[libclang] Introduce clang_Cursor_isVariadic, which returns non-zero if the given cursor is a variadic function or method.

rdar://13667150

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@179819 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/tools/libclang/CIndex.cpp b/tools/libclang/CIndex.cpp
index 8a56f4d..d29e3d8 100644
--- a/tools/libclang/CIndex.cpp
+++ b/tools/libclang/CIndex.cpp
@@ -5972,6 +5972,19 @@
   return Result;
 }
 
+unsigned clang_Cursor_isVariadic(CXCursor C) {
+  if (!clang_isDeclaration(C.kind))
+    return 0;
+
+  const Decl *D = getCursorDecl(C);
+  if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D))
+    return FD->isVariadic();
+  if (const ObjCMethodDecl *MD = dyn_cast<ObjCMethodDecl>(D))
+    return MD->isVariadic();
+
+  return 0;
+}
+
 CXSourceRange clang_Cursor_getCommentRange(CXCursor C) {
   if (!clang_isDeclaration(C.kind))
     return clang_getNullRange();