1 files changed, 62 insertions, 0 deletions
diff --git a/src/test/ui/span/borrowck-call-is-borrow-issue-12224.rs b/src/test/ui/span/borrowck-call-is-borrow-issue-12224.rs
new file mode 100644
index 000000000..938fdaf11
--- /dev/null
+++ b/src/test/ui/span/borrowck-call-is-borrow-issue-12224.rs
@@ -0,0 +1,62 @@
+#![feature(fn_traits)]
+
+// Ensure that invoking a closure counts as a unique immutable borrow
+
+type Fn<'a> = Box<dyn FnMut() + 'a>;
+
+struct Test<'a> {
+    f: Box<dyn FnMut() + 'a>
+}
+
+fn call<F>(mut f: F) where F: FnMut(Fn) {
+    f(Box::new(|| {
+    //~^ ERROR: cannot borrow `f` as mutable more than once
+        f((Box::new(|| {})))
+    }));
+}
+
+fn test1() {
+    call(|mut a| {
+        a.call_mut(());
+    });
+}
+
+fn test2<F>(f: &F) where F: FnMut() {
+    (*f)();
+    //~^ ERROR cannot borrow `*f` as mutable, as it is behind a `&` reference
+}
+
+fn test3<F>(f: &mut F) where F: FnMut() {
+    (*f)();
+}
+
+fn test4(f: &Test) {
+    f.f.call_mut(())
+    //~^ ERROR: cannot borrow `f.f` as mutable, as it is behind a `&` reference
+}
+
+fn test5(f: &mut Test) {
+    f.f.call_mut(())
+}
+
+fn test6() {
+    let mut f = || {};
+    (|| {
+        f();
+    })();
+}
+
+fn test7() {
+    fn foo<F>(_: F) where F: FnMut(Box<dyn FnMut(isize)>, isize) {}
+    let s = String::new();  // Capture to make f !Copy
+    let mut f = move |g: Box<dyn FnMut(isize)>, b: isize| {
+        let _ = s.len();
+    };
+    f(Box::new(|a| {
+        //~^ ERROR cannot move out of `f` because it is borrowed
+        foo(f);
+        //~^ ERROR cannot move out of `f`, a captured variable in an `FnMut` closure
+    }), 3);
+}
+
+fn main() {}