diff options
Diffstat (limited to 'src/test/ui/span/issue28498-reject-trait-bound.rs')
-rw-r--r-- | src/test/ui/span/issue28498-reject-trait-bound.rs | 38 |
1 files changed, 38 insertions, 0 deletions
diff --git a/src/test/ui/span/issue28498-reject-trait-bound.rs b/src/test/ui/span/issue28498-reject-trait-bound.rs new file mode 100644 index 000000000..444cebb19 --- /dev/null +++ b/src/test/ui/span/issue28498-reject-trait-bound.rs @@ -0,0 +1,38 @@ +// Demonstrate that having a trait bound causes dropck to reject code +// that might indirectly access previously dropped value. +// +// Compare with run-pass/issue28498-ugeh-with-trait-bound.rs + +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); + +impl<T: fmt::Debug> Drop for Foo<T> { + fn drop(&mut self) { + // Use of `may_dangle` is unsound, because we access `T` fmt method when we pass + // `self.1` below, and thus potentially read from borrowed data. + println!("Dropping Foo({}, {:?})", self.0, self.1); + } +} + +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); // OK + foo1 = Foo(1, &first_dropped); + //~^ ERROR `first_dropped` does not live long enough + + println!("foo0.1: {:?} foo1.1: {:?}", foo0.1, foo1.1); +} |