1 files changed, 20 insertions, 0 deletions
diff --git a/src/test/ui/unboxed-closures/unboxed-closures-infer-fnmut-calling-fnmut-no-mut.rs b/src/test/ui/unboxed-closures/unboxed-closures-infer-fnmut-calling-fnmut-no-mut.rs
new file mode 100644
index 000000000..6401b5e01
--- /dev/null
+++ b/src/test/ui/unboxed-closures/unboxed-closures-infer-fnmut-calling-fnmut-no-mut.rs
@@ -0,0 +1,20 @@
+// Test that we are able to infer a suitable kind for this closure
+// that is just called (`FnMut`).
+
+fn main() {
+    let mut counter = 0;
+
+    // Here this must be inferred to FnMut so that it can mutate counter,
+    // but we forgot the mut.
+    let tick1 = || {
+        counter += 1;
+    };
+
+    // In turn, tick2 must be inferred to FnMut so that it can call
+    // tick1, but we forgot the mut.
+    let tick2 = || {
+        tick1(); //~ ERROR cannot borrow `tick1` as mutable
+    };
+
+    tick2(); //~ ERROR cannot borrow
+}