests/ui/async_yields_async.rs:48:9
    |
 LL |        let _j = async || {
    |  ________________________-
@@ -52,7 +52,7 @@ LL +         }.await
    |
 
 error: an async construct yields a type which is itself awaitable
-  --> tests/ui/async_yields_async.rs:54:9
+  --> tests/ui/async_yields_async.rs:53:9
    |
 LL |       let _k = async || {
    |  _______________________-
@@ -65,7 +65,7 @@ LL | |     };
    | |_____- outer async construct
 
 error: an async construct yields a type which is itself awaitable
-  --> tests/ui/async_yields_async.rs:56:23
+  --> tests/ui/async_yields_async.rs:55:23
    |
 LL |     let _l = async || CustomFutureType;
    |                       ^^^^^^^^^^^^^^^^
@@ -75,7 +75,7 @@ LL |     let _l = async || CustomFutureType;
    |                       help: consider awaiting this value: `CustomFutureType.await`
 
 error: an async construct yields a type which is itself awaitable
-  --> tests/ui/async_yields_async.rs:62:9
+  --> tests/ui/async_yields_async.rs:61:9
    |
 LL |       let _m = async || {
    |  _______________________-

src/tools/clippy/tests/ui/author/blocks.rs

@@ -2,7 +2,6 @@
 
 #![allow(redundant_semicolons, clippy::no_effect)]
 #![feature(stmt_expr_attributes)]
-#![feature(async_closure)]
 
 #[rustfmt::skip]
 fn main() {

src/tools/clippy/tests/ui/infinite_loops.rs

@@ -3,7 +3,6 @@
 
 #![allow(clippy::never_loop)]
 #![warn(clippy::infinite_loop)]
-#![feature(async_closure)]
 
 extern crate proc_macros;
 use proc_macros::{external, with_span};

src/tools/clippy/tests/ui/infinite_loops.stderr

@@ -1,5 +1,5 @@
 error: infinite loop detected
-  --> tests/ui/infinite_loops.rs:14:5
+  --> tests/ui/infinite_loops.rs:13:5
    |
 LL | /     loop {
 LL | |
@@ -15,7 +15,7 @@ LL | fn no_break() -> ! {
    |               ++++
 
 error: infinite loop detected
-  --> tests/ui/infinite_loops.rs:21:5
+  --> tests/ui/infinite_loops.rs:20:5
    |
 LL | /     loop {
 LL | |
@@ -32,7 +32,7 @@ LL | fn all_inf() -> ! {
    |              ++++
 
 error: infinite loop detected
-  --> tests/ui/infinite_loops.rs:23:9
+  --> tests/ui/infinite_loops.rs:22:9
    |
 LL | /         loop {
 LL | |
@@ -49,7 +49,7 @@ LL | fn all_inf() -> ! {
    |              ++++
 
 error: infinite loop detected
-  --> tests/ui/infinite_loops.rs:25:13
+  --> tests/ui/infinite_loops.rs:24:13
    |
 LL | /             loop {
 LL | |
@@ -63,7 +63,7 @@ LL | fn all_inf() -> ! {
    |              ++++
 
 error: infinite loop detected
-  --> tests/ui/infinite_loops.rs:39:5
+  --> tests/ui/infinite_loops.rs:38:5
    |
 LL | /     loop {
 LL | |
@@ -74,7 +74,7 @@ LL | |     }
    = help: if this is not intended, try adding a `break` or `return` condition in the loop
 
 error: infinite loop detected
-  --> tests/ui/infinite_loops.rs:52:5
+  --> tests/ui/infinite_loops.rs:51:5
    |
 LL | /     loop {
 LL | |         fn inner_fn() -> ! {
@@ -90,7 +90,7 @@ LL | fn no_break_never_ret_noise() -> ! {
    |                               ++++
 
