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