34 lines
1.2 KiB
Rust
34 lines
1.2 KiB
Rust
// The purpose of this test is to demonstrate that duplicating dyn-compatible traits
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// that are not auto-traits is rejected even though one could reasonably accept this.
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// Some arbitrary dyn-compatible trait:
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trait Obj {}
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// Demonstrate that recursive expansion of trait aliases doesn't affect stable behavior:
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type _0 = dyn Obj + Obj;
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//~^ ERROR only auto traits can be used as additional traits in a trait object [E0225]
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// Some variations:
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type _1 = dyn Send + Obj + Obj;
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//~^ ERROR only auto traits can be used as additional traits in a trait object [E0225]
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type _2 = dyn Obj + Send + Obj;
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//~^ ERROR only auto traits can be used as additional traits in a trait object [E0225]
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type _3 = dyn Obj + Send + Send; // But it is OK to duplicate auto traits.
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// Take higher ranked types into account.
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// Note that `'a` and `'b` are intentionally different to make sure we consider
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// them semantically the same.
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trait ObjL<'l> {}
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type _4 = dyn for<'a> ObjL<'a> + for<'b> ObjL<'b>;
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//~^ ERROR only auto traits can be used as additional traits in a trait object [E0225]
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trait ObjT<T> {}
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type _5 = dyn ObjT<for<'a> fn(&'a u8)> + ObjT<for<'b> fn(&'b u8)>;
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//~^ ERROR only auto traits can be used as additional traits in a trait object [E0225]
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fn main() {}
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