1 files changed, 42 insertions, 0 deletions
diff --git a/src/test/ui/span/issue-26656.rs b/src/test/ui/span/issue-26656.rs
new file mode 100644
index 000000000..cde68da18
--- /dev/null
+++ b/src/test/ui/span/issue-26656.rs
@@ -0,0 +1,42 @@
+// Issue #26656: Verify that trait objects cannot bypass dropck.
+
+// Using this instead of Fn etc. to take HRTB out of the equation.
+trait Trigger<B> { fn fire(&self, b: &mut B); }
+impl<B: Button> Trigger<B> for () {
+    fn fire(&self, b: &mut B) {
+        b.push();
+    }
+}
+
+// Still unsound Zook
+trait Button { fn push(&self); }
+struct Zook<B> { button: B, trigger: Box<dyn Trigger<B>+'static> }
+
+impl<B> Drop for Zook<B> {
+    fn drop(&mut self) {
+        self.trigger.fire(&mut self.button);
+    }
+}
+
+// AND
+struct Bomb { usable: bool }
+impl Drop for Bomb { fn drop(&mut self) { self.usable = false; } }
+impl Bomb { fn activate(&self) { assert!(self.usable) } }
+
+enum B<'a> { HarmlessButton, BigRedButton(&'a Bomb) }
+impl<'a> Button for B<'a> {
+    fn push(&self) {
+        if let B::BigRedButton(borrowed) = *self {
+            borrowed.activate();
+        }
+    }
+}
+
+fn main() {
+    let (mut zook, ticking);
+    zook = Zook { button: B::HarmlessButton,
+                  trigger: Box::new(()) };
+    ticking = Bomb { usable: true };
+    zook.button = B::BigRedButton(&ticking);
+}
+//~^^ ERROR `ticking` does not live long enough