19 lines
457 B
Rust
19 lines
457 B
Rust
#![feature(fn_traits, unboxed_closures)]
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fn test<F: for<'x> FnOnce<(&'x str,)>>(_: F) {}
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struct Compose<F,G>(F,G);
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impl<T,F,G> FnOnce<(T,)> for Compose<F,G>
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where F: FnOnce<(T,)>, G: FnOnce<(F::Output,)> {
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type Output = G::Output;
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extern "rust-call" fn call_once(self, (x,): (T,)) -> G::Output {
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(self.1)((self.0)(x))
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}
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}
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fn bad<T>(f: fn(&'static str) -> T) {
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test(Compose(f, |_| {})); //~ ERROR: mismatched types
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}
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fn main() {}
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