test.cpp

int main(int argc, char** argv) {
	int a;
	int b;

	a = b = 1;

	a == b;

	return 0;
}

/*

$ gcc test.cpp 

test.cpp:7:4: warning: equality comparison result unused [-Wunused-comparison]
        a == b;
        ~~^~~~
test.cpp:7:4: note: use '=' to turn this equality comparison into an assignment
        a == b;
          ^~
          =
1 warning generated.

*/