support PRODUCT_SOURCE_ROOT_DIRS product variable

Soong analyzes the entire source tree even though not every lunch target
needs to know about every module. For example, OEM sources can be
ignored for cuttlefish products. This functionality allows blueprint to
ignore a list of undesired directories.

Bug: 269457150
Change-Id: I1eec5d7b6a268cae4c633d8d89ed485598ebca45

android/config.go

@@ -1179,6 +1179,10 @@ func (c *config) ExportedNamespaces() []string {
 	return append([]string(nil), c.productVariables.NamespacesToExport...)
 }
 
+func (c *config) SourceRootDirs() []string {
+	return c.productVariables.SourceRootDirs
+}
+
 func (c *config) IncludeTags() []string {
 	return c.productVariables.IncludeTags
 }

android/namespace.go

@@ -225,6 +225,10 @@ func (r *NameResolver) NewModule(ctx blueprint.NamespaceContext, moduleGroup blu
 	return ns, nil
 }
 
+func (r *NameResolver) NewSkippedModule(ctx blueprint.NamespaceContext, name string, skipInfo blueprint.SkippedModuleInfo) {
+	r.rootNamespace.moduleContainer.NewSkippedModule(ctx, name, skipInfo)
+}
+
 func (r *NameResolver) AllModules() []blueprint.ModuleGroup {
 	childLists := [][]blueprint.ModuleGroup{}
 	totalCount := 0
@@ -300,7 +304,7 @@ func (r *NameResolver) FindNamespaceImports(namespace *Namespace) (err error) {
 	for _, name := range namespace.importedNamespaceNames {
 		imp, ok := r.namespaceAt(name)
 		if !ok {
-			return fmt.Errorf("namespace %v does not exist", name)
+			return fmt.Errorf("namespace %v does not exist; Some necessary modules may have been skipped by Soong. Check if PRODUCT_SOURCE_ROOT_DIRS is pruning necessary Android.bp files.", name)
 		}
 		namespace.visibleNamespaces = append(namespace.visibleNamespaces, imp)
 	}

android/register.go

@@ -162,6 +162,7 @@ func NewContext(config Config) *Context {
 	ctx := &Context{blueprint.NewContext(), config}
 	ctx.SetSrcDir(absSrcDir)
 	ctx.AddIncludeTags(config.IncludeTags()...)
+	ctx.AddSourceRootDirs(config.SourceRootDirs()...)
 	return ctx
 }
 

android/variable.go

@@ -461,7 +461,8 @@ type productVariables struct {
 
 	IgnorePrefer32OnDevice bool `json:",omitempty"`
 
-	IncludeTags []string `json:",omitempty"`
+	IncludeTags    []string `json:",omitempty"`
+	SourceRootDirs []string `json:",omitempty"`
 }
 
 func boolPtr(v bool) *bool {

cmd/soong_build/main.go

@@ -104,6 +104,7 @@ func newContext(configuration android.Config) *android.Context {
 	ctx.SetNameInterface(newNameResolver(configuration))
 	ctx.SetAllowMissingDependencies(configuration.AllowMissingDependencies())
 	ctx.AddIncludeTags(configuration.IncludeTags()...)
+	ctx.AddSourceRootDirs(configuration.SourceRootDirs()...)
 	return ctx
 }
 

ui/build/config.go

@@ -117,7 +117,8 @@ type configImpl struct {
 
 	bazelForceEnabledModules string
 
-	includeTags []string
+	includeTags    []string
+	sourceRootDirs []string
 
 	// Data source to write ninja weight list
 	ninjaWeightListSource NinjaWeightListSource
@@ -1185,6 +1186,14 @@ func (c *configImpl) Parallel() int {
 	return c.parallel
 }
 
+func (c *configImpl) GetSourceRootDirs() []string {
+	return c.sourceRootDirs
+}
+
+func (c *configImpl) SetSourceRootDirs(i []string) {
+	c.sourceRootDirs = i
+}
+
 func (c *configImpl) GetIncludeTags() []string {
 	return c.includeTags
 }

ui/build/dumpvars.go

@@ -148,6 +148,7 @@ var BannerVars = []string{
 	"PLATFORM_VERSION_CODENAME",
 	"PLATFORM_VERSION",
 	"PRODUCT_INCLUDE_TAGS",
+	"PRODUCT_SOURCE_ROOT_DIRS",
 	"TARGET_PRODUCT",
 	"TARGET_BUILD_VARIANT",
 	"TARGET_BUILD_APPS",
@@ -299,4 +300,5 @@ func runMakeProductConfig(ctx Context, config Config) {
 	config.SetBuildBrokenUsesNetwork(makeVars["BUILD_BROKEN_USES_NETWORK"] == "true")
 	config.SetBuildBrokenNinjaUsesEnvVars(strings.Fields(makeVars["BUILD_BROKEN_NINJA_USES_ENV_VARS"]))
 	config.SetIncludeTags(strings.Fields(makeVars["PRODUCT_INCLUDE_TAGS"]))
+	config.SetSourceRootDirs(strings.Fields(makeVars["PRODUCT_SOURCE_ROOT_DIRS"]))
 }

ui/build/soong.go

@@ -410,6 +410,7 @@ func bootstrapBlueprint(ctx Context, config Config) {
 
 	blueprintCtx := blueprint.NewContext()
 	blueprintCtx.AddIncludeTags(config.GetIncludeTags()...)
+	blueprintCtx.AddSourceRootDirs(config.GetSourceRootDirs()...)
 	blueprintCtx.SetIgnoreUnknownModuleTypes(true)
 	blueprintConfig := BlueprintConfig{
 		soongOutDir: config.SoongOutDir(),