diff options
Diffstat (limited to 'tests/ui/dropck/issue-28498-ugeh-with-passed-to-fn.rs')
-rw-r--r-- | tests/ui/dropck/issue-28498-ugeh-with-passed-to-fn.rs | 46 |
1 files changed, 46 insertions, 0 deletions
diff --git a/tests/ui/dropck/issue-28498-ugeh-with-passed-to-fn.rs b/tests/ui/dropck/issue-28498-ugeh-with-passed-to-fn.rs new file mode 100644 index 000000000..04d0d3203 --- /dev/null +++ b/tests/ui/dropck/issue-28498-ugeh-with-passed-to-fn.rs @@ -0,0 +1,46 @@ +// run-pass + +// Demonstrate the use of the unguarded escape hatch with a type param in negative position +// to assert that destructor will not access any dead data. +// +// Compare with ui/span/issue28498-reject-lifetime-param.rs + +// Demonstrate that a type param in negative position causes dropck to reject code +// that might indirectly access previously dropped value. +// +// Compare with run-pass/issue28498-ugeh-with-passed-to-fn.rs + +#![feature(dropck_eyepatch)] + +#[derive(Debug)] +struct ScribbleOnDrop(String); + +impl Drop for ScribbleOnDrop { + fn drop(&mut self) { + self.0 = format!("DROPPED"); + } +} + +struct Foo<T>(u32, T, #[allow(unused_tuple_struct_fields)] Box<for <'r> fn(&'r T) -> String>); + +unsafe impl<#[may_dangle] T> Drop for Foo<T> { + fn drop(&mut self) { + // Use of `may_dangle` is sound, because destructor never passes a `self.1` + // to the callback (in `self.2`) despite having it available. + println!("Dropping Foo({}, _)", self.0); + } +} + +fn callback(s: & &ScribbleOnDrop) -> String { format!("{:?}", s) } + +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, Box::new(callback)); + foo1 = Foo(1, &first_dropped, Box::new(callback)); + + println!("foo0.1: {:?} foo1.1: {:?}", foo0.1, foo1.1); +} |