Re: AC_CHECK_FUNCS and gcc with -Werror

[Steffen Dettmer]

On Wed, Mar 3, 2010 at 2:44 PM, Eric Blake <address@hidden> wrote:
> According to Steffen Dettmer on 3/3/2010 6:33 AM:
> > Do I understand correctly that it is generally adviced to not use
> > the option -Werror?
>
> Not quite.  The advice is to not mix -Werror and configure.

ahh ok, this is fine!
There is no need to have -Werror during configure.
So it seems again we just do the things wrongly :)
But how to do it correctly?

> Post-configure, you can use -Werror to your heart's content, and I do it
> all the time in packages that I maintain.

I'm not sure if I get this...
How do I use -Werror or -WX post-configure correctly?

> And it is even possible to let configure check whether -Werror
> works, and if so, automatically add it to CFLAGS.

but CFLAGS are used by AC_CHECK_FUNCS?
(I think this is exactly my problem. my configure adds -Werror/-WX
automatically to CFLAGS).

> It's just that configure checks themselves are not guaranteed
> to be warning-free, so converting warnings to errors during
> configure is a recipe for disaster.  In other words, the advice
> is that you shouldn't use './configure CFLAGS=-Werror'.

we use `./configure --enable-errors' (yes, the option name isn't
the best possible) which internally appends -Werror/-WX to
CFLAGS.

>> mmm... (I think the idea is to make a warning hurting to ensure
>> that it is fixed instantly and cannot be overseen / forgotten).
>
> The problem is that no one has submitted a patch to make configure and
> -Werror try to play nicely, until last month; and even then, it is not the
> easiest thing in the world to do.

I'm sorry, I didn't express well what we want. We do not
need/want -Werror inside configure. Just inside make.

I'm afraid again I just fail to see the obvious and it is very
easy to do?

>> Yes, inside configure -Werror isn't needed but for compiling
>> all the programs source files. How to add it for the program but
>> not for the configure run? Via libxyz_a_CFLAGS of all libs?
>
> That's one way.  Or even via CFLAGS itself.  It's just that you
> have to be careful that the CFLAGS are different during the
> configure run than during make in that case.

We now have in configure.in (or actually an included .m4 file)
`CFLAGS="$CFLAGS -Werror";' and `CFLAGS="$CFLAGS -WX"'. Is this
`via CFLAGS itself'? sorry for my silly questions but I just
don't get it...

oki,

Steffen