Skip to content

Commit

Permalink
Rollup merge of rust-lang#105655 - RedDocMD:bug-105645, r=oli-obk
Browse files Browse the repository at this point in the history
Remove invalid case for mutable borrow suggestion

If we have a call such as `foo(&mut buf)` and after reference
collapsing the type is inferred as `&T` where-as the required type is
`&mut T`, don't suggest `foo(&mut mut buf)`. This is wrong syntactically
and the issue lies elsewhere, not in the borrow.

Fixes rust-lang#105645
  • Loading branch information
Yuki Okushi authored Jan 9, 2023
2 parents 4f8a55c + afefbb6 commit 1255b6f
Show file tree
Hide file tree
Showing 3 changed files with 33 additions and 0 deletions.
Original file line number Diff line number Diff line change
Expand Up @@ -1519,6 +1519,13 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
.source_map()
.span_take_while(span, |c| c.is_whitespace() || *c == '&');
if points_at_arg && mutability.is_not() && refs_number > 0 {
// If we have a call like foo(&mut buf), then don't suggest foo(&mut mut buf)
if snippet
.trim_start_matches(|c: char| c.is_whitespace() || c == '&')
.starts_with("mut")
{
return;
}
err.span_suggestion_verbose(
sp,
"consider changing this borrow's mutability",
Expand Down
8 changes: 8 additions & 0 deletions src/test/ui/suggestions/issue-105645.rs
Original file line number Diff line number Diff line change
@@ -0,0 +1,8 @@
fn main() {
let mut buf = [0u8; 50];
let mut bref = buf.as_slice();
foo(&mut bref);
//~^ ERROR 4:9: 4:18: the trait bound `&[u8]: std::io::Write` is not satisfied [E0277]
}

fn foo(_: &mut impl std::io::Write) {}
18 changes: 18 additions & 0 deletions src/test/ui/suggestions/issue-105645.stderr
Original file line number Diff line number Diff line change
@@ -0,0 +1,18 @@
error[E0277]: the trait bound `&[u8]: std::io::Write` is not satisfied
--> $DIR/issue-105645.rs:4:9
|
LL | foo(&mut bref);
| --- ^^^^^^^^^ the trait `std::io::Write` is not implemented for `&[u8]`
| |
| required by a bound introduced by this call
|
= help: the trait `std::io::Write` is implemented for `&mut [u8]`
note: required by a bound in `foo`
--> $DIR/issue-105645.rs:8:21
|
LL | fn foo(_: &mut impl std::io::Write) {}
| ^^^^^^^^^^^^^^ required by this bound in `foo`

error: aborting due to previous error

For more information about this error, try `rustc --explain E0277`.

0 comments on commit 1255b6f

Please sign in to comment.