testing the value of ${CXX} in ports Makefile

[Don Lewis]

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
PORTVERSION=	0.0.0
CATEGORIES=	devel
DISTFILES=

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


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.

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.