Rollup of 8 pull requests

.gitattributes

@@ -9,7 +9,6 @@
 src/etc/installer/gfx/* binary
 src/vendor/** -text
 Cargo.lock linguist-generated=false
-config.toml.example linguist-language=TOML
 
 # Older git versions try to fix line endings on images and fonts, this prevents it.
 *.png binary

.reuse/dep5

@@ -16,7 +16,7 @@ Files: compiler/*
        Cargo.lock
        Cargo.toml
        CODE_OF_CONDUCT.md
-       config.toml.example
+       config.example.toml
        configure
        CONTRIBUTING.md
        COPYRIGHT

README.md

@@ -99,7 +99,7 @@ See [the rustc-dev-guide for more info][sysllvm].
    The Rust build system uses a file named `config.toml` in the root of the
    source tree to determine various configuration settings for the build.
    Set up the defaults intended for distros to get started. You can see a full
-   list of options in `config.toml.example`.
+   list of options in `config.example.toml`.
 
    ```sh
    printf 'profile = "user" \nchangelog-seen = 2 \n' > config.toml

compiler/rustc_ast_passes/src/feature_gate.rs

@@ -337,9 +337,6 @@ impl<'a> Visitor<'a> for PostExpansionVisitor<'a> {
             ast::TyKind::Never => {
                 gate_feature_post!(&self, never_type, ty.span, "the `!` type is experimental");
             }
-            ast::TyKind::TraitObject(_, ast::TraitObjectSyntax::DynStar, ..) => {
-                gate_feature_post!(&self, dyn_star, ty.span, "dyn* trait objects are unstable");
-            }
             _ => {}
         }
         visit::walk_ty(self, ty)
@@ -425,14 +422,6 @@ impl<'a> Visitor<'a> for PostExpansionVisitor<'a> {
             ast::ExprKind::TryBlock(_) => {
                 gate_feature_post!(&self, try_blocks, e.span, "`try` expression is experimental");
             }
-            ast::ExprKind::Closure(box ast::Closure { constness: ast::Const::Yes(_), .. }) => {
-                gate_feature_post!(
-                    &self,
-                    const_closures,
-                    e.span,
-                    "const closures are experimental"
-                );
-            }
             _ => {}
         }
         visit::walk_expr(self, e)
@@ -594,6 +583,8 @@ pub fn check_crate(krate: &ast::Crate, sess: &Session) {
     gate_all!(inline_const_pat, "inline-const in pattern position is experimental");
     gate_all!(associated_const_equality, "associated const equality is incomplete");
     gate_all!(yeet_expr, "`do yeet` expression is experimental");
+    gate_all!(dyn_star, "`dyn*` trait objects are experimental");
+    gate_all!(const_closures, "const closures are experimental");
 
     // All uses of `gate_all!` below this point were added in #65742,
     // and subsequently disabled (with the non-early gating readded).

compiler/rustc_codegen_ssa/src/codegen_attrs.rs

@@ -242,6 +242,9 @@ fn codegen_fn_attrs(tcx: TyCtxt<'_>, did: DefId) -> CodegenFnAttrs {
                     // Note that this is also allowed if `actually_rustdoc` so
                     // if a target is documenting some wasm-specific code then
                     // it's not spuriously denied.
+                    //
+                    // This exception needs to be kept in sync with allowing
+                    // `#[target_feature]` on `main` and `start`.
                 } else if !tcx.features().target_feature_11 {
                     let mut err = feature_err(
                         &tcx.sess.parse_sess,

compiler/rustc_hir_analysis/messages.ftl

@@ -128,9 +128,14 @@ hir_analysis_where_clause_on_main = `main` function is not allowed to have a `wh
 hir_analysis_track_caller_on_main = `main` function is not allowed to be `#[track_caller]`
     .suggestion = remove this annotation
 
+hir_analysis_target_feature_on_main = `main` function is not allowed to have `#[target_feature]`
+
 hir_analysis_start_not_track_caller = `start` is not allowed to be `#[track_caller]`
     .label = `start` is not allowed to be `#[track_caller]`
 
