cosmetic: fail fast on empty module list

also minor refactoring to limit var scopes

Test: m nothing and ensure ninja files are generated
Bug: N/A
Change-Id: If7bdede4e54687955896b03ab11ef771855d2225

bootstrap/command.go

@@ -74,22 +74,22 @@ func RunBlueprint(args Args, stopBefore StopBefore, ctx *blueprint.Context, conf
 		defer trace.Stop()
 	}
 
-	srcDir := "."
+	if args.ModuleListFile == "" {
-
-	ninjaDeps := make([]string, 0)
-
-	if args.ModuleListFile != "" {
-		ctx.SetModuleListFile(args.ModuleListFile)
-		ninjaDeps = append(ninjaDeps, args.ModuleListFile)
-	} else {
 		fatalf("-l <moduleListFile> is required and must be nonempty")
 	}
+	ctx.SetModuleListFile(args.ModuleListFile)
+
+	var ninjaDeps []string
+	ninjaDeps = append(ninjaDeps, args.ModuleListFile)
+
 	ctx.BeginEvent("list_modules")
-	filesToParse, err := ctx.ListModulePaths(srcDir)
+	var filesToParse []string
-	ctx.EndEvent("list_modules")
+	if f, err := ctx.ListModulePaths("."); err != nil {
-	if err != nil {
 		fatalf("could not enumerate files: %v\n", err.Error())
+	} else {
+		filesToParse = f
 	}
+	ctx.EndEvent("list_modules")
 
 	ctx.RegisterBottomUpMutator("bootstrap_plugin_deps", pluginDeps)
 	ctx.RegisterModuleType("bootstrap_go_package", newGoPackageModuleFactory())
@@ -97,37 +97,34 @@ func RunBlueprint(args Args, stopBefore StopBefore, ctx *blueprint.Context, conf
 	ctx.RegisterSingletonType("bootstrap", newSingletonFactory())
 
 	ctx.BeginEvent("parse_bp")
-	blueprintFiles, errs := ctx.ParseFileList(".", filesToParse, config)
+	if blueprintFiles, errs := ctx.ParseFileList(".", filesToParse, config); len(errs) > 0 {
-	if len(errs) > 0 {
 		fatalErrors(errs)
+	} else {
+		ctx.EndEvent("parse_bp")
+		ninjaDeps = append(ninjaDeps, blueprintFiles...)
 	}
-	ctx.EndEvent("parse_bp")
 
-	// Add extra ninja file dependencies
+	if resolvedDeps, errs := ctx.ResolveDependencies(config); len(errs) > 0 {
-	ninjaDeps = append(ninjaDeps, blueprintFiles...)
-
-	extraDeps, errs := ctx.ResolveDependencies(config)
-	if len(errs) > 0 {
 		fatalErrors(errs)
+	} else {
+		ninjaDeps = append(ninjaDeps, resolvedDeps...)
 	}
-	ninjaDeps = append(ninjaDeps, extraDeps...)
 
 	if stopBefore == StopBeforePrepareBuildActions {
 		return ninjaDeps
 	}
 
 	if ctx.BeforePrepareBuildActionsHook != nil {
-		err := ctx.BeforePrepareBuildActionsHook()
+		if err := ctx.BeforePrepareBuildActionsHook(); err != nil {
-		if err != nil {
 			fatalErrors([]error{err})
 		}
 	}
 
-	extraDeps, errs = ctx.PrepareBuildActions(config)
+	if buildActionsDeps, errs := ctx.PrepareBuildActions(config); len(errs) > 0 {
-	if len(errs) > 0 {
 		fatalErrors(errs)
+	} else {
+		ninjaDeps = append(ninjaDeps, buildActionsDeps...)
 	}
-	ninjaDeps = append(ninjaDeps, extraDeps...)
 
 	if stopBefore == StopBeforeWriteNinja {
 		return ninjaDeps
@@ -147,7 +144,7 @@ func RunBlueprint(args Args, stopBefore StopBefore, ctx *blueprint.Context, conf
 	}
 
 	if !args.EmptyNinjaFile {
-		f, err = os.OpenFile(joinPath(ctx.SrcDir(), args.OutFile), os.O_WRONLY|os.O_CREATE|os.O_TRUNC, outFilePermissions)
+		f, err := os.OpenFile(joinPath(ctx.SrcDir(), args.OutFile), os.O_WRONLY|os.O_CREATE|os.O_TRUNC, outFilePermissions)
 		if err != nil {
 			fatalf("error opening Ninja file: %s", err)
 		}
@@ -157,21 +154,18 @@ func RunBlueprint(args Args, stopBefore StopBefore, ctx *blueprint.Context, conf
 		out = io.Discard.(io.StringWriter)
 	}
 
-	err = ctx.WriteBuildFile(out)
+	if err := ctx.WriteBuildFile(out); err != nil {
-	if err != nil {
 		fatalf("error writing Ninja file contents: %s", err)
 	}
 
 	if buf != nil {
-		err = buf.Flush()
+		if err := buf.Flush(); err != nil {
-		if err != nil {
 			fatalf("error flushing Ninja file contents: %s", err)
 		}
 	}
 
 	if f != nil {
-		err = f.Close()
+		if err := f.Close(); err != nil {
-		if err != nil {
 			fatalf("error closing Ninja file: %s", err)
 		}
 	}