Rollup of 7 pull requests

compiler/rustc_ast/src/token.rs

@@ -527,13 +527,13 @@ impl TokenKind {
 
     /// Returns tokens that are likely to be typed accidentally instead of the current token.
     /// Enables better error recovery when the wrong token is found.
-    pub fn similar_tokens(&self) -> Option<Vec<TokenKind>> {
-        match *self {
-            Comma => Some(vec![Dot, Lt, Semi]),
-            Semi => Some(vec![Colon, Comma]),
-            Colon => Some(vec![Semi]),
-            FatArrow => Some(vec![Eq, RArrow, Ge, Gt]),
-            _ => None,
+    pub fn similar_tokens(&self) -> &[TokenKind] {
+        match self {
+            Comma => &[Dot, Lt, Semi],
+            Semi => &[Colon, Comma],
+            Colon => &[Semi],
+            FatArrow => &[Eq, RArrow, Ge, Gt],
+            _ => &[],
         }
     }
 

compiler/rustc_builtin_macros/src/format.rs

@@ -101,15 +101,14 @@ fn parse_args<'a>(ecx: &ExtCtxt<'a>, sp: Span, tts: TokenStream) -> PResult<'a,
 
             match p.expect(exp!(Comma)) {
                 Err(err) => {
-                    match token::TokenKind::Comma.similar_tokens() {
-                        Some(tks) if tks.contains(&p.token.kind) => {
-                            // If a similar token is found, then it may be a typo. We
-                            // consider it as a comma, and continue parsing.
-                            err.emit();
-                            p.bump();
-                        }
+                    if token::TokenKind::Comma.similar_tokens().contains(&p.token.kind) {
+                        // If a similar token is found, then it may be a typo. We
+                        // consider it as a comma, and continue parsing.
+                        err.emit();
+                        p.bump();
+                    } else {
                         // Otherwise stop the parsing and return the error.
-                        _ => return Err(err),
+                        return Err(err);
                     }
                 }
                 Ok(Recovered::Yes(_)) => (),

compiler/rustc_hir_typeck/src/pat.rs

@@ -243,8 +243,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
     fn downgrade_mut_inside_shared(&self) -> bool {
         // NB: RFC 3627 proposes stabilizing Rule 3 in all editions. If we adopt the same behavior
         // across all editions, this may be removed.
-        self.tcx.features().ref_pat_eat_one_layer_2024()
-            || self.tcx.features().ref_pat_eat_one_layer_2024_structural()
+        self.tcx.features().ref_pat_eat_one_layer_2024_structural()
     }
 
     /// Experimental pattern feature: when do reference patterns match against inherited references?
@@ -435,7 +434,10 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         max_ref_mutbl: MutblCap,
     ) -> (Ty<'tcx>, ByRef, MutblCap) {
         #[cfg(debug_assertions)]
-        if def_br == ByRef::Yes(Mutability::Mut) && max_ref_mutbl != MutblCap::Mut {
+        if def_br == ByRef::Yes(Mutability::Mut)
+            && max_ref_mutbl != MutblCap::Mut
+            && self.downgrade_mut_inside_shared()
+        {
             span_bug!(pat.span, "Pattern mutability cap violated!");
         }
         match adjust_mode {
@@ -2328,22 +2330,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                         // (RFC 3627, Rule 5). If we implement a pattern typing ruleset with Rule 4E
                         // but not Rule 5, we'll need to check that here.
                         debug_assert!(ref_pat_matches_mut_ref);
-                        let err_msg = "mismatched types";
-                        let err = if let Some(span) = pat_prefix_span {
-                            let mut err = self.dcx().struct_span_err(span, err_msg);
-                            err.code(E0308);
-                            err.note("cannot match inherited `&` with `&mut` pattern");
-                            err.span_suggestion_verbose(
-                                span,
-                                "replace this `&mut` pattern with `&`",
-                                "&",
-                                Applicability::MachineApplicable,
-                            );
-                            err
-                        } else {
-                            self.dcx().struct_span_err(pat.span, err_msg)
-                        };
-                        err.emit();
+                        self.error_inherited_ref_mutability_mismatch(pat, pat_prefix_span);
                     }
 
