rust/tests/ui/consts/const_in_pattern/cross-crate-fail.rs
Esteban Küber 335d05aee5 Add additional context for non-sructural type constant used in pattern
- Point at type that should derive `PartialEq` to be structural.
- Point at manual `impl PartialEq`, explaining that it is not sufficient to be structural.

```
error: constant of non-structural type `MyType` in a pattern
  --> $DIR/const-partial_eq-fallback-ice.rs:14:12
   |
LL | struct MyType;
   | ------------- `MyType` must be annotated with `#[derive(PartialEq)]` to be usable in patterns
...
LL | const CONSTANT: &&MyType = &&MyType;
   | ------------------------ constant defined here
...
LL |     if let CONSTANT = &&MyType {
   |            ^^^^^^^^ constant of non-structural type
   |
note: the `PartialEq` trait must be derived, manual `impl`s are not sufficient; see https://doc.rust-lang.org/stable/std/marker/trait.StructuralPartialEq.html for details
  --> $DIR/const-partial_eq-fallback-ice.rs:5:1
   |
LL | impl PartialEq<usize> for MyType {
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
```
2024-12-04 20:29:36 +00:00

22 lines
469 B
Rust

//@ aux-build:consts.rs
extern crate consts;
struct Defaulted;
impl consts::AssocConst for Defaulted {}
fn main() {
let _ = Defaulted;
match None {
consts::SOME => panic!(),
//~^ ERROR constant of non-structural type `CustomEq` in a pattern
_ => {}
}
match None {
<Defaulted as consts::AssocConst>::SOME => panic!(),
//~^ ERROR constant of non-structural type `CustomEq` in a pattern
_ => {}
}
}