diff --git a/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs b/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs index c52365ae3b7c7..439854958270c 100644 --- a/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs +++ b/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs @@ -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", diff --git a/src/test/ui/suggestions/issue-105645.rs b/src/test/ui/suggestions/issue-105645.rs new file mode 100644 index 0000000000000..681ce1c6e37a6 --- /dev/null +++ b/src/test/ui/suggestions/issue-105645.rs @@ -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) {} diff --git a/src/test/ui/suggestions/issue-105645.stderr b/src/test/ui/suggestions/issue-105645.stderr new file mode 100644 index 0000000000000..895f5ffd1e1c7 --- /dev/null +++ b/src/test/ui/suggestions/issue-105645.stderr @@ -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`.