Rollup of 9 pull requests

compiler/rustc_codegen_ssa/src/codegen_attrs.rs

@@ -61,25 +61,29 @@ fn codegen_fn_attrs(tcx: TyCtxt<'_>, did: DefId) -> CodegenFnAttrs {
 
     let supported_target_features = tcx.supported_target_features(LOCAL_CRATE);
 
-    // In some cases, attribute are only valid on functions, but it's the `check_attr`
-    // pass that check that they aren't used anywhere else, rather this module.
-    // In these cases, we bail from performing further checks that are only meaningful for
-    // functions (such as calling `fn_sig`, which ICEs if given a non-function). We also
-    // report a delayed bug, just in case `check_attr` isn't doing its job.
-    let validate_fn_only_attr = |attr_sp| -> bool {
-        let def_kind = tcx.def_kind(did);
-        if let DefKind::Fn | DefKind::AssocFn | DefKind::Variant | DefKind::Ctor(..) = def_kind {
-            true
-        } else {
-            tcx.sess.delay_span_bug(attr_sp, "this attribute can only be applied to functions");
-            false
-        }
-    };
-
     let mut inline_span = None;
     let mut link_ordinal_span = None;
     let mut no_sanitize_span = None;
+
     for attr in attrs.iter() {
+        // In some cases, attribute are only valid on functions, but it's the `check_attr`
+        // pass that check that they aren't used anywhere else, rather this module.
+        // In these cases, we bail from performing further checks that are only meaningful for
+        // functions (such as calling `fn_sig`, which ICEs if given a non-function). We also
+        // report a delayed bug, just in case `check_attr` isn't doing its job.
+        let fn_sig = || {
+            use DefKind::*;
+
+            let def_kind = tcx.def_kind(did);
+            if let Fn | AssocFn | Variant | Ctor(..) = def_kind {
+                Some(tcx.fn_sig(did))
+            } else {
+                tcx.sess
+                    .delay_span_bug(attr.span, "this attribute can only be applied to functions");
+                None
+            }
+        };
+
         if attr.has_name(sym::cold) {
             codegen_fn_attrs.flags |= CodegenFnAttrFlags::COLD;
         } else if attr.has_name(sym::rustc_allocator) {
@@ -169,8 +173,8 @@ fn codegen_fn_attrs(tcx: TyCtxt<'_>, did: DefId) -> CodegenFnAttrs {
                 }
             }
         } else if attr.has_name(sym::cmse_nonsecure_entry) {
-            if validate_fn_only_attr(attr.span)
-                && !matches!(tcx.fn_sig(did).skip_binder().abi(), abi::Abi::C { .. })
+            if let Some(fn_sig) = fn_sig()
+                && !matches!(fn_sig.skip_binder().abi(), abi::Abi::C { .. })
             {
                 struct_span_err!(
                     tcx.sess,
@@ -189,8 +193,8 @@ fn codegen_fn_attrs(tcx: TyCtxt<'_>, did: DefId) -> CodegenFnAttrs {
             codegen_fn_attrs.flags |= CodegenFnAttrFlags::THREAD_LOCAL;
         } else if attr.has_name(sym::track_caller) {
             if !tcx.is_closure(did.to_def_id())
-                && validate_fn_only_attr(attr.span)
-                && tcx.fn_sig(did).skip_binder().abi() != abi::Abi::Rust
+                && let Some(fn_sig) = fn_sig()
+                && fn_sig.skip_binder().abi() != abi::Abi::Rust
             {
                 struct_span_err!(tcx.sess, attr.span, E0737, "`#[track_caller]` requires Rust ABI")
                     .emit();
@@ -222,7 +226,8 @@ fn codegen_fn_attrs(tcx: TyCtxt<'_>, did: DefId) -> CodegenFnAttrs {
             }
         } else if attr.has_name(sym::target_feature) {
             if !tcx.is_closure(did.to_def_id())
-                && tcx.fn_sig(did).skip_binder().unsafety() == hir::Unsafety::Normal
+                && let Some(fn_sig) = fn_sig()
+                && fn_sig.skip_binder().unsafety() == hir::Unsafety::Normal
             {
                 if tcx.sess.target.is_like_wasm || tcx.sess.opts.actually_rustdoc {
                     // The `#[target_feature]` attribute is allowed on

