Re: [PATCH 04/12] use a shell function for _AC_RUN_IFELSE

[Ralf Wildenhues]

* Eric Blake wrote on Thu, Oct 23, 2008 at 04:46:39AM CEST:
> According to Ralf Wildenhues on 10/22/2008 2:34 PM:
> > 
> > While I haven't looked at this in detail, I do know there are places in
> > Autoconf where removing the output files before evaluating the actions
> > breaks user scripts.  So this sounds quite unsafe to me.
> 
> For that matter, the current refactoring results in more rm processes than
> before.  Maybe it is worth making _AC_COMPILE_IFELSE_BODY and friends
> merely set a shell variable with the list of files to rm, then call a
> single rm after the AS_IF has completed the if-pass/if-fail actions of
> ac_func_c_try_compile?

Sounds like an idea.

> Also, the 'rm -rf conftest.dSYM' is a wasted fork
> on most platforms (particularly on those like cygwin where forks are
> expensive); should we add a 'test -d conftest.dSYM' first?

I guess, although stat isn't all that cheap either.  Hmm, could ask
Peter whether it would be sufficient to test the first compile (or the
$host type?) and then
  ac_compile_cleanup="rm -rf conftest.dSYM"
  ...
  $ac_compile_cleanup


You may also want to take note that some scripts use 'break' or even
'break 2' to get out of some tests early; unfortunately, this is even
documented in the manual in some places.  I see that of course we don't
exercise this in our test suite  :-/
but its semantics may be relevant for your patches (or not; haven't
checked).

Cheers,
Ralf