--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/clang/test/SemaObjC/attr-called-once.m	Tue Jun 08 06:07:14 2021 +0900
@@ -0,0 +1,20 @@
+// RUN: %clang_cc1 -verify -fsyntax-only -fobjc-arc -fblocks %s
+
+#define CALLED_ONCE __attribute__((called_once))
+
+void test1(int x CALLED_ONCE);    // expected-error{{'called_once' attribute only applies to function-like parameters}}
+void test2(double x CALLED_ONCE); // expected-error{{'called_once' attribute only applies to function-like parameters}}
+
+void test3(void (*foo)() CALLED_ONCE);   // no-error
+void test4(int (^foo)(int) CALLED_ONCE); // no-error
+
+void test5(void (*foo)() __attribute__((called_once(1))));
+// expected-error@-1{{'called_once' attribute takes no arguments}}
+void test6(void (*foo)() __attribute__((called_once("str1", "str2"))));
+// expected-error@-1{{'called_once' attribute takes no arguments}}
+
+CALLED_ONCE void test7(); // expected-warning{{'called_once' attribute only applies to parameters}}
+void test8() {
+  void (*foo)() CALLED_ONCE; // expected-warning{{'called_once' attribute only applies to parameters}}
+  foo();
+}