Allow overriding of Clang prebuilts

These are the environment variables used by make to override the
llvm/clang prebuilts. As far as I know, these should only be used when
building or testing a new clang drop.

I would have this handled by make and put in soong.variables, but I
expect this to be one of the first options removed from make and
exported from Soong to Kati.

Change-Id: I7a3a70ee44fc4b1e56a5e200e2a7ced77d4c5692

1 files changed, 14 insertions, 1 deletions

diff --git a/cc/cc.go b/cc/cc.go
index e091be3f..41058116 100644
--- a/cc/cc.go
+++ b/cc/cc.go
@@ -153,7 +153,20 @@ func init() {
 	pctx.PrefixedPathsForOptionalSourceVariable("commonNativehelperInclude", "-I",
 		[]string{"libnativehelper/include/nativehelper"})
 
-	pctx.SourcePathVariable("clangPath", "prebuilts/clang/host/${HostPrebuiltTag}/clang-2658975/bin")
+	pctx.SourcePathVariable("clangDefaultBase", "prebuilts/clang/host")
+	pctx.VariableFunc("clangBase", func(config interface{}) (string, error) {
+		if override := config.(common.Config).Getenv("LLVM_PREBUILTS_BASE"); override != "" {
+			return override, nil
+		}
+		return "${clangDefaultBase}", nil
+	})
+	pctx.VariableFunc("clangVersion", func(config interface{}) (string, error) {
+		if override := config.(common.Config).Getenv("LLVM_PREBUILTS_VERSION"); override != "" {
+			return override, nil
+		}
+		return "clang-2658975", nil
+	})
+	pctx.StaticVariable("clangPath", "${clangBase}/${HostPrebuiltTag}/${clangVersion}/bin")
 }
 
 type CCModuleContext common.AndroidBaseContext