Merge "core/buildsystem: check the actual compiler being version"

Makefile.rules

@@ -70,11 +70,16 @@ ifneq ($(findstring darwin,$(OSARCH)),)
   endif
 endif
 
-# gcc version 8.2.1 and above must have partial-inlining disabled to avoid documented bug
-GCC_VER_GTE821:=$(shell expr `gcc --version | grep ^gcc | cut -d ' ' -f 3 | sed -e 's/\.\([0-9][0-9]\)/\1/g' -e 's/\.\([0-9]\)/0\1/g' -e 's/^[0-9]\{3,4\}$$/&00/'` \>= 80201)
+# gcc version 8.2.1 and above must have partial-inlining disabled to avoid documented bug.
+# We must handle cross-compiling and clang so make sure the compiler version string has "gcc"
+# somewhere in it before testing the version.
+CC_VERS_STRING=$(shell $(CC) --version | grep -i gcc)
+ifneq ($(CC_VERS_STRING),)
+GCC_VER_GTE821:=$(shell expr `echo '$(CC_VERS_STRING)' | cut -d ' ' -f 3 | sed -e 's/\.\([0-9][0-9]\)/\1/g' -e 's/\.\([0-9]\)/0\1/g' -e 's/^[0-9]\{3,4\}$$/&00/'` \>= 80201)
 ifeq ($(GCC_VER_GTE821),1)
     OPTIMIZE+=-fno-partial-inlining
 endif
+endif
 
 ifeq ($(findstring DONT_OPTIMIZE,$(MENUSELECT_CFLAGS))$(AST_CODE_COVERAGE),no)
     _ASTCFLAGS+=$(OPTIMIZE)