[PATCH, Makefile.in] refine selftest recipes to restore mingw bootstrap

[Tamar Christina]

Sending reply to list.

> -----Original Message-----
> From: Tamar Christina
> Sent: Tuesday, November 28, 2017 10:02
> To: 'David Malcolm' <dmalcolm@redhat.com>; Olivier Hainque
> <hainque@adacore.com>; Jeff Law <law@redhat.com>
> Cc: GCC Patches <gcc-patches@gcc.gnu.org>
> Subject: RE: [PATCH, Makefile.in] refine selftest recipes to restore mingw
> bootstrap
> 
> > -----Original Message-----
> > From: David Malcolm [mailto:dmalcolm@redhat.com]
> > Sent: Monday, November 27, 2017 22:16
> > To: Olivier Hainque <hainque@adacore.com>; Jeff Law <law@redhat.com>
> > Cc: GCC Patches <gcc-patches@gcc.gnu.org>; Tamar Christina
> > <Tamar.Christina@arm.com>
> > Subject: Re: [PATCH, Makefile.in] refine selftest recipes to restore
> > mingw bootstrap
> >
> > On Mon, 2017-11-27 at 09:40 +0100, Olivier Hainque wrote:
> > > (typo in David's email address in the previous message, resending.
> > > sorry for the duplicates)
> > >
> > > Hi Jeff,
> > >
> > > (Thanks for your feedback)
> > >
> > > > On Nov 27, 2017, at 04:55 , Jeff Law <law@redhat.com> wrote:
> > > >
> > > > > 	* Makefile.in (SELFTEST_FLAGS): Use nul instead of /dev/null
> > > > > 	on mingw build hosts.
> > > >
> > > > Would it make more sense to set the output file to HOST_BIT_BUCKET
> > > > when -fselftest is active?
> > >
> > >
> > > Hmm, possibly. Interesting suggestion :)
> > >
> > > David, who introduced the framework, would know for sure - cc'ed.
> > >
> > > David, thoughts on this ?
> >
> > [CCing Tamar]
> >
> > The selftests currently assume both:
> > (a) reading a source file from /dev/null, and
> > (b) writing the generated asm to /dev/null
> >
> > I note that r241895 added "-o /dev/null" for the asm output to "Fix
> > the Windows native x86-64 build.":
> >
> > +2016-11-07  Tamar Christina  <tamar.christina@arm.com>
> > +
> > +       PR driver/78196
> > +       * Makefile.in (SELFTEST_FLAGS): Added -o /dev/null.
> > +
> 
 Yeah I choose this fix because /dev/null is converted to "nul" by the
 Cygwin/msys2 runtime. So when invoked On the shell it gets converted
 before GCC sees it.
 
 Nothing against using nul directly, though I am surprised that there's an
 environment that provides Configure, automake and coreutils which doesn't
 convert /dev/null to nul.
 
Thanks,
Tamar
> 
> 
> > HOST_BIT_BUCKET seems to be a header thing, rather than a Makefile
> > thing; presumably there would need to be logic to handle both input
> > and output for the HOST_BIT_BUCKET approach.
> >
> > Given that, I prefer Olivier's patch - it seems simpler to me.
> >
> > Dave