Re: [PATCH 1/5] objc++: initial support for Objective C++

[Stefano Lattarini]

Hi Peter, sorry for the delay.

On 04/27/2012 10:19 AM, Stefano Lattarini wrote:
> From: Peter Breitenlohner <address@hidden>
> 
> Original thread (dating back to almost three years ago):
> <http://lists.gnu.org/archive/html/automake-patches/2009-07/msg00016.html>
> 
> * automake.in: Register new language 'objcxx'.
> (lang_objcxx_rewrite): New subroutine.
> (resolve_linker): Add OBJCXXLINK.
> (%_am_macro_for_cond): Add am__fastdepOBJCXX and AC_PROG_OBJCXX.
> (%_ac_macro_for_var): Add OBJCXX and OBJCXXFLAGS.
> * m4/depend.m4 (_AM_DEPENDENCIES): Add OBJCXX.
> * m4/init.m4 (AM_INIT_AUTOMAKE): Add AC_PROG_OBJCXX hook.
> 
Unfortunately, this patch breaks automake with older autoconfs (e.g., 2.62),
even when the  Objective C++ is not used.  For example:

  $ cat t/whoami.sh
  #! /bin/sh
  # Copyright (C) 1998-2012 Free Software Foundation, Inc.
  # ...
  . ./defs || Exit 1
  cat >> configure.ac << 'END'
  WHO_AM_I=17
  END
  $ACLOCAL

  $ PATH=/opt/extra/autoconf-2.62/bin:$PATH t/whoami.sh
  whoami: exec /bin/sh t/whoami.sh
  Running from installcheck: no
  Using TAP: no
  PATH = ...
  ++ pwd
  /home/stefano/src/am/branches/objc++-support/t/whoami.dir
  + cat
  + aclocal-1.12a -Werror
  configure.ac:2: error: defn: undefined macro: AC_PROG_OBJCXX
  /home/stefano/src/am/branches/objc++-support/m4/options.m4:31: _AM_IF_OPTION 
is expanded from...
  /home/stefano/src/am/branches/objc++-support/m4/init.m4:25: AM_INIT_AUTOMAKE 
is expanded from...
  configure.ac:2: the top level
  autom4te: /usr/bin/m4 failed with exit status: 1
  aclocal: error: autom4te failed with exit status: 1
  + exit_status=1
  + set +e
  + cd /home/stefano/src/am/branches/objc++-support
  + test no = yes
  + case $am_explicit_skips in
  + test 1 -eq 0
  + keep_testdirs=yes
  + am_keeping_testdirs
  + case $keep_testdirs in
  + return 0
  + set +x
  whoami: exit 1

This is due to the unconditional use of 'AC_PROG_OBJCXX' in AM_INIT_AUTOMAKE.  
I've
squashed in the diff below, that solves the issue.

Regards,
  Stefano

-*-*-

diff --git a/m4/init.m4 b/m4/init.m4
index dd4ac67..07ed584 100644
--- a/m4/init.m4
+++ b/m4/init.m4
@@ -100,10 +100,13 @@ AC_PROVIDE_IFELSE([AC_PROG_OBJC],
                  [_AM_DEPENDENCIES([OBJC])],
                  [define([AC_PROG_OBJC],
                          defn([AC_PROG_OBJC])[_AM_DEPENDENCIES([OBJC])])])dnl
-AC_PROVIDE_IFELSE([AC_PROG_OBJCXX],
+dnl Support for Objective C++ was only introduced in Autoconf 2.65,
+dnl but we still cater to Autoconf 2.62.
+m4_ifdef([AC_PROG_OBJCXX],
+[AC_PROVIDE_IFELSE([AC_PROG_OBJCXX],
                  [_AM_DEPENDENCIES([OBJCXX])],
                  [define([AC_PROG_OBJCXX],
-                         
defn([AC_PROG_OBJCXX])[_AM_DEPENDENCIES([OBJCXX])])])dnl
+                         
defn([AC_PROG_OBJCXX])[_AM_DEPENDENCIES([OBJCXX])])])])dnl
 ])
 _AM_IF_OPTION([silent-rules], [AC_REQUIRE([AM_SILENT_RULES])])dnl
 dnl The 'parallel-tests' driver may need to know about EXEEXT, so add the