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Re: Why I can not overwrite CXXFLAGS values?
From: |
Ralf Wildenhues |
Subject: |
Re: Why I can not overwrite CXXFLAGS values? |
Date: |
Sat, 14 Jun 2008 11:07:36 +0200 |
User-agent: |
Mutt/1.5.18 (2008-05-17) |
Hello Steven,
* Steven Woody wrote on Sat, Jun 07, 2008 at 04:01:06PM CEST:
> On Sat, Jun 7, 2008 at 3:38 PM, Ralf Wildenhues <address@hidden> wrote:
>
> > That said, you can
> > CXXFLAGS =
> > AM_CXXFLAGS = $(CXXFLAGS)
> > xxx_CXXFLAGS = -O0
>
> Set AM_ and xxx_ both? Manual said, only one of them will be used.
Yes, that is right. For the sources of xxx, xxx_CXXFLAGS will be used.
For all sources in this Makefile.am which do not have per-target flags,
AM_CXXFLAGS will be used. I figured you might have other sources in
that file that wanted no special treatment.
> > Alternatively, you can modify $CXXFLAGS within configure.ac; find out
> > whether CXXFLAGS was set by the user _before_ AC_PROG_CXX, and if it
> > wasn't, you can default it to your liking.
>
> How? Thanks.
Example:
if test x"${CXXFLAGS+set}" = xset; then
# the user set CXXFLAGS; don't override it.
flags_were_set=true
else
flags_were_set=false
fi
# This macro will set suitable CXXFLAGS (-g if possible, additionally
# -O2 if using g++), if CXXFLAGS were not set by the user.
AC_PROG_CXX
if $flags_were_set; then
...
else
...
fi
A similar scheme comes up here regularly.
Cheers,
Ralf