feat: new fmt command with dedicated formatter configuration

.github/workflows/pr.yml

@@ -128,6 +128,9 @@ jobs:
 
       - run: ./golangci-lint
 
+      - run: ./golangci-lint fmt
+      - run: ./golangci-lint fmt --diff
+
       - run: ./golangci-lint cache
       - run: ./golangci-lint cache status
       - run: ./golangci-lint cache clean

cmd/golangci-lint/main.go

@@ -64,11 +64,10 @@ func createBuildInfo() commands.BuildInfo {
 		}
 	}
 
-	revision = cmp.Or(revision, "unknown")
-	modified = cmp.Or(modified, "?")
 	info.Date = cmp.Or(info.Date, "(unknown)")
 
-	info.Commit = fmt.Sprintf("(%s, modified: %s, mod sum: %q)", revision, modified, buildInfo.Main.Sum)
+	info.Commit = fmt.Sprintf("(%s, modified: %s, mod sum: %q)",
+		cmp.Or(revision, "unknown"), cmp.Or(modified, "?"), buildInfo.Main.Sum)
 
 	return info
 }

pkg/commands/flagsets.go

@@ -38,6 +38,11 @@ func setupLintersFlagSet(v *viper.Viper, fs *pflag.FlagSet) {
 		color.GreenString("Override linters configuration section to only run the specific linter(s)")) // Flags only.
 }
 
+func setupFormattersFlagSet(v *viper.Viper, fs *pflag.FlagSet) {
+	internal.AddFlagAndBindP(v, fs, fs.StringSliceP, "enable", "E", "formatters.enable", nil,
+		color.GreenString("Enable specific formatter"))
+}
+
 func setupRunFlagSet(v *viper.Viper, fs *pflag.FlagSet) {
 	internal.AddFlagAndBindP(v, fs, fs.IntP, "concurrency", "j", "run.concurrency", getDefaultConcurrency(),
 		color.GreenString("Number of CPUs to use (Default: number of logical CPUs)"))
@@ -102,7 +107,7 @@ func setupIssuesFlagSet(v *viper.Viper, fs *pflag.FlagSet) {
 	internal.AddFlagAndBind(v, fs, fs.Bool, "exclude-dirs-use-default", "issues.exclude-dirs-use-default", true,
 		formatList("Use or not use default excluded directories:", processors.StdExcludeDirRegexps))
 
-	internal.AddFlagAndBind(v, fs, fs.String, "exclude-generated", "issues.exclude-generated", processors.AutogeneratedModeLax,
+	internal.AddFlagAndBind(v, fs, fs.String, "exclude-generated", "issues.exclude-generated", config.GeneratedModeLax,
 		color.GreenString("Mode of the generated files analysis"))
 
 	const newDesc = "Show only new issues: if there are unstaged changes or untracked files, only those changes " +

