Implement auto-fixing for gofmt,goimports,misspell

Also, add more identifier marking patterns.

.golangci.yml

@@ -43,15 +43,15 @@ run:
   skip-dirs:
     - test/testdata_etc
 
-# golangci.com configuration
-# https://github.com/golangci/golangci/wiki/Configuration
-service:
-  golangci-lint-version: 1.13.x # use fixed version to not introduce new linters unexpectedly
-  prepare:
-    - echo "here I can run custom commands, but no preparation needed"
-
 issues:
   exclude-rules:
     - text: "weak cryptographic primitive"
       linters:
-        - gosec
+        - gosec
+
+# golangci.com configuration
+# https://github.com/golangci/golangci/wiki/Configuration
+service:
+  golangci-lint-version: 1.14.x # use the fixed version to not introduce new linters unexpectedly
+  prepare:
+    - echo "here I can run custom commands, but no preparation needed"

README.md

@@ -185,16 +185,16 @@ GolangCI-Lint can be used with zero configuration. By default the following lint
 ```bash
 $ golangci-lint help linters
 Enabled by default linters:
-govet (vet, vetshadow): Vet examines Go source code and reports suspicious constructs, such as Printf calls whose arguments do not align with the format string [fast: true]
+govet (vet, vetshadow): Vet examines Go source code and reports suspicious constructs, such as Printf calls whose arguments do not align with the format string [fast: true, auto-fix: false]
-errcheck: Errcheck is a program for checking for unchecked errors in go programs. These unchecked errors can be critical bugs in some cases [fast: true]
+errcheck: Errcheck is a program for checking for unchecked errors in go programs. These unchecked errors can be critical bugs in some cases [fast: true, auto-fix: false]
-staticcheck: Staticcheck is a go vet on steroids, applying a ton of static analysis checks [fast: false]
+staticcheck: Staticcheck is a go vet on steroids, applying a ton of static analysis checks [fast: false, auto-fix: false]
-unused: Checks Go code for unused constants, variables, functions and types [fast: false]
+unused: Checks Go code for unused constants, variables, functions and types [fast: false, auto-fix: false]
-gosimple: Linter for Go source code that specializes in simplifying a code [fast: false]
+gosimple: Linter for Go source code that specializes in simplifying a code [fast: false, auto-fix: false]
-structcheck: Finds an unused struct fields [fast: true]
+structcheck: Finds an unused struct fields [fast: true, auto-fix: false]
-varcheck: Finds unused global variables and constants [fast: true]
+varcheck: Finds unused global variables and constants [fast: true, auto-fix: false]
-ineffassign: Detects when assignments to existing variables are not used [fast: true]
+ineffassign: Detects when assignments to existing variables are not used [fast: true, auto-fix: false]
-deadcode: Finds unused code [fast: true]
+deadcode: Finds unused code [fast: true, auto-fix: false]
-typecheck: Like the front-end of a Go compiler, parses and type-checks Go code [fast: true]
+typecheck: Like the front-end of a Go compiler, parses and type-checks Go code [fast: true, auto-fix: false]
 ```
 
 and the following linters are disabled by default:
@@ -203,27 +203,27 @@ and the following linters are disabled by default:
 $ golangci-lint help linters
 ...
 Disabled by default linters:
-golint: Golint differs from gofmt. Gofmt reformats Go source code, whereas golint prints out style mistakes [fast: true]
+golint: Golint differs from gofmt. Gofmt reformats Go source code, whereas golint prints out style mistakes [fast: true, auto-fix: false]
-stylecheck: Stylecheck is a replacement for golint [fast: false]
+stylecheck: Stylecheck is a replacement for golint [fast: false, auto-fix: false]
-gosec (gas): Inspects source code for security problems [fast: true]
+gosec (gas): Inspects source code for security problems [fast: true, auto-fix: false]
-interfacer: Linter that suggests narrower interface types [fast: false]
+interfacer: Linter that suggests narrower interface types [fast: false, auto-fix: false]
-unconvert: Remove unnecessary type conversions [fast: true]
+unconvert: Remove unnecessary type conversions [fast: true, auto-fix: false]
-dupl: Tool for code clone detection [fast: true]
+dupl: Tool for code clone detection [fast: true, auto-fix: false]
-goconst: Finds repeated strings that could be replaced by a constant [fast: true]
+goconst: Finds repeated strings that could be replaced by a constant [fast: true, auto-fix: false]
-gocyclo: Computes and checks the cyclomatic complexity of functions [fast: true]
+gocyclo: Computes and checks the cyclomatic complexity of functions [fast: true, auto-fix: false]
-gofmt: Gofmt checks whether code was gofmt-ed. By default this tool runs with -s option to check for code simplification [fast: true]
+gofmt: Gofmt checks whether code was gofmt-ed. By default this tool runs with -s option to check for code simplification [fast: true, auto-fix: true]
-goimports: Goimports does everything that gofmt does. Additionally it checks unused imports [fast: true]
+goimports: Goimports does everything that gofmt does. Additionally it checks unused imports [fast: true, auto-fix: true]
-maligned: Tool to detect Go structs that would take less memory if their fields were sorted [fast: true]
+maligned: Tool to detect Go structs that would take less memory if their fields were sorted [fast: true, auto-fix: false]
-depguard: Go linter that checks if package imports are in a list of acceptable packages [fast: true]
+depguard: Go linter that checks if package imports are in a list of acceptable packages [fast: true, auto-fix: false]
-misspell: Finds commonly misspelled English words in comments [fast: true]
+misspell: Finds commonly misspelled English words in comments [fast: true, auto-fix: true]
-lll: Reports long lines [fast: true]
+lll: Reports long lines [fast: true, auto-fix: false]
-unparam: Reports unused function parameters [fast: false]
+unparam: Reports unused function parameters [fast: false, auto-fix: false]
-nakedret: Finds naked returns in functions greater than a specified function length [fast: true]
+nakedret: Finds naked returns in functions greater than a specified function length [fast: true, auto-fix: false]
-prealloc: Finds slice declarations that could potentially be preallocated [fast: true]
+prealloc: Finds slice declarations that could potentially be preallocated [fast: true, auto-fix: false]
-scopelint: Scopelint checks for unpinned variables in go programs [fast: true]
+scopelint: Scopelint checks for unpinned variables in go programs [fast: true, auto-fix: false]
-gocritic: The most opinionated Go source code linter [fast: true]
+gocritic: The most opinionated Go source code linter [fast: true, auto-fix: false]
-gochecknoinits: Checks that no init functions are present in Go code [fast: true]
+gochecknoinits: Checks that no init functions are present in Go code [fast: true, auto-fix: false]
-gochecknoglobals: Checks that no globals are present in Go code [fast: true]
+gochecknoglobals: Checks that no globals are present in Go code [fast: true, auto-fix: false]
 ```
 
 Pass `-E/--enable` to enable linter and `-D/--disable` to disable:
@@ -499,6 +499,7 @@ Flags:
                                     For CI setups, prefer --new-from-rev=HEAD~, as --new can skip linting the current patch if any scripts generate unstaged files before golangci-lint runs.
       --new-from-rev REV            Show only new issues created after git revision REV
       --new-from-patch PATH         Show only new issues created in git patch with file path PATH
+      --fix                         Fix found issues (if it's supported by the linter)
   -h, --help                        help for run
 
 Global Flags:
@@ -829,18 +830,18 @@ run:
   skip-dirs:
     - test/testdata_etc
 
-# golangci.com configuration
-# https://github.com/golangci/golangci/wiki/Configuration
-service:
-  golangci-lint-version: 1.13.x # use fixed version to not introduce new linters unexpectedly
-  prepare:
-    - echo "here I can run custom commands, but no preparation needed"
-
 issues:
   exclude-rules:
     - text: "weak cryptographic primitive"
       linters:
         - gosec
+
+# golangci.com configuration
+# https://github.com/golangci/golangci/wiki/Configuration
+service:
+  golangci-lint-version: 1.14.x # use the fixed version to not introduce new linters unexpectedly
+  prepare:
+    - echo "here I can run custom commands, but no preparation needed"
 ```
 
 ## False Positives

pkg/commands/help.go

@@ -41,8 +41,8 @@ func printLinterConfigs(lcs []*linter.Config) {
 		if len(lc.AlternativeNames) != 0 {
 			altNamesStr = fmt.Sprintf(" (%s)", strings.Join(lc.AlternativeNames, ", "))
 		}
-		fmt.Fprintf(logutils.StdOut, "%s%s: %s [fast: %t]\n", color.YellowString(lc.Name()),
+		fmt.Fprintf(logutils.StdOut, "%s%s: %s [fast: %t, auto-fix: %t]\n", color.YellowString(lc.Name()),
-			altNamesStr, lc.Linter.Desc(), !lc.NeedsSSARepr)
+			altNamesStr, lc.Linter.Desc(), !lc.NeedsSSARepr, lc.CanAutoFix)
 	}
 }
 

pkg/commands/run.go

@@ -10,6 +10,8 @@ import (
 	"strings"
 	"time"
 
