feat: migration command (golangci#5506)

Author: ldez

.golangci.yml

@@ -171,6 +171,17 @@ linters:
         linters: [gosec]
         text: "G306: Expect WriteFile permissions to be 0600 or less"
 
+      # Related to migration command.
+      - path: pkg/commands/internal/migrate/two/
+        linters:
+          - lll
+
+      # Related to migration command.
+      - path: pkg/commands/internal/migrate/
+        linters:
+          - gocritic
+        text: "hugeParam:"
+
 formatters:
   enable:
     - gofmt

Makefile

@@ -60,6 +60,11 @@ fast_check_generated:
 	git checkout -- go.mod go.sum # can differ between go1.16 and go1.17
 	git diff --exit-code # check no changes
 
+# Migration
+
+clone_config:
+	go run ./pkg/commands/internal/migrate/cloner/
+
 # Benchmark
 
 # Benchmark with a local version

pkg/commands/internal/migrate/cloner/cloner.go

@@ -0,0 +1,195 @@
+package main
+
+import (
+	"bytes"
+	"fmt"
+	"go/ast"
+	"go/parser"
+	"go/printer"
+	"go/token"
+	"log"
+	"os"
+	"path/filepath"
+	"reflect"
+	"strings"
+
+	"golang.org/x/tools/imports"
+)
+
+const newPkgName = "versiontwo"
+
+const (
+	srcDir = "./pkg/config"
+	dstDir = "./pkg/commands/internal/migrate/versiontwo"
+)
+
+func main() {
+	stat, err := os.Stat(srcDir)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	if !stat.IsDir() {
+		log.Fatalf("%s is not a directory", srcDir)
+	}
+
+	_ = os.RemoveAll(dstDir)
+
+	err = processPackage(srcDir, dstDir)
+	if err != nil {
+		log.Fatalf("Processing package error: %v", err)
+	}
+}
+
+func processPackage(srcDir, dstDir string) error {
+	return filepath.Walk(srcDir, func(srcPath string, _ os.FileInfo, err error) error {
+		if err != nil {
+			return err
+		}
+
+		if skipFile(srcPath) {
+			return nil
+		}
+
+		fset := token.NewFileSet()
+
+		file, err := parser.ParseFile(fset, srcPath, nil, parser.AllErrors)
+		if err != nil {
+			return fmt.Errorf("parsing %s: %w", srcPath, err)
+		}
+
+		processFile(file)
+
+		return writeNewFile(fset, file, srcPath, dstDir)
+	})
+}
+
+func skipFile(path string) bool {
+	if !strings.HasSuffix(path, ".go") || strings.HasSuffix(path, "_test.go") {
+		return true
+	}
+
+	switch filepath.Base(path) {
+	case "base_loader.go", "loader.go":
+		return true
+	default:
+		return false
+	}
+}
+
+func processFile(file *ast.File) {
+	file.Name.Name = newPkgName
+
+	var newDecls []ast.Decl
+	for _, decl := range file.Decls {
+		d, ok := decl.(*ast.GenDecl)
+		if !ok {
+			continue
+		}
+
+		switch d.Tok {
+		case token.CONST, token.VAR:
+			continue
+		case token.TYPE:
+			for _, spec := range d.Specs {
+				typeSpec, ok := spec.(*ast.TypeSpec)
+				if !ok {
+					continue
+				}
+
+				structType, ok := typeSpec.Type.(*ast.StructType)
+				if !ok {
+					continue
+				}
+
+				processStructFields(structType)
+			}
+		default:
+			// noop
+		}
+
+		newDecls = append(newDecls, decl)
+	}
+
+	file.Decls = newDecls
+}
+
+func processStructFields(structType *ast.StructType) {
+	var newFields []*ast.Field
+
+	for _, field := range structType.Fields.List {
+		if len(field.Names) > 0 && !field.Names[0].IsExported() {
+			continue
+		}
+
+		if field.Tag == nil {
+			continue
+		}
+
+		field.Type = convertType(field.Type)
+		field.Tag.Value = convertStructTag(field.Tag.Value)
+
+		newFields = append(newFields, field)
+	}
+
+	structType.Fields.List = newFields
+}
+
+func convertType(expr ast.Expr) ast.Expr {
+	ident, ok := expr.(*ast.Ident)
+	if !ok {
+		return expr
+	}
+
+	switch ident.Name {
+	case "bool", "string", "int", "int8", "int16", "int32", "int64", "float32", "float64":
+		return &ast.StarExpr{X: ident}
+
+	default:
+		return expr
+	}
+}
+
+func convertStructTag(value string) string {
+	structTag := reflect.StructTag(strings.Trim(value, "`"))
+
+	key := structTag.Get("mapstructure")
+
+	if key == ",squash" {
+		return wrapStructTag(`yaml:",inline"`)
+	}
+
+	return wrapStructTag(fmt.Sprintf(`yaml:"%[1]s,omitempty" toml:"%[1]s,multiline,omitempty"`, key))
+}
+
+func wrapStructTag(s string) string {
+	return "`" + s + "`"
+}
+
+func writeNewFile(fset *token.FileSet, file *ast.File, srcPath, dstDir string) error {
+	var buf bytes.Buffer
+
+	buf.WriteString("// Code generated by pkg/commands/internal/migrate/cloner/cloner.go. DO NOT EDIT.\n\n")
+
+	err := printer.Fprint(&buf, fset, file)
+	if err != nil {
+		return fmt.Errorf("printing %s: %w", srcPath, err)
+	}
+
+	dstPath := filepath.Join(dstDir, filepath.Base(srcPath))
+
+	_ = os.MkdirAll(filepath.Dir(dstPath), os.ModePerm)
+
+	formatted, err := imports.Process(dstPath, buf.Bytes(), nil)
+	if err != nil {
+		return fmt.Errorf("formatting %s: %w", dstPath, err)
+	}
+
+	//nolint:gosec,mnd // The permission is right.
+	err = os.WriteFile(dstPath, formatted, 0o644)
+	if err != nil {
+		return fmt.Errorf("writing file %s: %w", dstPath, err)
+	}
+
+	return nil
+}