 error: infinite loop detected
-  --> tests/ui/infinite_loops.rs:95:5
+  --> tests/ui/infinite_loops.rs:94:5
    |
 LL | /     loop {
 LL | |
@@ -107,7 +107,7 @@ LL | fn break_inner_but_not_outer_1(cond: bool) -> ! {
    |                                            ++++
 
 error: infinite loop detected
-  --> tests/ui/infinite_loops.rs:106:5
+  --> tests/ui/infinite_loops.rs:105:5
    |
 LL | /     loop {
 LL | |
@@ -124,7 +124,7 @@ LL | fn break_inner_but_not_outer_2(cond: bool) -> ! {
    |                                            ++++
 
 error: infinite loop detected
-  --> tests/ui/infinite_loops.rs:120:9
+  --> tests/ui/infinite_loops.rs:119:9
    |
 LL | /         loop {
 LL | |
@@ -138,7 +138,7 @@ LL | fn break_outer_but_not_inner() -> ! {
    |                                ++++
 
 error: infinite loop detected
-  --> tests/ui/infinite_loops.rs:143:9
+  --> tests/ui/infinite_loops.rs:142:9
    |
 LL | /         loop {
 LL | |
@@ -155,7 +155,7 @@ LL | fn break_wrong_loop(cond: bool) -> ! {
    |                                 ++++
 
 error: infinite loop detected
-  --> tests/ui/infinite_loops.rs:183:5
+  --> tests/ui/infinite_loops.rs:182:5
    |
 LL | /     loop {
 LL | |
@@ -172,7 +172,7 @@ LL | fn match_like() -> ! {
    |                 ++++
 
 error: infinite loop detected
-  --> tests/ui/infinite_loops.rs:224:5
+  --> tests/ui/infinite_loops.rs:223:5
    |
 LL | /     loop {
 LL | |
@@ -186,7 +186,7 @@ LL | fn match_like() -> ! {
    |                 ++++
 
 error: infinite loop detected
-  --> tests/ui/infinite_loops.rs:229:5
+  --> tests/ui/infinite_loops.rs:228:5
    |
 LL | /     loop {
 LL | |
@@ -203,7 +203,7 @@ LL | fn match_like() -> ! {
    |                 ++++
 
 error: infinite loop detected
-  --> tests/ui/infinite_loops.rs:334:9
+  --> tests/ui/infinite_loops.rs:333:9
    |
 LL | /         loop {
 LL | |
@@ -217,7 +217,7 @@ LL |     fn problematic_trait_method() -> ! {
    |                                   ++++
 
 error: infinite loop detected
-  --> tests/ui/infinite_loops.rs:344:9
+  --> tests/ui/infinite_loops.rs:343:9
    |
 LL | /         loop {
 LL | |
@@ -231,7 +231,7 @@ LL |     fn could_be_problematic() -> ! {
    |                               ++++
 
 error: infinite loop detected
-  --> tests/ui/infinite_loops.rs:353:9
+  --> tests/ui/infinite_loops.rs:352:9
    |
 LL | /         loop {
 LL | |
@@ -245,7 +245,7 @@ LL |     let _loop_forever = || -> ! {
    |                            ++++
 
 error: infinite loop detected
-  --> tests/ui/infinite_loops.rs:367:8
+  --> tests/ui/infinite_loops.rs:366:8
    |
 LL |       Ok(loop {
    |  ________^
@@ -256,7 +256,7 @@ LL | |     })
    = help: if this is not intended, try adding a `break` or `return` condition in the loop
 
 error: infinite loop detected
-  --> tests/ui/infinite_loops.rs:409:5
+  --> tests/ui/infinite_loops.rs:408:5
    |
 LL | /     'infinite: loop {
 LL | |
@@ -272,7 +272,7 @@ LL | fn continue_outer() -> ! {
    |                     ++++
 
 error: infinite loop detected
-  --> tests/ui/infinite_loops.rs:416:5
+  --> tests/ui/infinite_loops.rs:415:5
    |
 LL | /     loop {
 LL | |
@@ -289,7 +289,7 @@ LL | fn continue_outer() -> ! {
    |                     ++++
 
