Auto merge of #54599 - nikomatsakis:issue-54593-impl-Trait, r=eddyb
use closure def-id in returns, but base def-id in locals The refactorings to handle `let x: impl Trait` wound up breaking `impl Trait` in closure return types. I think there are some deeper problems with the code in question, but this a least should make @eddyb's example work. Fixes #54593 r? @eddyb
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eb50e75729
@ -70,6 +70,7 @@ impl<'a, 'gcx, 'tcx> TypeChecker<'a, 'gcx, 'tcx> {
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if let Err(terr) = self.eq_opaque_type_and_type(
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mir_output_ty,
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normalized_output_ty,
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self.mir_def_id,
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Locations::All(output_span),
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ConstraintCategory::BoringNoLocation,
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) {
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@ -901,6 +901,10 @@ impl<'a, 'gcx, 'tcx> TypeChecker<'a, 'gcx, 'tcx> {
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)
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}
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/// Try to relate `sub <: sup`; if this fails, instantiate opaque
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/// variables in `sub` with their inferred definitions and try
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/// again. This is used for opaque types in places (e.g., `let x:
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/// impl Foo = ..`).
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fn sub_types_or_anon(
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&mut self,
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sub: Ty<'tcx>,
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@ -910,7 +914,11 @@ impl<'a, 'gcx, 'tcx> TypeChecker<'a, 'gcx, 'tcx> {
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) -> Fallible<()> {
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if let Err(terr) = self.sub_types(sub, sup, locations, category) {
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if let TyKind::Opaque(..) = sup.sty {
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return self.eq_opaque_type_and_type(sub, sup, locations, category);
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// When you have `let x: impl Foo = ...` in a closure,
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// the resulting inferend values are stored with the
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// def-id of the base function.
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let parent_def_id = self.tcx().closure_base_def_id(self.mir_def_id);
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return self.eq_opaque_type_and_type(sub, sup, parent_def_id, locations, category);
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} else {
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return Err(terr);
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}
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@ -958,13 +966,20 @@ impl<'a, 'gcx, 'tcx> TypeChecker<'a, 'gcx, 'tcx> {
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&mut self,
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revealed_ty: Ty<'tcx>,
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anon_ty: Ty<'tcx>,
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anon_owner_def_id: DefId,
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locations: Locations,
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category: ConstraintCategory,
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) -> Fallible<()> {
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debug!(
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"eq_opaque_type_and_type( \
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revealed_ty={:?}, \
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anon_ty={:?})",
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revealed_ty, anon_ty
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);
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let infcx = self.infcx;
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let tcx = infcx.tcx;
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let param_env = self.param_env;
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let parent_def_id = infcx.tcx.closure_base_def_id(self.mir_def_id);
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debug!("eq_opaque_type_and_type: mir_def_id={:?}", self.mir_def_id);
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let opaque_type_map = self.fully_perform_op(
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locations,
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category,
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@ -975,7 +990,7 @@ impl<'a, 'gcx, 'tcx> TypeChecker<'a, 'gcx, 'tcx> {
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let dummy_body_id = ObligationCause::dummy().body_id;
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let (output_ty, opaque_type_map) =
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obligations.add(infcx.instantiate_opaque_types(
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parent_def_id,
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anon_owner_def_id,
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dummy_body_id,
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param_env,
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&anon_ty,
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@ -996,8 +1011,10 @@ impl<'a, 'gcx, 'tcx> TypeChecker<'a, 'gcx, 'tcx> {
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let opaque_defn_ty = opaque_defn_ty.subst(tcx, opaque_decl.substs);
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let opaque_defn_ty = renumber::renumber_regions(infcx, &opaque_defn_ty);
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debug!(
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"eq_opaque_type_and_type: concrete_ty={:?} opaque_defn_ty={:?}",
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opaque_decl.concrete_ty, opaque_defn_ty
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"eq_opaque_type_and_type: concrete_ty={:?}={:?} opaque_defn_ty={:?}",
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opaque_decl.concrete_ty,
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infcx.resolve_type_vars_if_possible(&opaque_decl.concrete_ty),
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opaque_defn_ty
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);
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obligations.add(infcx
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.at(&ObligationCause::dummy(), param_env)
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14
src/test/ui/impl-trait/closure-calling-parent-fn.rs
Normal file
14
src/test/ui/impl-trait/closure-calling-parent-fn.rs
Normal file
@ -0,0 +1,14 @@
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#![feature(nll)]
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// Regression test for #54593: the MIR type checker was going wrong
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// when a closure returns the `impl Copy` from its parent fn. It was
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// (incorrectly) replacing the `impl Copy` in its return type with the
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// hidden type (`()`) but that type resulted from a recursive call to
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// `foo` and hence is treated opaquely within the closure body. This
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// resulted in a failed subtype relationship.
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//
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// run-pass
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fn foo() -> impl Copy { || foo(); }
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fn bar() -> impl Copy { || bar(); }
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fn main() { }
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