+hir_analysis_start_not_target_feature = `start` is not allowed to have `#[target_feature]`
+    .label = `start` is not allowed to have `#[target_feature]`
+
 hir_analysis_start_not_async = `start` is not allowed to be `async`
     .label = `start` is not allowed to be `async`
 

compiler/rustc_hir_analysis/src/errors.rs

@@ -327,6 +327,14 @@ pub(crate) struct TrackCallerOnMain {
     pub annotated: Span,
 }
 
+#[derive(Diagnostic)]
+#[diag(hir_analysis_target_feature_on_main)]
+pub(crate) struct TargetFeatureOnMain {
+    #[primary_span]
+    #[label(hir_analysis_target_feature_on_main)]
+    pub main: Span,
+}
+
 #[derive(Diagnostic)]
 #[diag(hir_analysis_start_not_track_caller)]
 pub(crate) struct StartTrackCaller {
@@ -336,6 +344,15 @@ pub(crate) struct StartTrackCaller {
     pub start: Span,
 }
 
+#[derive(Diagnostic)]
+#[diag(hir_analysis_start_not_target_feature)]
+pub(crate) struct StartTargetFeature {
+    #[primary_span]
+    pub span: Span,
+    #[label]
+    pub start: Span,
+}
+
 #[derive(Diagnostic)]
 #[diag(hir_analysis_start_not_async, code = "E0752")]
 pub(crate) struct StartAsync {

compiler/rustc_hir_analysis/src/lib.rs

@@ -283,6 +283,15 @@ fn check_main_fn_ty(tcx: TyCtxt<'_>, main_def_id: DefId) {
         error = true;
     }
 
+    if !tcx.codegen_fn_attrs(main_def_id).target_features.is_empty()
+        // Calling functions with `#[target_feature]` is not unsafe on WASM, see #84988
+        && !tcx.sess.target.is_like_wasm
+        && !tcx.sess.opts.actually_rustdoc
+    {
+        tcx.sess.emit_err(errors::TargetFeatureOnMain { main: main_span });
+        error = true;
+    }
+
     if error {
         return;
     }
@@ -373,6 +382,18 @@ fn check_start_fn_ty(tcx: TyCtxt<'_>, start_def_id: DefId) {
                             });
                             error = true;
                         }
+                        if attr.has_name(sym::target_feature)
+                            // Calling functions with `#[target_feature]` is
+                            // not unsafe on WASM, see #84988
+                            && !tcx.sess.target.is_like_wasm
+                            && !tcx.sess.opts.actually_rustdoc
+                        {
+                            tcx.sess.emit_err(errors::StartTargetFeature {
+                                span: attr.span,
+                                start: start_span,
+                            });
+                            error = true;
+                        }
                     }
 
                     if error {

compiler/rustc_parse/src/parser/expr.rs

@@ -2105,7 +2105,7 @@ impl<'a> Parser<'a> {
             ClosureBinder::NotPresent
         };
 
-        let constness = self.parse_closure_constness(Case::Sensitive);
+        let constness = self.parse_closure_constness();
 
         let movability =
             if self.eat_keyword(kw::Static) { Movability::Static } else { Movability::Movable };

compiler/rustc_parse/src/parser/mod.rs

@@ -1196,9 +1196,13 @@ impl<'a> Parser<'a> {
         self.parse_constness_(case, false)
     }
 
-    /// Parses constness for closures
-    fn parse_closure_constness(&mut self, case: Case) -> Const {
-        self.parse_constness_(case, true)
+    /// Parses constness for closures (case sensitive, feature-gated)
+    fn parse_closure_constness(&mut self) -> Const {
+        let constness = self.parse_constness_(Case::Sensitive, true);
+        if let Const::Yes(span) = constness {
+            self.sess.gated_spans.gate(sym::const_closures, span);
+        }
+        constness
     }
 
     fn parse_constness_(&mut self, case: Case, is_closure: bool) -> Const {

compiler/rustc_parse/src/parser/ty.rs

@@ -624,10 +624,12 @@ impl<'a> Parser<'a> {
     ///
     /// Note that this does *not* parse bare trait objects.
     fn parse_dyn_ty(&mut self, impl_dyn_multi: &mut bool) -> PResult<'a, TyKind> {
+        let lo = self.token.span;
         self.bump(); // `dyn`
 
