2 files changed, 22 insertions, 0 deletions
diff --git a/tests/ui/impl-trait/stranded-opaque.rs b/tests/ui/impl-trait/stranded-opaque.rs
new file mode 100644
index 00000000000..c7ab390e1fd
--- /dev/null
+++ b/tests/ui/impl-trait/stranded-opaque.rs
@@ -0,0 +1,13 @@
+trait Trait {}
+
+impl Trait for i32 {}
+
+// Since `Assoc` doesn't actually exist, it's "stranded", and won't show up in
+// the list of opaques that may be defined by the function. Make sure we don't
+// ICE in this case.
+fn produce<T>() -> impl Trait<Assoc = impl Trait> {
+    //~^ ERROR associated type `Assoc` not found for `Trait`
+    16
+}
+
+fn main () {}
diff --git a/tests/ui/impl-trait/stranded-opaque.stderr b/tests/ui/impl-trait/stranded-opaque.stderr
new file mode 100644
index 00000000000..75f5480bc8b
--- /dev/null
+++ b/tests/ui/impl-trait/stranded-opaque.stderr
@@ -0,0 +1,9 @@
+error[E0220]: associated type `Assoc` not found for `Trait`
+  --> $DIR/stranded-opaque.rs:8:31
+   |
+LL | fn produce<T>() -> impl Trait<Assoc = impl Trait> {
+   |                               ^^^^^ associated type `Assoc` not found
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0220`.