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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
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@ -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!
```