 error: infinite loop detected
-  --> tests/ui/infinite_loops.rs:418:9
+  --> tests/ui/infinite_loops.rs:417:9
    |
 LL | /         'inner: loop {
 LL | |             loop {
@@ -304,7 +304,7 @@ LL | fn continue_outer() -> ! {
    |                     ++++
 
 error: infinite loop detected
-  --> tests/ui/infinite_loops.rs:426:5
+  --> tests/ui/infinite_loops.rs:425:5
    |
 LL | /     loop {
 LL | |

src/tools/clippy/tests/ui/redundant_closure_call_fixable.fixed

@@ -1,4 +1,3 @@
-#![feature(async_closure)]
 #![warn(clippy::redundant_closure_call)]
 #![allow(clippy::redundant_async_block)]
 #![allow(clippy::type_complexity)]

src/tools/clippy/tests/ui/redundant_closure_call_fixable.rs

@@ -1,4 +1,3 @@
-#![feature(async_closure)]
 #![warn(clippy::redundant_closure_call)]
 #![allow(clippy::redundant_async_block)]
 #![allow(clippy::type_complexity)]

src/tools/clippy/tests/ui/redundant_closure_call_fixable.stderr

@@ -1,5 +1,5 @@
 error: try not to call a closure in the expression where it is declared
-  --> tests/ui/redundant_closure_call_fixable.rs:16:13
+  --> tests/ui/redundant_closure_call_fixable.rs:15:13
    |
 LL |     let a = (|| 42)();
    |             ^^^^^^^^^ help: try doing something like: `42`
@@ -8,7 +8,7 @@ LL |     let a = (|| 42)();
    = help: to override `-D warnings` add `#[allow(clippy::redundant_closure_call)]`
 
 error: try not to call a closure in the expression where it is declared
-  --> tests/ui/redundant_closure_call_fixable.rs:17:13
+  --> tests/ui/redundant_closure_call_fixable.rs:16:13
    |
 LL |       let b = (async || {
    |  _____________^
@@ -28,7 +28,7 @@ LL ~     };
    |
 
 error: try not to call a closure in the expression where it is declared
-  --> tests/ui/redundant_closure_call_fixable.rs:22:13
+  --> tests/ui/redundant_closure_call_fixable.rs:21:13
    |
 LL |       let c = (|| {
    |  _____________^
@@ -48,13 +48,13 @@ LL ~     };
    |
 
 error: try not to call a closure in the expression where it is declared
-  --> tests/ui/redundant_closure_call_fixable.rs:27:13
+  --> tests/ui/redundant_closure_call_fixable.rs:26:13
    |
 LL |     let d = (async || something().await)();
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try doing something like: `async { something().await }`
 
 error: try not to call a closure in the expression where it is declared
-  --> tests/ui/redundant_closure_call_fixable.rs:36:13
+  --> tests/ui/redundant_closure_call_fixable.rs:35:13
    |
 LL |             (|| m!())()
    |             ^^^^^^^^^^^ help: try doing something like: `m!()`
@@ -65,7 +65,7 @@ LL |     m2!();
    = note: this error originates in the macro `m2` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: try not to call a closure in the expression where it is declared
-  --> tests/ui/redundant_closure_call_fixable.rs:31:13
+  --> tests/ui/redundant_closure_call_fixable.rs:30:13
    |
 LL |             (|| 0)()
    |             ^^^^^^^^ help: try doing something like: `0`
@@ -76,67 +76,67 @@ LL |     m2!();
    = note: this error originates in the macro `m` which comes from the expansion of the macro `m2` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: try not to call a closure in the expression where it is declared
-  --> tests/ui/redundant_closure_call_fixable.rs:44:16
+  --> tests/ui/redundant_closure_call_fixable.rs:43:16
    |
 LL |     assert_eq!((|| || 43)()(), 42);
    |                ^^^^^^^^^^^^^^ help: try doing something like: `43`
 
