Use protobuf-codegen default and add mod_stem.rs

* Upgrade to new protobuf-codegen; use its standard
  default output without local change.
* Allow a sourceProvider to have multiple output files.
  For a stem.proto file, output stem.rs and mod_stem.rs.
* New protobuf-codegen option gen_mod_rs always generates
  output file named "mod.rs". To generate multiple .proto
  files into the same output directory, we need to rename
  mod.rs to mod_<stem>.rs.
* Instead of using the gen_mod_rs option and renaming mod.rs
  to mod_<stem>.rs, we generate the same mod_<stem>.rs
  directly with a simple printf command.

Bug: 170256643
Test: atest -c --host --include-subdirs external/crosvm
Change-Id: Ia09e41029099a6de4d35c96dbabd9ba5514c9019

5 files changed, 19 insertions, 12 deletions

diff --git a/rust/androidmk.go b/rust/androidmk.go
index 5a33f77fa..29e4bd75b 100644
--- a/rust/androidmk.go
+++ b/rust/androidmk.go
@@ -156,7 +156,7 @@ func (procMacro *procMacroDecorator) AndroidMk(ctx AndroidMkContext, ret *androi
 }
 
 func (sourceProvider *BaseSourceProvider) AndroidMk(ctx AndroidMkContext, ret *android.AndroidMkData) {
-	outFile := sourceProvider.OutputFile
+	outFile := sourceProvider.OutputFiles[0]
 	ret.Class = "ETC"
 	ret.OutputFile = android.OptionalPathForPath(outFile)
 	ret.SubName += sourceProvider.subName
diff --git a/rust/bindgen.go b/rust/bindgen.go
index ac33ff7ef..68f219e45 100644
--- a/rust/bindgen.go
+++ b/rust/bindgen.go
@@ -202,7 +202,7 @@ func (b *bindgenDecorator) GenerateSource(ctx ModuleContext, deps PathDeps) andr
 		},
 	})
 
-	b.BaseSourceProvider.OutputFile = outputFile
+	b.BaseSourceProvider.OutputFiles = android.Paths{outputFile}
 	return outputFile
 }
 
diff --git a/rust/protobuf.go b/rust/protobuf.go
index 897300f19..ebb1c3cb6 100644
--- a/rust/protobuf.go
+++ b/rust/protobuf.go
@@ -61,15 +61,22 @@ func (proto *protobufDecorator) GenerateSource(ctx ModuleContext, deps PathDeps)
 	}
 
 	outDir := android.PathForModuleOut(ctx)
-	depFile := android.PathForModuleOut(ctx, proto.BaseSourceProvider.getStem(ctx)+".d")
-	outputs := android.WritablePaths{android.PathForModuleOut(ctx, proto.BaseSourceProvider.getStem(ctx)+".rs")}
+	stem := proto.BaseSourceProvider.getStem(ctx)
+	// rust protobuf-codegen output <stem>.rs
+	stemFile := android.PathForModuleOut(ctx, stem+".rs")
+	// add mod_<stem>.rs to import <stem>.rs
+	modFile := android.PathForModuleOut(ctx, "mod_"+stem+".rs")
+	// mod_<stem>.rs is the main/first output file to be included/compiled
+	outputs := android.WritablePaths{modFile, stemFile}
+	depFile := android.PathForModuleOut(ctx, "mod_"+stem+".d")
 
 	rule := android.NewRuleBuilder()
 	android.ProtoRule(ctx, rule, protoFile.Path(), protoFlags, protoFlags.Deps, outDir, depFile, outputs)
+	rule.Command().Text("printf '// @generated\\npub mod %s;\\n' '" + stem + "' >").Output(modFile)
 	rule.Build(pctx, ctx, "protoc_"+protoFile.Path().Rel(), "protoc "+protoFile.Path().Rel())
 
-	proto.BaseSourceProvider.OutputFile = outputs[0]
-	return outputs[0]
+	proto.BaseSourceProvider.OutputFiles = android.Paths{modFile, stemFile}
+	return modFile
 }
 
 func (proto *protobufDecorator) SourceProviderProps() []interface{} {
diff --git a/rust/rust.go b/rust/rust.go
index ba8673c94..3f0f6e27d 100644
--- a/rust/rust.go
+++ b/rust/rust.go
@@ -709,7 +709,7 @@ func (mod *Module) GenerateAndroidBuildActions(actx android.ModuleContext) {
 		} else {
 			sourceMod := actx.GetDirectDepWithTag(mod.Name(), sourceDepTag)
 			sourceLib := sourceMod.(*Module).compiler.(*libraryDecorator)
-			mod.sourceProvider.setOutputFile(sourceLib.sourceProvider.Srcs()[0])
+			mod.sourceProvider.setOutputFiles(sourceLib.sourceProvider.Srcs())
 		}
 	}
 
diff --git a/rust/source_provider.go b/rust/source_provider.go
index 03adf9e6f..436518c70 100644
--- a/rust/source_provider.go
+++ b/rust/source_provider.go
@@ -30,7 +30,7 @@ type SourceProviderProperties struct {
 type BaseSourceProvider struct {
 	Properties SourceProviderProperties
 
-	OutputFile       android.Path
+	OutputFiles      android.Paths
 	subAndroidMkOnce map[SubAndroidMkProvider]bool
 	subName          string
 }
@@ -43,11 +43,11 @@ type SourceProvider interface {
 	SourceProviderProps() []interface{}
 	SourceProviderDeps(ctx DepsContext, deps Deps) Deps
 	setSubName(subName string)
-	setOutputFile(outputFile android.Path)
+	setOutputFiles(outputFiles android.Paths)
 }
 
 func (sp *BaseSourceProvider) Srcs() android.Paths {
-	return android.Paths{sp.OutputFile}
+	return sp.OutputFiles
 }
 
 func (sp *BaseSourceProvider) GenerateSource(ctx ModuleContext, deps PathDeps) android.Path {
@@ -97,6 +97,6 @@ func (sp *BaseSourceProvider) setSubName(subName string) {
 	sp.subName = subName
 }
 
-func (sp *BaseSourceProvider) setOutputFile(outputFile android.Path) {
-	sp.OutputFile = outputFile
+func (sp *BaseSourceProvider) setOutputFiles(outputFiles android.Paths) {
+	sp.OutputFiles = outputFiles
 }