testing the value of ${CXX} in ports Makefile

Shane Ambler FreeBSD at ShaneWare.Biz
Fri Jan 30 18:14:26 UTC 2015

On 30/01/2015 14:13, Don Lewis wrote:
> I need to test the value of ${CXX} in the Makefile for a port and am
> getting unexpected results.  Here is a simplified version of the
> Makefile:
> PORTNAME=	junk
> MAINTAINER=	truckman at FreeBSD.org
> COMMENT=	junk
> USE_GCC=	4.9+
> .include <bsd.port.pre.mk>
> post-patch:
> 	echo CXX=${CXX}
> .if ${CXX} == g++49
> 	echo detected g++49
> .else
> 	echo did not detect g++49
> .endif
> .include <bsd.port.post.mk>
> If I run "make patch", this is what I get:
> # make patch
> ===>   junk-0.0.0 depends on file: /usr/local/sbin/pkg - found
> ===> Fetching all distfiles required by junk-0.0.0 for building
> ===>  Extracting for junk-0.0.0
> ===>  Patching for junk-0.0.0
> echo CXX=g++49
> CXX=g++49
> echo did not detect g++49
> did not detect g++49

You want to use @${ECHO} in the port makefile for that to print right

> If I run "make -dA patch" and look at the debug output, I observe
> bsd.gcc.mk getting processed after the .if is evaluated.  When the .if
> is processed, the value of ${CXX} is still c++.  It sort of looks like
> bsd.gcc.mk isn't getting included until bsd.port.post.mk and we are
> relying on lazy expansion to get the correct value of ${CXX} for the
> actions.

Maybe more to the point is that CXX used to build might only be defined
as part of MAKE_ENV to be passed as the environment for the make
command when it is run.

> It sort of looks like I'll have to do something like:
> post-patch:
> 	[ ${CXX} = g++49 ] && echo detected g++49
> but that just seems goofy.

I believe the correct way to what you want is -

USES= compiler

.include <bsd.port.pre.mk>

EXTRA_PATCHES=	${FILESDIR}/extra-patch-srcfile.c

and/or comments in /usr/ports/Mk/Uses/compiler.mk

You may also want to consider patching with -

#if (__GNUC__ == 4) && (__GNUC_MINOR__ == 9)
// 4.9 specific changes

Of note is that clang identifies itself as gcc 4.2 so you may also want
to test for __clang__ if you want to use < with __GNUC_MINOR__

You can also define more control over gcc version - USE_GCC=4.8 will
require gcc 4.8 while USE_GCC=4.8+ says you can use 4.8 or higher.

FreeBSD - the place to B...Software Developing

Shane Ambler

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