pkg/commands/fmt.go

@@ -0,0 +1,152 @@
+package commands
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"strings"
+
+	"github.com/fatih/color"
+	"github.com/spf13/cobra"
+	"github.com/spf13/viper"
+
+	"github.com/golangci/golangci-lint/pkg/config"
+	"github.com/golangci/golangci-lint/pkg/goformat"
+	"github.com/golangci/golangci-lint/pkg/goformatters"
+	"github.com/golangci/golangci-lint/pkg/logutils"
+	"github.com/golangci/golangci-lint/pkg/result/processors"
+)
+
+type fmtOptions struct {
+	config.LoaderOptions
+
+	diff bool // Flag only.
+}
+
+type fmtCommand struct {
+	viper *viper.Viper
+	cmd   *cobra.Command
+
+	opts fmtOptions
+
+	cfg *config.Config
+
+	buildInfo BuildInfo
+
+	runner *goformat.Runner
+
+	log    logutils.Log
+	debugf logutils.DebugFunc
+}
+
+func newFmtCommand(logger logutils.Log, info BuildInfo) *fmtCommand {
+	c := &fmtCommand{
+		viper:     viper.New(),
+		log:       logger,
+		debugf:    logutils.Debug(logutils.DebugKeyExec),
+		cfg:       config.NewDefault(),
+		buildInfo: info,
+	}
+
+	fmtCmd := &cobra.Command{
+		Use:               "fmt",
+		Short:             "Format Go source files",
+		RunE:              c.execute,
+		PreRunE:           c.preRunE,
+		PersistentPreRunE: c.persistentPreRunE,
+		PersistentPostRun: c.persistentPostRun,
+		SilenceUsage:      true,
+	}
+
+	fmtCmd.SetOut(logutils.StdOut) // use custom output to properly color it in Windows terminals
+	fmtCmd.SetErr(logutils.StdErr)
+
+	fs := fmtCmd.Flags()
+	fs.SortFlags = false // sort them as they are defined here
+
+	setupConfigFileFlagSet(fs, &c.opts.LoaderOptions)
+
+	setupFormattersFlagSet(c.viper, fs)
+
+	fs.BoolVarP(&c.opts.diff, "diff", "d", false, color.GreenString("Display diffs instead of rewriting files"))
+
+	c.cmd = fmtCmd
+
+	return c
+}
+
+func (c *fmtCommand) persistentPreRunE(cmd *cobra.Command, args []string) error {
+	c.log.Infof("%s", c.buildInfo.String())
+
+	loader := config.NewLoader(c.log.Child(logutils.DebugKeyConfigReader), c.viper, cmd.Flags(), c.opts.LoaderOptions, c.cfg, args)
+
+	err := loader.Load(config.LoadOptions{CheckDeprecation: true, Validation: true})
+	if err != nil {
+		return fmt.Errorf("can't load config: %w", err)
+	}
+
+	return nil
+}
+
+func (c *fmtCommand) preRunE(_ *cobra.Command, _ []string) error {
+	metaFormatter, err := goformatters.NewMetaFormatter(c.log, &c.cfg.Formatters, &c.cfg.Run)
+	if err != nil {
+		return fmt.Errorf("failed to create meta-formatter: %w", err)
+	}
+
+	matcher := processors.NewGeneratedFileMatcher(c.cfg.Formatters.Exclusions.Generated)
+
+	opts, err := goformat.NewRunnerOptions(c.cfg, c.opts.diff)
+	if err != nil {
+		return fmt.Errorf("build walk options: %w", err)
+	}
+
+	c.runner = goformat.NewRunner(c.log, metaFormatter, matcher, opts)
+
+	return nil
+}
+
+func (c *fmtCommand) execute(_ *cobra.Command, args []string) error {
+	paths, err := cleanArgs(args)
+	if err != nil {
+		return fmt.Errorf("failed to clean arguments: %w", err)
+	}
+
+	c.log.Infof("Formatting Go files...")
+
+	err = c.runner.Run(paths)
+	if err != nil {
+		return fmt.Errorf("failed to process files: %w", err)
+	}
+
+	return nil
+}
+
+func (c *fmtCommand) persistentPostRun(_ *cobra.Command, _ []string) {
+	if c.runner.ExitCode() != 0 {
+		os.Exit(c.runner.ExitCode())
+	}
+}
+
+func cleanArgs(args []string) ([]string, error) {
+	if len(args) == 0 {
+		abs, err := filepath.Abs(".")
+		if err != nil {
+			return nil, err
+		}
+
+		return []string{abs}, nil
+	}
+
+	var expanded []string
+	for _, arg := range args {
+		abs, err := filepath.Abs(strings.ReplaceAll(arg, "...", ""))
+		if err != nil {
+			return nil, err
+		}
+
+		expanded = append(expanded, abs)
+	}
+
+	return expanded, nil
+}

pkg/commands/root.go

@@ -60,6 +60,7 @@ func newRootCommand(info BuildInfo) *rootCommand {
 	rootCmd.AddCommand(
 		newLintersCommand(log).cmd,
 		newRunCommand(log, info).cmd,
+		newFmtCommand(log, info).cmd,
 		newCacheCommand().cmd,
 		newConfigCommand(log, info).cmd,
 		newVersionCommand(info).cmd,

pkg/config/config.go

@@ -29,6 +29,8 @@ type Config struct {
 	Issues          Issues          `mapstructure:"issues"`
 	Severity        Severity        `mapstructure:"severity"`
 
