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Re: AM_PROG_CC_C_O and subdir-objects
From: |
Ralf Wildenhues |
Subject: |
Re: AM_PROG_CC_C_O and subdir-objects |
Date: |
Fri, 19 May 2006 04:36:46 +0200 |
User-agent: |
Mutt/1.5.11+cvs20060403 |
Hi Lars,
* Lars Hecking wrote on Thu, May 18, 2006 at 07:14:10PM CEST:
>
> Why does the 'subdir-objects' option require AM_PROG_CC_C_O?
> I think I figured it out - the generated compile rules do something like
> $CC -c -o dir/file.o dir/file.c, is that correct?
Yes. Actually, per-target compile flags require AM_PROG_CC_C_O as well
(and that is a very common case), only that Automake 1.9.6 forgot to
notice that. This has been fixed in the CVS version of Automake, but
also the requirement for AM_PROG_CC_C_O in both cases has been made a
portability warning, not a hard error.
That way, with Automake-1.10 I guess you will be able to ignore the
portability warning (you need -Wportability or -Wall to even see it),
just your code won't work with a losing compiler. This is more
reasonable: it may, for completely unrelated reasons, not work with such
a compiler anyway.
> This is kind of obscure, though, and the connection should be documented.
Probably. I'm working on a patch to implement AM_PROG_{CXX,F77,FC}_C_O
as well, I may look into adding such a note.
Cheers,
Ralf