fmt.go

Documentation: cmd/go/internal/fmtcmd

     1  // Copyright 2011 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  // Package fmtcmd implements the ``go fmt'' command.
     6  package fmtcmd
     7  
     8  import (
     9  	"context"
    10  	"errors"
    11  	"fmt"
    12  	"os"
    13  	"path/filepath"
    14  	"runtime"
    15  	"sync"
    16  
    17  	"cmd/go/internal/base"
    18  	"cmd/go/internal/cfg"
    19  	"cmd/go/internal/load"
    20  	"cmd/go/internal/modload"
    21  	"cmd/go/internal/str"
    22  )
    23  
    24  func init() {
    25  	base.AddBuildFlagsNX(&CmdFmt.Flag)
    26  	base.AddModFlag(&CmdFmt.Flag)
    27  	base.AddModCommonFlags(&CmdFmt.Flag)
    28  }
    29  
    30  var CmdFmt = &base.Command{
    31  	Run:       runFmt,
    32  	UsageLine: "go fmt [-n] [-x] [packages]",
    33  	Short:     "gofmt (reformat) package sources",
    34  	Long: `
    35  Fmt runs the command 'gofmt -l -w' on the packages named
    36  by the import paths. It prints the names of the files that are modified.
    37  
    38  For more about gofmt, see 'go doc cmd/gofmt'.
    39  For more about specifying packages, see 'go help packages'.
    40  
    41  The -n flag prints commands that would be executed.
    42  The -x flag prints commands as they are executed.
    43  
    44  The -mod flag's value sets which module download mode
    45  to use: readonly or vendor. See 'go help modules' for more.
    46  
    47  To run gofmt with specific options, run gofmt itself.
    48  
    49  See also: go fix, go vet.
    50  	`,
    51  }
    52  
    53  func runFmt(ctx context.Context, cmd *base.Command, args []string) {
    54  	printed := false
    55  	gofmt := gofmtPath()
    56  	procs := runtime.GOMAXPROCS(0)
    57  	var wg sync.WaitGroup
    58  	wg.Add(procs)
    59  	fileC := make(chan string, 2*procs)
    60  	for i := 0; i < procs; i++ {
    61  		go func() {
    62  			defer wg.Done()
    63  			for file := range fileC {
    64  				base.Run(str.StringList(gofmt, "-l", "-w", file))
    65  			}
    66  		}()
    67  	}
    68  	for _, pkg := range load.PackagesAndErrors(ctx, load.PackageOpts{}, args) {
    69  		if modload.Enabled() && pkg.Module != nil && !pkg.Module.Main {
    70  			if !printed {
    71  				fmt.Fprintf(os.Stderr, "go: not formatting packages in dependency modules\n")
    72  				printed = true
    73  			}
    74  			continue
    75  		}
    76  		if pkg.Error != nil {
    77  			var nogo *load.NoGoError
    78  			var embed *load.EmbedError
    79  			if (errors.As(pkg.Error, &nogo) || errors.As(pkg.Error, &embed)) && len(pkg.InternalAllGoFiles()) > 0 {
    80  				// Skip this error, as we will format
    81  				// all files regardless.
    82  			} else {
    83  				base.Errorf("%v", pkg.Error)
    84  				continue
    85  			}
    86  		}
    87  		// Use pkg.gofiles instead of pkg.Dir so that
    88  		// the command only applies to this package,
    89  		// not to packages in subdirectories.
    90  		files := base.RelPaths(pkg.InternalAllGoFiles())
    91  		for _, file := range files {
    92  			fileC <- file
    93  		}
    94  	}
    95  	close(fileC)
    96  	wg.Wait()
    97  }
    98  
    99  func gofmtPath() string {
   100  	gofmt := "gofmt"
   101  	if base.ToolIsWindows {
   102  		gofmt += base.ToolWindowsExtension
   103  	}
   104  
   105  	gofmtPath := filepath.Join(cfg.GOBIN, gofmt)
   106  	if _, err := os.Stat(gofmtPath); err == nil {
   107  		return gofmtPath
   108  	}
   109  
   110  	gofmtPath = filepath.Join(cfg.GOROOT, "bin", gofmt)
   111  	if _, err := os.Stat(gofmtPath); err == nil {
   112  		return gofmtPath
   113  	}
   114  
   115  	// fallback to looking for gofmt in $PATH
   116  	return "gofmt"
   117  }
   118
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