Add funlen linter (#603)

Author: NiseVoid

.golangci.example.yml

@@ -78,6 +78,11 @@ linters-settings:
     # path to a file containing a list of functions to exclude from checking
     # see https://github.com/kisielk/errcheck#excluding-functions for details
     exclude: /path/to/file.txt
+
+  funlen:
+    lines: 60
+    statements: 40
+
   govet:
     # report about shadowed variables
     check-shadowing: true

.golangci.yml

@@ -46,6 +46,7 @@ linters:
     - maligned
     - prealloc
     - gochecknoglobals
+    - funlen
 
 run:
   skip-dirs:

README.md

@@ -208,6 +208,7 @@ Disabled by default linters:
 bodyclose: checks whether HTTP response body is closed successfully [fast: false, auto-fix: false]
 depguard: Go linter that checks if package imports are in a list of acceptable packages [fast: true, auto-fix: false]
 dupl: Tool for code clone detection [fast: true, auto-fix: false]
+funlen: Tool for detection of long functions [fast: true, auto-fix: false]
 gochecknoglobals: Checks that no globals are present in Go code [fast: true, auto-fix: false]
 gochecknoinits: Checks that no init functions are present in Go code [fast: true, auto-fix: false]
 goconst: Finds repeated strings that could be replaced by a constant [fast: true, auto-fix: false]
@@ -440,6 +441,7 @@ golangci-lint help linters
 - [gocritic](https://github.com/go-critic/go-critic) - The most opinionated Go source code linter
 - [gochecknoinits](https://github.com/leighmcculloch/gochecknoinits) - Checks that no init functions are present in Go code
 - [gochecknoglobals](https://github.com/leighmcculloch/gochecknoglobals) - Checks that no globals are present in Go code
+- [funlen](https://github.com/ultraware/funlen) - Tool for detection of long functions
 
 ## Configuration
 
@@ -629,6 +631,11 @@ linters-settings:
     # path to a file containing a list of functions to exclude from checking
     # see https://github.com/kisielk/errcheck#excluding-functions for details
     exclude: /path/to/file.txt
+
+  funlen:
+    lines: 60
+    statements: 40
+
   govet:
     # report about shadowed variables
     check-shadowing: true
@@ -859,6 +866,7 @@ linters:
     - maligned
     - prealloc
     - gochecknoglobals
+    - funlen
 
 run:
   skip-dirs:
@@ -999,6 +1007,7 @@ Thanks to developers and authors of used linters:
 - [kyoh86](https://github.com/kyoh86)
 - [go-critic](https://github.com/go-critic)
 - [leighmcculloch](https://github.com/leighmcculloch)
+- [ultraware](https://github.com/ultraware)
 
 ## Changelog
 

go.mod

@@ -49,6 +49,7 @@ require (
 	github.com/spf13/pflag v1.0.1
 	github.com/spf13/viper v1.0.2
 	github.com/stretchr/testify v1.2.2
+	github.com/ultraware/funlen v0.0.1
 	github.com/timakin/bodyclose v0.0.0-00010101000000-87058b9bfcec
 	github.com/valyala/quicktemplate v1.1.1
 	golang.org/x/crypto v0.0.0-20190313024323-a1f597ede03a // indirect

go.sum

@@ -164,6 +164,8 @@ github.com/spf13/viper v1.0.2 h1:Ncr3ZIuJn322w2k1qmzXDnkLAdQMlJqBa9kfAH+irso=
 github.com/spf13/viper v1.0.2/go.mod h1:A8kyI5cUJhb8N+3pkfONlcEcZbueH6nhAm0Fq7SrnBM=
 github.com/stretchr/testify v1.2.2 h1:bSDNvY7ZPG5RlJ8otE/7V6gMiyenm9RtJ7IUVIAoJ1w=
 github.com/stretchr/testify v1.2.2/go.mod h1:a8OnRcib4nhh0OaRAV+Yts87kKdq0PP7pXfy6kDkUVs=
+github.com/ultraware/funlen v0.0.1 h1:UeC9tpM4wNWzUJfan8z9sFE4QCzjjzlCZmuJN+aOkH0=
+github.com/ultraware/funlen v0.0.1/go.mod h1:Dp4UiAus7Wdb9KUZsYWZEWiRzGuM2kXM1lPbfaF6xhA=
 github.com/timakin/bodyclose v0.0.0-00010101000000-87058b9bfcec h1:Ha5Eixh5Dgi14hDFFWsxoB/jR95rHjB1biKdK9VKkbQ=
 github.com/timakin/bodyclose v0.0.0-00010101000000-87058b9bfcec/go.mod h1:Qimiffbc6q9tBWlVV6x0P9sat/ao1xEkREYPPj9hphk=
 github.com/valyala/bytebufferpool v1.0.0 h1:GqA5TC/0021Y/b9FG4Oi9Mr3q7XYx6KllzawFIhcdPw=

