54 lines
1.2 KiB
Rust
54 lines
1.2 KiB
Rust
#![feature(generators)]
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#![feature(auto_traits)]
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#![feature(negative_impls)]
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auto trait Foo {}
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struct No;
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impl !Foo for No {}
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struct A<'a, 'b>(&'a mut bool, &'b mut bool, No);
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impl<'a, 'b: 'a> Foo for A<'a, 'b> {}
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struct OnlyFooIfStaticRef(No);
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impl Foo for &'static OnlyFooIfStaticRef {}
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struct OnlyFooIfRef(No);
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impl<'a> Foo for &'a OnlyFooIfRef {}
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fn assert_foo<T: Foo>(f: T) {}
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fn main() {
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// Make sure 'static is erased for generator interiors so we can't match it in trait selection
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let x: &'static _ = &OnlyFooIfStaticRef(No);
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let gen = move || {
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let x = x;
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yield;
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assert_foo(x);
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};
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assert_foo(gen);
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//~^ ERROR implementation of `Foo` is not general enough
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// Allow impls which matches any lifetime
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let x = &OnlyFooIfRef(No);
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let gen = move || {
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let x = x;
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yield;
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assert_foo(x);
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};
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assert_foo(gen); // ok
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// Disallow impls which relates lifetimes in the generator interior
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let gen = move || {
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let a = A(&mut true, &mut true, No);
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//~^ temporary value dropped while borrowed
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//~| temporary value dropped while borrowed
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yield;
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assert_foo(a);
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};
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assert_foo(gen);
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//~^ ERROR not general enough
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}
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