1 files changed, 12 insertions, 0 deletions
diff --git a/src/test/ui/inference/inference_unstable_forced.rs b/src/test/ui/inference/inference_unstable_forced.rs
new file mode 100644
index 000000000..649b3ed2a
--- /dev/null
+++ b/src/test/ui/inference/inference_unstable_forced.rs
@@ -0,0 +1,12 @@
+// If the unstable API is the only possible solution,
+// still emit E0658 "use of unstable library feature".
+
+// aux-build:inference_unstable_iterator.rs
+
+extern crate inference_unstable_iterator;
+
+use inference_unstable_iterator::IpuIterator;
+
+fn main() {
+    assert_eq!('x'.ipu_flatten(), 0);   //~ ERROR E0658
+}