pkg/config/config.go

@@ -164,6 +164,10 @@ type LintersSettings struct {
 	Unused struct {
 		CheckExported bool `mapstructure:"check-exported"`
 	}
+	Funlen struct {
+		Lines      int
+		Statements int
+	}
 
 	Lll      LllSettings
 	Unparam  UnparamSettings

pkg/golinters/funlen.go

@@ -0,0 +1,46 @@
+package golinters
+
+import (
+	"context"
+	"go/token"
+
+	"github.com/golangci/golangci-lint/pkg/lint/linter"
+	"github.com/golangci/golangci-lint/pkg/result"
+
+	"github.com/ultraware/funlen"
+)
+
+type Funlen struct{}
+
+func (Funlen) Name() string {
+	return "funlen"
+}
+
+func (Funlen) Desc() string {
+	return "Tool for detection of long functions"
+}
+
+func (f Funlen) Run(ctx context.Context, lintCtx *linter.Context) ([]result.Issue, error) {
+	var issues []funlen.Message
+	for _, file := range lintCtx.ASTCache.GetAllValidFiles() {
+		issues = append(issues, funlen.Run(file.F, file.Fset, lintCtx.Settings().Funlen.Lines, lintCtx.Settings().Funlen.Statements)...)
+	}
+
+	if len(issues) == 0 {
+		return nil, nil
+	}
+
+	res := make([]result.Issue, len(issues))
+	for k, i := range issues {
+		res[k] = result.Issue{
+			Pos: token.Position{
+				Filename: i.Pos.Filename,
+				Line:     i.Pos.Line,
+			},
+			Text:       i.Message,
+			FromLinter: f.Name(),
+		}
+	}
+
+	return res, nil
+}

pkg/lint/lintersdb/manager.go

@@ -237,6 +237,10 @@ func (m Manager) GetAllSupportedLinterConfigs() []*linter.Config {
 			WithPresets(linter.PresetStyle).
 			WithSpeed(10).
 			WithURL("https://github.com/leighmcculloch/gochecknoglobals"),
+		linter.NewConfig(golinters.Funlen{}).
+			WithPresets(linter.PresetStyle).
+			WithSpeed(10).
+			WithURL("https://github.com/ultraware/funlen"),
 	}
 
 	isLocalRun := os.Getenv("GOLANGCI_COM_RUN") == ""

test/testdata/funlen.go

@@ -0,0 +1,43 @@
+//args: -Efunlen
+//config: linters-settings.funlen.lines=20
+//config: linters-settings.funlen.statements=10
+package testdata
+
+func TooManyLines() { // ERROR "Function 'TooManyLines' is too long \(22 > 20\)"
+	t := struct {
+		A string
+		B string
+		C string
+		D string
+		E string
+		F string
+		G string
+		H string
+		I string
+	}{
+		`a`,
+		`b`,
+		`c`,
+		`d`,
+		`e`,
+		`f`,
+		`g`,
+		`h`,
+		`i`,
+	}
+	_ = t
+}
+
+func TooManyStatements() { // ERROR "Function 'TooManyStatements' has too many statements \(11 > 10\)"
+	a := 1
+	b := a
+	c := b
+	d := c
+	e := d
+	f := e
+	g := f
+	h := g
+	i := h
+	j := i
+	_ = j
+}