Add proto.canonical_path_from_root

Historically, we've always passed '-I .' as the first argument to
protoc, essentially treating all proto file package names as their full
path in the android source tree. This would make sense in a monorepo
world, but it makes less sense when we're pulling in external projects
with established package names.

So keep the same default (for now), but allow individual builds to opt
into using local paths as the default names with
'canonical_path_from_root: false'. A cleanup effort and/or large scale
change in the future could change the default to false.

As part of this, run protoc once per input proto file, since the flags
may need to change per-file. We'll also need this in order to specify
--dependency_out in the future.

Bug: 70704330
Test: aosp/master build-aosp_arm.ninja is identical
Test: aosp/master soong/build.ninja has expected changes
Test: m
Test: Build protobuf test
Change-Id: I9d6de9fd630326bbcced1c62a4a7e9546429b0ce

1 files changed, 17 insertions, 2 deletions

diff --git a/android/proto.go b/android/proto.go
index 0cf7c26e..801837e0 100644
--- a/android/proto.go
+++ b/android/proto.go
@@ -23,8 +23,7 @@ package android
 // generate the source.
 
 func ProtoFlags(ctx ModuleContext, p *ProtoProperties) []string {
-	// -I . must come first, it affects where protoc places the output files.
-	protoFlags := []string{"-I ."}
+	protoFlags := []string{}
 
 	if len(p.Proto.Local_include_dirs) > 0 {
 		localProtoIncludeDirs := PathsForModuleSrc(ctx, p.Proto.Local_include_dirs)
@@ -38,6 +37,13 @@ func ProtoFlags(ctx ModuleContext, p *ProtoProperties) []string {
 	return protoFlags
 }
 
+func ProtoCanonicalPathFromRoot(ctx ModuleContext, p *ProtoProperties) bool {
+	if p.Proto.Canonical_path_from_root == nil {
+		return true
+	}
+	return *p.Proto.Canonical_path_from_root
+}
+
 // ProtoDir returns the module's "gen/proto" directory
 func ProtoDir(ctx ModuleContext) ModuleGenPath {
 	return PathForModuleGen(ctx, "proto")
@@ -59,5 +65,14 @@ type ProtoProperties struct {
 		// list of directories relative to the bp file that will
 		// be added to the protoc include paths.
 		Local_include_dirs []string
+
+		// whether to identify the proto files from the root of the
+		// source tree (the original method in Android, useful for
+		// android-specific protos), or relative from where they were
+		// specified (useful for external/third party protos).
+		//
+		// This defaults to true today, but is expected to default to
+		// false in the future.
+		Canonical_path_from_root *bool
 	} `android:"arch_variant"`
 }