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Diffstat (limited to 'src/test/ui/drop/dropck-eyepatch.rs')
-rw-r--r-- | src/test/ui/drop/dropck-eyepatch.rs | 102 |
1 files changed, 0 insertions, 102 deletions
diff --git a/src/test/ui/drop/dropck-eyepatch.rs b/src/test/ui/drop/dropck-eyepatch.rs deleted file mode 100644 index 3c4840d5c..000000000 --- a/src/test/ui/drop/dropck-eyepatch.rs +++ /dev/null @@ -1,102 +0,0 @@ -// run-pass -#![feature(dropck_eyepatch)] - -// The point of this test is to illustrate that the `#[may_dangle]` -// attribute specifically allows, in the context of a type -// implementing `Drop`, a generic parameter to be instantiated with a -// lifetime that does not strictly outlive the owning type itself. -// -// Here we test that a model use of `#[may_dangle]` will compile and run. -// -// The illustration is made concrete by comparison with two variations -// on the type with `#[may_dangle]`: -// -// 1. an analogous type that does not implement `Drop` (and thus -// should exhibit maximal flexibility with respect to dropck), and -// -// 2. an analogous type that does not use `#[may_dangle]` (and thus -// should exhibit the standard limitations imposed by dropck. -// -// The types in this file follow a pattern, {D,P,S}{t,r}, where: -// -// - D means "I implement Drop" -// -// - P means "I implement Drop but guarantee my (first) parameter is -// pure, i.e., not accessed from the destructor"; no other parameters -// are pure. -// -// - S means "I do not implement Drop" -// -// - t suffix is used when the first generic is a type -// -// - r suffix is used when the first generic is a lifetime. - -trait Foo { fn foo(&self, _: &str); } - -struct Dt<A: Foo>(&'static str, A); -struct Dr<'a, B:'a+Foo>(&'static str, &'a B); -struct Pt<A,B: Foo>(&'static str, #[allow(unused_tuple_struct_fields)] A, B); -struct Pr<'a, 'b, B:'a+'b+Foo>(&'static str, #[allow(unused_tuple_struct_fields)] &'a B, &'b B); -struct St<A: Foo>(&'static str, #[allow(unused_tuple_struct_fields)] A); -struct Sr<'a, B:'a+Foo>(&'static str, #[allow(unused_tuple_struct_fields)] &'a B); - -impl<A: Foo> Drop for Dt<A> { - fn drop(&mut self) { println!("drop {}", self.0); self.1.foo(self.0); } -} -impl<'a, B: Foo> Drop for Dr<'a, B> { - fn drop(&mut self) { println!("drop {}", self.0); self.1.foo(self.0); } -} -unsafe impl<#[may_dangle] A, B: Foo> Drop for Pt<A, B> { - // (unsafe to access self.1 due to #[may_dangle] on A) - fn drop(&mut self) { println!("drop {}", self.0); self.2.foo(self.0); } -} -unsafe impl<#[may_dangle] 'a, 'b, B: Foo> Drop for Pr<'a, 'b, B> { - // (unsafe to access self.1 due to #[may_dangle] on 'a) - fn drop(&mut self) { println!("drop {}", self.0); self.2.foo(self.0); } -} - -fn main() { - use std::cell::RefCell; - - impl Foo for RefCell<String> { - fn foo(&self, s: &str) { - let s2 = format!("{}|{}", *self.borrow(), s); - *self.borrow_mut() = s2; - } - } - - impl<'a, T:Foo> Foo for &'a T { - fn foo(&self, s: &str) { - (*self).foo(s); - } - } - - struct CheckOnDrop(RefCell<String>, &'static str); - impl Drop for CheckOnDrop { - fn drop(&mut self) { assert_eq!(*self.0.borrow(), self.1); } - } - - let c_long; - let (c, dt, dr, pt, pr, st, sr) - : (CheckOnDrop, Dt<_>, Dr<_>, Pt<_, _>, Pr<_>, St<_>, Sr<_>); - c_long = CheckOnDrop(RefCell::new("c_long".to_string()), - "c_long|pr|pt|dr|dt"); - c = CheckOnDrop(RefCell::new("c".to_string()), - "c"); - - // No error: sufficiently long-lived state can be referenced in dtors - dt = Dt("dt", &c_long.0); - dr = Dr("dr", &c_long.0); - - // No error: Drop impl asserts .1 (A and &'a _) are not accessed - pt = Pt("pt", &c.0, &c_long.0); - pr = Pr("pr", &c.0, &c_long.0); - - // No error: St and Sr have no destructor. - st = St("st", &c.0); - sr = Sr("sr", &c.0); - - println!("{:?}", (dt.0, dr.0, pt.0, pr.0, st.0, sr.0)); - assert_eq!(*c_long.0.borrow(), "c_long"); - assert_eq!(*c.0.borrow(), "c"); -} |