pkg/commands/internal/migrate/fakeloader/config.go

@@ -0,0 +1,22 @@
+package fakeloader
+
+// Config implements [config.BaseConfig].
+// This only the stub for the real file loader.
+type Config struct {
+	Version string `mapstructure:"version"`
+
+	cfgDir string // Path to the directory containing golangci-lint config file.
+}
+
+func NewConfig() *Config {
+	return &Config{}
+}
+
+// SetConfigDir sets the path to directory that contains golangci-lint config file.
+func (c *Config) SetConfigDir(dir string) {
+	c.cfgDir = dir
+}
+
+func (*Config) IsInternalTest() bool {
+	return false
+}

pkg/commands/internal/migrate/fakeloader/fakeloader.go

@@ -0,0 +1,48 @@
+package fakeloader
+
+import (
+	"fmt"
+	"os"
+
+	"github.com/go-viper/mapstructure/v2"
+
+	"github.com/golangci/golangci-lint/pkg/commands/internal/migrate/parser"
+	"github.com/golangci/golangci-lint/pkg/config"
+)
+
+// Load is used to keep case of configuration.
+// Viper serialize raw map keys in lowercase, this is a problem with the configuration of some linters.
+func Load(srcPath string, old any) error {
+	file, err := os.Open(srcPath)
+	if err != nil {
+		return fmt.Errorf("open file: %w", err)
+	}
+
+	defer func() { _ = file.Close() }()
+
+	raw := map[string]any{}
+
+	err = parser.Decode(file, raw)
+	if err != nil {
+		return err
+	}
+
+	// NOTE: this is inspired by viper internals.
+	cc := &mapstructure.DecoderConfig{
+		Result:           old,
+		WeaklyTypedInput: true,
+		DecodeHook:       config.DecodeHookFunc(),
+	}
+
+	decoder, err := mapstructure.NewDecoder(cc)
+	if err != nil {
+		return fmt.Errorf("constructing mapstructure decoder: %w", err)
+	}
+
+	err = decoder.Decode(raw)
+	if err != nil {
+		return fmt.Errorf("decoding configuration file: %w", err)
+	}
+
+	return nil
+}

pkg/commands/internal/migrate/migrate.go

@@ -0,0 +1,19 @@
+package migrate
+
+import (
+	"github.com/golangci/golangci-lint/pkg/commands/internal/migrate/ptr"
+	"github.com/golangci/golangci-lint/pkg/commands/internal/migrate/versionone"
+	"github.com/golangci/golangci-lint/pkg/commands/internal/migrate/versiontwo"
+)
+
+func ToConfig(old *versionone.Config) *versiontwo.Config {
+	return &versiontwo.Config{
+		Version:    ptr.Pointer("2"),
+		Linters:    toLinters(old),
+		Formatters: toFormatters(old),
+		Issues:     toIssues(old),
+		Output:     toOutput(old),
+		Severity:   toSeverity(old),
+		Run:        toRun(old),
+	}
+}