fmt.go

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