+	"github.com/golangci/golangci-lint/pkg/result/processors"
+
 	"github.com/fatih/color"
 	"github.com/pkg/errors"
 	"github.com/spf13/cobra"
@@ -177,7 +179,7 @@ func initFlagSet(fs *pflag.FlagSet, cfg *config.Config, m *lintersdb.Manager, is
 		wh("Show only new issues created after git revision `REV`"))
 	fs.StringVar(&ic.DiffPatchFilePath, "new-from-patch", "",
 		wh("Show only new issues created in git patch with file path `PATH`"))
-
+	fs.BoolVar(&ic.NeedFix, "fix", false, "Fix found issues (if it's supported by the linter)")
 }
 
 func (e *Executor) initRunConfiguration(cmd *cobra.Command) {
@@ -281,7 +283,9 @@ func (e *Executor) runAnalysis(ctx context.Context, args []string) (<-chan resul
 		return nil, err
 	}
 
-	return runner.Run(ctx, enabledLinters, lintCtx), nil
+	issuesCh := runner.Run(ctx, enabledLinters, lintCtx)
+	fixer := processors.NewFixer(e.cfg, e.log)
+	return fixer.Process(issuesCh), nil
 }
 
 func (e *Executor) setOutputToDevNull() (savedStdout, savedStderr *os.File) {

pkg/config/config.go

@@ -278,6 +278,8 @@ type Issues struct {
 	DiffFromRevision  string `mapstructure:"new-from-rev"`
 	DiffPatchFilePath string `mapstructure:"new-from-patch"`
 	Diff              bool   `mapstructure:"new"`
+
+	NeedFix bool `mapstructure:"fix"`
 }
 
 type Config struct { //nolint:maligned

pkg/golinters/gofmt.go

@@ -5,9 +5,11 @@ import (
 	"context"
 	"fmt"
 	"go/token"
+	"strings"
 
 	gofmtAPI "github.com/golangci/gofmt/gofmt"
 	goimportsAPI "github.com/golangci/gofmt/goimports"
+	"github.com/pkg/errors"
 	"golang.org/x/tools/imports"
 	diffpkg "sourcegraph.com/sourcegraph/go-diff/diff"
 
@@ -37,31 +39,204 @@ func (g Gofmt) Desc() string {
 		"this tool runs with -s option to check for code simplification"
 }
 
-func getFirstDeletedAndAddedLineNumberInHunk(h *diffpkg.Hunk) (firstDeleted, firstAdded int, err error) {
+type Change struct {
-	lines := bytes.Split(h.Body, []byte{'\n'})
+	LineRange   result.Range
-	lineNumber := int(h.OrigStartLine - 1)
+	Replacement result.Replacement
-	firstAddedLineNumber := -1
+}
-	for _, line := range lines {
-		lineNumber++
 
-		if len(line) == 0 {
+type diffLineType string
-			continue
+
+const (
+	diffLineAdded    diffLineType = "added"
+	diffLineOriginal diffLineType = "original"
+	diffLineDeleted  diffLineType = "deleted"
+)
+
+type diffLine struct {
+	originalNumber int // 1-based original line number
+	typ            diffLineType
+	data           string // "+" or "-" stripped line
+}
+
+type hunkChangesParser struct {
+	// needed because we merge currently added lines with the last original line
+	lastOriginalLine *diffLine
+
+	// if the first line of diff is an adding we save all additions to replacementLinesToPrepend
+	replacementLinesToPrepend []string
+
+	log logutils.Log
+
+	lines []diffLine
+
+	ret []Change
+}
+
+func (p *hunkChangesParser) parseDiffLines(h *diffpkg.Hunk) {
+	lines := bytes.Split(h.Body, []byte{'\n'})
+	currentOriginalLineNumer := int(h.OrigStartLine)
+	var ret []diffLine
+
+	for i, line := range lines {
+		dl := diffLine{
+			originalNumber: currentOriginalLineNumer,
 		}
-		if line[0] == '+' && firstAddedLineNumber == -1 {
+
-			firstAddedLineNumber = lineNumber
+		lineStr := string(line)
-		}
+
-		if line[0] == '-' {
+		//nolint:gocritic
-			return lineNumber, firstAddedLineNumber, nil
+		if strings.HasPrefix(lineStr, "-") {
+			dl.typ = diffLineDeleted
+			dl.data = strings.TrimPrefix(lineStr, "-")
+			currentOriginalLineNumer++
+		} else if strings.HasPrefix(lineStr, "+") {
+			dl.typ = diffLineAdded
+			dl.data = strings.TrimPrefix(lineStr, "+")
+		} else {
+			if i == len(lines)-1 && lineStr == "" {
+				// handle last \n: don't add an empty original line
+				break
+			}
+
+			dl.typ = diffLineOriginal
+			dl.data = strings.TrimPrefix(lineStr, " ")
+			currentOriginalLineNumer++
 		}
+
+		ret = append(ret, dl)
 	}
 
-	return 0, firstAddedLineNumber, fmt.Errorf("didn't find deletion line in hunk %s", string(h.Body))
+	p.lines = ret
+}
+
+func (p *hunkChangesParser) handleOriginalLine(line diffLine, i *int) {
+	if len(p.replacementLinesToPrepend) == 0 {
+		p.lastOriginalLine = &line
+		*i++
+		return
+	}
+
+	// check following added lines for the case:
+	// + added line 1
+	// original line
+	// + added line 2
+
+	*i++
+	var followingAddedLines []string
+	for ; *i < len(p.lines) && p.lines[*i].typ == diffLineAdded; *i++ {
+		followingAddedLines = append(followingAddedLines, p.lines[*i].data)
+	}
+
+	p.ret = append(p.ret, Change{
+		LineRange: result.Range{
+			From: line.originalNumber,
+			To:   line.originalNumber,
+		},
+		Replacement: result.Replacement{
+			NewLines: append(p.replacementLinesToPrepend, append([]string{line.data}, followingAddedLines...)...),
+		},
+	})
+	p.replacementLinesToPrepend = nil
+	p.lastOriginalLine = &line
+}
+
+func (p *hunkChangesParser) handleDeletedLines(deletedLines []diffLine, addedLines []string) {
+	change := Change{
+		LineRange: result.Range{
+			From: deletedLines[0].originalNumber,
+			To:   deletedLines[len(deletedLines)-1].originalNumber,
+		},
+	}
+
+	if len(addedLines) != 0 {
+		//nolint:gocritic
+		change.Replacement.NewLines = append(p.replacementLinesToPrepend, addedLines...)
+		if len(p.replacementLinesToPrepend) != 0 {
+			p.replacementLinesToPrepend = nil
+		}
+
+		p.ret = append(p.ret, change)
+		return
+	}
+
+	// delete-only change with possible prepending
+	if len(p.replacementLinesToPrepend) != 0 {
+		change.Replacement.NewLines = p.replacementLinesToPrepend
+		p.replacementLinesToPrepend = nil
+	} else {
+		change.Replacement.NeedOnlyDelete = true
+	}
+
+	p.ret = append(p.ret, change)
+}
+
+func (p *hunkChangesParser) handleAddedOnlyLines(addedLines []string) {
+	if p.lastOriginalLine == nil {
+		// the first line is added; the diff looks like:
+		// 1. + ...
+		// 2. - ...
+		// or
+		// 1. + ...
+		// 2. ...
+
+		p.replacementLinesToPrepend = addedLines
+		return
+	}
+
+	// add-only change merged into the last original line with possible prepending
+	p.ret = append(p.ret, Change{
+		LineRange: result.Range{
+			From: p.lastOriginalLine.originalNumber,
+			To:   p.lastOriginalLine.originalNumber,
+		},
+		Replacement: result.Replacement{
+			NewLines: append(p.replacementLinesToPrepend, append([]string{p.lastOriginalLine.data}, addedLines...)...),
+		},
+	})
+	p.replacementLinesToPrepend = nil
+}
+
+func (p *hunkChangesParser) parse(h *diffpkg.Hunk) []Change {
+	p.parseDiffLines(h)
+
+	for i := 0; i < len(p.lines); {
+		line := p.lines[i]
+		if line.typ == diffLineOriginal {
+			p.handleOriginalLine(line, &i) //nolint:scopelint
+			continue
+		}
+
+		var deletedLines []diffLine
+		for ; i < len(p.lines) && p.lines[i].typ == diffLineDeleted; i++ {
+			deletedLines = append(deletedLines, p.lines[i])
+		}
+
+		var addedLines []string
+		for ; i < len(p.lines) && p.lines[i].typ == diffLineAdded; i++ {
+			addedLines = append(addedLines, p.lines[i].data)
+		}
+
+		if len(deletedLines) != 0 {
+			p.handleDeletedLines(deletedLines, addedLines)
+			continue
+		}
+
+		// no deletions, only addings
+		p.handleAddedOnlyLines(addedLines)
+	}
+
+	if len(p.replacementLinesToPrepend) != 0 {
+		p.log.Infof("The diff contains only additions: no original or deleted lines: %#v", p.lines)
+		return nil
+	}
+
+	return p.ret
 }
 
