1 files changed, 26 insertions, 0 deletions
diff --git a/src/test/ui/unboxed-closures/unboxed-closures-monomorphization.rs b/src/test/ui/unboxed-closures/unboxed-closures-monomorphization.rs
new file mode 100644
index 000000000..2df360d4a
--- /dev/null
+++ b/src/test/ui/unboxed-closures/unboxed-closures-monomorphization.rs
@@ -0,0 +1,26 @@
+// run-pass
+// Test that unboxed closures in contexts with free type parameters
+// monomorphize correctly (issue #16791)
+
+fn main(){
+    fn bar<'a, T:Clone+'a> (t: T) -> Box<dyn FnMut()->T + 'a> {
+        Box::new(move || t.clone())
+    }
+
+    let mut f = bar(42_u32);
+    assert_eq!(f(), 42);
+
+    let mut f = bar("forty-two");
+    assert_eq!(f(), "forty-two");
+
+    let x = 42_u32;
+    let mut f = bar(&x);
+    assert_eq!(f(), &x);
+
+    #[derive(Clone, Copy, Debug, PartialEq)]
+    struct Foo(usize, &'static str);
+
+    let x = Foo(42, "forty-two");
+    let mut f = bar(x);
+    assert_eq!(f(), x);
+}