compiler/rustc_hir_analysis/src/coherence/inherent_impls.rs

@@ -11,7 +11,7 @@ use rustc_errors::struct_span_err;
 use rustc_hir as hir;
 use rustc_hir::def::DefKind;
 use rustc_hir::def_id::{CrateNum, DefId, LocalDefId};
-use rustc_middle::ty::fast_reject::{simplify_type, SimplifiedType, TreatParams};
+use rustc_middle::ty::fast_reject::{simplify_type, SimplifiedType, TreatParams, TreatProjections};
 use rustc_middle::ty::{self, CrateInherentImpls, Ty, TyCtxt};
 use rustc_span::symbol::sym;
 
@@ -99,7 +99,12 @@ impl<'tcx> InherentCollect<'tcx> {
                 }
             }
 
-            if let Some(simp) = simplify_type(self.tcx, self_ty, TreatParams::AsInfer) {
+            if let Some(simp) = simplify_type(
+                self.tcx,
+                self_ty,
+                TreatParams::AsCandidateKey,
+                TreatProjections::AsCandidateKey,
+            ) {
                 self.impls_map.incoherent_impls.entry(simp).or_default().push(impl_def_id);
             } else {
                 bug!("unexpected self type: {:?}", self_ty);
@@ -159,7 +164,12 @@ impl<'tcx> InherentCollect<'tcx> {
             }
         }
 
-        if let Some(simp) = simplify_type(self.tcx, ty, TreatParams::AsInfer) {
+        if let Some(simp) = simplify_type(
+            self.tcx,
+            ty,
+            TreatParams::AsCandidateKey,
+            TreatProjections::AsCandidateKey,
+        ) {
             self.impls_map.incoherent_impls.entry(simp).or_default().push(impl_def_id);
         } else {
             bug!("unexpected primitive type: {:?}", ty);

compiler/rustc_hir_typeck/src/method/probe.rs

@@ -15,6 +15,7 @@ use rustc_infer::infer::canonical::OriginalQueryValues;
 use rustc_infer::infer::canonical::{Canonical, QueryResponse};
 use rustc_infer::infer::{self, InferOk, TyCtxtInferExt};
 use rustc_middle::middle::stability;
+use rustc_middle::ty::fast_reject::TreatProjections;
 use rustc_middle::ty::fast_reject::{simplify_type, TreatParams};
 use rustc_middle::ty::AssocItem;
 use rustc_middle::ty::GenericParamDefKind;
@@ -699,7 +700,7 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
     }
 
     fn assemble_inherent_candidates_for_incoherent_ty(&mut self, self_ty: Ty<'tcx>) {
-        let Some(simp) = simplify_type(self.tcx, self_ty, TreatParams::AsInfer) else {
+        let Some(simp) = simplify_type(self.tcx, self_ty, TreatParams::AsCandidateKey, TreatProjections::AsCandidateKey) else {
             bug!("unexpected incoherent type: {:?}", self_ty)
         };
         for &impl_def_id in self.tcx.incoherent_impls(simp) {

