Rollup merge of rust-lang#87107 - oli-obk:tait_double, r=nikomatsakis

Loop over all opaque types instead of looking at just the first one with the same DefId

This exposed a bug in VecMap and is needed for rust-lang#86410 anyway

r? ``@spastorino``

cc ``@nikomatsakis``

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_typeck/src/collect/type_of.rs

@@ -509,11 +509,10 @@ pub(super) fn type_of(tcx: TyCtxt<'_>, def_id: DefId) -> Ty<'_> {
  }
 }
 
+#[instrument(skip(tcx), level = "debug")]
 fn find_opaque_ty_constraints(tcx: TyCtxt<'_>, def_id: LocalDefId) -> Ty<'_> {
  use rustc_hir::{Expr, ImplItem, Item, TraitItem};
 
- debug!("find_opaque_ty_constraints({:?})", def_id);
-
  struct ConstraintLocator<'tcx> {
  tcx: TyCtxt<'tcx>,
  def_id: DefId,
@@ -522,13 +521,11 @@ fn find_opaque_ty_constraints(tcx: TyCtxt<'_>, def_id: LocalDefId) -> Ty<'_> {
  }
 
  impl ConstraintLocator<'_> {
+ #[instrument(skip(self), level = "debug")]
  fn check(&mut self, def_id: LocalDefId) {
  // Don't try to check items that cannot possibly constrain the type.
  if !self.tcx.has_typeck_results(def_id) {
- debug!(
- "find_opaque_ty_constraints: no constraint for `{:?}` at `{:?}`: no typeck results",
- self.def_id, def_id,
- );
+ debug!("no constraint: no typeck results");
  return;
  }
  // Calling `mir_borrowck` can lead to cycle errors through
@@ -540,21 +537,19 @@ fn find_opaque_ty_constraints(tcx: TyCtxt<'_>, def_id: LocalDefId) -> Ty<'_> {
  .get_by(|(key, _)| key.def_id == self.def_id)
  .is_none()
  {
- debug!(
- "find_opaque_ty_constraints: no constraint for `{:?}` at `{:?}`",
- self.def_id, def_id,
- );
+ debug!("no constraints in typeck results");
  return;
  }
  // Use borrowck to get the type with unerased regions.
  let concrete_opaque_types = &self.tcx.mir_borrowck(def_id).concrete_opaque_types;
- if let Some((opaque_type_key, concrete_type)) =
- concrete_opaque_types.iter().find(|(key, _)| key.def_id == self.def_id)
- {
- debug!(
- "find_opaque_ty_constraints: found constraint for `{:?}` at `{:?}`: {:?}",
- self.def_id, def_id, concrete_type,
- );
+ debug!(?concrete_opaque_types);
+ for (opaque_type_key, concrete_type) in concrete_opaque_types {
+ if opaque_type_key.def_id != self.def_id {
+ // Ignore constraints for other opaque types.
+ continue;
+ }
+
+ debug!(?concrete_type, ?opaque_type_key.substs, "found constraint");
 
  // FIXME(oli-obk): trace the actual span from inference to improve errors.
  let span = self.tcx.def_span(def_id);
@@ -603,7 +598,7 @@ fn find_opaque_ty_constraints(tcx: TyCtxt<'_>, def_id: LocalDefId) -> Ty<'_> {
 
  if let Some((prev_span, prev_ty)) = self.found {
  if *concrete_type != prev_ty {
- debug!("find_opaque_ty_constraints: span={:?}", span);
+ debug!(?span);
  // Found different concrete types for the opaque type.
  let mut err = self.tcx.sess.struct_span_err(
  span,
@@ -619,11 +614,6 @@ fn find_opaque_ty_constraints(tcx: TyCtxt<'_>, def_id: LocalDefId) -> Ty<'_> {
  } else {
  self.found = Some((span, concrete_type));
  }
- } else {
- debug!(
- "find_opaque_ty_constraints: no constraint for `{:?}` at `{:?}`",
- self.def_id, def_id,
- );
  }
  }
  }

src/test/ui/type-alias-impl-trait/issue-85113.rs

@@ -12,6 +12,7 @@ trait Output<'a> {}
 impl<'a> Output<'a> for &'a str {}
 
 fn cool_fn<'a>(arg: &'a str) -> OpaqueOutputImpl<'a> {
+ //~^ ERROR: concrete type differs from previous defining opaque type use
  let out: OpaqueOutputImpl<'a> = arg;
  arg
 }

src/test/ui/type-alias-impl-trait/issue-85113.stderr

@@ -10,6 +10,18 @@ note: hidden type `&'<empty> str` captures lifetime smaller than the function bo
 LL | type OpaqueOutputImpl<'a> = impl Output<'a> + 'a;
  | ^^^^^^^^^^^^^^^^^^^^
 
+error: concrete type differs from previous defining opaque type use
+ --> $DIR/issue-85113.rs:14:1
+ |
+LL | fn cool_fn<'a>(arg: &'a str) -> OpaqueOutputImpl<'a> {
+ | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `&'<empty> str`, got `&'a str`
+ |
+note: previous use here
+ --> $DIR/issue-85113.rs:14:1
+ |
+LL | fn cool_fn<'a>(arg: &'a str) -> OpaqueOutputImpl<'a> {
+ | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
 error[E0477]: the type `&'<empty> str` does not fulfill the required lifetime
  --> $DIR/issue-85113.rs:5:29
  |
@@ -42,7 +54,7 @@ LL | type OpaqueOutputImpl<'a> = impl Output<'a> + 'a;
  = note: expected `Output<'a>`
  found `Output<'_>`
 
-error: aborting due to 3 previous errors
+error: aborting due to 4 previous errors
 
 Some errors have detailed explanations: E0477, E0495, E0700.
 For more information about an error, try `rustc --explain E0477`.