Add additional tests to check suppression in variadic functions and their callers.

Author: MalavikaSamak

clang/test/SemaCXX/warn-unsafe-buffer-usage-function-attr.cpp

@@ -280,3 +280,19 @@ void check_no_warnings(unsigned idx) {
   A a;
   a.ptr = arr; // no-warning
 }
+
+[[clang::unsafe_buffer_usage]]
+void check_no_warning_variadic(unsigned idx, int arr[20], ...) {
+  int k = arr[idx]; // no-warning
+
+  std::span<int> sp = {arr, 20}; // no-warning
+  A *ptr = reinterpret_cast<A*> (sp.data()); // no-warning
+  A a;
+  a.ptr = arr; // no-warning
+}
+
+void invoke_methods() {
+  int array[20];
+  check_no_warnings(30); //expected-warning{{function introduces unsafe buffer manipulation}}
+  check_no_warning_variadic(20, array); //expected-warning{{function introduces unsafe buffer manipulation}}
+}