[OE-core] [PATCH 1/6] gcc: Use alternatives for the *-symlinks packages.

[Mark Hatle]

The various gcc related symlinks should be provided as alternatives instead
of hard coded symlinks.  This will permit multiple toolchains on a system.

Multiple toolchains could come from multilib configurations or alternative
open source or commerical sources.

Note, gccbug was skipped since it doesn't seem to be generated anymore.

Signed-off-by: Mark Hatle <mark.hatle at windriver.com>
---
 meta/recipes-devtools/gcc/gcc-target.inc | 91 ++++++++++++++++++++------------
 1 file changed, 58 insertions(+), 33 deletions(-)

diff --git a/meta/recipes-devtools/gcc/gcc-target.inc b/meta/recipes-devtools/gcc/gcc-target.inc
index e1179ac..ee41d3f 100644
--- a/meta/recipes-devtools/gcc/gcc-target.inc
+++ b/meta/recipes-devtools/gcc/gcc-target.inc
@@ -50,11 +50,8 @@ FILES_${PN}-plugin-dev = "\
   ${libexecdir}/gcc/${TARGET_SYS}/${BINV}/plugin/gengtype \
   ${gcclibdir}/${TARGET_SYS}/${BINV}/plugin/gtype.state \
 "
-FILES_${PN}-symlinks = "\
-  ${bindir}/cc \
-  ${bindir}/gcc \
-  ${bindir}/gccbug \
-"
+FILES_${PN}-symlinks = ""
+ALLOW_EMPTY_${PN}-symlinks = "1"
 
 FILES_${PN}-plugins = "\
   ${gcclibdir}/${TARGET_SYS}/${BINV}/plugin \
@@ -65,36 +62,33 @@ FILES_g77 = "\
   ${bindir}/${TARGET_PREFIX}g77 \
   ${libexecdir}/gcc/${TARGET_SYS}/${BINV}/f771 \
 "
-FILES_g77-symlinks = "\
-  ${bindir}/g77 \
-  ${bindir}/f77 \
-"
+FILES_g77-symlinks = ""
+ALLOW_EMPTY_g77-symlinks = "1"
+
 FILES_gfortran = "\
   ${bindir}/${TARGET_PREFIX}gfortran \
   ${libexecdir}/gcc/${TARGET_SYS}/${BINV}/f951 \
 "
-FILES_gfortran-symlinks = "\
-  ${bindir}/gfortran \
-  ${bindir}/f95"
+FILES_gfortran-symlinks = ""
+ALLOW_EMPTY_gfortran-symlinks = "1"
 
 FILES_cpp = "\
   ${bindir}/${TARGET_PREFIX}cpp \
   ${base_libdir}/cpp \
   ${libexecdir}/gcc/${TARGET_SYS}/${BINV}/cc1"
-FILES_cpp-symlinks = "${bindir}/cpp"
+FILES_cpp-symlinks = ""
+ALLOW_EMPTY_cpp-symlinks = "1"
 
 FILES_gcov = "${bindir}/${TARGET_PREFIX}gcov"
-FILES_gcov-symlinks = "${bindir}/gcov"
+FILES_gcov-symlinks = ""
+ALLOW_EMPTY_gconv-symlinks = "1"
 
 FILES_g++ = "\
   ${bindir}/${TARGET_PREFIX}g++ \
   ${libexecdir}/gcc/${TARGET_SYS}/${BINV}/cc1plus \
 "
-FILES_g++-symlinks = "\
-  ${bindir}/c++ \
-  ${bindir}/g++ \
-"
-
+FILES_g++-symlinks = ""
+ALLOW_EMPTY_g++-symlinks = "1"
 
 FILES_${PN}-doc = "\
   ${infodir} \
@@ -133,22 +127,53 @@ do_install () {
 	# Not sure why we end up with these but we don't want them...
 	rm -f ${TARGET_PREFIX}${TARGET_PREFIX}*
 
