mirror of https://github.com/rust-lang/rust
42 lines
894 B
Rust
42 lines
894 B
Rust
// Another example from issue #84660, this time weaponized as a safe transmute: an opaque type in an
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// impl header being accepted was used to create unsoundness.
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#![feature(type_alias_impl_trait)]
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trait Foo {}
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impl Foo for () {}
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type Bar = impl Foo;
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fn _defining_use() -> Bar {}
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trait Trait<T, In> {
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type Out;
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fn convert(i: In) -> Self::Out;
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}
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impl<In, Out> Trait<Bar, In> for Out {
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type Out = Out;
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fn convert(_i: In) -> Self::Out {
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unreachable!();
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}
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}
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impl<In, Out> Trait<(), In> for Out { //~ ERROR conflicting implementations of trait `Trait<Bar, _>`
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type Out = In;
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fn convert(i: In) -> Self::Out {
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i
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}
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}
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fn transmute<In, Out>(i: In) -> Out {
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<Out as Trait<Bar, In>>::convert(i)
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}
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fn main() {
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let d;
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{
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let x = "Hello World".to_string();
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d = transmute::<&String, &String>(&x);
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}
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println!("{}", d);
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}
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