40 lines
1.6 KiB
Rust
40 lines
1.6 KiB
Rust
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//@ revisions: current next
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//@ ignore-compare-mode-next-solver (explicit revisions)
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//@[next] compile-flags: -Znext-solver
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// A variation of #135246 where the cyclic bounds are part of
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// the impl instead of the impl associated item.
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trait Trait<R>: Sized {
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type Proof: Trait<R, Proof = Self>;
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}
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// We need to use indirection here as we otherwise normalize
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// `<L::Proof as Trait<R>>::Proof` before recursing into
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// `R: Trait<R, Proof = <L::Proof as Trait<R>>::Proof>`.
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trait Indir<L: Trait<R>, R>: Trait<R, Proof = <L::Proof as Trait<R>>::Proof> {}
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impl<L, R> Indir<L, R> for R
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where
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L: Trait<R>,
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R: Trait<R, Proof = <L::Proof as Trait<R>>::Proof>,
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{}
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impl<L, R> Trait<R> for L
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where
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L: Trait<R>,
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R: Indir<L, R>,
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{
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type Proof = R;
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}
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fn transmute<L: Trait<R>, R>(r: L) -> <L::Proof as Trait<R>>::Proof { r }
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fn main() {
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let s: String = transmute::<_, String>(vec![65_u8, 66, 67]);
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//~^ ERROR overflow evaluating the requirement `Vec<u8>: Trait<String>`
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//[next]~| ERROR overflow evaluating the requirement `<<Vec<u8> as Trait<String>>::Proof as Trait<String>>::Proof == _`
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//[next]~| ERROR overflow evaluating the requirement `<<Vec<u8> as Trait<String>>::Proof as Trait<String>>::Proof == String`
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//[next]~| ERROR overflow evaluating the requirement `<<Vec<u8> as Trait<String>>::Proof as Trait<String>>::Proof: Sized`
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//[next]~| ERROR overflow evaluating the requirement `<<Vec<u8> as Trait<String>>::Proof as Trait<String>>::Proof well-formed`
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//[next]~| ERROR overflow evaluating the requirement `<<Vec<u8> as Trait<String>>::Proof as Trait<String>>::Proof == _`
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println!("{}", s); // ABC
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}
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