Add build_flag_declarations module

And generate build-flags/build_flags.{pb,textproto} files

Bug: 328495189
Test: manual,TH
Change-Id: I97eb864e2d84bc606fef7e9077554894338edaa0

aconfig/build_flags/declarations.go

@@ -0,0 +1,118 @@
+// Copyright 2023 Google Inc. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package build_flags
+
+import (
+	"fmt"
+	"strings"
+
+	"android/soong/android"
+
+	"github.com/google/blueprint"
+)
+
+type BuildFlagDeclarationsProviderData struct {
+	IntermediateCacheOutputPath android.WritablePath
+	IntermediateDumpOutputPath  android.WritablePath
+}
+
+var BuildFlagDeclarationsProviderKey = blueprint.NewProvider[BuildFlagDeclarationsProviderData]()
+
+type DeclarationsModule struct {
+	android.ModuleBase
+	android.DefaultableModuleBase
+
+	// Properties for "aconfig_declarations"
+	properties struct {
+		// aconfig files, relative to this Android.bp file
+		Srcs []string `android:"path"`
+	}
+
+	intermediatePath android.WritablePath
+}
+
+func DeclarationsFactory() android.Module {
+	module := &DeclarationsModule{}
+
+	android.InitAndroidModule(module)
+	android.InitDefaultableModule(module)
+	module.AddProperties(&module.properties)
+
+	return module
+}
+
+func (module *DeclarationsModule) OutputFiles(tag string) (android.Paths, error) {
+	switch tag {
+	case "":
+		// The default output of this module is the intermediates format, which is
+		// not installable and in a private format that no other rules can handle
+		// correctly.
+		return []android.Path{module.intermediatePath}, nil
+	default:
+		return nil, fmt.Errorf("unsupported build_flags_declarations module reference tag %q", tag)
+	}
+}
+
+func joinAndPrefix(prefix string, values []string) string {
+	var sb strings.Builder
+	for _, v := range values {
+		sb.WriteString(prefix)
+		sb.WriteString(v)
+	}
+	return sb.String()
+}
+
+func optionalVariable(prefix string, value string) string {
+	var sb strings.Builder
+	if value != "" {
+		sb.WriteString(prefix)
+		sb.WriteString(value)
+	}
+	return sb.String()
+}
+
+func (module *DeclarationsModule) GenerateAndroidBuildActions(ctx android.ModuleContext) {
+	// Intermediate format
+	declarationFiles := android.PathsForModuleSrc(ctx, module.properties.Srcs)
+	intermediateCacheFilePath := android.PathForModuleOut(ctx, "build_flag_intermediate.pb")
+	inputFiles := make([]android.Path, len(declarationFiles))
+	copy(inputFiles, declarationFiles)
+
+	// TODO(lamont): generate the rc_proto.FlagArtifacts message for the sources.
+	args := map[string]string{
+		"release_version": ctx.Config().ReleaseVersion(),
+		"declarations":    android.JoinPathsWithPrefix(declarationFiles, "--decl "),
+	}
+	ctx.Build(pctx, android.BuildParams{
+		Rule:        buildFlagRule,
+		Output:      intermediateCacheFilePath,
+		Inputs:      inputFiles,
+		Description: "build_flag_declarations",
+		Args:        args,
+	})
+
+	intermediateDumpFilePath := android.PathForModuleOut(ctx, "build_flag_intermediate.textproto")
+	ctx.Build(pctx, android.BuildParams{
+		Rule:        buildFlagTextRule,
+		Output:      intermediateDumpFilePath,
+		Input:       intermediateCacheFilePath,
+		Description: "build_flag_declarations_text",
+	})
+
+	android.SetProvider(ctx, BuildFlagDeclarationsProviderKey, BuildFlagDeclarationsProviderData{
+		IntermediateCacheOutputPath: intermediateCacheFilePath,
+		IntermediateDumpOutputPath:  intermediateDumpFilePath,
+	})
+}