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+Variadic parameters have been used on a non-C ABI function.
+
+Erroneous code example:
+
+```compile_fail,E0045
+#![feature(unboxed_closures)]
+
+extern "rust-call" {
+    fn foo(x: u8, ...); // error!
+}
+```
+
+Rust only supports variadic parameters for interoperability with C code in its
+FFI. As such, variadic parameters can only be used with functions which are
+using the C ABI. To fix such code, put them in an extern "C" block:
+
+```
+extern "C" {
+    fn foo (x: u8, ...);
+}
+```