Merge "Revert "Revert "Add external projects only CFlags option"""

am: 8d29e1e024

Change-Id: I8806ce876fe68ab36e79e36318af0740b3a9b4c8

cc/compiler.go

@@ -392,6 +392,12 @@ func (compiler *baseCompiler) compilerFlags(ctx ModuleContext, flags Flags, deps
 			fmt.Sprintf("${config.%sGlobalCflags}", hod))
 	}
 
+	if flags.Clang {
+		if strings.HasPrefix(android.PathForModuleSrc(ctx).String(), "external/") {
+			flags.GlobalFlags = append([]string{"${config.ClangExternalCflags}"}, flags.GlobalFlags...)
+		}
+	}
+
 	if ctx.Device() {
 		if Bool(compiler.Properties.Rtti) {
 			flags.CppFlags = append(flags.CppFlags, "-frtti")

cc/config/clang.go

@@ -182,6 +182,11 @@ func init() {
 		// compatibility.
 		"-Wno-c++98-compat-extra-semi",
 	}, " "))
+
+	// Extra cflags for projects under external/ directory
+	pctx.StaticVariable("ClangExtraExternalCflags", strings.Join([]string{
+		// TODO(yikong): Move -Wno flags here
+	}, " "))
 }
 
 func ClangFilterUnknownCflags(cflags []string) []string {

cc/config/global.go

@@ -170,6 +170,8 @@ func init() {
 	pctx.StaticVariable("CommonClangGlobalCppflags",
 		strings.Join(append(ClangFilterUnknownCflags(commonGlobalCppflags), "${ClangExtraCppflags}"), " "))
 
+	pctx.StaticVariable("ClangExternalCflags", "${ClangExtraExternalCflags}")
+
 	// Everything in these lists is a crime against abstraction and dependency tracking.
 	// Do not add anything to this list.
 	pctx.PrefixedExistentPathsForSourcesVariable("CommonGlobalIncludes", "-I",

cc/makevars.go

@@ -83,6 +83,7 @@ func makeVarsProvider(ctx android.MakeVarsContext) {
 	ctx.Strict("RS_LLVM_AS", "${config.RSLLVMPrebuiltsPath}/llvm-as")
 	ctx.Strict("RS_LLVM_LINK", "${config.RSLLVMPrebuiltsPath}/llvm-link")
 
+	ctx.Strict("CLANG_EXTERNAL_CFLAGS", "${config.ClangExternalCflags}")
 	ctx.Strict("GLOBAL_CFLAGS_NO_OVERRIDE", "${config.NoOverrideGlobalCflags}")
 	ctx.Strict("GLOBAL_CLANG_CFLAGS_NO_OVERRIDE", "${config.ClangExtraNoOverrideCflags}")
 	ctx.Strict("GLOBAL_CPPFLAGS_NO_OVERRIDE", "")