 func (g Gofmt) extractIssuesFromPatch(patch string, log logutils.Log) ([]result.Issue, error) {
 	diffs, err := diffpkg.ParseMultiFileDiff([]byte(patch))
 	if err != nil {
-		return nil, fmt.Errorf("can't parse patch: %s", err)
+		return nil, errors.Wrap(err, "can't parse patch")
 	}
 
 	if len(diffs) == 0 {
@@ -76,28 +251,31 @@ func (g Gofmt) extractIssuesFromPatch(patch string, log logutils.Log) ([]result.
 		}
 
 		for _, hunk := range d.Hunks {
-			deletedLine, addedLine, err := getFirstDeletedAndAddedLineNumberInHunk(hunk)
-			if err != nil {
-				if addedLine > 1 {
-					deletedLine = addedLine - 1 // use previous line, TODO: use both prev and next lines
-				} else {
-					deletedLine = 1
-				}
-			}
-
 			text := "File is not `gofmt`-ed with `-s`"
 			if g.UseGoimports {
 				text = "File is not `goimports`-ed"
 			}
-			i := result.Issue{
+			p := hunkChangesParser{
-				FromLinter: g.Name(),
+				log: log,
-				Pos: token.Position{
+			}
-					Filename: d.NewName,
+			changes := p.parse(hunk)
-					Line:     deletedLine,
+			for _, change := range changes {
-				},
+				change := change // fix scope
-				Text: text,
+				i := result.Issue{
+					FromLinter: g.Name(),
+					Pos: token.Position{
+						Filename: d.NewName,
+						Line:     change.LineRange.From,
+					},
+					Text:        text,
+					Replacement: &change.Replacement,
+				}
+				if change.LineRange.From != change.LineRange.To {
+					i.LineRange = &change.LineRange
+				}
+
+				issues = append(issues, i)
 			}
-			issues = append(issues, i)
 		}
 	}
 

pkg/golinters/gofmt_test.go

@@ -0,0 +1,353 @@
+package golinters
+
+import (
+	"testing"
+
+	"github.com/golang/mock/gomock"
+
+	"github.com/golangci/golangci-lint/pkg/result"
+
+	"github.com/stretchr/testify/assert"
+	diffpkg "sourcegraph.com/sourcegraph/go-diff/diff"
+
+	"github.com/golangci/golangci-lint/pkg/logutils"
+)
+
+func testDiffProducesChanges(t *testing.T, log logutils.Log, diff string, expectedChanges ...Change) {
+	diffs, err := diffpkg.ParseMultiFileDiff([]byte(diff))
+	if err != nil {
+		assert.NoError(t, err)
+	}
+
+	assert.Len(t, diffs, 1)
+	hunks := diffs[0].Hunks
+	assert.NotEmpty(t, hunks)
+
+	var changes []Change
+	for _, hunk := range hunks {
+		p := hunkChangesParser{
+			log: log,
+		}
+		changes = append(changes, p.parse(hunk)...)
+	}
+
+	assert.Equal(t, expectedChanges, changes)
+}
+
+func TestExtractChangesFromHunkAddOnly(t *testing.T) {
+	const diff = `diff --git a/internal/shared/logutil/log.go b/internal/shared/logutil/log.go
+index 258b340..43d04bf 100644
+--- a/internal/shared/logutil/log.go
++++ b/internal/shared/logutil/log.go
+@@ -1,5 +1,6 @@
+ package logutil
+
++// added line
+ type Func func(format string, args ...interface{})
+
+ type Log interface {
+`
+
+	testDiffProducesChanges(t, nil, diff, Change{
+		LineRange: result.Range{
+			From: 2,
+			To:   2,
+		},
+		Replacement: result.Replacement{
+			NewLines: []string{
+				"",
+				"// added line",
+			},
+		},
+	})
+}
+
+func TestExtractChangesFromHunkAddOnlyOnFirstLine(t *testing.T) {
+	const diff = `diff --git a/internal/shared/logutil/log.go b/internal/shared/logutil/log.go
+index 258b340..97e6660 100644
+--- a/internal/shared/logutil/log.go
++++ b/internal/shared/logutil/log.go
+@@ -1,3 +1,4 @@
++// added line
+ package logutil
+
+ type Func func(format string, args ...interface{})
+`
+
+	testDiffProducesChanges(t, nil, diff, Change{
+		LineRange: result.Range{
+			From: 1,
+			To:   1,
+		},
+		Replacement: result.Replacement{
+			NewLines: []string{
+				"// added line",
+				"package logutil",
+			},
+		},
+	})
+}
+
+func TestExtractChangesFromHunkAddOnlyOnFirstLineWithSharedOriginalLine(t *testing.T) {
+	const diff = `diff --git a/internal/shared/logutil/log.go b/internal/shared/logutil/log.go
+index 258b340..7ff80c9 100644
+--- a/internal/shared/logutil/log.go
++++ b/internal/shared/logutil/log.go
+@@ -1,4 +1,7 @@
++// added line 1
+ package logutil
++// added line 2
++// added line 3
+
+ type Func func(format string, args ...interface{})
+`
+	testDiffProducesChanges(t, nil, diff, Change{
+		LineRange: result.Range{
+			From: 1,
+			To:   1,
+		},
+		Replacement: result.Replacement{
+			NewLines: []string{
+				"// added line 1",
+				"package logutil",
+				"// added line 2",
+				"// added line 3",
+			},
+		},
+	})
+}
+
+func TestExtractChangesFromHunkAddOnlyInAllDiff(t *testing.T) {
+	const diff = `diff --git a/test.go b/test.go
+new file mode 100644
+index 0000000..6399915
+--- /dev/null
++++ b/test.go
+@@ -0,0 +1,3 @@
++package test
++
++// line
+`
+
+	ctrl := gomock.NewController(t)
+	defer ctrl.Finish()
+	log := logutils.NewMockLog(ctrl)
+	log.EXPECT().Infof("The diff contains only additions: no original or deleted lines: %#v", gomock.Any())
+	var noChanges []Change
+	testDiffProducesChanges(t, log, diff, noChanges...)
+}
+
+func TestExtractChangesFromHunkAddOnlyMultipleLines(t *testing.T) {
+	const diff = `diff --git a/internal/shared/logutil/log.go b/internal/shared/logutil/log.go
+index 258b340..3b83a94 100644
+--- a/internal/shared/logutil/log.go
++++ b/internal/shared/logutil/log.go
+@@ -2,6 +2,9 @@ package logutil
+
+ type Func func(format string, args ...interface{})
+
++// add line 1
++// add line 2
++
+ type Log interface {
+        Fatalf(format string, args ...interface{})
+		Errorf(format string, args ...interface{})
+`
+
+	testDiffProducesChanges(t, nil, diff, Change{
+		LineRange: result.Range{
+			From: 4,
+			To:   4,
+		},
+		Replacement: result.Replacement{
+			NewLines: []string{
+				"",
+				"// add line 1",
+				"// add line 2",
+				"",
+			},
+		},
+	})
+}
+
+func TestExtractChangesFromHunkAddOnlyDifferentLines(t *testing.T) {
+	const diff = `diff --git a/internal/shared/logutil/log.go b/internal/shared/logutil/log.go
+index 258b340..e5ed2ad 100644
+--- a/internal/shared/logutil/log.go
++++ b/internal/shared/logutil/log.go
+@@ -2,9 +2,12 @@ package logutil
+
+ type Func func(format string, args ...interface{})
+
++// add line 1
++
+ type Log interface {
+        Fatalf(format string, args ...interface{})
+        Errorf(format string, args ...interface{})
++       // add line 2
+        Warnf(format string, args ...interface{})
+        Infof(format string, args ...interface{})
+		Debugf(key string, format string, args ...interface{})
+`
+
+	expectedChanges := []Change{
+		{
+			LineRange: result.Range{
+				From: 4,
+				To:   4,
+			},
+			Replacement: result.Replacement{
+				NewLines: []string{
+					"",
+					"// add line 1",
+					"",
+				},
+			},
+		},
+		{
+			LineRange: result.Range{
+				From: 7,
+				To:   7,
+			},
+			Replacement: result.Replacement{
+				NewLines: []string{
+					"       Errorf(format string, args ...interface{})",
+					"       // add line 2",
+				},
+			},
+		},
+	}
+
+	testDiffProducesChanges(t, nil, diff, expectedChanges...)
+}
+
+func TestExtractChangesDeleteOnlyFirstLines(t *testing.T) {
+	const diff = `diff --git a/internal/shared/logutil/log.go b/internal/shared/logutil/log.go
+index 258b340..0fb554e 100644
+--- a/internal/shared/logutil/log.go
++++ b/internal/shared/logutil/log.go
+@@ -1,5 +1,3 @@
+-package logutil
+-
+ type Func func(format string, args ...interface{})
+
+ type Log interface {
+`
+
+	testDiffProducesChanges(t, nil, diff, Change{
+		LineRange: result.Range{
+			From: 1,
+			To:   2,
+		},
+		Replacement: result.Replacement{
+			NeedOnlyDelete: true,
+		},
+	})
+}
+
+func TestExtractChangesReplaceLine(t *testing.T) {
+	const diff = `diff --git a/internal/shared/logutil/log.go b/internal/shared/logutil/log.go
+index 258b340..c2a8516 100644
+--- a/internal/shared/logutil/log.go
++++ b/internal/shared/logutil/log.go
+@@ -1,4 +1,4 @@
+-package logutil
++package test2
+
+ type Func func(format string, args ...interface{})
+`
+
+	testDiffProducesChanges(t, nil, diff, Change{
+		LineRange: result.Range{
+			From: 1,
+			To:   1,
+		},
+		Replacement: result.Replacement{
+			NewLines: []string{"package test2"},
+		},
+	})
+}
+
+func TestExtractChangesReplaceLineAfterFirstLineAdding(t *testing.T) {
+	const diff = `diff --git a/internal/shared/logutil/log.go b/internal/shared/logutil/log.go
+index 258b340..43fc0de 100644
+--- a/internal/shared/logutil/log.go
++++ b/internal/shared/logutil/log.go
+@@ -1,6 +1,7 @@
++// added line
+ package logutil
+
+-type Func func(format string, args ...interface{})
++// changed line
+
+ type Log interface {
+        Fatalf(format string, args ...interface{})`
+
+	testDiffProducesChanges(t, nil, diff, Change{
+		LineRange: result.Range{
+			From: 1,
+			To:   1,
+		},
+		Replacement: result.Replacement{
+			NewLines: []string{
+				"// added line",
+				"package logutil",
+			},
+		},
+	}, Change{
+		LineRange: result.Range{
+			From: 3,
+			To:   3,
+		},
+		Replacement: result.Replacement{
+			NewLines: []string{
+				"// changed line",
+			},
+		},
+	})
+}
+
+func TestGofmtDiff(t *testing.T) {
+	const diff = `diff --git a/gofmt.go b/gofmt.go
+index 2c9f78d..c0d5791 100644
+--- a/gofmt.go
++++ b/gofmt.go
+@@ -1,9 +1,9 @@
+ //args: -Egofmt
+ package p
+
+- func gofmt(a, b int) int {
+-         if a != b {
+-                 return 1
++func gofmt(a, b int) int {
++       if a != b {
++               return 1
+        }
+-         return 2
++       return 2
+ }
+`
+	testDiffProducesChanges(t, nil, diff, Change{
+		LineRange: result.Range{
+			From: 4,
+			To:   6,
+		},
+		Replacement: result.Replacement{
+			NewLines: []string{
+				"func gofmt(a, b int) int {",
+				"       if a != b {",
+				"               return 1",
+			},
+		},
+	}, Change{
+		LineRange: result.Range{
+			From: 8,
+			To:   8,
+		},
+		Replacement: result.Replacement{
+			NewLines: []string{
+				"       return 2",
+			},
+		},
+	})
+}

