diff options
Diffstat (limited to 'tests/ui/dropck/issue-28498-ugeh-with-trait-bound.rs')
-rw-r--r-- | tests/ui/dropck/issue-28498-ugeh-with-trait-bound.rs | 41 |
1 files changed, 41 insertions, 0 deletions
diff --git a/tests/ui/dropck/issue-28498-ugeh-with-trait-bound.rs b/tests/ui/dropck/issue-28498-ugeh-with-trait-bound.rs new file mode 100644 index 000000000..61d11cf38 --- /dev/null +++ b/tests/ui/dropck/issue-28498-ugeh-with-trait-bound.rs @@ -0,0 +1,41 @@ +// run-pass + +// Demonstrate the use of the unguarded escape hatch with a trait bound +// to assert that destructor will not access any dead data. +// +// Compare with ui/span/issue28498-reject-trait-bound.rs + +#![feature(dropck_eyepatch)] + +use std::fmt; + +#[derive(Debug)] +struct ScribbleOnDrop(String); + +impl Drop for ScribbleOnDrop { + fn drop(&mut self) { + self.0 = format!("DROPPED"); + } +} + +struct Foo<T: fmt::Debug>(u32, T); + +unsafe impl<#[may_dangle] T: fmt::Debug> Drop for Foo<T> { + fn drop(&mut self) { + // Use of `may_dangle` is sound, because destructor never accesses + // the `Debug::fmt` method of `T`, despite having it available. + println!("Dropping Foo({}, _)", self.0); + } +} + +fn main() { + let (last_dropped, foo0); + let (foo1, first_dropped); + + last_dropped = ScribbleOnDrop(format!("last")); + first_dropped = ScribbleOnDrop(format!("first")); + foo0 = Foo(0, &last_dropped); + foo1 = Foo(1, &first_dropped); + + println!("foo0.1: {:?} foo1.1: {:?}", foo0.1, foo1.1); +} |