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Auto merge of #118261 - spastorino:fix-placeholder-replacer, r=compiler-errors

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Make PlaceholderReplacer shallow_resolver and recur when infer vars

This makes resolve type and const infer vars resolve.

Given:

```rust
#![feature(inherent_associated_types)]
#![allow(incomplete_features)]

struct Foo<T>(T);

impl<'a> Foo<fn(&'a ())> {
    type Assoc = &'a ();
}

fn bar(_: for<'a> fn(Foo<fn(Foo<fn(&'static ())>::Assoc)>::Assoc)) {}

fn main() {}
```

We should normalize `for<'a> fn(Foo<fn(Foo<fn(&'static ())>::Assoc)>::Assoc)` to `for<'0> fn(&'1 ())` with `'1 == '0` and `'0 == 'static` constraints. We have to resolve `'1` to `'static` in the infcx associated to `PlaceholderReplacer`.

This is part of https://github.com/rust-lang/rust/pull/118118 but unrelated to that PR.

r? `@compiler-errors` `@lcnr`
This commit is contained in:
bors 2023-11-25 05:10:10 +00:00
commit b2e73e9aad
1 changed files with 18 additions and 4 deletions
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22
compiler/rustc_trait_selection/src/traits/project.rs
View file

@ -1001,7 +1001,7 @@ impl<'tcx> TypeFolder<TyCtxt<'tcx>> for PlaceholderReplacer<'_, 'tcx> {
&mut self,
t: ty::Binder<'tcx, T>,
) -> ty::Binder<'tcx, T> {
if !t.has_placeholders() && !t.has_infer_regions() {
if !t.has_placeholders() && !t.has_infer() {
return t;
}
self.current_index.shift_in(1);
@ -1048,6 +1048,7 @@ impl<'tcx> TypeFolder<TyCtxt<'tcx>> for PlaceholderReplacer<'_, 'tcx> {
}
fn fold_ty(&mut self, ty: Ty<'tcx>) -> Ty<'tcx> {
let ty = self.infcx.shallow_resolve(ty);
match *ty.kind() {
ty::Placeholder(p) => {
let replace_var = self.mapped_types.get(&p);
@ -1063,16 +1064,23 @@ impl<'tcx> TypeFolder<TyCtxt<'tcx>> for PlaceholderReplacer<'_, 'tcx> {
);
Ty::new_bound(self.infcx.tcx, db, *replace_var)
}
None => ty,
None => {
if ty.has_infer() {
ty.super_fold_with(self)
} else {
ty
}
}
}
}
_ if ty.has_placeholders() || ty.has_infer_regions() => ty.super_fold_with(self),
_ if ty.has_placeholders() || ty.has_infer() => ty.super_fold_with(self),
_ => ty,
}
}
fn fold_const(&mut self, ct: ty::Const<'tcx>) -> ty::Const<'tcx> {
let ct = self.infcx.shallow_resolve(ct);
if let ty::ConstKind::Placeholder(p) = ct.kind() {
let replace_var = self.mapped_consts.get(&p);
match replace_var {
@ -1087,7 +1095,13 @@ impl<'tcx> TypeFolder<TyCtxt<'tcx>> for PlaceholderReplacer<'_, 'tcx> {
);
ty::Const::new_bound(self.infcx.tcx, db, *replace_var, ct.ty())
}
None => ct,
None => {
if ct.has_infer() {
ct.super_fold_with(self)
} else {
ct
}
}
}
} else {
ct.super_fold_with(self)