51 lines
1.7 KiB
Rust
51 lines
1.7 KiB
Rust
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#![feature(dropck_eyepatch)]
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// The point of this test is to illustrate that the `#[may_dangle]`
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// attribute specifically allows, in the context of a type
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// implementing `Drop`, a generic parameter to be instantiated with a
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// lifetime that does not strictly outlive the owning type itself,
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// and that this attributes effects are preserved when importing
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// the type from another crate.
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//
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// See also dropck-eyepatch.rs for more information about the general
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// structure of the test.
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use std::cell::RefCell;
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pub trait Foo { fn foo(&self, _: &str); }
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pub struct Dt<A: Foo>(pub &'static str, pub A);
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pub struct Dr<'a, B:'a+Foo>(pub &'static str, pub &'a B);
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pub struct Pt<A,B: Foo>(pub &'static str, pub A, pub B);
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pub struct Pr<'a, 'b, B:'a+'b+Foo>(pub &'static str, pub &'a B, pub &'b B);
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pub struct St<A: Foo>(pub &'static str, pub A);
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pub struct Sr<'a, B:'a+Foo>(pub &'static str, pub &'a B);
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impl<A: Foo> Drop for Dt<A> {
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fn drop(&mut self) { println!("drop {}", self.0); self.1.foo(self.0); }
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}
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impl<'a, B: Foo> Drop for Dr<'a, B> {
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fn drop(&mut self) { println!("drop {}", self.0); self.1.foo(self.0); }
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}
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unsafe impl<#[may_dangle] A, B: Foo> Drop for Pt<A, B> {
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// (unsafe to access self.1 due to #[may_dangle] on A)
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fn drop(&mut self) { println!("drop {}", self.0); self.2.foo(self.0); }
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}
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unsafe impl<#[may_dangle] 'a, 'b, B: Foo> Drop for Pr<'a, 'b, B> {
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// (unsafe to access self.1 due to #[may_dangle] on 'a)
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fn drop(&mut self) { println!("drop {}", self.0); self.2.foo(self.0); }
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}
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impl Foo for RefCell<String> {
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fn foo(&self, s: &str) {
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let s2 = format!("{}|{}", *self.borrow(), s);
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*self.borrow_mut() = s2;
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}
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}
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impl<'a, T:Foo> Foo for &'a T {
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fn foo(&self, s: &str) {
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(*self).foo(s);
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}
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}
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