                     pat_info.binding_mode = ByRef::No;
@@ -2352,28 +2339,38 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                     return expected;
                 }
                 InheritedRefMatchRule::EatInner => {
-                    if let ty::Ref(_, _, r_mutbl) = *expected.kind() {
+                    if let ty::Ref(_, _, r_mutbl) = *expected.kind()
+                        && pat_mutbl <= r_mutbl
+                    {
                         // Match against the reference type; don't consume the inherited ref.
-                        pat_info.binding_mode = pat_info.binding_mode.cap_ref_mutability(r_mutbl);
+                        // NB: The check for compatible pattern and ref type mutability assumes that
+                        // `&` patterns can match against mutable references (RFC 3627, Rule 5). If
+                        // we implement a pattern typing ruleset with Rule 4 (including the fallback
+                        // to matching the inherited ref when the inner ref can't match) but not
+                        // Rule 5, we'll need to check that here.
+                        debug_assert!(ref_pat_matches_mut_ref);
+                        // NB: For RFC 3627's Rule 3, we limit the default binding mode's ref
+                        // mutability to `pat_info.max_ref_mutbl`. If we implement a pattern typing
+                        // ruleset with Rule 4 but not Rule 3, we'll need to check that here.
+                        debug_assert!(self.downgrade_mut_inside_shared());
+                        let mutbl_cap = cmp::min(r_mutbl, pat_info.max_ref_mutbl.as_mutbl());
+                        pat_info.binding_mode = pat_info.binding_mode.cap_ref_mutability(mutbl_cap);
                     } else {
-                        // The expected type isn't a reference, so match against the inherited ref.
+                        // The reference pattern can't match against the expected type, so try
+                        // matching against the inherited ref instead.
                         if pat_mutbl > inh_mut {
-                            // We can't match an inherited shared reference with `&mut`. This will
-                            // be a type error later, since we're matching a reference pattern
-                            // against a non-reference type.
+                            // We can't match an inherited shared reference with `&mut`.
                             // NB: This assumes that `&` patterns can match against mutable
                             // references (RFC 3627, Rule 5). If we implement a pattern typing
                             // ruleset with Rule 4 but not Rule 5, we'll need to check that here.
                             debug_assert!(ref_pat_matches_mut_ref);
-                        } else {
-                            pat_info.binding_mode = ByRef::No;
-                            self.typeck_results
-                                .borrow_mut()
-                                .skipped_ref_pats_mut()
-                                .insert(pat.hir_id);
-                            self.check_pat(inner, expected, pat_info);
-                            return expected;
+                            self.error_inherited_ref_mutability_mismatch(pat, pat_prefix_span);
                         }
+
+                        pat_info.binding_mode = ByRef::No;
+                        self.typeck_results.borrow_mut().skipped_ref_pats_mut().insert(pat.hir_id);
+                        self.check_pat(inner, expected, pat_info);
+                        return expected;
                     }
                 }
                 InheritedRefMatchRule::EatBoth => {
@@ -2447,6 +2444,29 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         Ty::new_ref(self.tcx, region, ty, mutbl)
     }
 
+    fn error_inherited_ref_mutability_mismatch(
+        &self,
+        pat: &'tcx Pat<'tcx>,
+        pat_prefix_span: Option<Span>,
+    ) -> ErrorGuaranteed {
+        let err_msg = "mismatched types";
+        let err = if let Some(span) = pat_prefix_span {
+            let mut err = self.dcx().struct_span_err(span, err_msg);
+            err.code(E0308);
+            err.note("cannot match inherited `&` with `&mut` pattern");
+            err.span_suggestion_verbose(
+                span,
+                "replace this `&mut` pattern with `&`",
+                "&",
+                Applicability::MachineApplicable,
+            );
+            err
+        } else {
+            self.dcx().struct_span_err(pat.span, err_msg)
+        };
+        err.emit()
+    }
+
     fn try_resolve_slice_ty_to_array_ty(
         &self,
         before: &'tcx [Pat<'tcx>],

compiler/rustc_middle/src/ty/layout.rs

@@ -504,6 +504,9 @@ impl<'tcx> SizeSkeleton<'tcx> {
                 }
             }
 
