Re: Bug in LT 1.5 AC_LIBTOOL_PROG_CC_C_O

[Gary V . Vaughan]

On Friday, January 2, 2004, at 07:44  pm, Jeff Squyres wrote:
> Greetings / happy new year

Happy New Year!

> If this patch is to be rejected, no problem, but please give some kind 
> of NACK response.
>
> -   # According to Tom Tromey, Ian Lance Taylor reported there are C 
> compilers
> -   # that will create temporary files in the current directory 
> regardless of
> -   # the output directory.  Thus, making CWD read-only will cause 
> this test
> -   # to fail, enabling locking or at least warning the user not to do 
> parallel
> -   # builds.
> -   chmod -w .

The comment shows that the intent of the chmod is to prevent compilers 
which create tmpfile droppings in the working directory from barfing 
during parallel builds.

I think it is correct to test for this condition and to set 
enable_libtool_lock if it occurs.  I do agree that 
AC_LIBTOOL_PROG_CC_C_O is the wrong place to do that.

Are you willing to enhance your patch to move the chmod test to another 
macro? I would be happy to accept your patch in that case.  Otherwise, 
keep pinging, and I'll aspire to writing the other macro myself, and 
commit your patch at the same time.

Cheers,
        Gary.

> On Wed, 5 Nov 2003, Jeff Squyres wrote:
>
> > Short version:
> > --------------
> >
> > Problem: Libtool's AC_LIBTOOL_PROG_CC_C_O m4 macro (in m4/libtool.m4)
> > executes "chmod -w ." before testing to see if the compiler supports 
> > "$CC
> > -c foo.c -o whatever".  This causes the Intel compiler on Linux (icc) 
> > to
> > fail because it tries to write temporary files in the pwd regardless 
> > of
> > the output directory.
> >
> > Through a long sequence of cause-and-effects, this eventually causes a
> > failure of Automake/Libtool to build libraries when using Automake's
> > _CPPFLAGS suffix functionality.
> >
> > Solution: Removing the "chmod -w ." does not seem to have any adverse
> > effects, and makes the Intel compiler pass this test (as it should,
> > because icc supports "icc -c foo.c -o whatever"), and therefore 
> > Automake's
> > _CPPFLAGS functionality works as expected.
--
Gary V. Vaughan      ())_.  address@hidden,gnu.org}
Research Scientist   ( '/   http://www.oranda.demon.co.uk
GNU Hacker           / )=   http://www.gnu.org/software/libtool
Technical Author   `(_~)_   http://sources.redhat.com/autobook