1 files changed, 13 insertions, 0 deletions
diff --git a/src/test/ui/coherence/coherence-overlap-issue-23516-inherent.rs b/src/test/ui/coherence/coherence-overlap-issue-23516-inherent.rs
new file mode 100644
index 000000000..a272e620f
--- /dev/null
+++ b/src/test/ui/coherence/coherence-overlap-issue-23516-inherent.rs
@@ -0,0 +1,13 @@
+// Tests that we consider `Box<U>: !Sugar` to be ambiguous, even
+// though we see no impl of `Sugar` for `Box`. Therefore, an overlap
+// error is reported for the following pair of impls (#23516).
+
+pub trait Sugar {}
+
+struct Cake<X>(X);
+
+impl<T:Sugar> Cake<T> { fn dummy(&self) { } }
+//~^ ERROR E0592
+impl<U:Sugar> Cake<Box<U>> { fn dummy(&self) { } }
+
+fn main() { }