Using the word "SING" in a C enum errors to "expected an identifier"

Question

In a header file I have the following enum:

namespace OBJ_VERBS {
    enum { zero, 
    CUDDLE, EMBRACE, FLIP, GROPE, HUG, 
    KISS, LICK, NUDGE, PAT, PINCH, 
    POKE, PULL, RUB, SHAKE, SQUEEZE, 
    TAP, TUG, TURN, WAVE, PEER, 
    PET, CLENCH, CURSE, NUZZLE, SNAP, 
    STROKE, TWIRL, LEAN, GRIP, SMELL,
    GRUNT, SQUEAL, SCOLD, GAZE, WIND, 
    SPIT, SPIN, DANCE, SING, 
    zTOTAL};

    const int _MAX_ = int(OBJ_VERBS::zTOTAL - 1);
}

I get the following error: Error: expected an identifier

I tried searching the web to see if "SING" was a keyword, but it's not.

Any ideas?

Answer 1

I am betting you are including (directly or indirectly) math.h.

A little investigation reveals:

$ grep -r -w SING /usr/include/
/usr/include/math.h:#define SING 2

As it's #defined to 2, the enum attempts to use 2 as an enum member, which fails with the error given above.

Note that I'm (necessarily) guessing what's happening here based on the include files I have locally. It's possible you have something entirely different causing the issue, but the most likely culprit is a #define in an include file. See the grep I used above for how I found it.

This is why it's often a good idea to use (e.g.) OV_CUDDLE, OV_EMBRACE etc., to minimise collisions.

For what it's worth, the context of SING in math.h is:

/* Types of exceptions in the `type' field.  */
# define DOMAIN         1
# define SING           2
# define OVERFLOW       3
# define UNDERFLOW      4
# define TLOSS          5
# define PLOSS          6