1 files changed, 37 insertions, 0 deletions
diff --git a/tests/ui/abi/union/union-c-interop.rs b/tests/ui/abi/union/union-c-interop.rs
new file mode 100644
index 000000000..00f04d5b7
--- /dev/null
+++ b/tests/ui/abi/union/union-c-interop.rs
@@ -0,0 +1,37 @@
+// run-pass
+#![allow(non_snake_case)]
+
+// ignore-wasm32-bare no libc to test ffi with
+
+#[derive(Clone, Copy)]
+#[repr(C)]
+struct LARGE_INTEGER_U {
+    LowPart: u32,
+    HighPart: u32,
+}
+
+#[derive(Clone, Copy)]
+#[repr(C)]
+union LARGE_INTEGER {
+  __unnamed__: LARGE_INTEGER_U,
+  u: LARGE_INTEGER_U,
+  QuadPart: u64,
+}
+
+#[link(name = "rust_test_helpers", kind = "static")]
+extern "C" {
+    fn increment_all_parts(_: LARGE_INTEGER) -> LARGE_INTEGER;
+}
+
+fn main() {
+    unsafe {
+        let mut li = LARGE_INTEGER { QuadPart: 0 };
+        let li_c = increment_all_parts(li);
+        li.__unnamed__.LowPart += 1;
+        li.__unnamed__.HighPart += 1;
+        li.u.LowPart += 1;
+        li.u.HighPart += 1;
+        li.QuadPart += 1;
+        assert_eq!(li.QuadPart, li_c.QuadPart);
+    }
+}