llvm-project/clang/test/Sema/block-printf-attribute-1.c

// RUN: %clang_cc1 %s -fsyntax-only -verify -fblocks

int main() {
  void (^b) (int arg, const char * format, ...) __attribute__ ((__format__ (__printf__, 1, 3))) =   // expected-error {{format argument not a string type}}
    ^ __attribute__ ((__format__ (__printf__, 1, 3))) (int arg, const char * format, ...) {}; // expected-error {{format argument not a string type}}
 
  void (^z) (int arg, const char * format, ...) __attribute__ ((__format__ (__printf__, 2, 3))) = ^ __attribute__ ((__format__ (__printf__, 2, 3))) (int arg, const char * format, ...) {};

  z(1, "%s", 1); // expected-warning{{conversion specifies type 'char *' but the argument has type 'int'}}
  z(1, "%s", "HELLO"); // no-warning
}