add econf_build helper for cross-compiling some packages

diff --git a/eclass/toolchain-funcs.eclass b/eclass/toolchain-funcs.eclass
index 7acd8f937ae77e5d3ecadba090acc18500fe3fec..8815ceafe083808658f8d2464c29a17e27fe5677 100644 (file)
--- a/eclass/toolchain-funcs.eclass
+++ b/eclass/toolchain-funcs.eclass
@@ -1,6 +1,6 @@
-# Copyright 1999-2007 Gentoo Foundation
+# Copyright 1999-2011 Gentoo Foundation
 # Distributed under the terms of the GNU General Public License v2
-# $Header: /var/cvsroot/gentoo-x86/eclass/toolchain-funcs.eclass,v 1.107 2011/09/12 21:42:08 vapier Exp $
+# $Header: /var/cvsroot/gentoo-x86/eclass/toolchain-funcs.eclass,v 1.108 2011/10/17 19:11:49 vapier Exp $
 
 # @ECLASS: toolchain-funcs.eclass
 # @MAINTAINER:
@@ -220,6 +220,73 @@ tc-is-static-only() {
        return $([[ ${host} == *-mint* ]])
 }
 
+# @FUNCTION: tc-env_build
+# @USAGE: <command> [command args]
+# @INTERNAL
+# @DESCRIPTION:
+# Setup the compile environment to the build tools and then execute the
+# specified command.  We use tc-getBUILD_XX here so that we work with
+# all of the semi-[non-]standard env vars like $BUILD_CC which often
+# the target build system does not check.
+tc-env_build() {
+       CFLAGS=${BUILD_CFLAGS:--O1 -pipe} \
+       CXXFLAGS=${BUILD_CXXFLAGS:--O1 -pipe} \
+       CPPFLAGS=${BUILD_CPPFLAGS} \
+       LDFLAGS=${BUILD_LDFLAGS} \
+       AR=$(tc-getBUILD_AR) \
+       AS=$(tc-getBUILD_AS) \
+       CC=$(tc-getBUILD_CC) \
+       CPP=$(tc-getBUILD_CPP) \
+       CXX=$(tc-getBUILD_CXX) \
+       LD=$(tc-getBUILD_LD) \
+       NM=$(tc-getBUILD_NM) \
+       PKG_CONFIG=$(tc-getBUILD_PKG_CONFIG) \
+       RANLIB=$(tc-getBUILD_RANLIB) \
+       "$@"
+}
+
+# @FUNCTION: econf_build
+# @USAGE: [econf flags]
+# @DESCRIPTION:
+# Sometimes we need to locally build up some tools to run on CBUILD because
+# the package has helper utils which are compiled+executed when compiling.
+# This won't work when cross-compiling as the CHOST is set to a target which
+# we cannot natively execute.
+#
+# For example, the python package will build up a local python binary using
+# a portable build system (configure+make), but then use that binary to run
+# local python scripts to build up other components of the overall python.
+# We cannot rely on the python binary in $PATH as that often times will be
+# a different version, or not even installed in the first place.  Instead,
+# we compile the code in a different directory to run on CBUILD, and then
+# use that binary when compiling the main package to run on CHOST.
+#
+# For example, with newer EAPIs, you'd do something like:
+# @CODE
+# src_configure() {
+#      ECONF_SOURCE=${S}
+#      if tc-is-cross-compiler ; then
+#              mkdir "${WORKDIR}"/${CBUILD}
+#              pushd "${WORKDIR}"/${CBUILD} >/dev/null
+#              econf_build --disable-some-unused-stuff
+#              popd >/dev/null
+#      fi
+#      ... normal build paths ...
+# }
+# src_compile() {
+#      if tc-is-cross-compiler ; then
+#              pushd "${WORKDIR}"/${CBUILD} >/dev/null
+#              emake one-or-two-build-tools
+#              ln/mv build-tools to normal build paths in ${S}/
+#              popd >/dev/null
+#      fi
+#      ... normal build paths ...
+# }
+# @CODE
+econf_build() {
+       tc-env_build econf --build=${CBUILD:-${CHOST}} "$@"
+}
+
 # @FUNCTION: tc-has-openmp
 # @USAGE: [toolchain prefix]
 # @DESCRIPTION: