Why does this #define STMT ( 0 || g() ) produce a compiler error [-Werror=unused-value]?

during the compilation of a program using Petsc I stumbled upon a construct similar to the following. In Petsc they use it, as far as I understand, to wrap calls to MPI in order to monitor calls to functions using collective communication.

#include <stdio.h>

int f() {return 0;}
int g() {printf("g()\n");return 0;}

#define STMT (  0  || g() )

int main()
{
                STMT;
                printf("main()\n");
                return 0;
}

compiling with gcc:

gcc -Wall -Werror ./test.c

raises the following error/warning:

./test.c:7:20: error: value computed is not used [-Werror=unused-value]
 #define STMT (  0  || g() )
              ~~~~~~^~~~~~~~
              ./test.c:11:3: note: in expansion of macro ‘STMT’
                 STMT;
                    ^~~~
                    cc1: all warnings being treated as errors

Why does the compiler issue this warning ? IMHO g() is always executed and the value computed is always used.

Note: tested with: gcc version 7.4.0 (Ubuntu 7.4.0-1ubuntu1~18.04.1), gcc version 8.3 and gcc version 9