syntax: account for CVarArgs being in the argument list.

3 files changed, 15 insertions, 1 deletions

diff --git a/src/libsyntax/parse/parser.rs b/src/libsyntax/parse/parser.rs
index 1c1428c5713..2286e74e633 100644
--- a/src/libsyntax/parse/parser.rs
+++ b/src/libsyntax/parse/parser.rs
@@ -1236,7 +1236,7 @@ impl<'a> Parser<'a> {
 
         let args: Vec<_> = args.into_iter().filter_map(|x| x).collect();
 
-        if c_variadic && args.is_empty() {
+        if c_variadic && args.len() <= 1 {
             self.span_err(sp,
                           "C-variadic function must be declared with at least one named argument");
         }
diff --git a/src/test/ui/c-variadic/variadic-ffi-no-fixed-args.rs b/src/test/ui/c-variadic/variadic-ffi-no-fixed-args.rs
new file mode 100644
index 00000000000..e3b642a9d41
--- /dev/null
+++ b/src/test/ui/c-variadic/variadic-ffi-no-fixed-args.rs
@@ -0,0 +1,6 @@
+extern {
+    fn foo(...);
+    //~^ ERROR C-variadic function must be declared with at least one named argument
+}
+
+fn main() {}
diff --git a/src/test/ui/c-variadic/variadic-ffi-no-fixed-args.stderr b/src/test/ui/c-variadic/variadic-ffi-no-fixed-args.stderr
new file mode 100644
index 00000000000..cb6060525fc
--- /dev/null
+++ b/src/test/ui/c-variadic/variadic-ffi-no-fixed-args.stderr
@@ -0,0 +1,8 @@
+error: C-variadic function must be declared with at least one named argument
+  --> $DIR/variadic-ffi-no-fixed-args.rs:2:11
+   |
+LL |     fn foo(...);
+   |           ^
+
+error: aborting due to previous error
+