SETPGRP and autoconf

[Mark Kettenis]

   Date: Wed, 25 Jul 2001 16:24:20 -0700
   From: Daniel Jacobowitz <dmj+@andrew.cmu.edu>

   I should have objected :)  But it'd been so long since I last saw this issue
   that I forgot about it.

   AC_FUNC_SETPGRP has some regrettable problems.  Witness:

   checking whether setpgrp takes no argument... configure: error: cannot check
     setpgrp if cross compiling

   Thus breaking all host-x-host cross builds.

Bugger!

   This is what I really hate about autoconf.  There's no good reason for
   AC_FUNC_SETPGRP to be an executed test.  If you have a prototype for
   setpgrp(void),  setpgrp(1,1) won't compile, and you don't need to execute
   anything at all.

Who says you've got a prototype?  Even though GDB requires an ISO C
compiler now, this doesn't mean the host's headers have to be ISO
C-compliant.

   What can we do about this?  Besides my usual hack: I have a huge list of
   autoconf cache variables in my build environment, preset.

Dunno.  I don't think there are too many people cross-compiling GDB.
If we want to fix this, we could use an alternative check for
AC_FUNC_SETPGRP when cross-compiling based on the setpgrp prototype.
I don't think it would hurts not defining SETPGRP_VOID if no
prototypes are available, since passing the extra arguments should be
harmless.

Mark