pkg/golinters/golint.go

@@ -61,7 +61,7 @@ func (g Golint) lintPkg(minConfidence float64, files []*ast.File, fset *token.Fi
 		if ps[idx].Confidence >= minConfidence {
 			issues = append(issues, result.Issue{
 				Pos:        ps[idx].Position,
-				Text:       markIdentifiers(ps[idx].Text),
+				Text:       ps[idx].Text,
 				FromLinter: g.Name(),
 			})
 			// TODO: use p.Link and p.Category

pkg/golinters/gosec.go

@@ -40,7 +40,7 @@ func (lint Gosec) Run(ctx context.Context, lintCtx *linter.Context) ([]result.Is
 
 	res := make([]result.Issue, 0, len(issues))
 	for _, i := range issues {
-		text := fmt.Sprintf("%s: %s", i.RuleID, markIdentifiers(i.What)) // TODO: use severity and confidence
+		text := fmt.Sprintf("%s: %s", i.RuleID, i.What) // TODO: use severity and confidence
 		var r *result.Range
 		line, err := strconv.Atoi(i.Line)
 		if err != nil {

pkg/golinters/govet.go

@@ -39,7 +39,7 @@ func (g Govet) Run(_ context.Context, lintCtx *linter.Context) ([]result.Issue,
 	for _, i := range govetIssues {
 		res = append(res, result.Issue{
 			Pos:        i.Pos,
-			Text:       markIdentifiers(i.Message),
+			Text:       i.Message,
 			FromLinter: g.Name(),
 		})
 	}

pkg/golinters/interfacer.go

@@ -37,7 +37,7 @@ func (lint Interfacer) Run(ctx context.Context, lintCtx *linter.Context) ([]resu
 		pos := lintCtx.SSAProgram.Fset.Position(i.Pos())
 		res = append(res, result.Issue{
 			Pos:        pos,
-			Text:       markIdentifiers(i.Message()),
+			Text:       i.Message(),
 			FromLinter: lint.Name(),
 		})
 	}

pkg/golinters/megacheck.go

@@ -259,7 +259,7 @@ func (m megacheck) Run(ctx context.Context, lintCtx *linter.Context) ([]result.I
 
 		res = append(res, result.Issue{
 			Pos:        i.Position,
-			Text:       markIdentifiers(i.Text),
+			Text:       i.Text,
 			FromLinter: i.Checker,
 		})
 	}

pkg/golinters/unparam.go

@@ -40,7 +40,7 @@ func (lint Unparam) Run(ctx context.Context, lintCtx *linter.Context) ([]result.
 	for _, i := range unparamIssues {
 		res = append(res, result.Issue{
 			Pos:        lintCtx.Program.Fset.Position(i.Pos()),
-			Text:       markIdentifiers(i.Message()),
+			Text:       i.Message(),
 			FromLinter: lint.Name(),
 		})
 	}

pkg/golinters/util.go

@@ -4,9 +4,7 @@ import (
 	"fmt"
 	"go/ast"
 	"go/token"
-	"regexp"
 	"strings"
-	"sync"
 
 	gopackages "golang.org/x/tools/go/packages"
 
@@ -30,68 +28,6 @@ func formatCodeBlock(code string, _ *config.Config) string {
 	return fmt.Sprintf("```\n%s\n```", code)
 }
 
-type replacePattern struct {
-	re   string
-	repl string
-}
-
-type replaceRegexp struct {
-	re   *regexp.Regexp
-	repl string
-}
-
-var replaceRegexps []replaceRegexp
-var replaceRegexpsOnce sync.Once
-
-var replacePatterns = []replacePattern{
-	// unparam
-	{`^(\S+) - (\S+) is unused$`, "`${1}` - `${2}` is unused"},
-	{`^(\S+) - (\S+) always receives (\S+) \((.*)\)$`, "`${1}` - `${2}` always receives `${3}` (`${4}`)"},
-	{`^(\S+) - (\S+) always receives (.*)$`, "`${1}` - `${2}` always receives `${3}`"},
-
-	// interfacer
-	{`^(\S+) can be (\S+)$`, "`${1}` can be `${2}`"},
-
-	// govet
-	{`^(\S+) arg list ends with redundant newline$`, "`${1}` arg list ends with redundant newline"},
-	{`^(\S+) composite literal uses unkeyed fields$`, "`${1}` composite literal uses unkeyed fields"},
-
-	// gosec
-	{`^Blacklisted import (\S+): weak cryptographic primitive$`,
-		"Blacklisted import `${1}`: weak cryptographic primitive"},
-	{`^TLS InsecureSkipVerify set true.$`, "TLS `InsecureSkipVerify` set true."},
-
-	// gosimple
-	{`^should replace loop with (.*)$`, "should replace loop with `${1}`"},
-
-	// megacheck
-	{`^this value of (\S+) is never used$`, "this value of `${1}` is never used"},
-	{`^should use time.Since instead of time.Now().Sub$`,
-		"should use `time.Since` instead of `time.Now().Sub`"},
-	{`^(func|const|field|type) (\S+) is unused$`, "${1} `${2}` is unused"},
-}
-
-func markIdentifiers(s string) string {
-	replaceRegexpsOnce.Do(func() {
-		for _, p := range replacePatterns {
-			r := replaceRegexp{
-				re:   regexp.MustCompile(p.re),
-				repl: p.repl,
-			}
-			replaceRegexps = append(replaceRegexps, r)
-		}
-	})
-
-	for _, rr := range replaceRegexps {
-		rs := rr.re.ReplaceAllString(s, rr.repl)
-		if rs != s {
-			return rs
-		}
-	}
-
-	return s
-}
-
 func getAllFileNames(ctx *linter.Context) []string {
 	var ret []string
 	uniqFiles := map[string]bool{} // files are duplicated for test packages

pkg/lint/linter/config.go

@@ -22,6 +22,7 @@ type Config struct {
 
 	OriginalURL      string // URL of original (not forked) repo, needed for autogenerated README
 	ParentLinterName string // used only for megacheck's children now
+	CanAutoFix       bool
 }
 
 func (lc *Config) WithTypeInfo() *Config {
@@ -60,6 +61,11 @@ func (lc *Config) WithParent(parentLinterName string) *Config {
 	return lc
 }
 
