[PATCH v2 01/18] tools build: Support compiling C++ source file

[Wang Nan]

Add new rule to compile .cpp file to .o use g++. C++ support is
required for built-in clang and LLVM support.

Linker side support will be introduced by following commits.

Signed-off-by: Wang Nan <wangnan0@xxxxxxxxxx>
Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Cc: Alexei Starovoitov <ast@xxxxxx>
Cc: He Kuang <hekuang@xxxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
---
 tools/build/Build.include  | 1 +
 tools/build/Makefile.build | 7 +++++++
 2 files changed, 8 insertions(+)

diff --git a/tools/build/Build.include b/tools/build/Build.include
index 4d000bc..b9f014d 100644
--- a/tools/build/Build.include
+++ b/tools/build/Build.include
@@ -90,3 +90,4 @@ if_changed = $(if $(strip $(any-prereq) $(arg-check)),             \
 # - per object C flags
 # - BUILD_STR macro to allow '-D"$(variable)"' constructs
 c_flags = -Wp,-MD,$(depfile),-MT,$@ $(CFLAGS) -D"BUILD_STR(s)=\#s" $(CFLAGS_$(basetarget).o) $(CFLAGS_$(obj))
+cxx_flags = -Wp,-MD,$(depfile),-MT,$@ $(CXXFLAGS) -D"BUILD_STR(s)=\#s" $(CXXFLAGS_$(basetarget).o) $(CXXFLAGS_$(obj))
diff --git a/tools/build/Makefile.build b/tools/build/Makefile.build
index 27f3583..b84be2e 100644
--- a/tools/build/Makefile.build
+++ b/tools/build/Makefile.build
@@ -58,6 +58,9 @@ quiet_cmd_mkdir = MKDIR    $(dir $@)
 quiet_cmd_cc_o_c = CC       $@
       cmd_cc_o_c = $(CC) $(c_flags) -c -o $@ $<
 
+quiet_cmd_cxx_o_c = CXX      $@
+      cmd_cxx_o_c = $(CXX) $(cxx_flags) -c -o $@ $<
+
 quiet_cmd_cpp_i_c = CPP      $@
       cmd_cpp_i_c = $(CC) $(c_flags) -E -o $@ $<
 
@@ -77,6 +80,10 @@ $(OUTPUT)%.o: %.c FORCE
 	$(call rule_mkdir)
 	$(call if_changed_dep,cc_o_c)
 
+$(OUTPUT)%.o: %.cpp FORCE
+	$(call rule_mkdir)
+	$(call if_changed_dep,cxx_o_c)
+
 $(OUTPUT)%.o: %.S FORCE
 	$(call rule_mkdir)
 	$(call if_changed_dep,cc_o_c)
-- 
1.8.3.4