mirror of https://github.com/rust-lang/rust
45 lines
1.4 KiB
Rust
45 lines
1.4 KiB
Rust
//@ needs-sanitizer-cfi
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//@ compile-flags: -Ccodegen-units=1 -Clto -Ctarget-feature=-crt-static -Zsanitizer=cfi
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//@ no-prefer-dynamic
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//@ only-x86_64-unknown-linux-gnu
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//@ build-pass
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// See comment below for why this test exists.
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trait Tr<U> {
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type Projection;
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}
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impl<F, U> Tr<U> for F
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where
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F: Fn() -> U
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{
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type Projection = U;
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}
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fn test<B: Tr<U>, U>(b: B) -> B::Projection
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{
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todo!()
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}
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fn main() {
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fn rpit_fn() -> impl Sized {}
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// When CFI runs, it tries to compute the signature of the call. This
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// ends up giving us a signature of:
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// `fn test::<rpit_fn, ()>() -> <rpit_fn as Tr<()>>::Projection`,
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// where `rpit_fn` is the ZST FnDef for the function. However, we were
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// previously using a Reveal::UserFacing param-env. This means that the
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// `<rpit_fn as Tr<()>>::Projection` return type is impossible to normalize,
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// since it would require proving `rpit_fn: Fn() -> ()`, but we cannot
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// prove that the `impl Sized` opaque is `()` with a user-facing param-env.
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// This leads to a normalization error, and then an ICE.
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//
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// Side-note:
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// So why is the second generic of `test` "`()`", and not the
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// `impl Sized` since we inferred it from the return type of `rpit_fn`
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// during typeck? Well, that's because we're using the generics from the
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// terminator of the MIR, which has had the RevealAll pass performed on it.
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let _ = test(rpit_fn);
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}
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