external-toolchain: fix support

The recent commit adding the external toolchain wrapper has broken the
support for external toolchain. The check_arm_eabi, check_cplusplus
and check_cross_compiler_exists functions were using TARGET_CC, which
points to the toolchain wrapper, but at the moment those functions are
called, the wrapper hasn't been generated yet.

We fix this by passing to these functions the path to the C or C++
compiler they should use for their tests.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>

toolchain/helpers.mk

@@ -201,8 +201,11 @@ check_uclibc = \
 # Check that the Buildroot configuration of the ABI matches the
 # configuration of the external toolchain.
 #
+# $1: cross-gcc path
+#
 check_arm_abi = \
-	EXT_TOOLCHAIN_TARGET=$(shell LANG=C $(TARGET_CC) -v 2>&1 | grep ^Target | cut -f2 -d ' ') ; \
+	__CROSS_CC=$(strip $1) ; \
+	EXT_TOOLCHAIN_TARGET=`LANG=C $${__CROSS_CC} -v 2>&1 | grep ^Target | cut -f2 -d ' '` ; \
 	if echo $${EXT_TOOLCHAIN_TARGET} | grep -q 'eabi$$' ; then \
 		EXT_TOOLCHAIN_ABI="eabi" ; \
 	else \
@@ -220,8 +223,11 @@ check_arm_abi = \
 #
 # Check that the external toolchain supports C++
 #
+# $1: cross-g++ path
+#
 check_cplusplus = \
-	$(TARGET_CXX) -v > /dev/null 2>&1 ; \
+	__CROSS_CXX=$(strip $1) ; \
+	$${__CROSS_CXX} -v > /dev/null 2>&1 ; \
 	if test $$? -ne 0 ; then \
 		echo "C++ support is selected but is not available in external toolchain" ; \
 		exit 1 ; \
@@ -230,9 +236,12 @@ check_cplusplus = \
 #
 # Check that the cross-compiler given in the configuration exists
 #
+# $1: cross-gcc path
+#
 check_cross_compiler_exists = \
-	$(TARGET_CC) -v > /dev/null 2>&1 ; \
+	__CROSS_CC=$(strip $1) ; \
+	$${__CROSS_CC} -v > /dev/null 2>&1 ; \
 	if test $$? -ne 0 ; then \
-		echo "Cannot execute cross-compiler '$(TARGET_CC)'" ; \
+		echo "Cannot execute cross-compiler '$${__CROSS_CC}'" ; \
 		exit 1 ; \
 	fi

toolchain/toolchain-external/ext-tool.mk

@@ -122,6 +122,7 @@ endif
 
 TOOLCHAIN_EXTERNAL_CROSS=$(TOOLCHAIN_EXTERNAL_BIN)/$(TOOLCHAIN_EXTERNAL_PREFIX)-
 TOOLCHAIN_EXTERNAL_CC=$(TOOLCHAIN_EXTERNAL_CROSS)gcc
+TOOLCHAIN_EXTERNAL_CXX=$(TOOLCHAIN_EXTERNAL_CROSS)g++
 TOOLCHAIN_EXTERNAL_WRAPPER_ARGS = \
 	-DBR_CROSS_PATH='"$(TOOLCHAIN_EXTERNAL_BIN)/"' \
 	-DBR_SYSROOT='"$(STAGING_DIR)"'
@@ -201,7 +202,7 @@ $(TOOLCHAIN_EXTERNAL_DIR)/.extracted: $(DL_DIR)/$(TOOLCHAIN_EXTERNAL_SOURCE)
 # type of C library and all C library features.
 $(STAMP_DIR)/ext-toolchain-checked:
 	@echo "Checking external toolchain settings"
-	$(Q)$(call check_cross_compiler_exists)
+	$(Q)$(call check_cross_compiler_exists,$(TOOLCHAIN_EXTERNAL_CC))
 	$(Q)SYSROOT_DIR=`$(TOOLCHAIN_EXTERNAL_CC) -print-sysroot 2>/dev/null` ; \
 	if test -z "$${SYSROOT_DIR}" ; then \
 		SYSROOT_DIR=`readlink -f $$(LANG=C $(TOOLCHAIN_EXTERNAL_CC) -print-file-name=libc.a) |sed -r -e 's:usr/lib/libc\.a::;'` ; \
@@ -211,10 +212,10 @@ $(STAMP_DIR)/ext-toolchain-checked:
 		exit 1 ; \
 	fi ; \
 	if test x$(BR2_arm) == x"y" ; then \
-		$(call check_arm_abi) ; \
+		$(call check_arm_abi,$(TOOLCHAIN_EXTERNAL_CC)) ; \
 	fi ; \
 	if test x$(BR2_INSTALL_LIBSTDCPP) == x"y" ; then \
-		$(call check_cplusplus) ; \
+		$(call check_cplusplus,$(TOOLCHAIN_EXTERNAL_CXX)) ; \
 	fi ; \
 	if test x$(BR2_TOOLCHAIN_EXTERNAL_UCLIBC) == x"y" ; then \
 		$(call check_uclibc,$${SYSROOT_DIR}) ; \