+func (lc *Config) WithAutoFix() *Config {
+	lc.CanAutoFix = true
+	return lc
+}
+
 func (lc *Config) GetSpeed() int {
 	return lc.Speed
 }

pkg/lint/lintersdb/manager.go

@@ -169,10 +169,12 @@ func (Manager) GetAllSupportedLinterConfigs() []*linter.Config {
 		linter.NewConfig(golinters.Gofmt{}).
 			WithPresets(linter.PresetFormatting).
 			WithSpeed(7).
+			WithAutoFix().
 			WithURL("https://golang.org/cmd/gofmt/"),
 		linter.NewConfig(golinters.Gofmt{UseGoimports: true}).
 			WithPresets(linter.PresetFormatting).
 			WithSpeed(5).
+			WithAutoFix().
 			WithURL("https://godoc.org/golang.org/x/tools/cmd/goimports"),
 		linter.NewConfig(golinters.Maligned{}).
 			WithTypeInfo().
@@ -187,6 +189,7 @@ func (Manager) GetAllSupportedLinterConfigs() []*linter.Config {
 		linter.NewConfig(golinters.Misspell{}).
 			WithPresets(linter.PresetStyle).
 			WithSpeed(7).
+			WithAutoFix().
 			WithURL("https://github.com/client9/misspell"),
 		linter.NewConfig(golinters.Lll{}).
 			WithPresets(linter.PresetStyle).

pkg/lint/runner.go

@@ -66,16 +66,18 @@ func NewRunner(astCache *astcache.Cache, cfg *config.Config, log logutils.Log, g
 			skipDirsProcessor, // must be after path prettifier
 
 			processors.NewAutogeneratedExclude(astCache),
+			processors.NewIdentifierMarker(), // must be befor exclude
 			processors.NewExclude(excludeTotalPattern),
 			processors.NewExcludeRules(excludeRules),
 			processors.NewNolint(astCache, log.Child("nolint")),
 
 			processors.NewUniqByLine(),
 			processors.NewDiff(icfg.Diff, icfg.DiffFromRevision, icfg.DiffPatchFilePath),
-			processors.NewMaxPerFileFromLinter(),
+			processors.NewMaxPerFileFromLinter(cfg),
-			processors.NewMaxSameIssues(icfg.MaxSameIssues, log.Child("max_same_issues")),
+			processors.NewMaxSameIssues(icfg.MaxSameIssues, log.Child("max_same_issues"), cfg),
-			processors.NewMaxFromLinter(icfg.MaxIssuesPerLinter, log.Child("max_from_linter")),
+			processors.NewMaxFromLinter(icfg.MaxIssuesPerLinter, log.Child("max_from_linter"), cfg),
 			processors.NewSourceCode(log.Child("source_code")),
+			processors.NewReplacementBuilder(log.Child("replacement_builder")), // must be after source code
 			processors.NewPathShortener(),
 		},
 		Log: log,

pkg/result/issue.go

@@ -6,15 +6,26 @@ type Range struct {
 	From, To int
 }
 
+type Replacement struct {
+	NeedOnlyDelete bool     // need to delete all lines of the issue without replacement with new lines
+	NewLines       []string // is NeedDelete is false it's the replacement lines
+}
+
 type Issue struct {
 	FromLinter string
 	Text       string
 
 	Pos       token.Position
 	LineRange *Range `json:",omitempty"`
-	HunkPos   int    `json:",omitempty"`
 
+	// HunkPos is used only when golangci-lint is run over a diff
+	HunkPos int `json:",omitempty"`
+
+	// Source lines of a code with the issue to show
 	SourceLines []string
+
+	// If we know how to fix the issue we can provide replacement lines
+	Replacement *Replacement
 }
 
 func (i *Issue) FilePath() string {

pkg/result/processors/fixer.go

@@ -0,0 +1,149 @@
+package processors
+
+import (
+	"bytes"
+	"fmt"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"sort"
+	"strings"
+
+	"github.com/golangci/golangci-lint/pkg/logutils"
+
+	"github.com/pkg/errors"
+
+	"github.com/golangci/golangci-lint/pkg/config"
+	"github.com/golangci/golangci-lint/pkg/result"
+)
+
+type Fixer struct {
+	cfg *config.Config
+	log logutils.Log
+}
+
+func NewFixer(cfg *config.Config, log logutils.Log) *Fixer {
+	return &Fixer{cfg: cfg, log: log}
+}
+
+func (f Fixer) Process(issues <-chan result.Issue) <-chan result.Issue {
+	if !f.cfg.Issues.NeedFix {
+		return issues
+	}
+
+	outCh := make(chan result.Issue, 1024)
+
+	go func() {
+		issuesToFixPerFile := map[string][]result.Issue{}
+		for issue := range issues {
+			if issue.Replacement == nil {
+				outCh <- issue
+				continue
+			}
+
+			issuesToFixPerFile[issue.FilePath()] = append(issuesToFixPerFile[issue.FilePath()], issue)
+		}
+
+		for file, issuesToFix := range issuesToFixPerFile {
+			if err := f.fixIssuesInFile(file, issuesToFix); err != nil {
+				f.log.Errorf("Failed to fix issues in file %s: %s", file, err)
+
+				// show issues only if can't fix them
+				for _, issue := range issuesToFix {
+					outCh <- issue
+				}
+			}
+		}
+		close(outCh)
+	}()
+
+	return outCh
+}
+
+func (f Fixer) fixIssuesInFile(filePath string, issues []result.Issue) error {
+	// TODO: don't read the whole file into memory: read line by line;
+	// can't just use bufio.scanner: it has a line length limit
+	origFileData, err := ioutil.ReadFile(filePath)
+	if err != nil {
+		return errors.Wrapf(err, "failed to read %s", filePath)
+	}
+	origFileLines := bytes.Split(origFileData, []byte("\n"))
+
+	tmpFileName := filepath.Join(filepath.Dir(filePath), fmt.Sprintf(".%s.golangci_fix", filepath.Base(filePath)))
+	tmpOutFile, err := os.Create(tmpFileName)
+	if err != nil {
+		return errors.Wrapf(err, "failed to make file %s", tmpFileName)
+	}
+
+	issues = f.findNotIntersectingIssues(issues)
+
+	if err = f.writeFixedFile(origFileLines, issues, tmpOutFile); err != nil {
+		tmpOutFile.Close()
+		os.Remove(tmpOutFile.Name())
+		return err
+	}
+
+	tmpOutFile.Close()
+	if err = os.Rename(tmpOutFile.Name(), filePath); err != nil {
+		os.Remove(tmpOutFile.Name())
+		return errors.Wrapf(err, "failed to rename %s -> %s", tmpOutFile.Name(), filePath)
+	}
+
+	return nil
+}
+
+func (f Fixer) findNotIntersectingIssues(issues []result.Issue) []result.Issue {
+	sort.SliceStable(issues, func(i, j int) bool {
+		return issues[i].Line() < issues[j].Line() //nolint:scopelint
+	})
+
+	var ret []result.Issue
+	var currentEnd int
+	for _, issue := range issues {
+		rng := issue.GetLineRange()
+		if rng.From <= currentEnd {
+			f.log.Infof("Skip issue %#v: intersects with end %d", issue, currentEnd)
+			continue // skip intersecting issue
+		}
+		f.log.Infof("Fix issue %#v with range %v", issue, issue.GetLineRange())
+		ret = append(ret, issue)
+		currentEnd = rng.To
+	}
+
+	return ret
+}
+
+func (f Fixer) writeFixedFile(origFileLines [][]byte, issues []result.Issue, tmpOutFile *os.File) error {
+	// issues aren't intersecting
+
+	nextIssueIndex := 0
+	for i := 0; i < len(origFileLines); i++ {
+		var outLine string
+		var nextIssue *result.Issue
+		if nextIssueIndex != len(issues) {
+			nextIssue = &issues[nextIssueIndex]
+		}
+
+		origFileLineNumber := i + 1
+		if nextIssue == nil || origFileLineNumber != nextIssue.Line() {
+			outLine = string(origFileLines[i])
+		} else {
+			nextIssueIndex++
+			rng := nextIssue.GetLineRange()
+			i += rng.To - rng.From
+			if nextIssue.Replacement.NeedOnlyDelete {
+				continue
+			}
+			outLine = strings.Join(nextIssue.Replacement.NewLines, "\n")
+		}
+
+		if i < len(origFileLines)-1 {
+			outLine += "\n"
+		}
+		if _, err := tmpOutFile.WriteString(outLine); err != nil {
+			return errors.Wrap(err, "failed to write output line")
+		}
+	}
+
+	return nil
+}