+	Formatters Formatters `mapstructure:"formatters"`
+
 	InternalCmdTest bool // Option is used only for testing golangci-lint command, don't use it
 	InternalTest    bool // Option is used only for testing golangci-lint code, don't use it
 }
@@ -64,6 +66,9 @@ func (c *Config) Validate() error {
 func NewDefault() *Config {
 	return &Config{
 		LintersSettings: defaultLintersSettings,
+		Formatters: Formatters{
+			Settings: defaultFormatterSettings,
+		},
 	}
 }
 

pkg/config/formatters.go

@@ -0,0 +1,12 @@
+package config
+
+type Formatters struct {
+	Enable     []string            `mapstructure:"enable"`
+	Settings   FormatterSettings   `mapstructure:"settings"`
+	Exclusions FormatterExclusions `mapstructure:"exclusions"`
+}
+
+type FormatterExclusions struct {
+	Generated string   `mapstructure:"generated"`
+	Paths     []string `mapstructure:"paths"`
+}

pkg/config/formatters_settings.go

@@ -0,0 +1,52 @@
+package config
+
+var defaultFormatterSettings = FormatterSettings{
+	GoFmt: GoFmtSettings{
+		Simplify: true,
+	},
+	Gci: GciSettings{
+		Sections:      []string{"standard", "default"},
+		SkipGenerated: true,
+	},
+}
+
+type FormatterSettings struct {
+	Gci       GciSettings       `mapstructure:"gci"`
+	GoFmt     GoFmtSettings     `mapstructure:"gofmt"`
+	GoFumpt   GoFumptSettings   `mapstructure:"gofumpt"`
+	GoImports GoImportsSettings `mapstructure:"goimports"`
+}
+
+type GciSettings struct {
+	Sections         []string `mapstructure:"sections"`
+	NoInlineComments bool     `mapstructure:"no-inline-comments"`
+	NoPrefixComments bool     `mapstructure:"no-prefix-comments"`
+	SkipGenerated    bool     `mapstructure:"skip-generated"`
+	CustomOrder      bool     `mapstructure:"custom-order"`
+	NoLexOrder       bool     `mapstructure:"no-lex-order"`
+
+	// Deprecated: use Sections instead.
+	LocalPrefixes string `mapstructure:"local-prefixes"`
+}
+
+type GoFmtSettings struct {
+	Simplify     bool
+	RewriteRules []GoFmtRewriteRule `mapstructure:"rewrite-rules"`
+}
+
+type GoFmtRewriteRule struct {
+	Pattern     string
+	Replacement string
+}
+
+type GoFumptSettings struct {
+	ModulePath string `mapstructure:"module-path"`
+	ExtraRules bool   `mapstructure:"extra-rules"`
+
+	// Deprecated: use the global `run.go` instead.
+	LangVersion string `mapstructure:"lang-version"`
+}
+
+type GoImportsSettings struct {
+	LocalPrefixes string `mapstructure:"local-prefixes"`
+}

pkg/config/linters_exclusions.go

@@ -5,6 +5,12 @@ import (
 	"slices"
 )
 
+const (
+	GeneratedModeLax     = "lax"
+	GeneratedModeStrict  = "strict"
+	GeneratedModeDisable = "disable"
+)
+
 const (
 	ExclusionPresetComments             = "comments"
 	ExclusionPresetStdErrorHandling     = "stdErrorHandling"