Add missing soong_docs inputs

Specifically, make Android.bp.list and soong.variables explicit inputs

While this is not a comprehensive list of all inputs
of this action (as the action depends on all blueprint
files in the source tree), this is closer to the truth.

This is a rollforward CL, which was originally rolled
back, as path validation failed for when OUT_DIR was
an absolute path. Validation has now been relaxed.

Test: Manually verified ninja output, checkbuild approved validation
  for aosp-crosshatch, and manually ran frameworks/rs/build_rs.py with
  patch fix
Change-Id: I4eb0d517f57336dd54eaa4bd31f46df9e93e6da2

android/config.go

@@ -93,8 +93,9 @@ type config struct {
 
 	deviceConfig *deviceConfig
 
-	srcDir   string // the path of the root source directory
-	buildDir string // the path of the build output directory
+	srcDir         string // the path of the root source directory
+	buildDir       string // the path of the build output directory
+	moduleListFile string // the path to the file which lists blueprint files to parse.
 
 	env       map[string]string
 	envLock   sync.Mutex
@@ -316,7 +317,7 @@ func TestArchConfig(buildDir string, env map[string]string, bp string, fs map[st
 
 // New creates a new Config object.  The srcDir argument specifies the path to
 // the root source directory. It also loads the config file, if found.
-func NewConfig(srcDir, buildDir string) (Config, error) {
+func NewConfig(srcDir, buildDir string, moduleListFile string) (Config, error) {
 	// Make a config with default options
 	config := &config{
 		ConfigFileName:           filepath.Join(buildDir, configFileName),
@@ -328,7 +329,8 @@ func NewConfig(srcDir, buildDir string) (Config, error) {
 		buildDir:          buildDir,
 		multilibConflicts: make(map[ArchType]bool),
 
-		fs: pathtools.NewOsFs(absSrcDir),
+		moduleListFile: moduleListFile,
+		fs:             pathtools.NewOsFs(absSrcDir),
 	}
 
 	config.deviceConfig = &deviceConfig{

android/paths.go

@@ -904,6 +904,22 @@ func (p OutputPath) buildDir() string {
 var _ Path = OutputPath{}
 var _ WritablePath = OutputPath{}
 
+// toolDepPath is a Path representing a dependency of the build tool.
+type toolDepPath struct {
+	basePath
+}
+
+var _ Path = toolDepPath{}
+
+// pathForBuildToolDep returns a toolDepPath representing the given path string.
+// There is no validation for the path, as it is "trusted": It may fail
+// normal validation checks. For example, it may be an absolute path.
+// Only use this function to construct paths for dependencies of the build
+// tool invocation.
+func pathForBuildToolDep(ctx PathContext, path string) toolDepPath {
+	return toolDepPath{basePath{path, ctx.Config(), ""}}
+}
+
 // PathForOutput joins the provided paths and returns an OutputPath that is
 // validated to not escape the build dir.
 // On error, it will return a usable, but invalid OutputPath, and report a ModuleError.

android/writedocs.go

@@ -44,6 +44,10 @@ func primaryBuilderPath(ctx SingletonContext) Path {
 }
 
 func (c *docsSingleton) GenerateBuildActions(ctx SingletonContext) {
+	var deps Paths
+	deps = append(deps, pathForBuildToolDep(ctx, ctx.Config().moduleListFile))
+	deps = append(deps, pathForBuildToolDep(ctx, ctx.Config().ProductVariablesFileName))
+
 	// Generate build system docs for the primary builder.  Generating docs reads the source
 	// files used to build the primary builder, but that dependency will be picked up through
 	// the dependency on the primary builder itself.  There are no dependencies on the
@@ -63,6 +67,7 @@ func (c *docsSingleton) GenerateBuildActions(ctx SingletonContext) {
 	ctx.Build(pctx, BuildParams{
 		Rule:   soongDocs,
 		Output: docsFile,
+		Inputs: deps,
 		Args: map[string]string{
 			"outDir": PathForOutput(ctx, "docs").String(),
 		},

cmd/soong_build/main.go

@@ -59,7 +59,7 @@ func main() {
 	ctx := android.NewContext()
 	ctx.Register()
 
-	configuration, err := android.NewConfig(srcDir, bootstrap.BuildDir)
+	configuration, err := android.NewConfig(srcDir, bootstrap.BuildDir, bootstrap.ModuleListFile)
 	if err != nil {
 		fmt.Fprintf(os.Stderr, "%s", err)
 		os.Exit(1)

ui/build/test_build.go

@@ -66,6 +66,8 @@ func testForDanglingRules(ctx Context, config Config) {
 	outDir := config.OutDir()
 	bootstrapDir := filepath.Join(outDir, "soong", ".bootstrap")
 	miniBootstrapDir := filepath.Join(outDir, "soong", ".minibootstrap")
+	modulePathsDir := filepath.Join(outDir, ".module_paths")
+	variablesFilePath := filepath.Join(outDir, "soong", "soong.variables")
 
 	danglingRules := make(map[string]bool)
 
@@ -76,7 +78,10 @@ func testForDanglingRules(ctx Context, config Config) {
 			// Leaf node is not in the out directory.
 			continue
 		}
-		if strings.HasPrefix(line, bootstrapDir) || strings.HasPrefix(line, miniBootstrapDir) {
+		if strings.HasPrefix(line, bootstrapDir) ||
+			strings.HasPrefix(line, miniBootstrapDir) ||
+			strings.HasPrefix(line, modulePathsDir) ||
+			line == variablesFilePath {
 			// Leaf node is in one of Soong's bootstrap directories, which do not have
 			// full build rules in the primary build.ninja file.
 			continue