pkg/result/processors/identifier_marker.go

@@ -0,0 +1,123 @@
+package processors
+
+import (
+	"regexp"
+
+	"github.com/golangci/golangci-lint/pkg/result"
+)
+
+type replacePattern struct {
+	re   string
+	repl string
+}
+
+type replaceRegexp struct {
+	re   *regexp.Regexp
+	repl string
+}
+
+var replacePatterns = []replacePattern{
+	// unparam
+	{`^(\S+) - (\S+) is unused$`, "`${1}` - `${2}` is unused"},
+	{`^(\S+) - (\S+) always receives (\S+) \((.*)\)$`, "`${1}` - `${2}` always receives `${3}` (`${4}`)"},
+	{`^(\S+) - (\S+) always receives (.*)$`, "`${1}` - `${2}` always receives `${3}`"},
+	{`^(\S+) - result (\S+) is always (\S+)`, "`${1}` - result `${2}` is always `${3}`"},
+
+	// interfacer
+	{`^(\S+) can be (\S+)$`, "`${1}` can be `${2}`"},
+
+	// govet
+	{`^(\S+) arg list ends with redundant newline$`, "`${1}` arg list ends with redundant newline"},
+	{`^(\S+) composite literal uses unkeyed fields$`, "`${1}` composite literal uses unkeyed fields"},
+
+	// gosec
+	{`^(\S+): Blacklisted import (\S+): weak cryptographic primitive$`,
+		"${1}: Blacklisted import `${2}`: weak cryptographic primitive"},
+	{`^TLS InsecureSkipVerify set true.$`, "TLS `InsecureSkipVerify` set true."},
+
+	// gosimple
+	{`^should replace loop with (.*)$`, "should replace loop with `${1}`"},
+	{`^should use a simple channel send/receive instead of select with a single case`,
+		"should use a simple channel send/receive instead of `select` with a single case"},
+	{`^should omit comparison to bool constant, can be simplified to (.+)$`,
+		"should omit comparison to bool constant, can be simplified to `${1}`"},
+	{`^should write (.+) instead of (.+)$`, "should write `${1}` instead of `${2}`"},
+	{`^redundant return statement$`, "redundant `return` statement"},
+
+	// staticcheck
+	{`^this value of (\S+) is never used$`, "this value of `${1}` is never used"},
+	{`^should use time.Since instead of time.Now\(\).Sub$`,
+		"should use `time.Since` instead of `time.Now().Sub`"},
+	{`^should check returned error before deferring response.Close\(\)$`,
+		"should check returned error before deferring `response.Close()`"},
+	{`^no value of type uint is less than 0$`, "no value of type `uint` is less than `0`"},
+
+	// unused
+	{`^(func|const|field|type|var) (\S+) is unused$`, "${1} `${2}` is unused"},
+
+	// typecheck
+	{`^unknown field (\S+) in struct literal$`, "unknown field `${1}` in struct literal"},
+	{`^invalid operation: (\S+) \(variable of type (\S+)\) has no field or method (\S+)$`,
+		"invalid operation: `${1}` (variable of type `${2}`) has no field or method `${3}`"},
+	{`^undeclared name: (\S+)$`, "undeclared name: `${1}`"},
+	{`^cannot use addr \(variable of type (\S+)\) as (\S+) value in argument to (\S+)$`,
+		"cannot use addr (variable of type `${1}`) as `${2}` value in argument to `${3}`"},
+	{`^other declaration of (\S+)$`, "other declaration of `${1}`"},
+	{`^(\S+) redeclared in this block$`, "`${1}` redeclared in this block"},
+
+	// golint
+	{`^exported (type|method|function|var|const) (\S+) should have comment or be unexported$`,
+		"exported ${1} `${2}` should have comment or be unexported"},
+	{`^comment on exported (type|method|function|var|const) (\S+) should be of the form "(\S+) ..."$`,
+		"comment on exported ${1} `${2}` should be of the form `${3} ...`"},
+	{`^should replace (.+) with (.+)$`, "should replace `${1}` with `${2}`"},
+	{`^if block ends with a return statement, so drop this else and outdent its block$`,
+		"`if` block ends with a `return` statement, so drop this `else` and outdent its block"},
+	{`^(struct field|var|range var|const|type|(?:func|method|interface method) (?:parameter|result)) (\S+) should be (\S+)$`,
+		"${1} `${2}` should be `${3}`"},
+	{`^don't use underscores in Go names; var (\S+) should be (\S+)$`,
+		"don't use underscores in Go names; var `${1}` should be `${2}`"},
+}
+
+type IdentifierMarker struct {
+	replaceRegexps []replaceRegexp
+}
+
+func NewIdentifierMarker() *IdentifierMarker {
+	var replaceRegexps []replaceRegexp
+	for _, p := range replacePatterns {
+		r := replaceRegexp{
+			re:   regexp.MustCompile(p.re),
+			repl: p.repl,
+		}
+		replaceRegexps = append(replaceRegexps, r)
+	}
+
+	return &IdentifierMarker{
+		replaceRegexps: replaceRegexps,
+	}
+}
+
+func (im IdentifierMarker) Process(issues []result.Issue) ([]result.Issue, error) {
+	return transformIssues(issues, func(i *result.Issue) *result.Issue {
+		iCopy := *i
+		iCopy.Text = im.markIdentifiers(iCopy.Text)
+		return &iCopy
+	}), nil
+}
+
+func (im IdentifierMarker) markIdentifiers(s string) string {
+	for _, rr := range im.replaceRegexps {
+		rs := rr.re.ReplaceAllString(s, rr.repl)
+		if rs != s {
+			return rs
+		}
+	}
+
+	return s
+}
+
+func (im IdentifierMarker) Name() string {
+	return "identifier_marker"
+}
+func (im IdentifierMarker) Finish() {}

pkg/result/processors/identifier_marker_test.go

@@ -0,0 +1,54 @@
+package processors
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+
+	"github.com/golangci/golangci-lint/pkg/result"
+)
+
+func TestIdentifierMarker(t *testing.T) {
+	//nolint:lll
+	cases := []struct{ in, out string }{
+		{"unknown field Address in struct literal", "unknown field `Address` in struct literal"},
+		{"invalid operation: res (variable of type github.com/iotexproject/iotex-core/explorer/idl/explorer.GetBlkOrActResponse) has no field or method Address",
+			"invalid operation: `res` (variable of type `github.com/iotexproject/iotex-core/explorer/idl/explorer.GetBlkOrActResponse`) has no field or method `Address`"},
+		{"should use a simple channel send/receive instead of select with a single case",
+			"should use a simple channel send/receive instead of `select` with a single case"},
+		{"var testInputs is unused", "var `testInputs` is unused"},
+		{"undeclared name: stateIDLabel", "undeclared name: `stateIDLabel`"},
+		{"exported type Metrics should have comment or be unexported",
+			"exported type `Metrics` should have comment or be unexported"},
+		{`comment on exported function NewMetrics should be of the form "NewMetrics ..."`,
+			"comment on exported function `NewMetrics` should be of the form `NewMetrics ...`"},
+		{"cannot use addr (variable of type string) as github.com/iotexproject/iotex-core/pkg/keypair.PublicKey value in argument to action.FakeSeal",
+			"cannot use addr (variable of type `string`) as `github.com/iotexproject/iotex-core/pkg/keypair.PublicKey` value in argument to `action.FakeSeal`"},
+		{"other declaration of out", "other declaration of `out`"},
+		{"should check returned error before deferring response.Close()", "should check returned error before deferring `response.Close()`"},
+		{"should use time.Since instead of time.Now().Sub", "should use `time.Since` instead of `time.Now().Sub`"},
+		{"TestFibZeroCount redeclared in this block", "`TestFibZeroCount` redeclared in this block"},
+		{"should replace i += 1 with i++", "should replace `i += 1` with `i++`"},
+		{"createEntry - result err is always nil", "`createEntry` - result `err` is always `nil`"},
+		{"should omit comparison to bool constant, can be simplified to !projectIntegration.Model.Storage",
+			"should omit comparison to bool constant, can be simplified to `!projectIntegration.Model.Storage`"},
+		{"if block ends with a return statement, so drop this else and outdent its block",
+			"`if` block ends with a `return` statement, so drop this `else` and outdent its block"},
+		{"should write pupData := ms.m[pupID] instead of pupData, _ := ms.m[pupID]",
+			"should write `pupData := ms.m[pupID]` instead of `pupData, _ := ms.m[pupID]`"},
+		{"no value of type uint is less than 0", "no value of type `uint` is less than `0`"},
+		{"redundant return statement", "redundant `return` statement"},
+		{"struct field Id should be ID", "struct field `Id` should be `ID`"},
+		{"don't use underscores in Go names; var Go_lint should be GoLint",
+			"don't use underscores in Go names; var `Go_lint` should be `GoLint`"},
+		{"G501: Blacklisted import crypto/md5: weak cryptographic primitive",
+			"G501: Blacklisted import `crypto/md5`: weak cryptographic primitive"},
+	}
+	p := NewIdentifierMarker()
+
+	for _, c := range cases {
+		out, err := p.Process([]result.Issue{{Text: c.in}})
+		assert.NoError(t, err)
+		assert.Equal(t, []result.Issue{{Text: c.out}}, out)
+	}
+}

pkg/result/processors/max_from_linter.go

@@ -1,6 +1,7 @@
 package processors
 
 import (
+	"github.com/golangci/golangci-lint/pkg/config"
 	"github.com/golangci/golangci-lint/pkg/logutils"
 	"github.com/golangci/golangci-lint/pkg/result"
 )
@@ -9,15 +10,17 @@ type MaxFromLinter struct {
 	lc    linterToCountMap
 	limit int
 	log   logutils.Log
+	cfg   *config.Config
 }
 
 var _ Processor = &MaxFromLinter{}
 
-func NewMaxFromLinter(limit int, log logutils.Log) *MaxFromLinter {
+func NewMaxFromLinter(limit int, log logutils.Log, cfg *config.Config) *MaxFromLinter {
 	return &MaxFromLinter{
 		lc:    linterToCountMap{},
 		limit: limit,
 		log:   log,
+		cfg:   cfg,
 	}
 }
 
