Re: gtk.m4 patch

[Owen Taylor <owt1 cornell edu>]

Tero Pulkkinen <terop@students.cc.tut.fi> writes:

> Here's a patch for gtk.m4 that will add CXXFLAGS support for it.
> 
> The gtk.m4 did not work correctly if there was AC_PROC_CC, AC_PROC_CXX and
> AC_LANG_CPLUSPLUS in the configure.in.
> 
> (still, it would prolly be better if AC_SUBST(GTK_CXXFLAGS) could be used,
> but I couldnt get that one working, so it modifies CXXFLAGS directly.. )

Actually, there is no need for GTK_CXXFLAGS; GTK_CFLAGS should
work fine with a C++ compiler in the end.

The code you modified does:

 * Save CFLAGS/LIBS
 * Modify them
 * Try running something
 * Restore them to the original position.

You've just noticed that when AC_LANG is set to CPLUSPLUS, AC_TRY_RUN
uses the C++ compiler and CXXFLAGS. Your patch is mostly OK, and I
don't see any reason not to include it; though in general it might be
that case that a test written for C would work for C++, so it might be
safer to do either such tests before you call AC_LANG_CPLUSPLUS in
your configure.in, or to put them in a

AC_LANG_SAVE
AC_LANG_C

AC_LANG_RESTORE

group.

> -- 
> -- Tero Pulkkinen -- terop@modeemi.cs.tut.fi --
> 
> --- gtk.m4	Wed Mar 18 00:04:12 1998
> +++ /home/p150650/modeemi-b/automake/share/aclocal/gtk.m4	Wed Mar 18 01:31:28 1998
> @@ -17,7 +17,9 @@
>      GTK_LIBS=`$GTK_CONFIG --libs`
>      ac_save_CFLAGS="$CFLAGS"
>      ac_save_LIBS="$LIBS"
> +    ac_save_CXXFLAGS="$CXXFLAGS"
>      CFLAGS="$CFLAGS $GTK_CFLAGS"
> +    CXXFLAGS="$CXXFLAGS $GTK_CFLAGS"
>      LIBS="$LIBS $GTK_LIBS"
>  dnl
>  dnl Now check if the installed GTK is sufficiently new. (Also sanity
> @@ -43,6 +45,7 @@
>  }
>  ],, no_gtk=yes,[echo $ac_n "cross compiling; assumed OK... $ac_c"])
>       CFLAGS="$ac_save_CFLAGS"
> +     CXXFLAGS="$ac_save_CXXFLAGS"
>       LIBS="$ac_save_LIBS"
>    else
>       no_gtk=yes
> @@ -56,6 +59,9 @@
>       GTK_LIBS=""
>       ifelse([$3], , :, [$3])
>    fi

> +  CXXFLAGS="$CXXFLAGS $GTK_CFLAGS"
> +  AC_SUBST(CXXFLAGS)

This part, though is incorrect. gtk.m4 has no business messing
with the callers CXXFLAGS. It leaves the caller the choice
of adding GTK_CFLAGS to CFLAGS or using it in a Makefile as
is. The caller can do the same with CXXFLAGS. [ And the
caller can use GTK_CFLAGS for that purpose ]

Also, the equivalent of AC_SUBST(CXXFLAGS) is already done
automatically.

Regards,
                                        Owen