 error: try not to call a closure in the expression where it is declared
-  --> tests/ui/redundant_closure_call_fixable.rs:53:10
+  --> tests/ui/redundant_closure_call_fixable.rs:52:10
    |
 LL |     dbg!((|| 42)());
    |          ^^^^^^^^^ help: try doing something like: `42`
 
 error: try not to call a closure in the expression where it is declared
-  --> tests/ui/redundant_closure_call_fixable.rs:56:13
+  --> tests/ui/redundant_closure_call_fixable.rs:55:13
    |
 LL |     let a = (|| || || 123)();
    |             ^^^^^^^^^^^^^^^^ help: try doing something like: `(|| || 123)`
 
 error: try not to call a closure in the expression where it is declared
-  --> tests/ui/redundant_closure_call_fixable.rs:60:13
+  --> tests/ui/redundant_closure_call_fixable.rs:59:13
    |
 LL |     let a = (|| || || || async || 1)()()()()();
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try doing something like: `async { 1 }`
 
 error: try not to call a closure in the expression where it is declared
-  --> tests/ui/redundant_closure_call_fixable.rs:69:13
+  --> tests/ui/redundant_closure_call_fixable.rs:68:13
    |
 LL |     let a = (|| echo!(|| echo!(|| 1)))()()();
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try doing something like: `1`
 
 error: try not to call a closure in the expression where it is declared
-  --> tests/ui/redundant_closure_call_fixable.rs:71:13
+  --> tests/ui/redundant_closure_call_fixable.rs:70:13
    |
 LL |     let a = (|| echo!((|| 123)))()();
    |             ^^^^^^^^^^^^^^^^^^^^^^^^ help: try doing something like: `123`
 
 error: try not to call a closure in the expression where it is declared
-  --> tests/ui/redundant_closure_call_fixable.rs:84:11
+  --> tests/ui/redundant_closure_call_fixable.rs:83:11
    |
 LL |     bar()((|| || 42)()(), 5);
    |           ^^^^^^^^^^^^^^ help: try doing something like: `42`
 
 error: try not to call a closure in the expression where it is declared
-  --> tests/ui/redundant_closure_call_fixable.rs:85:9
+  --> tests/ui/redundant_closure_call_fixable.rs:84:9
    |
 LL |     foo((|| || 42)()(), 5);
    |         ^^^^^^^^^^^^^^ help: try doing something like: `42`
 
 error: try not to call a closure in the expression where it is declared
-  --> tests/ui/redundant_closure_call_fixable.rs:89:5
+  --> tests/ui/redundant_closure_call_fixable.rs:88:5
    |
 LL |     (|| async {})().await;
    |     ^^^^^^^^^^^^^^^ help: try doing something like: `async {}`
 
 error: try not to call a closure in the expression where it is declared
-  --> tests/ui/redundant_closure_call_fixable.rs:98:18
+  --> tests/ui/redundant_closure_call_fixable.rs:97:18
    |
 LL |         spawn_on((|| async move {})());
    |                  ^^^^^^^^^^^^^^^^^^^^ help: try doing something like: `async move {}`
 
 error: try not to call a closure in the expression where it is declared
-  --> tests/ui/redundant_closure_call_fixable.rs:103:28
+  --> tests/ui/redundant_closure_call_fixable.rs:102:28
    |
 LL |     std::convert::identity((|| 13_i32 + 36_i32)()).leading_zeros();
    |                            ^^^^^^^^^^^^^^^^^^^^^^ help: try doing something like: `13_i32 + 36_i32`

src/tools/clippy/tests/ui/redundant_locals.rs

@@ -1,7 +1,7 @@
 //@aux-build:proc_macros.rs
 #![allow(unused, clippy::no_effect, clippy::needless_pass_by_ref_mut)]
 #![warn(clippy::redundant_locals)]
-#![feature(async_closure, coroutines, stmt_expr_attributes)]
+#![feature(coroutines, stmt_expr_attributes)]
 
 extern crate proc_macros;
 use proc_macros::{external, with_span};