From 59875158f8d2a03a3020d62afe84745286acd908 Mon Sep 17 00:00:00 2001
From: Scott Fleckenstein <nullstyle@gmail.com>
Date: Thu, 29 Sep 2016 17:21:26 -0700
Subject: [PATCH] Add support for source maps that use the local disk path of
 go source (#521)

---
 build/build.go | 28 +++++++++++++++++-----------
 tool.go        | 10 +++++++++-
 2 files changed, 26 insertions(+), 12 deletions(-)

diff --git a/build/build.go b/build/build.go
index b8c6a4682..8cce949c5 100644
--- a/build/build.go
+++ b/build/build.go
@@ -322,15 +322,16 @@ func parseAndAugment(pkg *build.Package, isTest bool, fileSet *token.FileSet) ([
 }
 
 type Options struct {
-	GOROOT        string
-	GOPATH        string
-	Verbose       bool
-	Quiet         bool
-	Watch         bool
-	CreateMapFile bool
-	Minify        bool
-	Color         bool
-	BuildTags     []string
+	GOROOT         string
+	GOPATH         string
+	Verbose        bool
+	Quiet          bool
+	Watch          bool
+	CreateMapFile  bool
+	MapToLocalDisk bool
+	Minify         bool
+	Color          bool
+	BuildTags      []string
 }
 
 func (o *Options) PrintError(format string, a ...interface{}) {
@@ -656,7 +657,7 @@ func (s *Session) WriteCommandPackage(archive *compiler.Archive, pkgObj string)
 			fmt.Fprintf(codeFile, "//# sourceMappingURL=%s.map\n", filepath.Base(pkgObj))
 		}()
 
-		sourceMapFilter.MappingCallback = NewMappingCallback(m, s.options.GOROOT, s.options.GOPATH)
+		sourceMapFilter.MappingCallback = NewMappingCallback(m, s.options.GOROOT, s.options.GOPATH, s.options.MapToLocalDisk)
 	}
 
 	deps, err := compiler.ImportDependencies(archive, func(path string) (*compiler.Archive, error) {
@@ -672,14 +673,18 @@ func (s *Session) WriteCommandPackage(archive *compiler.Archive, pkgObj string)
 	return compiler.WriteProgramCode(deps, sourceMapFilter)
 }
 
-func NewMappingCallback(m *sourcemap.Map, goroot, gopath string) func(generatedLine, generatedColumn int, originalPos token.Position) {
+func NewMappingCallback(m *sourcemap.Map, goroot, gopath string, localMap bool) func(generatedLine, generatedColumn int, originalPos token.Position) {
 	return func(generatedLine, generatedColumn int, originalPos token.Position) {
 		if !originalPos.IsValid() {
 			m.AddMapping(&sourcemap.Mapping{GeneratedLine: generatedLine, GeneratedColumn: generatedColumn})
 			return
 		}
+
 		file := originalPos.Filename
+
 		switch hasGopathPrefix, prefixLen := hasGopathPrefix(file, gopath); {
+		case localMap:
+			// no-op:  keep file as-is
 		case hasGopathPrefix:
 			file = filepath.ToSlash(file[prefixLen+4:])
 		case strings.HasPrefix(file, goroot):
@@ -687,6 +692,7 @@ func NewMappingCallback(m *sourcemap.Map, goroot, gopath string) func(generatedL
 		default:
 			file = filepath.Base(file)
 		}
+
 		m.AddMapping(&sourcemap.Mapping{GeneratedLine: generatedLine, GeneratedColumn: generatedColumn, OriginalFile: file, OriginalLine: originalPos.Line, OriginalColumn: originalPos.Column})
 	}
 }
diff --git a/tool.go b/tool.go
index bdd457273..4be0b375e 100644
--- a/tool.go
+++ b/tool.go
@@ -75,6 +75,9 @@ func main() {
 	tags := pflag.String("tags", "", "a list of build tags to consider satisfied during the build")
 	flagTags := pflag.Lookup("tags")
 
+	pflag.BoolVar(&options.MapToLocalDisk, "localmap", false, "use local paths for sourcemap")
+	flagLocalMap := pflag.Lookup("localmap")
+
 	cmdBuild := &cobra.Command{
 		Use:   "build [packages]",
 		Short: "compile packages and dependencies",
@@ -86,6 +89,7 @@ func main() {
 	cmdBuild.Flags().AddFlag(flagMinify)
 	cmdBuild.Flags().AddFlag(flagColor)
 	cmdBuild.Flags().AddFlag(flagTags)
+	cmdBuild.Flags().AddFlag(flagLocalMap)
 	cmdBuild.Run = func(cmd *cobra.Command, args []string) {
 		options.BuildTags = strings.Fields(*tags)
 		for {
@@ -162,6 +166,7 @@ func main() {
 	cmdInstall.Flags().AddFlag(flagMinify)
 	cmdInstall.Flags().AddFlag(flagColor)
 	cmdInstall.Flags().AddFlag(flagTags)
+	cmdInstall.Flags().AddFlag(flagLocalMap)
 	cmdInstall.Run = func(cmd *cobra.Command, args []string) {
 		options.BuildTags = strings.Fields(*tags)
 		for {
@@ -234,6 +239,7 @@ func main() {
 	cmdGet.Flags().AddFlag(flagMinify)
 	cmdGet.Flags().AddFlag(flagColor)
 	cmdGet.Flags().AddFlag(flagTags)
+	cmdGet.Flags().AddFlag(flagLocalMap)
 	cmdGet.Run = cmdInstall.Run
 
 	cmdRun := &cobra.Command{
@@ -289,6 +295,7 @@ func main() {
 	cmdTest.Flags().AddFlag(flagMinify)
 	cmdTest.Flags().AddFlag(flagColor)
 	cmdTest.Flags().AddFlag(flagTags)
+	cmdTest.Flags().AddFlag(flagLocalMap)
 	cmdTest.Run = func(cmd *cobra.Command, args []string) {
 		options.BuildTags = strings.Fields(*tags)
 		os.Exit(handleError(func() error {
@@ -475,6 +482,7 @@ func main() {
 	cmdServe.Flags().AddFlag(flagMinify)
 	cmdServe.Flags().AddFlag(flagColor)
 	cmdServe.Flags().AddFlag(flagTags)
+	cmdServe.Flags().AddFlag(flagLocalMap)
 	var addr string
 	cmdServe.Flags().StringVarP(&addr, "http", "", ":8080", "HTTP bind address to serve")
 	cmdServe.Run = func(cmd *cobra.Command, args []string) {
@@ -592,7 +600,7 @@ func (fs serveCommandFileSystem) Open(requestName string) (http.File, error) {
 
 				sourceMapFilter := &compiler.SourceMapFilter{Writer: buf}
 				m := &sourcemap.Map{File: base + ".js"}
-				sourceMapFilter.MappingCallback = gbuild.NewMappingCallback(m, fs.options.GOROOT, fs.options.GOPATH)
+				sourceMapFilter.MappingCallback = gbuild.NewMappingCallback(m, fs.options.GOROOT, fs.options.GOPATH, fs.options.MapToLocalDisk)
 
 				deps, err := compiler.ImportDependencies(archive, s.BuildImportPath)
 				if err != nil {