1 files changed, 84 insertions, 0 deletions
diff --git a/tests/ui/abi/variadic-ffi.rs b/tests/ui/abi/variadic-ffi.rs
new file mode 100644
index 00000000000..a952ea07793
--- /dev/null
+++ b/tests/ui/abi/variadic-ffi.rs
@@ -0,0 +1,84 @@
+// run-pass
+// ignore-wasm32-bare no libc to test ffi with
+#![feature(c_variadic)]
+
+use std::ffi::VaList;
+
+#[link(name = "rust_test_helpers", kind = "static")]
+extern "C" {
+    fn rust_interesting_average(_: u64, ...) -> f64;
+
+    // FIXME: we need to disable this lint for `VaList`,
+    // since it contains a `MaybeUninit<i32>` on the asmjs target,
+    // and this type isn't FFI-safe. This is OK for now,
+    // since the type is layout-compatible with `i32`.
+    #[cfg_attr(target_arch = "asmjs", allow(improper_ctypes))]
+    fn rust_valist_interesting_average(_: u64, _: VaList) -> f64;
+}
+
+pub unsafe extern "C" fn test_valist_forward(n: u64, mut ap: ...) -> f64 {
+    rust_valist_interesting_average(n, ap.as_va_list())
+}
+
+pub unsafe extern "C" fn test_va_copy(_: u64, mut ap: ...) {
+    let mut ap2 = ap.clone();
+    assert_eq!(rust_valist_interesting_average(2, ap2.as_va_list()) as i64, 30);
+
+    // Advance one pair in the copy before checking
+    let mut ap2 = ap.clone();
+    let _ = ap2.arg::<u64>();
+    let _ = ap2.arg::<f64>();
+    assert_eq!(rust_valist_interesting_average(2, ap2.as_va_list()) as i64, 50);
+
+    // Advance one pair in the original
+    let _ = ap.arg::<u64>();
+    let _ = ap.arg::<f64>();
+
+    let mut ap2 = ap.clone();
+    assert_eq!(rust_valist_interesting_average(2, ap2.as_va_list()) as i64, 50);
+
+    let mut ap2 = ap.clone();
+    let _ = ap2.arg::<u64>();
+    let _ = ap2.arg::<f64>();
+    assert_eq!(rust_valist_interesting_average(2, ap2.as_va_list()) as i64, 70);
+}
+
+pub fn main() {
+    // Call without variadic arguments
+    unsafe {
+        assert!(rust_interesting_average(0).is_nan());
+    }
+
+    // Call with direct arguments
+    unsafe {
+        assert_eq!(rust_interesting_average(1, 10i64, 10.0f64) as i64, 20);
+    }
+
+    // Call with named arguments, variable number of them
+    let (x1, x2, x3, x4) = (10i64, 10.0f64, 20i64, 20.0f64);
+    unsafe {
+        assert_eq!(rust_interesting_average(2, x1, x2, x3, x4) as i64, 30);
+    }
+
+    // A function that takes a function pointer
+    unsafe fn call(fp: unsafe extern "C" fn(u64, ...) -> f64) {
+        let (x1, x2, x3, x4) = (10i64, 10.0f64, 20i64, 20.0f64);
+        assert_eq!(fp(2, x1, x2, x3, x4) as i64, 30);
+    }
+
+    unsafe {
+        call(rust_interesting_average);
+
+        // Make a function pointer, pass indirectly
+        let x: unsafe extern "C" fn(u64, ...) -> f64 = rust_interesting_average;
+        call(x);
+    }
+
+    unsafe {
+        assert_eq!(test_valist_forward(2, 10i64, 10f64, 20i64, 20f64) as i64, 30);
+    }
+
+    unsafe {
+        test_va_copy(4, 10i64, 10f64, 20i64, 20f64, 30i64, 30f64, 40i64, 40f64);
+    }
+}