Rollup merge of #27617 - AlisdairO:diagnostics193, r=Manishearth
As title :-) Part of #24407. r? @Manishearth
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@ -1803,6 +1803,43 @@ information see the [opt-in builtin traits RFC](https://github.com/rust-lang/
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rfcs/blob/master/text/0019-opt-in-builtin-traits.md).
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"##,
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E0193: r##"
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`where` clauses must use generic type parameters: it does not make sense to use
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them otherwise. An example causing this error:
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```
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trait Foo {
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fn bar(&self);
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}
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#[derive(Copy,Clone)]
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struct Wrapper<T> {
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Wrapped: T
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}
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impl Foo for Wrapper<u32> where Wrapper<u32>: Clone {
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fn bar(&self) { }
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}
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```
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This use of a `where` clause is strange - a more common usage would look
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something like the following:
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```
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impl <T> Foo for Wrapper<T> where Wrapper<T>: Clone {
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fn bar(&self) { }
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}
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```
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Here, we're saying that the implementation exists on Wrapper only when the
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wrapped type `T` implements `Clone`. The `where` clause is important because
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some types will not implement `Clone`, and thus will not get this method.
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In our erroneous example, however, we're referencing a single concrete type.
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Since we know for certain that Wrapper<u32> implements Clone, there's no reason
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to also specify it in a `where` clause.
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"##,
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E0195: r##"
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Your method's lifetime parameters do not match the trait declaration.
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Erroneous code example:
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@ -2558,8 +2595,6 @@ register_diagnostics! {
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E0188, // can not cast a immutable reference to a mutable pointer
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E0189, // deprecated: can only cast a boxed pointer to a boxed object
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E0190, // deprecated: can only cast a &-pointer to an &-object
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E0193, // cannot bound type where clause bounds may only be attached to types
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// involving type parameters
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E0194,
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E0196, // cannot determine a type for this closure
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E0203, // type parameter has more than one relaxed default bound,
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