[Mesa-dev] [PATCH] build: Fix AX_PROG_{CC, CXX}_FOR_BUILD macros

[Thierry Reding]

On Tue, Nov 20, 2012 at 08:29:04PM +0100, Thierry Reding wrote:
> On Tue, Nov 20, 2012 at 11:07:03AM -0800, Matt Turner wrote:
> > On Tue, Nov 20, 2012 at 7:50 AM, Thierry Reding
> > <thierry.reding at avionic-design.de> wrote:
> > > Override the cross_compiling and ac_tool_prefix variables by reassigning
> > > to them instead of redefining the macros. Redefining them will actually
> > > cause the variable names to be replaced instead of their content.
> > >
> > > Furthermore push the definition of CPPFLAGS before running the checks
> > > for the build tools to avoid the host CPPFLAGS from leaking into the
> > > build CPPFLAGS.
> > >
> > > While at it drop the redefinition of AC_TRY_COMPILER which hasn't been
> > > used since autoconf 2.50 and make sure that all definitions are properly
> > > popped when done (LDFLAGS, ac_cv_prog_CPP, ac_cv_prog_CXXCPP).
> > >
> > > Signed-off-by: Thierry Reding <thierry.reding at avionic-design.de>
> > > ---
> > >  m4/ax_prog_cc_for_build.m4  | 37 +++++++++++--------------------------
> > >  m4/ax_prog_cxx_for_build.m4 | 38 ++++++++++++--------------------------
> > >  2 files changed, 23 insertions(+), 52 deletions(-)
> [...]
> > Are these changes from upstream? I really have concerns about making
> > non-trivial changes to these files.
> 
> No, they're not. I do plan to send these changes upstream, but quite
> honestly I'm not sure that they'll be accepted given that I have none of
> the copyright assigment forms filled with the FSF. Looking at the
> autoconf-archive website doesn't actually say anything about copyright
> assignment, but as the project is hosted on GNU I'm a bit sceptical.
> Also note that AX_PROG_CXX_FOR_BUILD doesn't actually exist upstream. I
> essentially copied it from AX_PROG_CC_FOR_BUILD.
> 
> I'm actually a bit confused as to why the original cross-compilation
> patches that I sent in worked at all (and I'm sure they did because I
> tested them fairly extensively at the time), but looking at configure
> as generated with the macros as they are in the repository right now,
> things are severely broken. Running the configure script shows a bunch
> of
> 
> 	checking for 2... no
> 
> messages, and cross-compiling doesn't actually succeed. With the above
> patches I've verified that Mesa cross-builds from x86_64 to ARM.
> 
> Still, if you have any doubts I can try feeding those changes upstream
> and see what comes of it. If that happens we can easily sync the changes
> back by copying the files.

For reference, I've submitted patches for both macros upstream. They are
available here:

	http://savannah.gnu.org/patch/index.php?7890
	http://savannah.gnu.org/patch/index.php?7891

Thierry
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