rust/tests/ui/const-generics/generic_const_exprs/different-fn.stderr
Esteban Küber 6b24fdf811 Provide structured suggestion for unconstrained generic constant
```
error: unconstrained generic constant
  --> $DIR/const-argument-if-length.rs:18:10
   |
LL |     pad: [u8; is_zst::<T>()],
   |          ^^^^^^^^^^^^^^^^^^^
   |
help: try adding a `where` bound
   |
LL | pub struct AtLeastByte<T: ?Sized> where [(); is_zst::<T>()]: {
   |                                   ++++++++++++++++++++++++++
```

Detect when the constant expression isn't `usize` and suggest casting:

```
error: unconstrained generic constant
 --> f300.rs:6:10
  |
6 |     bb::<{!N}>();
  |          ^^^^
-Ztrack-diagnostics: created at compiler/rustc_trait_selection/src/traits/error_reporting/type_err_ctxt_ext.rs:3539:36
  |
help: try adding a `where` bound
  |
5 | fn b<const N: bool>() where [(); {!N} as usize]: {
  |                       ++++++++++++++++++++++++++
```

Fix #122395.
2024-03-21 00:03:59 +00:00

24 lines
742 B
Plaintext

error[E0308]: mismatched types
--> $DIR/different-fn.rs:10:5
|
LL | [0; size_of::<Foo<T>>()]
| ^^^^^^^^^^^^^^^^^^^^^^^^ expected `size_of::<T>()`, found `size_of::<Foo<T>>()`
|
= note: expected constant `size_of::<T>()`
found constant `size_of::<Foo<T>>()`
error: unconstrained generic constant
--> $DIR/different-fn.rs:10:9
|
LL | [0; size_of::<Foo<T>>()]
| ^^^^^^^^^^^^^^^^^^^
|
help: try adding a `where` bound
|
LL | fn test<T>() -> [u8; size_of::<T>()] where [(); size_of::<Foo<T>>()]: {
| ++++++++++++++++++++++++++++++++
error: aborting due to 2 previous errors
For more information about this error, try `rustc --explain E0308`.