Re: [Enigma-devel] BUG: tolua verirrt

[Tacvek]

----- Original Message ----- 
From: "Ronald Lamprecht" <address@hidden>
To: "Tacvek" <address@hidden>
Cc: <address@hidden>; "Sidney Markowitz" <address@hidden>
Sent: Friday, December 08, 2006 10:47 AM
Subject: Re: [Enigma-devel] BUG: tolua verirrt


> Hi Tacvek,
>
> Tacvek wrote:
> > > > > > > make[1]: Leaving directory
> > > > > > > `/rep/svn/public/enigma-game-trunk/lib-src'
> > > > > > > Making all in tools
> > > > > > > make[1]: Entering directory 
> > > > > > > `/rep/svn/public/enigma-game-trunk/tools'
> > > > > > > gcc -I../lib-src/lua -x c++  -DENABLE_ASSERT -g -DCXXLUA -g -O2
> > > > > > > -o tolua tolua-tolua.o tolua-toluabind.o -L../lib-src/lua -
> > > > > > > llua -lstdc++ -lxerces-c -lpng -ldl
> >
> > Autoconf 2.61 with automake 1.10 does show the problem.
> > I've found the change between automake 1.9 and 1.10 that is responsible.
> >
> > The change is definately intentional. Indeed, it was only due to a bug
> > in older automakes that
> > my code worked at all. Automake deliberately passes CFLAGS to the linker.
> >
> > I think I have found a new workaround that is not likely to break.
> > I've attached the patch. The patch also does a little bit a unrelated
> > cleanup to make automake happier.
>
> Sidney reported some problems on MacOS. His fix proposal may generate
> trouble with the "dist" target. Could you try to analyse his problems:
>
> > 3) On MacOS there is some difference between gcc and g++ that requires
> > you to link using g++ if any of the source files are in C++. This causes
> > the link step of the build of the tools directory to break now that LUA
> > is C++ because tolua.c and toluabind.c both have '.c' extensions and gcc
> > was being used. I have attached a patch to configure.ac and
> > tools/Makefile.am that when the C++ version of LUA is being used creates
> > an empty file tools/dummy.cc and adds that to the list tolua.c and
> > toluabind.c to compile and link. The result builds and runs fine on my
> > Intel MacBook running MacOS 10.4.8.
Hmm... Interesting. I know that on linux it is generally better to use g++ 
to link
c++ .o files than to use gcc. For example it automatically links in the 
standard c++
library.

I'd be interested in knowing what other differences there are on OS X.
I am concerned about that patch causing problems.
If I recall correctly, _SOURCES is a bit special compaired to the others,
and if possible should not be conditionalized.

Is there a problem with making the dummy.cc non-conditional?
After all, a c++ linker should hapily link a bunch of c .o files.
In fact it would brobably have no net effect, as the linker would
notice that no symbols from the c++ library are actually used, and
thus omit it. Ironically, that solution would have fixed the recent problem,
without requiring the use of CPPFLAGS. It would also let us drop
the LDADD line.

I'm also curious about why this problem has not already come up.
When we made CXXLUA default on all platforms, the mac problem should
have appeared.



--------------------------------------------------------------------------------


> Index: tools/Makefile.am
> ===================================================================
> --- tools/Makefile.am (revision 510)
> +++ tools/Makefile.am (working copy)
> @@ -22,6 +22,7 @@
> tolua_CPPFLAGS= $(CPP_FLAGS)
>
> if CXXLUA
> +tolua_SOURCES += dummy.cc
> tolua_CPPFLAGS += -x c++ $(AM_CXXFLAGS) $(CXXFLAGS)
> tolua_LDADD += -lstdc++
> endif
> Index: configure.ac
> ===================================================================
> --- configure.ac (revision 510)
> +++ configure.ac (working copy)
> @@ -290,8 +290,10 @@
>   AS_HELP_STRING(--enable-cxxlua, Build Lua with C++ 
> [default=yes]),,enable_cxxlua=yes)
> if test "x$enable_cxxlua" = xyes; then
>   CXXFLAGS="$CXXFLAGS -DCXXLUA"
> +  echo > tools/dummy.cc
>   AC_MSG_RESULT(yes)
> else
> +  rm -f tools/dummy.cc
>   AC_MSG_RESULT(no)
> fi