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More tests and tweak comments

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This commit is contained in:
Michael Goulet 2024-09-20 22:59:03 -04:00
parent af24d0b660
commit 1de894f0c1
11 changed files with 298 additions and 11 deletions
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19
compiler/rustc_hir_analysis/src/collect/resolve_bound_vars.rs
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@ -1640,9 +1640,9 @@ impl<'a, 'tcx> BoundVarContext<'a, 'tcx> {
// }
// ```
// and a bound that looks like:
// `for<'a> T::Trait<'a, x(): for<'b> Other<'b>>`
// `for<'a> T::Trait<'a, x(..): for<'b> Other<'b>>`
// this is going to expand to something like:
// `for<'a> for<'r, T> <T as Trait<'a>>::x::<'r, T>::{opaque#0}: for<'b> Other<'b>`.
// `for<'a> for<'r> <T as Trait<'a>>::x::<'r, T>::{opaque#0}: for<'b> Other<'b>`.
if constraint.gen_args.parenthesized == hir::GenericArgsParentheses::ReturnTypeNotation
{
let bound_vars = if let Some(type_def_id) = type_def_id
@ -1853,13 +1853,13 @@ impl<'a, 'tcx> BoundVarContext<'a, 'tcx> {
// For example, given
// ```
// trait Foo {
// async fn x<'r, T>();
// async fn x<'r>();
// }
// ```
// and a bound that looks like:
// `for<'a, 'b> <T as Trait<'a>>::x(): Other<'b>`
// this is going to expand to something like:
// `for<'a, 'b, 'r, T> <T as Trait<'a>>::x::<'r, T>::{opaque#0}: Other<'b>`.
// `for<'a, 'b, 'r> <T as Trait<'a>>::x::<'r, T>::{opaque#0}: Other<'b>`.
//
// We handle this similarly for associated-type-bound style return-type-notation
// in `visit_segment_args`.
@ -2000,6 +2000,17 @@ impl<'a, 'tcx> BoundVarContext<'a, 'tcx> {
// the new bound vars. We do this because we need to know how many bound vars
// are present on the binder explicitly (i.e. not return-type-notation vars)
// to do bound var shifting correctly in HIR lowering.
//
// For example, in `where for<'a> <T as Trait<'a>>::method(..): Other`,
// the `late_bound_vars` of the where clause predicate (i.e. this HIR ty's
// parent) will include `'a` AND all the early- and late-bound vars of the
// method. But when lowering the RTN type, we just want the list of vars
// we used to resolve the trait ref. We explicitly stored those back onto
// the item segment, since there's no other good place to put them.
//
// See where these vars are used in `HirTyLowerer::lower_ty_maybe_return_type_notation`.
// And this is exercised in:
// `tests/ui/associated-type-bounds/return-type-notation/higher-ranked-bound-works.rs`.
let existing_bound_vars = self.map.late_bound_vars.get_mut(&hir_id).unwrap();
let existing_bound_vars_saved = existing_bound_vars.clone();
existing_bound_vars.extend(bound_vars);