Auto merge of rust-lang#87201 - GuillaumeGomez:rollup-4loi2q9, r=Guil…

…laumeGomez

Rollup of 7 pull requests

Successful merges:

 - rust-lang#87107 (Loop over all opaque types instead of looking at just the first one with the same DefId)
 - rust-lang#87158 (Suggest full enum variant for local modules)
 - rust-lang#87174 (Stabilize `[T; N]::map()`)
 - rust-lang#87179 (Mark `const_trait_impl` as active)
 - rust-lang#87180 (feat(rustdoc): open sidebar menu when links inside it are focused)
 - rust-lang#87188 (Add GUI test for auto-hide-trait-implementations setting)
 - rust-lang#87200 (TAIT: Infer all inference variables in opaque type substitutions via InferCx)

Failed merges:

r? `@ghost`
`@rustbot` modify labels: rollup

compiler/rustc_data_structures/src/vec_map.rs

@@ -127,13 +127,15 @@ impl<K, V> IntoIterator for VecMap<K, V> {
  }
 }
 
-impl<K, V> Extend<(K, V)> for VecMap<K, V> {
+impl<K: PartialEq, V> Extend<(K, V)> for VecMap<K, V> {
  fn extend<I: IntoIterator<Item = (K, V)>>(&mut self, iter: I) {
- self.0.extend(iter);
+ for (k, v) in iter {
+ self.insert(k, v);
+ }
  }
 
- fn extend_one(&mut self, item: (K, V)) {
- self.0.extend_one(item);
+ fn extend_one(&mut self, (k, v): (K, V)) {
+ self.insert(k, v);
  }
 
  fn extend_reserve(&mut self, additional: usize) {

compiler/rustc_feature/src/active.rs

@@ -534,7 +534,7 @@ declare_features! (
  (active, bindings_after_at, "1.41.0", Some(65490), None),
 
  /// Allows `impl const Trait for T` syntax.
- (incomplete, const_trait_impl, "1.42.0", Some(67792), None),
+ (active, const_trait_impl, "1.42.0", Some(67792), None),
 
  /// Allows `T: ?const Trait` syntax in bounds.
  (incomplete, const_trait_bound_opt_out, "1.42.0", Some(67794), None),

compiler/rustc_middle/src/ty/mod.rs

@@ -857,7 +857,7 @@ impl<'tcx> InstantiatedPredicates<'tcx> {
  }
 }
 
-#[derive(Copy, Clone, Debug, PartialEq, Eq, HashStable, TyEncodable, TyDecodable)]
+#[derive(Copy, Clone, Debug, PartialEq, Eq, HashStable, TyEncodable, TyDecodable, TypeFoldable)]
 pub struct OpaqueTypeKey<'tcx> {
  pub def_id: DefId,
  pub substs: SubstsRef<'tcx>,

compiler/rustc_trait_selection/src/opaque_types.rs

@@ -568,6 +568,7 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
  /// - `substs`, the substs used to instantiate this opaque type
  /// - `instantiated_ty`, the inferred type C1 -- fully resolved, lifted version of
  /// `opaque_defn.concrete_ty`
+ #[instrument(skip(self))]
  fn infer_opaque_definition_from_instantiation(
  &self,
  opaque_type_key: OpaqueTypeKey<'tcx>,
@@ -576,18 +577,14 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
  ) -> Ty<'tcx> {
  let OpaqueTypeKey { def_id, substs } = opaque_type_key;
 
- debug!(
- "infer_opaque_definition_from_instantiation(def_id={:?}, instantiated_ty={:?})",
- def_id, instantiated_ty
- );
-
  // Use substs to build up a reverse map from regions to their
  // identity mappings. This is necessary because of `impl
  // Trait` lifetimes are computed by replacing existing
  // lifetimes with 'static and remapping only those used in the
  // `impl Trait` return type, resulting in the parameters
  // shifting.
  let id_substs = InternalSubsts::identity_for_item(self.tcx, def_id);
+ debug!(?id_substs);
  let map: FxHashMap<GenericArg<'tcx>, GenericArg<'tcx>> =
  substs.iter().enumerate().map(|(index, subst)| (subst, id_substs[index])).collect();
 
@@ -602,7 +599,7 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
  instantiated_ty,
  span,
  ));
- debug!("infer_opaque_definition_from_instantiation: definition_ty={:?}", definition_ty);
+ debug!(?definition_ty);
 
  definition_ty
  }
@@ -857,14 +854,15 @@ impl TypeFolder<'tcx> for ReverseMapper<'tcx> {
  self.tcx.mk_generator(def_id, substs, movability)
  }
 
