Error in __func__

#include <stdio.h>    
char* __func__ = "hello";
void myfunc(void)
{
      printf("%s\n", __func__开发者_StackOverflow中文版);
}
int main()
{
  myfunc();
}

The above snippet gives error: expected identifier or ‘(’ before ‘__func__’. Why?

You know that __func__ is a predefined identifier (at least as of C99, see here for details)? Why are you using it? I'm guessing you get the error at the __func__ definition line, because of that.

Technically the behaviour is undefined as per C99 because you explicitly declare __func__ .

J.2 Undefined behavior
The behavior is undefined in the following circumstances:

...

The identifier __func__ is explicitly declared (6.4.2.2).

And it is known that undefined behaviour means anything can happen [and that includes compilation error as well]