blob: 408af52ffa016632d01ec4d91fed1a6f4ce378d6 [file] [log] [blame]
// Copyright 2011 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Package fmtcmd implements the ``go fmt'' command.
package fmtcmd
import (
func init() {
var CmdFmt = &base.Command{
Run: runFmt,
UsageLine: "go fmt [-n] [-x] [packages]",
Short: "gofmt (reformat) package sources",
Long: `
Fmt runs the command 'gofmt -l -w' on the packages named
by the import paths. It prints the names of the files that are modified.
For more about gofmt, see 'go doc cmd/gofmt'.
For more about specifying packages, see 'go help packages'.
The -n flag prints commands that would be executed.
The -x flag prints commands as they are executed.
The -mod flag's value sets which module download mode
to use: readonly or vendor. See 'go help modules' for more.
To run gofmt with specific options, run gofmt itself.
See also: go fix, go vet.
func runFmt(cmd *base.Command, args []string) {
printed := false
gofmt := gofmtPath()
procs := runtime.GOMAXPROCS(0)
var wg sync.WaitGroup
fileC := make(chan string, 2*procs)
for i := 0; i < procs; i++ {
go func() {
defer wg.Done()
for file := range fileC {
base.Run(str.StringList(gofmt, "-l", "-w", file))
for _, pkg := range load.PackagesAndErrors(args) {
if modload.Enabled() && pkg.Module != nil && !pkg.Module.Main {
if !printed {
fmt.Fprintf(os.Stderr, "go: not formatting packages in dependency modules\n")
printed = true
if pkg.Error != nil {
if strings.HasPrefix(pkg.Error.Err.Error(), "build constraints exclude all Go files") {
// Skip this error, as we will format
// all files regardless.
} else {
base.Errorf("can't load package: %s", pkg.Error)
// Use pkg.gofiles instead of pkg.Dir so that
// the command only applies to this package,
// not to packages in subdirectories.
files := base.RelPaths(pkg.InternalAllGoFiles())
for _, file := range files {
fileC <- file
func gofmtPath() string {
gofmt := "gofmt"
if base.ToolIsWindows {
gofmt += base.ToolWindowsExtension
gofmtPath := filepath.Join(cfg.GOBIN, gofmt)
if _, err := os.Stat(gofmtPath); err == nil {
return gofmtPath
gofmtPath = filepath.Join(cfg.GOROOT, "bin", gofmt)
if _, err := os.Stat(gofmtPath); err == nil {
return gofmtPath
// fallback to looking for gofmt in $PATH
return "gofmt"