-	# Symlinks so we can use these trivially on the target
-	if [ -e ${TARGET_PREFIX}g77 ]; then
-		ln -sf ${TARGET_PREFIX}g77 g77 || true
-		ln -sf g77 f77 || true
-	fi
-	if [ -e ${TARGET_PREFIX}gfortran ]; then
-		ln -sf ${TARGET_PREFIX}gfortran gfortran || true
-		ln -sf gfortran f95 || true
-	fi
-	ln -sf ${TARGET_PREFIX}g++ g++
-	ln -sf ${TARGET_PREFIX}gcc gcc
-	ln -sf ${TARGET_PREFIX}cpp cpp
 	install -d ${D}${base_libdir}
 	ln -sf ${bindir}/${TARGET_PREFIX}cpp ${D}${base_libdir}/cpp
-	ln -sf g++ c++
-	ln -sf gcc cc
 
 	chown -R root:root ${D}
 }
+
+inherit update-alternatives
+
+ALTERNATIVE_PRIORITY = "100"
+
+ALTERNATIVE_${PN}-symlinks = "cc gcc"
+ALTERNATIVE_g77-symlinks = "${@['', 'g77 f77']['f77' in d.getVar('FORTRAN', True)]}"
+ALTERNATIVE_gfortran-symlinks = "${@['', 'gfortran f95']['fortran' in d.getVar('FORTRAN', True)]}"
+ALTERNATIVE_cpp-symlinks = "cpp"
+ALTERNATIVE_gcov-symlinks = "gcov"
+ALTERNATIVE_g++-symlinks = "c++ g++"
+
+ALTERNATIVE_LINK_NAME[cc] = "${bindir}/cc"
+ALTERNATIVE_TARGET[cc] = "${bindir}/${TARGET_PREFIX}gcc"
+
+ALTERNATIVE_LINK_NAME[gcc] = "${bindir}/gcc"
+ALTERNATIVE_TARGET[gcc] = "${bindir}/${TARGET_PREFIX}gcc"
+
+# Not really generated any longer, avoid warnings...
+#ALTERNATIVE_LINK_NAME[gccbug] = "${bindir}/gccbug"
+#ALTERNATIVE_TARGET[gccbug] = "${bindir}/${TARGET_PREFIX}gccbug"
+
+ALTERNATIVE_LINK_NAME[g77] = "${bindir}/g77"
+ALTERNATIVE_TARGET[g77] = "${bindir}/${TARGET_PREFIX}g77"
+
+ALTERNATIVE_LINK_NAME[f77] = "${bindir}/f77"
+ALTERNATIVE_TARGET[f77] = "${bindir}/${TARGET_PREFIX}g77"
+
+ALTERNATIVE_LINK_NAME[gfortran] = "${bindir}/gfortran"
+ALTERNATIVE_TARGET[gfortran] = "${bindir}/${TARGET_PREFIX}gfortran"
+
+ALTERNATIVE_LINK_NAME[f95] = "${bindir}/f95"
+ALTERNATIVE_TARGET[f95] = "${bindir}/${TARGET_PREFIX}gfortran"
+
+ALTERNATIVE_LINK_NAME[cpp] = "${bindir}/cpp"
+ALTERNATIVE_TARGET[cpp] = "${bindir}/${TARGET_PREFIX}cpp"
+
+ALTERNATIVE_LINK_NAME[gcov] = "${bindir}/gcov"
+ALTERNATIVE_TARGET[gcov] = "${bindir}/${TARGET_PREFIX}gcov"
+
+ALTERNATIVE_LINK_NAME[c++] = "${bindir}/c++"
+ALTERNATIVE_TARGET[c++] = "${bindir}/${TARGET_PREFIX}g++"
+
+ALTERNATIVE_LINK_NAME[g++] = "${bindir}/g++"
+ALTERNATIVE_TARGET[g++] = "${bindir}/${TARGET_PREFIX}g++"
-- 
1.8.1.2.545.g2f19ada