bug#23640: 25.1.50; Getting rid of compiler warnings

[Paul Eggert]

On 06/01/2016 01:37 PM, Richard Stallman wrote:
> A macro UNUSED_LISP could handle the first.

Yes, we could have separate macros for each data type requiring 
syntactically different initializers. Something like this, say:

    int n UNUSED_0;
    Lisp_Object obj UNUSED_Qnil;

instead of the current:

    int n IF_LINT (= 0);
    Lisp_Object obj IF_LINT (= Qnil);

We could easily change the code in that way. Is it worth the trouble?

> What is the reason for writing IF_LINT (volatile)
> instead of just volatile?

Primarily, to tell the reader that the 'volatile' is not needed for 
correctness; it's present only to pacify a buggy compiler or lint 
checker. (In this case, it pacifies GCC; see GCC bug#54561.) It's 
basically the same reason the code uses 'IF_LINT (= 0)' rather than '= 0'.