[Martin Ebourne] Re: Small fix to configure.in in CVS

[Chong Yidong <cyd@stupidchicken.com>]

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From: Martin Ebourne <lists@ebourne.me.uk>
To: Yidong Chong <cyd@mit.edu>
Subject: Re: Small fix to configure.in in CVS
Date: Thu, 26 Oct 2006 17:54:52 +0100
Message-ID: <20061026175452.oddz2r8w00g8gggc@ebourne.me.uk>

Yidong Chong <cyd@MIT.EDU> wrote:
>> Fixes current CVS configure.in to refer to the right variable when
>> doing the scary macro undefining stuff.
>
> Could you explain in greater detail what the problem in the existing
> configure.in is, and how your change fixes it?

Sure.

The problem I had was that I was building to a prefix directory that  
included the word 'linux'. The emacs configure was preprocessing the  
Makefile through the C preprocessor, and this was substituting 'linux'  
to 1, thus making all the paths invalid.

I then found this code which caters for this problem by attemping to  
undefine any words found in paths etc by passing -U to the  
preprocessor. This wasn't working for me though, and I tracked it down  
to the top_srcdir. Looking through the generated configure script (as  
it exists in CVS) I could see there was no variable top_srcdir, but it  
did exist as ac_top_srcdir. I guess it depeneds on the version of  
autoconf used to generate the configure script, because more recent  
versions prefix ac_ onto vars. If emacs doesn't have a minimum  
autoconf version then maybe a better fix would be to include both  
top_srcdir and ac_top_srcdir.

Needless to say, after the change -Ulinux was passed to the  
preprocessor, the makefile output was correct, and emacs built and  
worked. :)

Cheers,

Martin.


>> - --- emacs/configure.in~	2006-09-28 06:47:26.000000000 +0100
>> +++ emacs/configure.in	2006-10-25 13:50:29.000000000 +0100
>> @@ -3230,7 +3230,7 @@
>>  # the C preprocessor to some helpful value like 1, or maybe the empty
>>  # string.  Needless to say consequent macro substitutions are less
>>  # than conducive to the makefile finding the correct directory.
>> - -[undefs="`echo $top_srcdir $configuration $canonical |
>> +[undefs="`echo $ac_top_srcdir $configuration $canonical |
>>  sed -e 's/[^a-zA-Z0-9_]/ /g' -e 's/^/ /' -e 's/  *$//' \
>>      -e 's/  */ -U/g' -e 's/-U[0-9][^ ]*//g' \
>>  `"]
>





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