@@ -30,6 +33,11 @@ func (p *MaxFromLinter) Process(issues []result.Issue) ([]result.Issue, error) {
 		return issues, nil
 	}
 
+	if p.cfg.Issues.NeedFix {
+		// we need to fix all issues at once => we need to return all of them
+		return issues, nil
+	}
+
 	return filterIssues(issues, func(i *result.Issue) bool {
 		p.lc[i.FromLinter]++ // always inc for stat
 		return p.lc[i.FromLinter] <= p.limit

pkg/result/processors/max_from_linter_test.go

@@ -3,11 +3,13 @@ package processors
 import (
 	"testing"
 
+	"github.com/golangci/golangci-lint/pkg/config"
+
 	"github.com/golangci/golangci-lint/pkg/logutils"
 )
 
 func TestMaxFromLinter(t *testing.T) {
-	p := NewMaxFromLinter(1, logutils.NewStderrLog(""))
+	p := NewMaxFromLinter(1, logutils.NewStderrLog(""), &config.Config{})
 	gosimple := newFromLinterIssue("gosimple")
 	gofmt := newFromLinterIssue("gofmt")
 	processAssertSame(t, p, gosimple)  // ok

pkg/result/processors/max_per_file_from_linter.go

@@ -1,6 +1,7 @@
 package processors
 
 import (
+	"github.com/golangci/golangci-lint/pkg/config"
 	"github.com/golangci/golangci-lint/pkg/result"
 )
 
@@ -8,14 +9,26 @@ type linterToCountMap map[string]int
 type fileToLinterToCountMap map[string]linterToCountMap
 
 type MaxPerFileFromLinter struct {
-	flc fileToLinterToCountMap
+	flc                        fileToLinterToCountMap
+	maxPerFileFromLinterConfig map[string]int
 }
 
 var _ Processor = &MaxPerFileFromLinter{}
 
-func NewMaxPerFileFromLinter() *MaxPerFileFromLinter {
+func NewMaxPerFileFromLinter(cfg *config.Config) *MaxPerFileFromLinter {
+	maxPerFileFromLinterConfig := map[string]int{
+		"typecheck": 3,
+	}
+	if !cfg.Issues.NeedFix {
+		// if we don't fix we do this limiting to not annoy user;
+		// otherwise we need to fix all issues in the file at once
+		maxPerFileFromLinterConfig["gofmt"] = 1
+		maxPerFileFromLinterConfig["goimports"] = 1
+	}
+
 	return &MaxPerFileFromLinter{
-		flc: fileToLinterToCountMap{},
+		flc:                        fileToLinterToCountMap{}, //nolint:goimports,gofmt
+		maxPerFileFromLinterConfig: maxPerFileFromLinterConfig,
 	}
 }
 
@@ -23,15 +36,9 @@ func (p MaxPerFileFromLinter) Name() string {
 	return "max_per_file_from_linter"
 }
 
-var maxPerFileFromLinterConfig = map[string]int{
-	"gofmt":     1,
-	"goimports": 1,
-	"typecheck": 3,
-}
-
 func (p *MaxPerFileFromLinter) Process(issues []result.Issue) ([]result.Issue, error) {
 	return filterIssues(issues, func(i *result.Issue) bool {
-		limit := maxPerFileFromLinterConfig[i.FromLinter]
+		limit := p.maxPerFileFromLinterConfig[i.FromLinter]
 		if limit == 0 {
 			return true
 		}

pkg/result/processors/max_per_file_from_linter_test.go

@@ -3,6 +3,7 @@ package processors
 import (
 	"testing"
 
+	"github.com/golangci/golangci-lint/pkg/config"
 	"github.com/golangci/golangci-lint/pkg/result"
 )
 
@@ -13,14 +14,14 @@ func newFromLinterIssue(linterName string) result.Issue {
 }
 
 func TestMaxPerFileFromLinterUnlimited(t *testing.T) {
-	p := NewMaxPerFileFromLinter()
+	p := NewMaxPerFileFromLinter(&config.Config{})
 	gosimple := newFromLinterIssue("gosimple")
 	processAssertSame(t, p, gosimple) // collect stat
 	processAssertSame(t, p, gosimple) // check not limits
 }
 
 func TestMaxPerFileFromLinter(t *testing.T) {
-	p := NewMaxPerFileFromLinter()
+	p := NewMaxPerFileFromLinter(&config.Config{})
 	for _, name := range []string{"gofmt", "goimports"} {
 		limited := newFromLinterIssue(name)
 		gosimple := newFromLinterIssue("gosimple")

pkg/result/processors/max_same_issues.go

@@ -3,6 +3,8 @@ package processors
 import (
 	"sort"
 
+	"github.com/golangci/golangci-lint/pkg/config"
+
 	"github.com/golangci/golangci-lint/pkg/logutils"
 	"github.com/golangci/golangci-lint/pkg/result"
 )
@@ -13,15 +15,17 @@ type MaxSameIssues struct {
 	tc    textToCountMap
 	limit int
 	log   logutils.Log
+	cfg   *config.Config
 }
 
 var _ Processor = &MaxSameIssues{}
 
-func NewMaxSameIssues(limit int, log logutils.Log) *MaxSameIssues {
+func NewMaxSameIssues(limit int, log logutils.Log, cfg *config.Config) *MaxSameIssues {
 	return &MaxSameIssues{
 		tc:    textToCountMap{},
 		limit: limit,
 		log:   log,
+		cfg:   cfg,
 	}
 }
 
@@ -34,6 +38,11 @@ func (p *MaxSameIssues) Process(issues []result.Issue) ([]result.Issue, error) {
 		return issues, nil
 	}
 
+	if p.cfg.Issues.NeedFix {
+		// we need to fix all issues at once => we need to return all of them
+		return issues, nil
+	}
+
 	return filterIssues(issues, func(i *result.Issue) bool {
 		p.tc[i.Text]++ // always inc for stat
 		return p.tc[i.Text] <= p.limit

pkg/result/processors/max_same_issues_test.go

@@ -3,12 +3,13 @@ package processors
 import (
 	"testing"
 
+	"github.com/golangci/golangci-lint/pkg/config"
 	"github.com/golangci/golangci-lint/pkg/logutils"
 	"github.com/golangci/golangci-lint/pkg/result"
 )
 
 func TestMaxSameIssues(t *testing.T) {
-	p := NewMaxSameIssues(1, logutils.NewStderrLog(""))
+	p := NewMaxSameIssues(1, logutils.NewStderrLog(""), &config.Config{})
 	i1 := result.Issue{
 		Text: "1",
 	}

pkg/result/processors/replacement_builder.go

@@ -0,0 +1,92 @@
+package processors
+
+import (
+	"fmt"
+	"regexp"
+	"strings"
+
+	"github.com/golangci/golangci-lint/pkg/golinters"
+	"github.com/golangci/golangci-lint/pkg/logutils"
+
+	"github.com/golangci/golangci-lint/pkg/result"
+)
+
+type ReplacementBuilder struct {
+	log logutils.Log
+}
+
+func NewReplacementBuilder(log logutils.Log) *ReplacementBuilder {
+	return &ReplacementBuilder{log: log}
+}
+
+func (p ReplacementBuilder) Process(issues []result.Issue) ([]result.Issue, error) {
+	return transformIssues(issues, p.processIssue), nil
+}
+
+func (p ReplacementBuilder) processIssue(i *result.Issue) *result.Issue {
+	misspellName := golinters.Misspell{}.Name()
+	if i.FromLinter == misspellName {
+		newIssue, err := p.processMisspellIssue(i)
+		if err != nil {
+			p.log.Warnf("Failed to build replacement for misspell issue: %s", err)
+			return i
+		}
+		return newIssue
+	}
+
+	return i
+}
+
+func (p ReplacementBuilder) processMisspellIssue(i *result.Issue) (*result.Issue, error) {
+	if len(i.SourceLines) != 1 {
+		return nil, fmt.Errorf("invalid count of source lines: %d", len(i.SourceLines))
+	}
+	sourceLine := i.SourceLines[0]
+
+	if i.Column() <= 0 {
+		return nil, fmt.Errorf("invalid column %d", i.Column())
+	}
+	col0 := i.Column() - 1
+	if col0 >= len(sourceLine) {
+		return nil, fmt.Errorf("too big column %d", i.Column())
+	}
+
+	issueTextRE := regexp.MustCompile("`(.+)` is a misspelling of `(.+)`")
+	submatches := issueTextRE.FindStringSubmatch(i.Text)
+	if len(submatches) != 3 {
+		return nil, fmt.Errorf("invalid count of submatches %d", len(submatches))
+	}
+
+	from, to := submatches[1], submatches[2]
+	if !strings.HasPrefix(sourceLine[col0:], from) {
+		return nil, fmt.Errorf("invalid prefix of source line `%s`", sourceLine)
+	}
+
+	newSourceLine := ""
+	if col0 != 0 {
+		newSourceLine += sourceLine[:col0]
+	}
+
+	newSourceLine += to
+
+	sourceLineFromEnd := col0 + len(from)
+	if sourceLineFromEnd < len(sourceLine) {
+		newSourceLine += sourceLine[sourceLineFromEnd:]
+	}
+
+	if i.Replacement != nil {
+		return nil, fmt.Errorf("issue replacement isn't nil")
+	}
+
+	iCopy := *i
+	iCopy.Replacement = &result.Replacement{
+		NewLines: []string{newSourceLine},
+	}
+	return &iCopy, nil
+}
+
+func (p ReplacementBuilder) Name() string {
+	return "replacement_builder"
+}
+
+func (p ReplacementBuilder) Finish() {}

