Merge "Add bp2build mode to soong_build." am: 946e0b69d2

Original change: https://android-review.googlesource.com/c/platform/build/soong/+/1515407

Change-Id: Ic200db7f6932a890a4814b6fdaf3f598ca9cb94f

android/mutator.go

@@ -44,6 +44,11 @@ func registerMutatorsToContext(ctx *blueprint.Context, mutators []*mutator) {
 	}
 }
 
+func registerMutatorsForBazelConversion(ctx *blueprint.Context) {
+	// FIXME(b/171263886): Start bringing in mutators to make the Bionic
+	// module subgraph suitable for automated conversion.
+}
+
 func registerMutators(ctx *blueprint.Context, preArch, preDeps, postDeps, finalDeps []RegisterMutatorFunc) {
 	mctx := &registerMutatorsContext{}
 

android/queryview.go

@@ -26,15 +26,40 @@ import (
 // for calling the soong_build primary builder in the main build.ninja file.
 func init() {
 	RegisterSingletonType("bazel_queryview", BazelQueryViewSingleton)
+	RegisterSingletonType("bazel_converter", BazelConverterSingleton)
 }
 
+// BazelQueryViewSingleton is the singleton responsible for registering the
+// soong_build build statement that will convert the Soong module graph after
+// applying *all* mutators, enabing the feature to query the final state of the
+// Soong graph. This mode is meant for querying the build graph state, and not meant
+// for generating BUILD files to be checked in.
 func BazelQueryViewSingleton() Singleton {
 	return &bazelQueryViewSingleton{}
 }
 
-type bazelQueryViewSingleton struct{}
+// BazelConverterSingleton is the singleton responsible for registering the soong_build
+// build statement that will convert the Soong module graph by applying an alternate
+// pipeline of mutators, with the goal of reaching semantic equivalence between the original
+// Blueprint and final BUILD files. Using this mode, the goal is to be able to
+// build with these BUILD files directly in the source tree.
+func BazelConverterSingleton() Singleton {
+	return &bazelConverterSingleton{}
+}
+
+type bazelQueryViewSingleton struct{}
+type bazelConverterSingleton struct{}
+
+func generateBuildActionsForBazelConversion(ctx SingletonContext, converterMode bool) {
+	name := "queryview"
+	additionalEnvVars := ""
+	descriptionTemplate := "[EXPERIMENTAL, PRE-PRODUCTION] Creating the Bazel QueryView workspace with %s at $outDir"
+	if converterMode {
+		name = "bp2build"
+		additionalEnvVars = "CONVERT_TO_BAZEL=true"
+		descriptionTemplate = "[EXPERIMENTAL, PRE-PRODUCTION] Converting all Android.bp to Bazel BUILD files with %s at $outDir"
+	}
 
-func (c *bazelQueryViewSingleton) GenerateBuildActions(ctx SingletonContext) {
 	// Create a build and rule statement, using the Bazel QueryView's WORKSPACE
 	// file as the output file marker.
 	var deps Paths
@@ -42,22 +67,23 @@ func (c *bazelQueryViewSingleton) GenerateBuildActions(ctx SingletonContext) {
 	deps = append(deps, moduleListFilePath)
 	deps = append(deps, pathForBuildToolDep(ctx, ctx.Config().ProductVariablesFileName))
 
-	bazelQueryViewDirectory := PathForOutput(ctx, "queryview")
+	bazelQueryViewDirectory := PathForOutput(ctx, name)
 	bazelQueryViewWorkspaceFile := bazelQueryViewDirectory.Join(ctx, "WORKSPACE")
 	primaryBuilder := primaryBuilderPath(ctx)
 	bazelQueryView := ctx.Rule(pctx, "bazelQueryView",
 		blueprint.RuleParams{
 			Command: fmt.Sprintf(
 				"rm -rf ${outDir}/* && "+
-					"%s --bazel_queryview_dir ${outDir} %s && "+
+					"%s %s --bazel_queryview_dir ${outDir} %s && "+
 					"echo WORKSPACE: `cat %s` > ${outDir}/.queryview-depfile.d",
+				additionalEnvVars,
 				primaryBuilder.String(),
 				strings.Join(os.Args[1:], " "),
 				moduleListFilePath.String(), // Use the contents of Android.bp.list as the depfile.
 			),
 			CommandDeps: []string{primaryBuilder.String()},
 			Description: fmt.Sprintf(
-				"[EXPERIMENTAL, PRE-PRODUCTION] Creating the Bazel QueryView workspace with %s at $outDir",
+				descriptionTemplate,
 				primaryBuilder.Base()),
 			Deps:    blueprint.DepsGCC,
 			Depfile: "${outDir}/.queryview-depfile.d",
@@ -73,6 +99,14 @@ func (c *bazelQueryViewSingleton) GenerateBuildActions(ctx SingletonContext) {
 		},
 	})
 
