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Improve error messages for generics with default parameters

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Fixes #120785
This commit is contained in:
Veera 2024-02-21 16:46:57 -05:00
parent c475e2303b
commit 49961947c8
4 changed files with 82 additions and 4 deletions
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11
tests/ui/type/clarify-error-for-generics-with-default-issue-120785.rs Normal file
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@ -0,0 +1,11 @@
struct What<W = usize, X = Vec<W>>(W, X);
fn main() {
let mut b: What<usize> = What(5, vec![1, 2, 3]);
let c: What<usize, String> = What(1, String::from("meow"));
b = c; //~ ERROR mismatched types
let mut e: What<usize> = What(5, vec![1, 2, 3]);
let f: What<usize, Vec<String>> = What(1, vec![String::from("meow")]);
e = f; //~ ERROR mismatched types
}

27
tests/ui/type/clarify-error-for-generics-with-default-issue-120785.stderr Normal file
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error[E0308]: mismatched types
--> $DIR/clarify-error-for-generics-with-default-issue-120785.rs:6:9
|
LL | let mut b: What<usize> = What(5, vec![1, 2, 3]);
| ----------- expected due to this type
LL | let c: What<usize, String> = What(1, String::from("meow"));
LL | b = c;
| ^ expected `What`, found `What<usize, String>`
|
= note: expected struct `What<_, Vec<usize>>`
found struct `What<_, String>`
error[E0308]: mismatched types
--> $DIR/clarify-error-for-generics-with-default-issue-120785.rs:10:9
|
LL | let mut e: What<usize> = What(5, vec![1, 2, 3]);
| ----------- expected due to this type
LL | let f: What<usize, Vec<String>> = What(1, vec![String::from("meow")]);
LL | e = f;
| ^ expected `What`, found `What<usize, Vec<String>>`
|
= note: expected struct `What<_, Vec<usize>>`
found struct `What<_, Vec<String>>`
error: aborting due to 2 previous errors
For more information about this error, try `rustc --explain E0308`.