test/.gitignore

@@ -0,0 +1 @@
+/testdata/fix.tmp/

test/fix_test.go

@@ -0,0 +1,59 @@
+package test
+
+import (
+	"io/ioutil"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"testing"
+
+	assert "github.com/stretchr/testify/require"
+	yaml "gopkg.in/yaml.v2"
+
+	"github.com/golangci/golangci-lint/test/testshared"
+)
+
+func TestFix(t *testing.T) {
+	findSources := func(pathPatterns ...string) []string {
+		sources, err := filepath.Glob(filepath.Join(pathPatterns...))
+		assert.NoError(t, err)
+		assert.NotEmpty(t, sources)
+		return sources
+	}
+
+	tmpDir := filepath.Join(testdataDir, "fix.tmp")
+	os.RemoveAll(tmpDir) // cleanup after previous runs
+
+	if os.Getenv("GL_KEEP_TEMP_FILES") != "1" {
+		defer os.RemoveAll(tmpDir)
+	}
+
+	err := exec.Command("cp", "-R", filepath.Join(testdataDir, "fix"), tmpDir).Run()
+	assert.NoError(t, err)
+
+	inputs := findSources(tmpDir, "in", "*.go")
+	for _, input := range inputs {
+		input := input
+		t.Run(filepath.Base(input), func(t *testing.T) {
+			args := []string{
+				"--disable-all", "--print-issued-lines=false", "--print-linter-name=false", "--out-format=line-number",
+				"--fix",
+				input,
+			}
+			rc := extractRunContextFromComments(t, input)
+			args = append(args, rc.args...)
+
+			cfg, err := yaml.Marshal(rc.config)
+			assert.NoError(t, err)
+
+			testshared.NewLintRunner(t).RunWithYamlConfig(string(cfg), args...)
+			output, err := ioutil.ReadFile(input)
+			assert.NoError(t, err)
+
+			expectedOutput, err := ioutil.ReadFile(filepath.Join(testdataDir, "fix", "out", filepath.Base(input)))
+			assert.NoError(t, err)
+
+			assert.Equal(t, string(expectedOutput), string(output))
+		})
+	}
+}

test/linters_test.go

@@ -214,7 +214,7 @@ func TestExtractRunContextFromComments(t *testing.T) {
 
 func TestGolintConsumesXTestFiles(t *testing.T) {
 	dir := getTestDataDir("withxtest")
-	const expIssue = "if block ends with a return statement, so drop this else and outdent its block"
+	const expIssue = "`if` block ends with a `return` statement, so drop this `else` and outdent its block"
 
 	r := testshared.NewLintRunner(t)
 	r.Run("--no-config", "--disable-all", "-Egolint", dir).ExpectHasIssue(expIssue)

test/run_test.go

@@ -47,7 +47,7 @@ func TestDeadline(t *testing.T) {
 
 func TestTestsAreLintedByDefault(t *testing.T) {
 	testshared.NewLintRunner(t).Run(getTestDataDir("withtests")).
-		ExpectHasIssue("if block ends with a return")
+		ExpectHasIssue("`if` block ends with a `return`")
 }
 
 func TestCgoOk(t *testing.T) {
@@ -68,8 +68,8 @@ func TestSkippedDirsNoMatchArg(t *testing.T) {
 	r := testshared.NewLintRunner(t).Run("--print-issued-lines=false", "--no-config", "--skip-dirs", dir, "-Egolint", dir)
 
 	r.ExpectExitCode(exitcodes.IssuesFound).
-		ExpectOutputEq("testdata/skipdirs/skip_me/nested/with_issue.go:8:9: if block ends with " +
+		ExpectOutputEq("testdata/skipdirs/skip_me/nested/with_issue.go:8:9: `if` block ends with " +
-			"a return statement, so drop this else and outdent its block (golint)\n")
+			"a `return` statement, so drop this `else` and outdent its block (golint)\n")
 }
 
 func TestSkippedDirsTestdata(t *testing.T) {
@@ -114,7 +114,7 @@ func TestAbsPathDirAnalysis(t *testing.T) {
 	assert.NoError(t, err)
 
 	r := testshared.NewLintRunner(t).Run("--print-issued-lines=false", "--no-config", "-Egolint", absDir)
-	r.ExpectHasIssue("if block ends with a return statement")
+	r.ExpectHasIssue("`if` block ends with a `return` statement")
 }
 
 func TestAbsPathFileAnalysis(t *testing.T) {
@@ -123,7 +123,7 @@ func TestAbsPathFileAnalysis(t *testing.T) {
 	assert.NoError(t, err)
 
 	r := testshared.NewLintRunner(t).Run("--print-issued-lines=false", "--no-config", "-Egolint", absDir)
-	r.ExpectHasIssue("if block ends with a return statement")
+	r.ExpectHasIssue("`if` block ends with a `return` statement")
 }
 
 func TestDisallowedOptionsInConfig(t *testing.T) {

test/testdata/fix/in/gofmt.go

@@ -0,0 +1,9 @@
+//args: -Egofmt
+package p
+
+ func gofmt(a, b int) int {
+ 	if a != b {
+ 		return 1 
+	}
+ 	return 2
+}

test/testdata/fix/in/goimports.go

@@ -0,0 +1,14 @@
+//args: -Egofmt,goimports
+package p
+
+import (
+    "os"
+    "fmt"
+)
+
+ func goimports(a, b int) int {
+ 	if a != b {
+ 		return 1 
+	}
+ 	return 2
+}

test/testdata/fix/in/misspell.go

@@ -0,0 +1,11 @@
+//args: -Emisspell
+package p
+
+// langauge lala
+// lala langauge
+// langauge
+// langauge langauge
+
+func langaugeMisspell() { // the function detects langauge of the text
+
+}

test/testdata/fix/out/gofmt.go

@@ -0,0 +1,9 @@
+//args: -Egofmt
+package p
+
+func gofmt(a, b int) int {
+	if a != b {
+		return 1
+	}
+	return 2
+}

test/testdata/fix/out/goimports.go

@@ -0,0 +1,9 @@
+//args: -Egofmt,goimports
+package p
+
+func goimports(a, b int) int {
+	if a != b {
+		return 1
+	}
+	return 2
+}

test/testdata/fix/out/misspell.go

@@ -0,0 +1,11 @@
+//args: -Emisspell
+package p
+
+// language lala
+// lala language
+// language
+// language langauge
+
+func langaugeMisspell() { // the function detects language of the text
+
+}

test/testdata/golint.go

@@ -1,7 +1,7 @@
 //args: -Egolint
 package testdata
 
-var Go_lint string // ERROR "don't use underscores in Go names; var Go_lint should be GoLint"
+var Go_lint string // ERROR "don't use underscores in Go names; var `Go_lint` should be `GoLint`"
 
 func ExportedFuncWithNoComment() {
 }

test/testdata/notcompiles/typecheck_many_issues.go

@@ -2,8 +2,8 @@
 package testdata
 
 func TypeCheckBadCalls() {
-	typecheckNotExists1.F1() // ERROR "undeclared name: typecheckNotExists1"
+	typecheckNotExists1.F1() // ERROR "undeclared name: `typecheckNotExists1`"
-	typecheckNotExists2.F2() // ERROR "undeclared name: typecheckNotExists2"
+	typecheckNotExists2.F2() // ERROR "undeclared name: `typecheckNotExists2`"
-	typecheckNotExists3.F3() // ERROR "undeclared name: typecheckNotExists3"
+	typecheckNotExists3.F3() // ERROR "undeclared name: `typecheckNotExists3`"
 	typecheckNotExists4.F4()
 }

test/testshared/testshared.go

@@ -22,9 +22,11 @@ type LintRunner struct {
 }
 
 func NewLintRunner(t assert.TestingT) *LintRunner {
+	log := logutils.NewStderrLog("test")
+	log.SetLevel(logutils.LogLevelInfo)
 	return &LintRunner{
 		t:   t,
-		log: logutils.NewStderrLog("test"),
+		log: log,
 	}
 }
 
@@ -67,7 +69,7 @@ func (r *RunResult) ExpectOutputContains(s string) *RunResult {
 }
 
 func (r *RunResult) ExpectOutputEq(s string) *RunResult {
-	assert.Equal(r.t, r.output, s, "exit code is %d", r.exitCode)
+	assert.Equal(r.t, s, r.output, "exit code is %d", r.exitCode)
 	return r
 }