- ty::Param(..) => {
+ ty::Param(param) => {
  // Look it up in the substitution list.
  match self.map.get(&ty.into()).map(|k| k.unpack()) {
  // Found it in the substitution list; replace with the parameter from the
  // opaque type.
  Some(GenericArgKind::Type(t1)) => t1,
  Some(u) => panic!("type mapped to unexpected kind: {:?}", u),
  None => {
+ debug!(?param, ?self.map);
  self.tcx
  .sess
  .struct_span_err(
@@ -931,8 +929,8 @@ struct Instantiator<'a, 'tcx> {
 }
 
 impl<'a, 'tcx> Instantiator<'a, 'tcx> {
+ #[instrument(skip(self))]
  fn instantiate_opaque_types_in_map<T: TypeFoldable<'tcx>>(&mut self, value: T) -> T {
- debug!("instantiate_opaque_types_in_map(value={:?})", value);
  let tcx = self.infcx.tcx;
  value.fold_with(&mut BottomUpFolder {
  tcx,

compiler/rustc_typeck/src/check/demand.rs

@@ -10,6 +10,7 @@ use rustc_hir::lang_items::LangItem;
 use rustc_hir::{is_range_literal, Node};
 use rustc_middle::lint::in_external_macro;
 use rustc_middle::ty::adjustment::AllowTwoPhase;
+use rustc_middle::ty::print::with_no_trimmed_paths;
 use rustc_middle::ty::{self, AssocItem, Ty, TypeAndMut};
 use rustc_span::symbol::sym;
 use rustc_span::Span;
@@ -201,7 +202,8 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
  let sole_field = &variant.fields[0];
  let sole_field_ty = sole_field.ty(self.tcx, substs);
  if self.can_coerce(expr_ty, sole_field_ty) {
- let variant_path = self.tcx.def_path_str(variant.def_id);
+ let variant_path =
+ with_no_trimmed_paths(|| self.tcx.def_path_str(variant.def_id));
  // FIXME #56861: DRYer prelude filtering
  if let Some(path) = variant_path.strip_prefix("std::prelude::") {
  if let Some((_, path)) = path.split_once("::") {

compiler/rustc_typeck/src/check/mod.rs

@@ -112,11 +112,9 @@ use rustc_hir::{HirIdMap, ImplicitSelfKind, Node};
 use rustc_index::bit_set::BitSet;
 use rustc_index::vec::Idx;
 use rustc_infer::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind};
-use rustc_middle::ty::fold::{TypeFoldable, TypeFolder};
 use rustc_middle::ty::query::Providers;
-use rustc_middle::ty::subst::GenericArgKind;
 use rustc_middle::ty::subst::{InternalSubsts, Subst, SubstsRef};
-use rustc_middle::ty::{self, RegionKind, Ty, TyCtxt, UserType};
+use rustc_middle::ty::{self, Ty, TyCtxt, UserType};
 use rustc_session::config;
 use rustc_session::parse::feature_err;
 use rustc_session::Session;
@@ -321,117 +319,6 @@ fn used_trait_imports(tcx: TyCtxt<'_>, def_id: LocalDefId) -> &FxHashSet<LocalDe
  &*tcx.typeck(def_id).used_trait_imports
 }
 
-/// Inspects the substs of opaque types, replacing any inference variables
-/// with proper generic parameter from the identity substs.
-///
-/// This is run after we normalize the function signature, to fix any inference
-/// variables introduced by the projection of associated types. This ensures that
-/// any opaque types used in the signature continue to refer to generic parameters,
-/// allowing them to be considered for defining uses in the function body
-///
-/// For example, consider this code.
-///
-/// ```rust
-/// trait MyTrait {
-/// type MyItem;
-/// fn use_it(self) -> Self::MyItem
-/// }
-/// impl<T, I> MyTrait for T where T: Iterator<Item = I> {
-/// type MyItem = impl Iterator<Item = I>;
-/// fn use_it(self) -> Self::MyItem {
-/// self
-/// }
-/// }
-/// ```
-///
-/// When we normalize the signature of `use_it` from the impl block,
-/// we will normalize `Self::MyItem` to the opaque type `impl Iterator<Item = I>`
-/// However, this projection result may contain inference variables, due
-/// to the way that projection works. We didn't have any inference variables
-/// in the signature to begin with - leaving them in will cause us to incorrectly
-/// conclude that we don't have a defining use of `MyItem`. By mapping inference
-/// variables back to the actual generic parameters, we will correctly see that
-/// we have a defining use of `MyItem`
-fn fixup_opaque_types<'tcx, T>(tcx: TyCtxt<'tcx>, val: T) -> T
-where
- T: TypeFoldable<'tcx>,
-{
- struct FixupFolder<'tcx> {
- tcx: TyCtxt<'tcx>,
- }
-
- impl<'tcx> TypeFolder<'tcx> for FixupFolder<'tcx> {
- fn tcx<'a>(&'a self) -> TyCtxt<'tcx> {
- self.tcx
- }
-
- fn fold_ty(&mut self, ty: Ty<'tcx>) -> Ty<'tcx> {
- match *ty.kind() {
- ty::Opaque(def_id, substs) => {
- debug!("fixup_opaque_types: found type {:?}", ty);
- // Here, we replace any inference variables that occur within
- // the substs of an opaque type. By definition, any type occurring
- // in the substs has a corresponding generic parameter, which is what
- // we replace it with.
- // This replacement is only run on the function signature, so any
- // inference variables that we come across must be the rust of projection
- // (there's no other way for a user to get inference variables into
- // a function signature).
- if ty.needs_infer() {
- let new_substs = InternalSubsts::for_item(self.tcx, def_id, |param, _| {
- let old_param = substs[param.index as usize];
- match old_param.unpack() {
- GenericArgKind::Type(old_ty) => {
- if let ty::Infer(_) = old_ty.kind() {
- // Replace inference type with a generic parameter
- self.tcx.mk_param_from_def(param)
- } else {
- old_param.fold_with(self)
- }
- }
- GenericArgKind::Const(old_const) => {
- if let ty::ConstKind::Infer(_) = old_const.val {
- // This should never happen - we currently do not support
- // 'const projections', e.g.:
- // `impl<T: SomeTrait> MyTrait for T where <T as SomeTrait>::MyConst == 25`
- // which should be the only way for us to end up with a const inference
- // variable after projection. If Rust ever gains support for this kind
- // of projection, this should *probably* be changed to
- // `self.tcx.mk_param_from_def(param)`
- bug!(
- "Found infer const: `{:?}` in opaque type: {:?}",
- old_const,
- ty
- );
- } else {
- old_param.fold_with(self)
- }
- }
- GenericArgKind::Lifetime(old_region) => {
- if let RegionKind::ReVar(_) = old_region {
- self.tcx.mk_param_from_def(param)
- } else {
- old_param.fold_with(self)
- }
- }
- }
- });
- let new_ty = self.tcx.mk_opaque(def_id, new_substs);
- debug!("fixup_opaque_types: new type: {:?}", new_ty);
- new_ty
- } else {
- ty
- }
- }
- _ => ty.super_fold_with(self),
- }
- }
- }
-
- debug!("fixup_opaque_types({:?})", val);
- val.fold_with(&mut FixupFolder { tcx })
-}
-
 fn typeck_const_arg<'tcx>(
  tcx: TyCtxt<'tcx>,
  (did, param_did): (LocalDefId, DefId),
@@ -510,8 +397,6 @@ fn typeck_with_fallback<'tcx>(
  fn_sig,
  );
 
