Properly synthesize fn sig value during cycle

2 files changed, 17 insertions, 0 deletions

diff --git a/src/test/ui/query-system/fn-sig-cycle-arity.rs b/src/test/ui/query-system/fn-sig-cycle-arity.rs
new file mode 100644
index 00000000000..7a9b8469c9e
--- /dev/null
+++ b/src/test/ui/query-system/fn-sig-cycle-arity.rs
@@ -0,0 +1,8 @@
+trait Dancer {
+    fn dance(&self) -> _ {
+        //~^ ERROR the placeholder `_` is not allowed within types on item signatures for return types
+        self.dance()
+    }
+}
+
+fn main() {}
diff --git a/src/test/ui/query-system/fn-sig-cycle-arity.stderr b/src/test/ui/query-system/fn-sig-cycle-arity.stderr
new file mode 100644
index 00000000000..67e0c254551
--- /dev/null
+++ b/src/test/ui/query-system/fn-sig-cycle-arity.stderr
@@ -0,0 +1,9 @@
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for return types
+  --> $DIR/fn-sig-cycle-arity.rs:2:24
+   |
+LL |     fn dance(&self) -> _ {
+   |                        ^ not allowed in type signatures
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0121`.