Incompatible pointer types passing in _Generic macro

Question

The following code generates 2 warnings which are described in the question\'s title.

#include 

static void _print_f(float *f){printf(\"float         


        

Answer 1

CORRECTION : This is not (as far as I can tell) a bug in clang, but a correct interpretation of how _Generic is supposed to behave. Only one of the generic associations in a generic-selection expression is evaluated, but all of them must be valid expressions. (_Generic does not act like a macro.)

See Jens Gustedt's answer.

---

This definitely looks like a bug in clang. I'm reasonably sure your code is valid C11. I see the same thing with version 3.4 on Linux Mint.

I've put together a slightly simplified demo :

#include 

static void print_i(int i)   { puts("int"); }
static void print_ip(int *i) { puts("int*"); }

#define print(num) _Generic((num), \
    int    : print_i(num),         \
    int*   : print_ip(num))

int main(void) {
    int i = 10;
    print(i);
    print(&i);
}

The output is correct, but I get the following warnings:

c.c:12:11: warning: incompatible integer to pointer conversion passing 'int' to parameter of type 'int *'; take the address with & [-Wint-conversion]
    print(i);
          ^
          &
c.c:8:23: note: expanded from macro 'print'
    int*   : print_ip(num))
                      ^
c.c:4:27: note: passing argument to parameter 'i' here
static void print_ip(int *i) { puts("int*"); }
                          ^
c.c:13:11: warning: incompatible pointer to integer conversion passing 'int *' to parameter of type 'int'; remove & [-Wint-conversion]
    print(&i);
          ^~
c.c:7:22: note: expanded from macro 'print'
    int    : print_i(num),         \
                     ^
c.c:3:25: note: passing argument to parameter 'i' here
static void print_i(int i)   { puts("int"); }
                        ^
2 warnings generated.