+            // Pattern types are always the same size as their base.
+            ty::Pat(base, _) => SizeSkeleton::compute(base, tcx, typing_env),
+
             _ => Err(err),
         }
     }

compiler/rustc_parse/src/parser/expr.rs

@@ -3114,9 +3114,8 @@ impl<'a> Parser<'a> {
             let span_before_body = this.prev_token.span;
             let arm_body;
             let is_fat_arrow = this.check(exp!(FatArrow));
-            let is_almost_fat_arrow = TokenKind::FatArrow
-                .similar_tokens()
-                .is_some_and(|similar_tokens| similar_tokens.contains(&this.token.kind));
+            let is_almost_fat_arrow =
+                TokenKind::FatArrow.similar_tokens().contains(&this.token.kind);
 
             // this avoids the compiler saying that a `,` or `}` was expected even though
             // the pattern isn't a never pattern (and thus an arm body is required)

compiler/rustc_parse/src/parser/mod.rs

@@ -924,10 +924,8 @@ impl<'a> Parser<'a> {
 
                                 _ => {
                                     // Attempt to keep parsing if it was a similar separator.
-                                    if let Some(tokens) = exp.tok.similar_tokens() {
-                                        if tokens.contains(&self.token.kind) {
-                                            self.bump();
-                                        }
+                                    if exp.tok.similar_tokens().contains(&self.token.kind) {
+                                        self.bump();
                                     }
                                 }
                             }

compiler/rustc_parse_format/src/lib.rs

@@ -363,12 +363,7 @@ impl<'a> Parser<'a> {
     /// Notifies of an error. The message doesn't actually need to be of type
     /// String, but I think it does when this eventually uses conditions so it
     /// might as well start using it now.
-    fn err<S1: Into<String>, S2: Into<String>>(
-        &mut self,
-        description: S1,
-        label: S2,
-        span: InnerSpan,
-    ) {
+    fn err(&mut self, description: impl Into<String>, label: impl Into<String>, span: InnerSpan) {
         self.errors.push(ParseError {
             description: description.into(),
             note: None,
@@ -382,11 +377,11 @@ impl<'a> Parser<'a> {
     /// Notifies of an error. The message doesn't actually need to be of type
     /// String, but I think it does when this eventually uses conditions so it
     /// might as well start using it now.
-    fn err_with_note<S1: Into<String>, S2: Into<String>, S3: Into<String>>(
+    fn err_with_note(
         &mut self,
-        description: S1,
-        label: S2,
-        note: S3,
+        description: impl Into<String>,
+        label: impl Into<String>,
+        note: impl Into<String>,
         span: InnerSpan,
     ) {
         self.errors.push(ParseError {

compiler/rustc_trait_selection/src/solve/delegate.rs

@@ -1,7 +1,7 @@
 use std::ops::Deref;
 
 use rustc_data_structures::fx::FxHashSet;
-use rustc_hir::def_id::DefId;
+use rustc_hir::def_id::{CRATE_DEF_ID, DefId};
 use rustc_infer::infer::canonical::query_response::make_query_region_constraints;
 use rustc_infer::infer::canonical::{
     Canonical, CanonicalExt as _, CanonicalQueryInput, CanonicalVarInfo, CanonicalVarValues,
@@ -98,9 +98,10 @@ impl<'tcx> rustc_next_trait_solver::delegate::SolverDelegate for SolverDelegate<
         param_env: ty::ParamEnv<'tcx>,
         arg: ty::GenericArg<'tcx>,
     ) -> Option<Vec<Goal<'tcx, ty::Predicate<'tcx>>>> {
-        crate::traits::wf::unnormalized_obligations(&self.0, param_env, arg).map(|obligations| {
-            obligations.into_iter().map(|obligation| obligation.into()).collect()
-        })
+        crate::traits::wf::unnormalized_obligations(&self.0, param_env, arg, DUMMY_SP, CRATE_DEF_ID)
+            .map(|obligations| {
+                obligations.into_iter().map(|obligation| obligation.into()).collect()
+            })
     }
 
     fn clone_opaque_types_for_query_response(&self) -> Vec<(ty::OpaqueTypeKey<'tcx>, Ty<'tcx>)> {