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fix min_const_generics oversight

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This commit is contained in:
lcnr 2022-02-09 12:29:43 +01:00
parent 775e480722
commit 76c562f3b3
3 changed files with 51 additions and 3 deletions
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25
compiler/rustc_typeck/src/astconv/mod.rs
View File

@ -2281,8 +2281,27 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
assert_eq!(opt_self_ty, None);
self.prohibit_generics(path.segments);
// Try to evaluate any array length constants.
let normalized_ty = self.normalize_ty(span, tcx.at(span).type_of(def_id));
if forbid_generic && normalized_ty.needs_subst() {
let ty = tcx.at(span).type_of(def_id);
// HACK(min_const_generics): Forbid generic `Self` types
// here as we can't easily do that during nameres.
//
// We do this before normalization as we otherwise allow
// ```rust
// trait AlwaysApplicable { type Assoc; }
// impl<T: ?Sized> AlwaysApplicable for T { type Assoc = usize; }
//
// trait BindsParam<T> {
// type ArrayTy;
// }
// impl<T> BindsParam<T> for <T as AlwaysApplicable>::Assoc {
// type ArrayTy = [u8; Self::MAX];
// }
// ```
// Note that the normalization happens in the param env of
// the anon const, which is empty. This is why the
// `AlwaysApplicable` impl needs a `T: ?Sized` bound for
// this to compile if we were to normalize here.
if forbid_generic && ty.needs_subst() {
let mut err = tcx.sess.struct_span_err(
path.span,
"generic `Self` types are currently not permitted in anonymous constants",
@ -2297,7 +2316,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
err.emit();
tcx.ty_error()
} else {
normalized_ty
self.normalize_ty(span, ty)
}
}
Res::Def(DefKind::AssocTy, def_id) => {

15
src/test/ui/const-generics/min_const_generics/forbid-self-no-normalize.rs Normal file
View File

@ -0,0 +1,15 @@
trait AlwaysApplicable {
type Assoc;
}
impl<T: ?Sized> AlwaysApplicable for T {
type Assoc = usize;
}
trait BindsParam<T> {
type ArrayTy;
}
impl<T> BindsParam<T> for <T as AlwaysApplicable>::Assoc {
type ArrayTy = [u8; Self::MAX]; //~ ERROR generic `Self` types
}
fn main() {}

14
src/test/ui/const-generics/min_const_generics/forbid-self-no-normalize.stderr Normal file
View File

@ -0,0 +1,14 @@
error: generic `Self` types are currently not permitted in anonymous constants
--> $DIR/forbid-self-no-normalize.rs:12:25
|
LL | type ArrayTy = [u8; Self::MAX];
| ^^^^
|
note: not a concrete type
--> $DIR/forbid-self-no-normalize.rs:11:27
|
LL | impl<T> BindsParam<T> for <T as AlwaysApplicable>::Assoc {
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
error: aborting due to previous error