Re: Inconsistency w.r.t. defining the same symbol more than once

[Thomas Schwinge]

Hello!

On Mon, Oct 09, 2006 at 01:03:57PM +0200, Stepan Kasal wrote:
> On Sun, Oct 08, 2006 at 02:16:00PM +0200, Thomas Schwinge wrote:
> > $ grep FOO config.h
> > /* FOO 1 */
> > #define FOO 0
> ...
> > The _first_ definition (i.e. `FOO=0') will be used.
> 
> this bug was fixed in the latest release.

Nice.


> But even though the fix was intentional, this behaviour is still
> undocumented, so the more important part of the answer is what Paul
> said: do not do that.
> 
> In detail:
> 1) The third parameter, the description, is read by autoheader, when
> it is creating config.h.in, and it should be the same for all calls.

`should be the same' --- if you require that (and it makes sense, as
autoheader otherwise would have to decide which one to use), I could
imagine there to be a way to introduce a mechanism that makes sure that
all occurrences of `AC_DEFINE' on the same symbol are checked to have the
same description fields and complains otherwise.

> 2) During the execution of ./configure, only one instance of
> AC_DEFINE should be reached.

Why?


Regards,
 Thomas

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