--enable-check-lisp-object-type lisp.h warnings

[Sean Whitton]

Hello,

There was a thread about this in April but I don't believe any
conclusion was reached about these particular warnings:

    lisp.h:409:38: warning: potential null pointer dereference 
[-Wnull-dereference]
      409 | #define lisp_h_XCAR(c) XCONS (c)->u.s.car
          |                        ~~~~~~~~~~~~~~^~~~
    lisp.h:1498:10: note: in expansion of macro 'lisp_h_XCAR'
     1498 |   return lisp_h_XCAR (c);
          |          ^~~~~~~~~~~
    lisp.h:409:38: warning: potential null pointer dereference 
[-Wnull-dereference]
      409 | #define lisp_h_XCAR(c) XCONS (c)->u.s.car
          |                        ~~~~~~~~~~~~~~^~~~

I hope that it is okay to ask about this again without being able to
propose a patch -- does anyone know if these are real bug, or if not,
how to silence them?  At present I have to mentally subtract 2 from the
number of warnings *Compilation* shows, and you know how those of us who
have studied Maths at university are with mental arithmetic.

-- 
Sean Whitton