bjoernager/rust
bjoernager/rust
1
Fork 0
Code Activity

Rollup merge of #95607 - compiler-errors:issue-95272, r=Aaron1011

Browse source 
Note invariance reason for FnDef types

Fixes #95272. Is it worthwhile even printing a variance explanation here? Or should I try to track down which function parameter is responsible for the invariance?

r? ``@Aaron1011`` since you wrote #89336
This commit is contained in:
Dylan DPC 2022-04-05 09:33:23 +02:00 • committed by GitHub
commit 2a7e7bd0e0
No known key found for this signature in database
GPG key ID: 4AEE18F83AFDEB23
31 changed files with 158 additions and 113 deletions
Download patch file Download diff file Expand all files Collapse all files

19
compiler/rustc_borrowck/src/diagnostics/region_errors.rs
View file

@ -330,14 +330,14 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
ty::RawPtr(ty_mut) => {
assert_eq!(ty_mut.mutbl, rustc_hir::Mutability::Mut);
(
format!("a mutable pointer to {}", ty_mut.ty),
format!("a mutable pointer to `{}`", ty_mut.ty),
"mutable pointers are invariant over their type parameter".to_string(),
)
}
ty::Ref(_, inner_ty, mutbl) => {
assert_eq!(*mutbl, rustc_hir::Mutability::Mut);
(
format!("a mutable reference to {}", inner_ty),
format!("a mutable reference to `{}`", inner_ty),
"mutable references are invariant over their type parameter"
.to_string(),
)
@ -351,10 +351,21 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
let adt_desc = adt.descr();
let desc = format!(
"the type {ty}, which makes the generic argument {generic_arg} invariant"
"the type `{ty}`, which makes the generic argument `{generic_arg}` invariant"
);
let note = format!(
"the {adt_desc} {base_ty} is invariant over the parameter {base_generic_arg}"
"the {adt_desc} `{base_ty}` is invariant over the parameter `{base_generic_arg}`"
);
(desc, note)
}
ty::FnDef(def_id, _) => {
let name = self.infcx.tcx.item_name(*def_id);
let identity_substs =
InternalSubsts::identity_for_item(self.infcx.tcx, *def_id);
let desc = format!("a function pointer to `{name}`");
let note = format!(
"the function `{name}` is invariant over the parameter `{}`",
identity_substs[param_index as usize]
);
(desc, note)
}