Re: thoughts on martin's proposed patch for GCC and UTF-8

[Tim Hollebeek <tim at wagner dot princeton dot edu>]

Craig Burley writes ...
> 
> >gcc really should complain "undeclared identifier 'x' in preprocessor
> >conditional expression has value 0" when -Wall is specified.  Only
> >BASIC and perl programmers, and Fortran programmers who don't use
> >"implicit none", should have to worry about creating new variables
> >every time they make a typo.
> 
> Long a pet peeve of mine as well, though I wonder if fixing this might
> cause gcc to warn about too many constructs like
> 
>   #if defined (FOO) && (FOO == 1)
> 
> and:
> 
>   #ifdef FOO
>   #if FOO == 1
> 
> The warning could be made smart enough to avoid most, maybe all, such
> spurious warnings.
> 
> If not all, the documentation should be pretty clear about what to
> do, and what to not bother doing, to eliminate the warnings.

Good points.  The second isn't a problem, though, since if FOO isn't
defined, we're skipping when we see #if, and don't need too parse the
expression.  In fact, if I remember correctly, ANSI forbids parsing of
the expression (other than recognizing pp-tokens).

The first case is more important, and one I hadn't thought of.
However, the boolean operators that short circuit are the only ones
that don't use one operand, so it seems consistent with C to not
evaluate (and hence not warn about) arguments that are short
circuited.  I believe this isn't ad hoc, and avoids all spurious
warnings in a consistent manner.

---------------------------------------------------------------------------
Tim Hollebeek                           | "Everything above is a true
email: tim@wfn-shop.princeton.edu       |  statement, for sufficiently
URL: http://wfn-shop.princeton.edu/~tim |  false values of true."