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Re: proposed gnulib-related additions to Autoconf
From: |
Gary V. Vaughan |
Subject: |
Re: proposed gnulib-related additions to Autoconf |
Date: |
Wed, 01 Mar 2006 20:39:44 +0000 |
User-agent: |
Mozilla Thunderbird 1.0.6 (Macintosh/20050716) |
Hi Paul,
Paul Eggert wrote:
> "Gary V. Vaughan" <address@hidden> writes:
>
>
>> i) Let's just improve AC_CHECK_HEADERS (et al) to always make configure
>> smaller and faster by despatching to (undocumented internal)
>> _AC_CHECK_HEADERS_ONCE when it can.
>
>
> Won't that break old scripts? If they do something like this:
>
> if test $ac_feature_foo = yes; then
> AC_CHECK_HEADERS([sys/param.h])
> fi
>
> then we'd hoist the test for sys/param.h out of the then-part, which
> is not what was intended.
Hmm. You're right :-( I was thinking that there might be a way to
detect from the argument signature of the call which flavour the user
wanted; but, looking at the implementation, the only way to do that
would be either an optional fifth argument (ugly), or perhaps if the
first argument does not end in `.h'. The latter is really a motter
of picking between:
AC_CHECK_HEADER_ONCE([sys/param.h])
and, for example:
AC_CHECK_HEADER([1], [sys/param.h])
On balance, the former is clearer. Pity, as it adds just adds another
function that has to be supported in later releases :-(
>> ii) I would have thought that use of shell functions in generated
>> configure scripts is safe enough by now
>
>
> That's the direction I'd like to head too, but it's a big enough
> change that it will cause problems. Let's wait until after 2.60 comes
> out.
Excellent. Yes, I think it is more important to get a release soon so
that the huge improvements since 2.59 can begin to make their way to
developers that don't want to risk a CVS snapshot.
> It might make sense to have an "Autoconf 3" that has a lot of changes
> along these lines (I'd like to assume at least C89 and POSIX-2.1992
> conformance, for example; sheesh, it's 2006 already!), and reserve
> "Autoconf 2" for the current basic approach.
That sounds like the best way forward to me!
Cheers,
Gary.
--
Gary V. Vaughan ())_. address@hidden,gnu.org}
Research Scientist ( '/ http://tkd.kicks-ass.net
GNU Hacker / )= http://www.gnu.org/software/libtool
Technical Author `(_~)_ http://sources.redhat.com/autobook
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