- let fn_sig = fixup_opaque_types(tcx, fn_sig);
-
  let fcx = check_fn(&inh, param_env, fn_sig, decl, id, body, None).0;
  fcx
  } else {

compiler/rustc_typeck/src/check/writeback.rs

@@ -496,6 +496,8 @@ impl<'cx, 'tcx> WritebackCx<'cx, 'tcx> {
 
  debug_assert!(!instantiated_ty.has_escaping_bound_vars());
 
+ let opaque_type_key = self.fcx.fully_resolve(opaque_type_key).unwrap();
+
  // Prevent:
  // * `fn foo<T>() -> Foo<T>`
  // * `fn foo<T: Bound + Other>() -> Foo<T>`
@@ -508,6 +510,8 @@ impl<'cx, 'tcx> WritebackCx<'cx, 'tcx> {
  // fn foo<U>() -> Foo<U> { .. }
  // ```
  // figures out the concrete type with `U`, but the stored type is with `T`.
+
+ // FIXME: why are we calling this here? This seems too early, and duplicated.
  let definition_ty = self.fcx.infer_opaque_definition_from_instantiation(
  opaque_type_key,
  instantiated_ty,
@@ -529,33 +533,33 @@ impl<'cx, 'tcx> WritebackCx<'cx, 'tcx> {
  }
  }
 
- if !opaque_type_key.substs.needs_infer() {
- // We only want to add an entry into `concrete_opaque_types`
- // if we actually found a defining usage of this opaque type.
- // Otherwise, we do nothing - we'll either find a defining usage
- // in some other location, or we'll end up emitting an error due
- // to the lack of defining usage
- if !skip_add {
- let old_concrete_ty = self
- .typeck_results
- .concrete_opaque_types
- .insert(opaque_type_key, definition_ty);
- if let Some(old_concrete_ty) = old_concrete_ty {
- if old_concrete_ty != definition_ty {
- span_bug!(
- span,
- "`visit_opaque_types` tried to write different types for the same \
+ if opaque_type_key.substs.needs_infer() {
+ span_bug!(span, "{:#?} has inference variables", opaque_type_key.substs)
+ }
+
+ // We only want to add an entry into `concrete_opaque_types`
+ // if we actually found a defining usage of this opaque type.
+ // Otherwise, we do nothing - we'll either find a defining usage
+ // in some other location, or we'll end up emitting an error due
+ // to the lack of defining usage
+ if !skip_add {
+ let old_concrete_ty = self
+ .typeck_results
+ .concrete_opaque_types
+ .insert(opaque_type_key, definition_ty);
+ if let Some(old_concrete_ty) = old_concrete_ty {
+ if old_concrete_ty != definition_ty {
+ span_bug!(
+ span,
+ "`visit_opaque_types` tried to write different types for the same \
  opaque type: {:?}, {:?}, {:?}, {:?}",
- opaque_type_key.def_id,
- definition_ty,
- opaque_defn,
- old_concrete_ty,
- );
- }
+ opaque_type_key.def_id,
+ definition_ty,
+ opaque_defn,
+ old_concrete_ty,
+ );
  }
  }
- } else {
- self.tcx().sess.delay_span_bug(span, "`opaque_defn` has inference variables");
  }
  }
  }