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Auto merge of #88312 - jackh726:issue-87748, r=nikomatsakis

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Treat types in unnormalized function signatures as well-formed

Fixes #87748

r? `@nikomatsakis`
This commit is contained in:
bors 2021-08-29 10:12:54 +00:00
commit 59ce765484
6 changed files with 90 additions and 9 deletions
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19
compiler/rustc_mir/src/borrow_check/type_check/free_region_relations.rs
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@ -256,6 +256,9 @@ impl UniversalRegionRelationsBuilder<'cx, 'tcx> {
let constraint_sets: Vec<_> = unnormalized_input_output_tys
.flat_map(|ty| {
debug!("build: input_or_output={:?}", ty);
// We add implied bounds from both the unnormalized and normalized ty
// See issue #87748
let constraints_implied_1 = self.add_implied_bounds(ty);
let TypeOpOutput { output: ty, constraints: constraints1, .. } = self
.param_env
.and(type_op::normalize::Normalize::new(ty))
@ -271,9 +274,21 @@ impl UniversalRegionRelationsBuilder<'cx, 'tcx> {
canonicalized_query: None,
}
});
let constraints2 = self.add_implied_bounds(ty);
// Note: we need this in examples like
// ```
// trait Foo {
// type Bar;
// fn foo(&self) -> &Self::Bar;
// }
// impl Foo for () {
// type Bar = ();
// fn foo(&self) ->&() {}
// }
// ```
// Both &Self::Bar and &() are WF
let constraints_implied_2 = self.add_implied_bounds(ty);
normalized_inputs_and_output.push(ty);
constraints1.into_iter().chain(constraints2)
constraints1.into_iter().chain(constraints_implied_1).chain(constraints_implied_2)
})
.collect();