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335d05aee5
- 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
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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
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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
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LL | impl PartialEq<usize> for MyType {
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
```
23 lines
431 B
Rust
23 lines
431 B
Rust
struct NoEq;
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enum Foo {
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Bar,
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Baz,
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Qux(NoEq),
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}
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// Even though any of these values can be compared structurally, we still disallow it in a pattern
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// because `Foo` does not impl `PartialEq`.
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const BAR_BAZ: Foo = if 42 == 42 {
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Foo::Baz
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} else {
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Foo::Bar
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};
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fn main() {
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match Foo::Qux(NoEq) {
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BAR_BAZ => panic!(), //~ ERROR constant of non-structural type `Foo` in a pattern
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_ => {}
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}
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}
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