Re: Order of AM_CPPFLAGS and other xxx_CFLAGS

[Michael Goffioul]

On Sun, Nov 17, 2013 at 12:14 PM, Rik <address@hidden> wrote:

On 11/14/2013 07:57 PM, Michael Goffioul wrote:
> Rik,
>
> This changeset breaks my compilation with MSVC:
>
> http://hg.savannah.gnu.org/hgweb/octave/rev/a230b996ae8a
>
> The problem is that compilation of (among others) __init_fltk__.cc uses
> now the following CPPFLAGS definition:
>
> $(GRAPHICS_CFLAGS) $(FT2_CPPFLAGS) $(FONTCONFIG_CPPFLAGS) $(AM_CPPFLAGS)
>
> The variable GRAPHICS_CFLAGS, pulled from fltk-config, contains a -Ixxx
> statement containing the base installation directory of my MXE system.
> The libgnu directory, on the other hand, is part of AM_CPPFLAGS. As a
> result, gnulib header substitution fails for some headers. A similar
> problem could also occur on Linux if any of the variables preceding
> AM_CPPFLAGS happen to contain -I/usr/include. I believe the libgnu
> directory should appear early in the include chain, otherwise it'll fail
> to override what it's supposed to override.
>

Ugh.  This doesn't look like it is going to be fun to solve.

Thanks Rik for all the suggestions. I know how to avoid the problem (I already made the change to be able to compile current octave tip), the easiest being to revert a230b996ae8a. I'm fine with a local patch. I was just raising the fact that having AM_CPPFLAGS at the end may defeat the whole gnulib stuff. Of course, this won't happen on POSIX-compliant platforms.

Michael.