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Properly report error when object type param default references self

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This commit is contained in:
Michael Goulet 2025-01-24 04:06:47 +00:00
parent 99768c80a1
commit ea9a253ff1
11 changed files with 71 additions and 21 deletions
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12
compiler/rustc_error_codes/src/error_codes/E0393.md
View file

@ -3,12 +3,10 @@ A type parameter which references `Self` in its default value was not specified.
Erroneous code example:
```compile_fail,E0393
trait A<T=Self> {}
trait A<T = Self> {}
fn together_we_will_rule_the_galaxy(son: &A) {}
// error: the type parameter `T` must be explicitly specified in an
// object type because its default value `Self` references the
// type `Self`
fn together_we_will_rule_the_galaxy(son: &dyn A) {}
// error: the type parameter `T` must be explicitly specified
```
A trait object is defined over a single, fully-defined trait. With a regular
@ -23,7 +21,7 @@ disallowed. Making the trait concrete by explicitly specifying the value of the
defaulted parameter will fix this issue. Fixed example:
```
trait A<T=Self> {}
trait A<T = Self> {}
fn together_we_will_rule_the_galaxy(son: &A<i32>) {} // Ok!
fn together_we_will_rule_the_galaxy(son: &dyn A<i32>) {} // Ok!
```

8
compiler/rustc_hir_analysis/messages.ftl
View file

@ -353,7 +353,13 @@ hir_analysis_missing_type_params =
[one] reference
*[other] references
} to {$parameters}
.note = because of the default `Self` reference, type parameters must be specified on object types
.note = because the parameter {$parameterCount ->
[one] default references
*[other] defaults reference
} `Self`, the {$parameterCount ->
[one] parameter
*[other] parameters
} must be specified on the object type
hir_analysis_multiple_relaxed_default_bounds =
type parameter has more than one relaxed default bound, only one is supported

8
compiler/rustc_hir_analysis/src/hir_ty_lowering/dyn_compatibility.rs
View file

@ -237,16 +237,10 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
// Skip `Self`
.skip(1)
.map(|(index, arg)| {
if arg == dummy_self.into() {
if arg.walk().any(|arg| arg == dummy_self.into()) {
let param = &generics.own_params[index];
missing_type_params.push(param.name);
Ty::new_misc_error(tcx).into()
} else if arg.walk().any(|arg| arg == dummy_self.into()) {
let guar = self.dcx().span_delayed_bug(
span,
"trait object trait bounds reference `Self`",
);
replace_dummy_self_with_error(tcx, arg, guar)
} else {
arg
}