Re: Darwin universal binaries and LDFLAGS conundrum

[Keith MARSHALL]

Martin-Gilles Lavoie wrote:
> At the strict minimum, I need to have the following flags set
> in the generated makefile:
>
>   CFLAGS  =  -c $(CPPFLAGS) -O3 -isysroot \
>     /Developer/SDKs/MacOSX10.4u.sdk -arch i386 -arch ppc
>   LDFLAGS =  -Wl,-syslibroot,/Developer/SDKs/MacOSX10.4u.sdk
>
> The problem is, whatever I set for LDFLAGS or CFLAGS in the .ac file
> passed to autoconf, the output Makefile is invariably stripped down
> to an empty LDFLAGS declaration and a CFLAGS devoid of the -isysroot
> and -arch parameters.

Well, firstly I wouldn't embed $(CPPFLAGS) within the CFLAGS definition;
neither would I add the `-c' flag at this point -- both are better placed
in the commands section of any rules in which they are required.

Now, consider this trivial example:

  $ cat configure.ac
  AC_INIT
  pop_CFLAGS="$CFLAGS" pop_LDFLAGS="$LDFLAGS"
  CFLAGS="" LDFLAGS=""
  AC_PROG_CC
  CFLAGS="$pop_CFLAGS" LDFLAGS="$pop_LDFLAGS"
  AC_CONFIG_FILES([Makefile])
  AC_OUTPUT

  $ cat Makefile.in
  CFLAGS = @CFLAGS@
  LDFLAGS = @LDFLAGS@

Note that your CFLAGS/LDFLAGS combination is invalid for my compiler;
(I'm running GCC on Woe32).  Thus, this example kludges them away, for
the purpose of the AC_PROG_CC test, since they would cause it to fail,
and `configure' would die.  In your case, they *should* work within
AC_PROG_CC, so the real example reduces to:

  $ cat configure.ac
  AC_INIT
  AC_PROG_CC
  AC_CONFIG_FILES([Makefile])
  AC_OUTPUT

Now, if I run:

  $ autoconf

  $ ./configure \
    CFLAGS='-O3 -isysroot /Developer/SDKs/MacOSX10.4u.sdk -arch i386 -arch ppc'\
    LDFLAGS='-Wl,-syslibroot,/Developer/SDKs/MacOSX10.4u.sdk'

I see:

  checking for gcc... gcc
  checking for C compiler default output file name... a.exe
  checking whether the C compiler works... yes
  checking whether we are cross compiling... no
  checking for suffix of executables... .exe
  checking for suffix of object files... o
  checking whether we are using the GNU C compiler... yes
  checking whether gcc accepts -g... yes
  checking for gcc option to accept ISO C89... none needed
  configure: creating ./config.status
  config.status: creating Makefile

and finally:

  $ cat makefile
  CFLAGS = -O3 -isysroot /Developer/SDKs/MacOSX10.4u.sdk -arch i386 -arch ppc
  LDFLAGS = -Wl,-syslibroot,/Developer/SDKs/MacOSX10.4u.sdk

which seems to have the flags you require, propagated into the Makefile.

HTH,
Keith.