-	// Add a phony target for building the Bazel QueryView
-	ctx.Phony("queryview", bazelQueryViewWorkspaceFile)
+	// Add a phony target for generating the workspace
+	ctx.Phony(name, bazelQueryViewWorkspaceFile)
+}
+
+func (c *bazelQueryViewSingleton) GenerateBuildActions(ctx SingletonContext) {
+	generateBuildActionsForBazelConversion(ctx, false)
+}
+
+func (c *bazelConverterSingleton) GenerateBuildActions(ctx SingletonContext) {
+	generateBuildActionsForBazelConversion(ctx, true)
 }

android/register.go

@@ -90,6 +90,21 @@ func NewContext(config Config) *Context {
 	return ctx
 }
 
+// RegisterForBazelConversion registers an alternate shadow pipeline of
+// singletons, module types and mutators to register for converting Blueprint
+// files to semantically equivalent BUILD files.
+func (ctx *Context) RegisterForBazelConversion() {
+	for _, t := range moduleTypes {
+		ctx.RegisterModuleType(t.name, ModuleFactoryAdaptor(t.factory))
+	}
+
+	bazelConverterSingleton := singleton{"bp2build", BazelConverterSingleton}
+	ctx.RegisterSingletonType(bazelConverterSingleton.name,
+		SingletonFactoryAdaptor(ctx, bazelConverterSingleton.factory))
+
+	registerMutatorsForBazelConversion(ctx.Context)
+}
+
 func (ctx *Context) Register() {
 	for _, t := range preSingletons {
 		ctx.RegisterPreSingletonType(t.name, SingletonFactoryAdaptor(ctx, t.factory))

cmd/soong_build/main.go

@@ -51,10 +51,22 @@ func newNameResolver(config android.Config) *android.NameResolver {
 	return android.NewNameResolver(exportFilter)
 }
 
+// bazelConversionRequested checks that the user is intending to convert
+// Blueprint to Bazel BUILD files.
+func bazelConversionRequested(configuration android.Config) bool {
+	return configuration.IsEnvTrue("CONVERT_TO_BAZEL")
+}
+
 func newContext(srcDir string, configuration android.Config) *android.Context {
 	ctx := android.NewContext(configuration)
-	ctx.Register()
-	if !shouldPrepareBuildActions() {
+	if bazelConversionRequested(configuration) {
+		// Register an alternate set of singletons and mutators for bazel
+		// conversion for Bazel conversion.
+		ctx.RegisterForBazelConversion()
+	} else {
+		ctx.Register()
+	}
+	if !shouldPrepareBuildActions(configuration) {
 		configuration.SetStopBefore(bootstrap.StopBeforePrepareBuildActions)
 	}
 	ctx.SetNameInterface(newNameResolver(configuration))
@@ -114,6 +126,8 @@ func main() {
 		ctx = newContext(srcDir, configuration)
 		bootstrap.Main(ctx.Context, configuration, extraNinjaDeps...)
 	}
+
+	// Convert the Soong module graph into Bazel BUILD files.
 	if bazelQueryViewDir != "" {
 		if err := createBazelQueryView(ctx, bazelQueryViewDir); err != nil {
 			fmt.Fprintf(os.Stderr, "%s", err)
@@ -130,7 +144,7 @@ func main() {
 
 	// TODO(ccross): make this a command line argument.  Requires plumbing through blueprint
 	//  to affect the command line of the primary builder.
-	if shouldPrepareBuildActions() {
+	if shouldPrepareBuildActions(configuration) {
 		metricsFile := filepath.Join(bootstrap.BuildDir, "soong_build_metrics.pb")
 		err := android.WriteMetrics(configuration, metricsFile)
 		if err != nil {
@@ -140,8 +154,19 @@ func main() {
 	}
 }
 
-func shouldPrepareBuildActions() bool {
-	// If we're writing soong_docs or queryview, don't write build.ninja or
-	// collect metrics.
-	return docFile == "" && bazelQueryViewDir == ""
+// shouldPrepareBuildActions reads configuration and flags if build actions
+// should be generated.
+func shouldPrepareBuildActions(configuration android.Config) bool {
+	// Generating Soong docs
+	if docFile != "" {
+		return false
+	}
+
+	// Generating a directory for Soong query (queryview)
+	if bazelQueryViewDir != "" {
+		return false
+	}
+
+	// Generating a directory for converted Bazel BUILD files
+	return !bazelConversionRequested(configuration)
 }