compiler/rustc_hir_typeck/src/method/suggest.rs

@@ -25,6 +25,7 @@ use rustc_infer::infer::{
 use rustc_middle::infer::unify_key::{ConstVariableOrigin, ConstVariableOriginKind};
 use rustc_middle::traits::util::supertraits;
 use rustc_middle::ty::fast_reject::DeepRejectCtxt;
+use rustc_middle::ty::fast_reject::TreatProjections;
 use rustc_middle::ty::fast_reject::{simplify_type, TreatParams};
 use rustc_middle::ty::print::{with_crate_prefix, with_forced_trimmed_paths};
 use rustc_middle::ty::{self, GenericArgKind, Ty, TyCtxt, TypeVisitableExt};
@@ -1257,7 +1258,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             let target_ty = self
                 .autoderef(sugg_span, rcvr_ty)
                 .find(|(rcvr_ty, _)| {
-                    DeepRejectCtxt { treat_obligation_params: TreatParams::AsInfer }
+                    DeepRejectCtxt { treat_obligation_params: TreatParams::AsCandidateKey }
                         .types_may_unify(*rcvr_ty, impl_ty)
                 })
                 .map_or(impl_ty, |(ty, _)| ty)
@@ -1516,7 +1517,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             .into_iter()
             .any(|info| self.associated_value(info.def_id, item_name).is_some());
         let found_assoc = |ty: Ty<'tcx>| {
-            simplify_type(tcx, ty, TreatParams::AsInfer)
+            simplify_type(tcx, ty, TreatParams::AsCandidateKey, TreatProjections::AsCandidateKey)
                 .and_then(|simp| {
                     tcx.incoherent_impls(simp)
                         .iter()
@@ -2645,9 +2646,12 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 // FIXME: Even though negative bounds are not implemented, we could maybe handle
                 // cases where a positive bound implies a negative impl.
                 (candidates, Vec::new())
-            } else if let Some(simp_rcvr_ty) =
-                simplify_type(self.tcx, rcvr_ty, TreatParams::AsPlaceholder)
-            {
+            } else if let Some(simp_rcvr_ty) = simplify_type(
+                self.tcx,
+                rcvr_ty,
+                TreatParams::ForLookup,
+                TreatProjections::ForLookup,
+            ) {
                 let mut potential_candidates = Vec::new();
                 let mut explicitly_negative = Vec::new();
                 for candidate in candidates {
@@ -2660,8 +2664,12 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                         })
                         .any(|imp_did| {
                             let imp = self.tcx.impl_trait_ref(imp_did).unwrap().subst_identity();
-                            let imp_simp =
-                                simplify_type(self.tcx, imp.self_ty(), TreatParams::AsPlaceholder);
+                            let imp_simp = simplify_type(
+                                self.tcx,
+                                imp.self_ty(),
+                                TreatParams::ForLookup,
+                                TreatProjections::ForLookup,
+                            );
                             imp_simp.map_or(false, |s| s == simp_rcvr_ty)
                         })
                     {

compiler/rustc_metadata/src/rmeta/encoder.rs

@@ -26,7 +26,7 @@ use rustc_middle::middle::exported_symbols::{
 use rustc_middle::mir::interpret;
 use rustc_middle::traits::specialization_graph;
 use rustc_middle::ty::codec::TyEncoder;
-use rustc_middle::ty::fast_reject::{self, SimplifiedType, TreatParams};
+use rustc_middle::ty::fast_reject::{self, SimplifiedType, TreatParams, TreatProjections};
 use rustc_middle::ty::query::Providers;
 use rustc_middle::ty::{self, SymbolName, Ty, TyCtxt};
 use rustc_middle::util::common::to_readable_str;
@@ -1858,7 +1858,8 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
                     let simplified_self_ty = fast_reject::simplify_type(
                         self.tcx,
                         trait_ref.self_ty(),
-                        TreatParams::AsInfer,
+                        TreatParams::AsCandidateKey,
+                        TreatProjections::AsCandidateKey,
                     );
 
                     fx_hash_map

compiler/rustc_middle/src/mir/mod.rs

@@ -1999,6 +1999,9 @@ impl BorrowKind {
 }
 
 impl BinOp {
+    /// The checkable operators are those whose overflow checking behavior is controlled by
+    /// -Coverflow-checks option. The remaining operators have either no overflow conditions (e.g.,
+    /// BitAnd, BitOr, BitXor) or are always checked for overflow (e.g., Div, Rem).
     pub fn is_checkable(self) -> bool {
         use self::BinOp::*;
         matches!(self, Add | Sub | Mul | Shl | Shr)

