69 lines
1.2 KiB
Rust
69 lines
1.2 KiB
Rust
// Check that we can manually implement an object-unsafe trait for its trait object.
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// revisions: current next
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//[next] compile-flags: -Znext-solver
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// run-pass
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#![feature(object_safe_for_dispatch)]
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trait Bad {
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fn stat() -> char {
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'A'
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}
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fn virt(&self) -> char {
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'B'
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}
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fn indirect(&self) -> char {
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Self::stat()
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}
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}
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trait Good {
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fn good_virt(&self) -> char {
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panic!()
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}
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fn good_indirect(&self) -> char {
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panic!()
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}
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}
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impl<'a> Bad for dyn Bad + 'a {
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fn stat() -> char {
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'C'
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}
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fn virt(&self) -> char {
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'D'
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}
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}
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struct Struct {}
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impl Bad for Struct {}
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impl Good for Struct {}
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fn main() {
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let s = Struct {};
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let mut res = String::new();
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// Directly call static.
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res.push(Struct::stat()); // "A"
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res.push(<dyn Bad>::stat()); // "AC"
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let good: &dyn Good = &s;
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// These look similar enough...
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let bad = unsafe { std::mem::transmute::<&dyn Good, &dyn Bad>(good) };
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// Call virtual.
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res.push(s.virt()); // "ACB"
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res.push(bad.virt()); // "ACBD"
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// Indirectly call static.
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res.push(s.indirect()); // "ACBDA"
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res.push(bad.indirect()); // "ACBDAC"
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assert_eq!(&res, "ACBDAC");
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}
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