36 lines
710 B
Rust
36 lines
710 B
Rust
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// check-pass
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// known-bug: #40582
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// Should fail. Should not be possible to implement `make_static`.
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#![feature(specialization)]
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#![allow(incomplete_features)]
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trait FromRef<'a, T: ?Sized> {
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fn from_ref(r: &'a T) -> Self;
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}
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impl<'a, T: ?Sized> FromRef<'a, T> for &'a T {
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fn from_ref(r: &'a T) -> Self {
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r
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}
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}
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impl<'a, T: ?Sized, R> FromRef<'a, T> for R {
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default fn from_ref(_: &'a T) -> Self {
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unimplemented!()
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}
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}
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fn make_static<T: ?Sized>(data: &T) -> &'static T {
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fn helper<T: ?Sized, R>(data: &T) -> R {
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R::from_ref(data)
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}
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helper(data)
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}
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fn main() {
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let s = "specialization".to_owned();
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println!("{:?}", make_static(s.as_str()));
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}
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