         // parse dyn* types
         let syntax = if self.eat(&TokenKind::BinOp(token::Star)) {
+            self.sess.gated_spans.gate(sym::dyn_star, lo.to(self.prev_token.span));
             TraitObjectSyntax::DynStar
         } else {
             TraitObjectSyntax::Dyn

compiler/rustc_trait_selection/src/traits/query/evaluate_obligation.rs

@@ -1,6 +1,5 @@
 use rustc_middle::traits::solve::{Certainty, Goal, MaybeCause};
 use rustc_middle::ty;
-use rustc_session::config::TraitSolver;
 
 use crate::infer::canonical::OriginalQueryValues;
 use crate::infer::InferCtxt;
@@ -80,13 +79,7 @@ impl<'tcx> InferCtxtExt<'tcx> for InferCtxt<'tcx> {
             _ => obligation.param_env.without_const(),
         };
 
-        if self.tcx.sess.opts.unstable_opts.trait_solver != TraitSolver::Next {
-            let c_pred = self.canonicalize_query_keep_static(
-                param_env.and(obligation.predicate),
-                &mut _orig_values,
-            );
-            self.tcx.at(obligation.cause.span()).evaluate_obligation(c_pred)
-        } else {
+        if self.tcx.trait_solver_next() {
             self.probe(|snapshot| {
                 if let Ok((_, certainty)) =
                     self.evaluate_root_goal(Goal::new(self.tcx, param_env, obligation.predicate))
@@ -111,6 +104,12 @@ impl<'tcx> InferCtxtExt<'tcx> for InferCtxt<'tcx> {
                     Ok(EvaluationResult::EvaluatedToErr)
                 }
             })
+        } else {
+            let c_pred = self.canonicalize_query_keep_static(
+                param_env.and(obligation.predicate),
+                &mut _orig_values,
+            );
+            self.tcx.at(obligation.cause.span()).evaluate_obligation(c_pred)
         }
     }
 

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

@@ -50,7 +50,6 @@ use rustc_middle::ty::relate::TypeRelation;
 use rustc_middle::ty::SubstsRef;
 use rustc_middle::ty::{self, EarlyBinder, PolyProjectionPredicate, ToPolyTraitRef, ToPredicate};
 use rustc_middle::ty::{Ty, TyCtxt, TypeFoldable, TypeVisitableExt};
-use rustc_session::config::TraitSolver;
 use rustc_span::symbol::sym;
 
 use std::cell::{Cell, RefCell};
@@ -545,13 +544,13 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
         obligation: &PredicateObligation<'tcx>,
     ) -> Result<EvaluationResult, OverflowError> {
         self.evaluation_probe(|this| {
-            if this.tcx().sess.opts.unstable_opts.trait_solver != TraitSolver::Next {
+            if this.tcx().trait_solver_next() {
+                this.evaluate_predicates_recursively_in_new_solver([obligation.clone()])
+            } else {
                 this.evaluate_predicate_recursively(
                     TraitObligationStackList::empty(&ProvisionalEvaluationCache::default()),
                     obligation.clone(),
                 )
-            } else {
-                this.evaluate_predicates_recursively_in_new_solver([obligation.clone()])
             }
         })
     }
@@ -591,7 +590,9 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
     where
         I: IntoIterator<Item = PredicateObligation<'tcx>> + std::fmt::Debug,
     {
-        if self.tcx().sess.opts.unstable_opts.trait_solver != TraitSolver::Next {
+        if self.tcx().trait_solver_next() {
+            self.evaluate_predicates_recursively_in_new_solver(predicates)
+        } else {
             let mut result = EvaluatedToOk;
             for obligation in predicates {
                 let eval = self.evaluate_predicate_recursively(stack, obligation.clone())?;
@@ -604,8 +605,6 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
                 }
             }
             Ok(result)
-        } else {
-            self.evaluate_predicates_recursively_in_new_solver(predicates)
         }
     }
 

