Re: Including config.h emits warnings from -Wundef

[Bruno Haible]

Jeffrey Walton wrote:
> My personal opinion is, there's nothing to fix.
> 
> That is exactly how macros are supposed to work. Anything undefined
> evaluates to 0. It has been that way since the early days of C and
> C++.
> 
> If there's a fix, then it is that you don't use -Wundef.

On the simple level "which gcc warning options do I find useful?", I agree
with you.

But one level higher, there are two more questions

1) "Are different GNU packages entitled to using different gcc warning options?"

Yes, of course. Different developers have made different experiences. If Tim
thinks that the '-Wundef' may possibly, some day, help him detect a mistake,
he's perfectly right in using it.

2) "Which warning options from a GNU package does Gnulib need to support,
when compiling a file from that package?"

Here, the answer is: Any except -Werror.

Note that when compiling a .c file from gnulib, we take the freedom to
deactivate warnings as we like; this is the GL_CFLAG_GNULIB_WARNINGS
mechanism.

Bruno