feat(tool): use go.mod; deprecate GOPATH

tool/cmd/kitex/args/args.go

@@ -56,10 +56,10 @@ type Arguments struct {
 	extends []*ExtraFlag
 }
 
-const cmdExample = `  # Generate client codes or update kitex_gen codes when a project is in $GOPATH:
+const cmdExample = `  # Generate client codes or update kitex_gen codes when a project has go.mod:
   kitex {{path/to/IDL_file.thrift}}
 
-  # Generate client codes or update kitex_gen codes  when a project is not in $GOPATH:
+  # Generate client codes or update kitex_gen codes  when a project doesn't have go.mod:
   kitex -module {{github.com/xxx_org/xxx_name}} {{path/to/IDL_file.thrift}}
 
   # Generate server codes:
@@ -260,46 +260,27 @@ func (a *Arguments) checkStreamX() error {
 }
 
 func (a *Arguments) checkPath(curpath string) error {
-	pathToGo, err := exec.LookPath("go")
-	if err != nil {
-		return err
-	}
-
-	gopath, err := util.GetGOPATH()
-	if err != nil {
-		return err
-	}
-	gosrc := util.JoinPath(gopath, "src")
-	gosrc, err = filepath.Abs(gosrc)
-	if err != nil {
-		return fmt.Errorf("get GOPATH/src path failed: %s", err.Error())
-	}
-
-	if strings.HasPrefix(curpath, gosrc) {
-		if a.PackagePrefix, err = filepath.Rel(gosrc, curpath); err != nil {
-			return fmt.Errorf("get GOPATH/src relpath failed: %s", err.Error())
-		}
-		a.PackagePrefix = util.JoinPath(a.PackagePrefix, a.GenPath)
-	} else {
-		if a.ModuleName == "" {
-			return fmt.Errorf("outside of $GOPATH. Please specify a module name with the '-module' flag")
+	goMod, goModPath, hasGoMod := util.SearchGoMod(curpath)
+	if a.ModuleName == "" {
+		if !hasGoMod {
+			return fmt.Errorf("go.mod not found. Please specify a module name with the '-module' flag")
 		}
+		a.ModuleName = goMod
 	}
 
 	if a.ModuleName != "" {
-		module, path, ok := util.SearchGoMod(curpath)
-		if ok {
-			// go.mod exists
-			if module != a.ModuleName {
+		var err error
+		if hasGoMod {
+			if goMod != a.ModuleName {
 				return fmt.Errorf("the module name given by the '-module' option ('%s') is not consist with the name defined in go.mod ('%s' from %s)",
-					a.ModuleName, module, path)
+					a.ModuleName, goMod, goModPath)
 			}
-			if a.PackagePrefix, err = filepath.Rel(path, curpath); err != nil {
+			if a.PackagePrefix, err = filepath.Rel(goModPath, curpath); err != nil {
 				return fmt.Errorf("get package prefix failed: %s", err.Error())
 			}
 			a.PackagePrefix = util.JoinPath(a.ModuleName, a.PackagePrefix, a.GenPath)
 		} else {
-			if err = initGoMod(pathToGo, a.ModuleName); err != nil {
+			if err = initGoMod(a.ModuleName); err != nil {
 				return fmt.Errorf("init go mod failed: %s", err.Error())
 			}
 			a.PackagePrefix = util.JoinPath(a.ModuleName, a.GenPath)
@@ -520,7 +501,6 @@ func LookupTool(idlType, compilerPath string) string {
 
 	path, err := exec.LookPath(tool)
 	if err != nil {
-		// log.Warnf("Failed to find %q from $PATH: %s.\nTry $GOPATH/bin/%s instead\n", path, err.Error(), tool)
 		gopath, er := util.GetGOPATH()
 		if er != nil {
 			return ""
@@ -530,11 +510,14 @@ func LookupTool(idlType, compilerPath string) string {
 	return path
 }
 
-func initGoMod(pathToGo, module string) error {
+func initGoMod(module string) error {
 	if util.Exists("go.mod") {
 		return nil
 	}
-
+	pathToGo, err := exec.LookPath("go")
+	if err != nil {
+		return err
+	}
 	cmd := &exec.Cmd{
 		Path:   pathToGo,
 		Args:   []string{"go", "mod", "init", module},