1 files changed, 26 insertions, 0 deletions
diff --git a/src/test/ui/unboxed-closures/unboxed-closures-unique-type-id.rs b/src/test/ui/unboxed-closures/unboxed-closures-unique-type-id.rs
new file mode 100644
index 000000000..4b7016def
--- /dev/null
+++ b/src/test/ui/unboxed-closures/unboxed-closures-unique-type-id.rs
@@ -0,0 +1,26 @@
+// run-pass
+
+// This code used to produce the following ICE:
+//
+//    error: internal compiler error: get_unique_type_id_of_type() -
+//    unexpected type: closure,
+//    Closure(rustc_ast::DefId{krate: 0, node: 66},
+//    ReScope(63))
+//
+// This is a regression test for issue #17021.
+//
+// compile-flags: -g
+// ignore-asmjs wasm2js does not support source maps yet
+
+use std::ptr;
+
+pub fn replace_map<'a, T, F>(src: &mut T, prod: F) where F: FnOnce(T) -> T {
+    unsafe { *src = prod(ptr::read(src as *mut T as *const T)); }
+}
+
+pub fn main() {
+    let mut a = 7;
+    let b = &mut a;
+    replace_map(b, |x: usize| x * 2);
+    assert_eq!(*b, 14);
+}