Re: RFC: Changing AC_DEFINE

[Alexandre Oliva]

On Jun  2, 2001, Akim Demaille <address@hidden> wrote:

>>>>>> "Alexandre" == Alexandre Oliva <address@hidden> writes:
Alexandre> On Jun 1, 2001, Akim Demaille <address@hidden> wrote:
>>> I would like to address the issues raised in
>>> http://gcc.gnu.org/ml/gcc/2001-03/msg00814.html for 2.51.  This
>>> basically means try to use `echo' instead of a heredoc when there
>>> are no funky characters.

Alexandre> Err...  I don't understand how this would help.  I mean,
Alexandre> you generally can't tell at autoconf-time whether there are
Alexandre> going to be funky characters in the macro definition so, in
Alexandre> general, you'll need to test it at run-time, and then,
Alexandre> you'll have a here-doc anyway in case there are funky
Alexandre> characters.  Right?

> I do agree, that's why I referred to AC_VAR_IFINDIR (or whatever the
> current name :).  I believe most uses are using literals, and we can
> address those cases.

Indeed.  Sounds reasonable.

Alexandre> IMO, the best way to go is for autoconf to come up with a
Alexandre> safe echo, i.e., one that won't mess up any characters,
Alexandre> will preserve backslashes, etc, in a similar way that
Alexandre> libtool does.  In fact, this would help libtool a lot as we
Alexandre> move more of it into m4sh.

> Well, why not!

Err...  Because someone has to do it? :-)

Alexandre> A shell parses the whole if/fi construct, creating
Alexandre> temporary files for each here document in it.  Some shells
Alexandre> create links for such here-documents on every fork(), so
Alexandre> that the clean-up code they had installed correctly removes
Alexandre> them.  It was in creating the links that the shell took
Alexandre> forever.

> Ah, I had not fully understood the diagnostics.  Actually, I think
> some part of the thread are missing from the archive.

> Thanks!

Thanks for getting this stuff into the manual!

-- 
Alexandre Oliva   Enjoy Guarana', see http://www.ic.unicamp.br/~oliva/
Red Hat GCC Developer                  address@hidden, redhat.com}
CS PhD student at IC-Unicamp        address@hidden, gnu.org}
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