compiler/rustc_middle/src/ty/fast_reject.rs

@@ -51,15 +51,35 @@ pub enum SimplifiedType {
 /// generic parameters as if they were inference variables in that case.
 #[derive(PartialEq, Eq, Debug, Clone, Copy)]
 pub enum TreatParams {
-    /// Treat parameters as placeholders in the given environment.
+    /// Treat parameters as infer vars. This is the correct mode for caching
+    /// an impl's type for lookup.
+    AsCandidateKey,
+    /// Treat parameters as placeholders in the given environment. This is the
+    /// correct mode for *lookup*, as during candidate selection.
+    ForLookup,
+}
+
+/// During fast-rejection, we have the choice of treating projection types
+/// as either simplifyable or not, depending on whether we expect the projection
+/// to be normalized/rigid.
+#[derive(PartialEq, Eq, Debug, Clone, Copy)]
+pub enum TreatProjections {
+    /// In candidates, we may be able to normalize the projection
+    /// after instantiating the candidate and equating it with a goal.
     ///
-    /// Note that this also causes us to treat projections as if they were
-    /// placeholders. This is only correct if the given projection cannot
-    /// be normalized in the current context. Even if normalization fails,
-    /// it may still succeed later if the projection contains any inference
-    /// variables.
-    AsPlaceholder,
-    AsInfer,
+    /// We must assume that the `impl<T> Trait<T> for <T as Id>::This`
+    /// can apply to all self types so we don't return a simplified type
+    /// for `<T as Id>::This`.
+    AsCandidateKey,
+    /// In the old solver we don't try to normalize projections
+    /// when looking up impls and only access them by using the
+    /// current self type. This means that if the self type is
+    /// a projection which could later be normalized, we must not
+    /// treat it as rigid.
+    ForLookup,
+    /// We can treat projections in the self type as opaque as
+    /// we separately look up impls for the normalized self type.
+    NextSolverLookup,
 }
 
 /// Tries to simplify a type by only returning the outermost injective¹ layer, if one exists.
@@ -87,6 +107,7 @@ pub fn simplify_type<'tcx>(
     tcx: TyCtxt<'tcx>,
     ty: Ty<'tcx>,
     treat_params: TreatParams,
+    treat_projections: TreatProjections,
 ) -> Option<SimplifiedType> {
     match *ty.kind() {
         ty::Bool => Some(BoolSimplifiedType),
@@ -115,19 +136,13 @@ pub fn simplify_type<'tcx>(
         ty::FnPtr(f) => Some(FunctionSimplifiedType(f.skip_binder().inputs().len())),
         ty::Placeholder(..) => Some(PlaceholderSimplifiedType),
         ty::Param(_) => match treat_params {
-            TreatParams::AsPlaceholder => Some(PlaceholderSimplifiedType),
-            TreatParams::AsInfer => None,
+            TreatParams::ForLookup => Some(PlaceholderSimplifiedType),
+            TreatParams::AsCandidateKey => None,
         },
-        ty::Alias(..) => match treat_params {
-            // When treating `ty::Param` as a placeholder, projections also
-            // don't unify with anything else as long as they are fully normalized.
-            //
-            // We will have to be careful with lazy normalization here.
-            TreatParams::AsPlaceholder if !ty.has_non_region_infer() => {
-                debug!("treating `{}` as a placeholder", ty);
-                Some(PlaceholderSimplifiedType)
-            }
-            TreatParams::AsPlaceholder | TreatParams::AsInfer => None,
+        ty::Alias(..) => match treat_projections {
+            TreatProjections::ForLookup if !ty.needs_infer() => Some(PlaceholderSimplifiedType),
+            TreatProjections::NextSolverLookup => Some(PlaceholderSimplifiedType),
+            TreatProjections::AsCandidateKey | TreatProjections::ForLookup => None,
         },
         ty::Foreign(def_id) => Some(ForeignSimplifiedType(def_id)),
         ty::Bound(..) | ty::Infer(_) | ty::Error(_) => None,
@@ -295,8 +310,8 @@ impl DeepRejectCtxt {
             // Depending on the value of `treat_obligation_params`, we either
             // treat generic parameters like placeholders or like inference variables.
             ty::Param(_) => match self.treat_obligation_params {
-                TreatParams::AsPlaceholder => false,
-                TreatParams::AsInfer => true,
+                TreatParams::ForLookup => false,
+                TreatParams::AsCandidateKey => true,
             },
 
             ty::Infer(_) => true,
@@ -333,8 +348,8 @@ impl DeepRejectCtxt {
         let k = impl_ct.kind();
         match obligation_ct.kind() {
             ty::ConstKind::Param(_) => match self.treat_obligation_params {
-                TreatParams::AsPlaceholder => false,
-                TreatParams::AsInfer => true,
+                TreatParams::ForLookup => false,
+                TreatParams::AsCandidateKey => true,
             },
 
             // As we don't necessarily eagerly evaluate constants,