compiler/rustc_type_ir/src/sty.rs

@@ -167,7 +167,7 @@ pub enum TyKind<I: Interner> {
     /// lifetimes bound by the witness itself.
     ///
     /// This variant is only using when `drop_tracking_mir` is set.
-    /// This contains the `DefId` and the `SubstRef` of the generator.
+    /// This contains the `DefId` and the `SubstsRef` of the generator.
     /// The actual witness types are computed on MIR by the `mir_generator_witnesses` query.
     ///
     /// Looking at the following example, the witness for this generator

library/alloc/src/rc.rs

@@ -681,6 +681,24 @@ impl<T> Rc<T> {
             Err(this)
         }
     }
+
+    /// Returns the inner value, if the `Rc` has exactly one strong reference.
+    ///
+    /// Otherwise, [`None`] is returned and the `Rc` is dropped.
+    ///
+    /// This will succeed even if there are outstanding weak references.
+    ///
+    /// If `Rc::into_inner` is called on every clone of this `Rc`,
+    /// it is guaranteed that exactly one of the calls returns the inner value.
+    /// This means in particular that the inner value is not dropped.
+    ///
+    /// This is equivalent to `Rc::try_unwrap(...).ok()`. (Note that these are not equivalent for
+    /// `Arc`, due to race conditions that do not apply to `Rc`.)
+    #[inline]
+    #[unstable(feature = "rc_into_inner", issue = "106894")]
+    pub fn into_inner(this: Self) -> Option<T> {
+        Rc::try_unwrap(this).ok()
+    }
 }
 
 impl<T> Rc<[T]> {

library/alloc/src/rc/tests.rs

@@ -151,6 +151,21 @@ fn try_unwrap() {
     assert_eq!(Rc::try_unwrap(x), Ok(5));
 }
 
+#[test]
+fn into_inner() {
+    let x = Rc::new(3);
+    assert_eq!(Rc::into_inner(x), Some(3));
+
+    let x = Rc::new(4);
+    let y = Rc::clone(&x);
+    assert_eq!(Rc::into_inner(x), None);
+    assert_eq!(Rc::into_inner(y), Some(4));
+
+    let x = Rc::new(5);
+    let _w = Rc::downgrade(&x);
+    assert_eq!(Rc::into_inner(x), Some(5));
+}
+
 #[test]
 fn into_from_raw() {
     let x = Rc::new(Box::new("hello"));

src/bootstrap/README.md

@@ -185,7 +185,7 @@ Some general areas that you may be interested in modifying are:
 If you make a major change, please remember to:
 
 + Update `VERSION` in `src/bootstrap/main.rs`.
-* Update `changelog-seen = N` in `config.toml.example`.
+* Update `changelog-seen = N` in `config.example.toml`.
 * Add an entry in `src/bootstrap/CHANGELOG.md`.
 
 A 'major change' includes

src/bootstrap/bin/main.rs

@@ -44,8 +44,8 @@ fn main() {
     if suggest_setup {
         println!("warning: you have not made a `config.toml`");
         println!(
-            "help: consider running `./x.py setup` or copying `config.toml.example` by running \
-            `cp config.toml.example config.toml`"
+            "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 {
         println!("{}", suggestion);
@@ -57,8 +57,8 @@ fn main() {
     if suggest_setup {
         println!("warning: you have not made a `config.toml`");
         println!(
-            "help: consider running `./x.py setup` or copying `config.toml.example` by running \
-            `cp config.toml.example config.toml`"
+            "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 {
         println!("{}", suggestion);

src/bootstrap/config.rs

@@ -55,7 +55,7 @@ pub enum DryRun {
 /// Note that this structure is not decoded directly into, but rather it is
 /// filled out from the decoded forms of the structs below. For documentation
 /// each field, see the corresponding fields in
-/// `config.toml.example`.
+/// `config.example.toml`.
 #[derive(Default)]
 #[cfg_attr(test, derive(Clone))]
 pub struct Config {
@@ -325,7 +325,7 @@ impl std::str::FromStr for SplitDebuginfo {
 
 impl SplitDebuginfo {
     /// Returns the default `-Csplit-debuginfo` value for the current target. See the comment for
-    /// `rust.split-debuginfo` in `config.toml.example`.
+    /// `rust.split-debuginfo` in `config.example.toml`.
     fn default_for_platform(target: &str) -> Self {
         if target.contains("apple") {
             SplitDebuginfo::Unpacked