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Rollup merge of #97169 - gimbles:u32-diagnostic, r=petrochenkov

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Improve `u32 as char` cast diagnostic

Fixes #97160
This commit is contained in:
Dylan DPC 2022-05-19 17:22:50 +02:00 • committed by GitHub
commit 3913d99c40
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4 changed files with 25 additions and 28 deletions
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26
compiler/rustc_typeck/src/check/cast.rs
View file

@ -347,16 +347,22 @@ impl<'a, 'tcx> CastCheck<'tcx> {
); );
err.span_label(self.span, "invalid cast"); err.span_label(self.span, "invalid cast");
if self.expr_ty.is_numeric() { if self.expr_ty.is_numeric() {
err.span_help( if self.expr_ty == fcx.tcx.types.u32 {
self.span, match fcx.tcx.sess.source_map().span_to_snippet(self.expr.span) {
if self.expr_ty == fcx.tcx.types.i8 { Ok(snippet) => err.span_suggestion(
"try casting from `u8` instead" self.span,
} else if self.expr_ty == fcx.tcx.types.u32 { "try `char::from_u32` instead",
"try `char::from_u32` instead" format!("char::from_u32({snippet})"),
} else { Applicability::MachineApplicable,
"try `char::from_u32` instead (via a `u32`)" ),
},
); Err(_) => err.span_help(self.span, "try `char::from_u32` instead"),
};
} else if self.expr_ty == fcx.tcx.types.i8 {
err.span_help(self.span, "try casting from `u8` instead");
} else {
err.span_help(self.span, "try `char::from_u32` instead (via a `u32`)");
};
} }
err.emit(); err.emit();
} }

9
src/test/ui/error-codes/E0604.stderr
View file

@ -1,14 +1,11 @@
error[E0604]: only `u8` can be cast as `char`, not `u32` error[E0604]: only `u8` can be cast as `char`, not `u32`
--> $DIR/E0604.rs:2:5 --> $DIR/E0604.rs:2:5
| |
LL | 1u32 as char;
| ^^^^^^^^^^^^ invalid cast
|
help: try `char::from_u32` instead
--> $DIR/E0604.rs:2:5
|
LL | 1u32 as char; LL | 1u32 as char;
| ^^^^^^^^^^^^ | ^^^^^^^^^^^^
| |
| invalid cast
| help: try `char::from_u32` instead: `char::from_u32(1u32)`
error: aborting due to previous error error: aborting due to previous error

9
src/test/ui/error-festival.stderr
View file

@ -56,14 +56,11 @@ LL | | }
error[E0604]: only `u8` can be cast as `char`, not `u32` error[E0604]: only `u8` can be cast as `char`, not `u32`
--> $DIR/error-festival.rs:25:5 --> $DIR/error-festival.rs:25:5
| |
LL | 0u32 as char;
| ^^^^^^^^^^^^ invalid cast
|
help: try `char::from_u32` instead
--> $DIR/error-festival.rs:25:5
|
LL | 0u32 as char; LL | 0u32 as char;
| ^^^^^^^^^^^^ | ^^^^^^^^^^^^
| |
| invalid cast
| help: try `char::from_u32` instead: `char::from_u32(0u32)`
error[E0605]: non-primitive cast: `u8` as `Vec<u8>` error[E0605]: non-primitive cast: `u8` as `Vec<u8>`
--> $DIR/error-festival.rs:29:5 --> $DIR/error-festival.rs:29:5

9
src/test/ui/mismatched_types/cast-rfc0401.stderr
View file

@ -97,14 +97,11 @@ LL | let _ = E::A as bool;
error[E0604]: only `u8` can be cast as `char`, not `u32` error[E0604]: only `u8` can be cast as `char`, not `u32`
--> $DIR/cast-rfc0401.rs:41:13 --> $DIR/cast-rfc0401.rs:41:13
| |
LL | let _ = 0x61u32 as char;
| ^^^^^^^^^^^^^^^ invalid cast
|
help: try `char::from_u32` instead
--> $DIR/cast-rfc0401.rs:41:13
|
LL | let _ = 0x61u32 as char; LL | let _ = 0x61u32 as char;
| ^^^^^^^^^^^^^^^ | ^^^^^^^^^^^^^^^
| |
| invalid cast
| help: try `char::from_u32` instead: `char::from_u32(0x61u32)`
error[E0606]: casting `bool` as `f32` is invalid error[E0606]: casting `bool` as `f32` is invalid
--> $DIR/cast-rfc0401.rs:43:13 --> $DIR/cast-rfc0401.rs:43:13