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Rollup merge of #119175 - veera-sivarajan:fix-cast-to-slice, r=WaffleLapkin

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fix: diagnostic for casting reference to slice

fixes:  #118790

Removes `if self.cast_ty.is_trait()` to produce the same diagnostic for cast to slice and trait.
This commit is contained in:
Matthias Krüger 2023-12-27 09:11:35 +01:00 committed by GitHub
commit d6382c785f
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GPG Key ID: 4AEE18F83AFDEB23
5 changed files with 45 additions and 32 deletions
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30
compiler/rustc_hir_typeck/src/cast.rs
View File

@ -539,25 +539,19 @@ fn report_cast_to_unsized_type(&self, fcx: &FnCtxt<'a, 'tcx>) -> ErrorGuaranteed
match self.expr_ty.kind() {
ty::Ref(_, _, mt) => {
let mtstr = mt.prefix_str();
if self.cast_ty.is_trait() {
match fcx.tcx.sess.source_map().span_to_snippet(self.cast_span) {
Ok(s) => {
err.span_suggestion(
self.cast_span,
"try casting to a reference instead",
format!("&{mtstr}{s}"),
Applicability::MachineApplicable,
);
}
Err(_) => {
let msg = format!("did you mean `&{mtstr}{tstr}`?");
err.span_help(self.cast_span, msg);
}
match fcx.tcx.sess.source_map().span_to_snippet(self.cast_span) {
Ok(s) => {
err.span_suggestion(
self.cast_span,
"try casting to a reference instead",
format!("&{mtstr}{s}"),
Applicability::MachineApplicable,
);
}
Err(_) => {
let msg = format!("did you mean `&{mtstr}{tstr}`?");
err.span_help(self.cast_span, msg);
}
} else {
let msg =
format!("consider using an implicit coercion to `&{mtstr}{tstr}` instead");
err.span_help(self.span, msg);
}
}
ty::Adt(def, ..) if def.is_box() => {

8
tests/ui/cast/cast-to-slice.rs Normal file
View File

@ -0,0 +1,8 @@
fn main() {
"example".as_bytes() as [char];
//~^ ERROR cast to unsized type
let arr: &[u8] = &[0, 2, 3];
arr as [char];
//~^ ERROR cast to unsized type
}

19
tests/ui/cast/cast-to-slice.stderr Normal file
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@ -0,0 +1,19 @@
error[E0620]: cast to unsized type: `&[u8]` as `[char]`
--> $DIR/cast-to-slice.rs:2:5
|
LL | "example".as_bytes() as [char];
| ^^^^^^^^^^^^^^^^^^^^^^^^------
| |
| help: try casting to a reference instead: `&[char]`
error[E0620]: cast to unsized type: `&[u8]` as `[char]`
--> $DIR/cast-to-slice.rs:6:5
|
LL | arr as [char];
| ^^^^^^^------
| |
| help: try casting to a reference instead: `&[char]`
error: aborting due to 2 previous errors
For more information about this error, try `rustc --explain E0620`.

10
tests/ui/error-codes/E0620.stderr
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@ -2,13 +2,9 @@ error[E0620]: cast to unsized type: `&[usize; 2]` as `[usize]`
--> $DIR/E0620.rs:2:16
|
LL | let _foo = &[1_usize, 2] as [usize];
| ^^^^^^^^^^^^^^^^^^^^^^^^
|
help: consider using an implicit coercion to `&[usize]` instead
--> $DIR/E0620.rs:2:16
|
LL | let _foo = &[1_usize, 2] as [usize];
| ^^^^^^^^^^^^^^^^^^^^^^^^
| ^^^^^^^^^^^^^^^^^-------
| |
| help: try casting to a reference instead: `&[usize]`
error: aborting due to 1 previous error

10
tests/ui/issues/issue-17441.stderr
View File

@ -2,13 +2,9 @@ error[E0620]: cast to unsized type: `&[usize; 2]` as `[usize]`
--> $DIR/issue-17441.rs:2:16
|
LL | let _foo = &[1_usize, 2] as [usize];
| ^^^^^^^^^^^^^^^^^^^^^^^^
|
help: consider using an implicit coercion to `&[usize]` instead
--> $DIR/issue-17441.rs:2:16
|
LL | let _foo = &[1_usize, 2] as [usize];
| ^^^^^^^^^^^^^^^^^^^^^^^^
| ^^^^^^^^^^^^^^^^^-------
| |
| help: try casting to a reference instead: `&[usize]`
error[E0620]: cast to unsized type: `Box<usize>` as `dyn Debug`
--> $DIR/issue-17441.rs:5:16