1 files changed, 14 insertions, 0 deletions
diff --git a/src/test/ui/impl-trait/closure-calling-parent-fn.rs b/src/test/ui/impl-trait/closure-calling-parent-fn.rs
new file mode 100644
index 00000000000..cb5f78bd6fc
--- /dev/null
+++ b/src/test/ui/impl-trait/closure-calling-parent-fn.rs
@@ -0,0 +1,14 @@
+#![feature(nll)]
+
+// Regression test for #54593: the MIR type checker was going wrong
+// when a closure returns the `impl Copy` from its parent fn. It was
+// (incorrectly) replacing the `impl Copy` in its return type with the
+// hidden type (`()`) but that type resulted from a recursive call to
+// `foo` and hence is treated opaquely within the closure body.  This
+// resulted in a failed subtype relationship.
+//
+// run-pass
+
+fn foo() -> impl Copy { || foo(); }
+fn bar() -> impl Copy { || bar(); }
+fn main() { }