summaryrefslogtreecommitdiffstats
path: root/src/test/ui/dropck/issue-28498-ugeh-with-trait-bound.rs
diff options
context:
space:
mode:
Diffstat (limited to 'src/test/ui/dropck/issue-28498-ugeh-with-trait-bound.rs')
-rw-r--r--src/test/ui/dropck/issue-28498-ugeh-with-trait-bound.rs41
1 files changed, 41 insertions, 0 deletions
diff --git a/src/test/ui/dropck/issue-28498-ugeh-with-trait-bound.rs b/src/test/ui/dropck/issue-28498-ugeh-with-trait-bound.rs
new file mode 100644
index 000000000..61d11cf38
--- /dev/null
+++ b/src/test/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);
+}