add varnamelen linter (#2240)

.golangci.example.yml

@@ -645,6 +645,21 @@ linters-settings:
     # Select the Go version to target. The default is '1.13'.
     go: "1.15"
 
+  varnamelen:
+    # The longest distance, in source lines, that is being considered a "small scope." (defaults to 5)
+    # Variables used in at most this many lines will be ignored.
+    max-distance: 5
+    # The minimum length of a variable's name that is considered "long." (defaults to 3)
+    # Variable names that are at least this long will be ignored.
+    min-name-length: 3
+    # Check method receiver names. (defaults to false)
+    check-receiver: false
+    # Check named return values. (defaults to false)
+    check-return: false
+    # Optional list of variable names that should be ignored completely. (defaults to empty list)
+    ignore-names:
+      - err
+
   whitespace:
     multi-if: false   # Enforces newlines (or comments) after every multi-line if statement
     multi-func: false # Enforces newlines (or comments) after every multi-line function signature

go.mod

@@ -13,6 +13,7 @@ require (
 	github.com/ashanbrown/forbidigo v1.2.0
 	github.com/ashanbrown/makezero v0.0.0-20210520155254-b6261585ddde
 	github.com/bkielbasa/cyclop v1.2.0
+	github.com/blizzy78/varnamelen v0.3.0
 	github.com/bombsimon/wsl/v3 v3.3.0
 	github.com/butuzov/ireturn v0.1.1
 	github.com/charithe/durationcheck v0.0.9

pkg/config/linters_settings.go

@@ -136,6 +136,7 @@ type LintersSettings struct {
 	Unparam          UnparamSettings
 	Unused           StaticCheckSettings
 	Varcheck         VarCheckSettings
+	Varnamelen       VarnamelenSettings
 	Whitespace       WhitespaceSettings
 	Wrapcheck        WrapcheckSettings
 	WSL              WSLSettings
@@ -478,6 +479,14 @@ type VarCheckSettings struct {
 	CheckExportedFields bool `mapstructure:"exported-fields"`
 }
 
+type VarnamelenSettings struct {
+	MaxDistance   int      `mapstructure:"max-distance"`
+	MinNameLength int      `mapstructure:"min-name-length"`
+	CheckReceiver bool     `mapstructure:"check-receiver"`
+	CheckReturn   bool     `mapstructure:"check-return"`
+	IgnoreNames   []string `mapstructure:"ignore-names"`
+}
+
 type WhitespaceSettings struct {
 	MultiIf   bool `mapstructure:"multi-if"`
 	MultiFunc bool `mapstructure:"multi-func"`

pkg/golinters/varnamelen.go

@@ -0,0 +1,41 @@
+package golinters
+
+import (
+	"strconv"
+	"strings"
+
+	"github.com/blizzy78/varnamelen"
+	"golang.org/x/tools/go/analysis"
+
+	"github.com/golangci/golangci-lint/pkg/config"
+	"github.com/golangci/golangci-lint/pkg/golinters/goanalysis"
+)
+
+func NewVarnamelen(settings *config.VarnamelenSettings) *goanalysis.Linter {
+	a := varnamelen.NewAnalyzer()
+
+	cfg := map[string]map[string]interface{}{}
+	if settings != nil {
+		vnlCfg := map[string]interface{}{
+			"checkReceiver": strconv.FormatBool(settings.CheckReceiver),
+			"checkReturn":   strconv.FormatBool(settings.CheckReturn),
+			"ignoreNames":   strings.Join(settings.IgnoreNames, ","),
+		}
+
+		if settings.MaxDistance > 0 {
+			vnlCfg["maxDistance"] = strconv.Itoa(settings.MaxDistance)
+		}
+		if settings.MinNameLength > 0 {
+			vnlCfg["minNameLength"] = strconv.Itoa(settings.MinNameLength)
+		}
+
+		cfg[a.Name] = vnlCfg
+	}
+
+	return goanalysis.NewLinter(
+		a.Name,
+		"checks that the length of a variable's name matches its scope",
+		[]*analysis.Analyzer{a},
+		cfg,
+	).WithLoadMode(goanalysis.LoadModeSyntax)
+}

pkg/lint/lintersdb/manager.go

@@ -121,6 +121,7 @@ func (m Manager) GetAllSupportedLinterConfigs() []*linter.Config {
 	var testpackageCfg *config.TestpackageSettings
 	var thelperCfg *config.ThelperSettings
 	var unusedCfg *config.StaticCheckSettings
+	var varnamelenCfg *config.VarnamelenSettings
 	var wrapcheckCfg *config.WrapcheckSettings
 	var nlreturnCfg *config.NlreturnSettings
 
@@ -146,6 +147,7 @@ func (m Manager) GetAllSupportedLinterConfigs() []*linter.Config {
 		testpackageCfg = &m.cfg.LintersSettings.Testpackage
 		thelperCfg = &m.cfg.LintersSettings.Thelper
 		unusedCfg = &m.cfg.LintersSettings.Unused
+		varnamelenCfg = &m.cfg.LintersSettings.Varnamelen
 		wrapcheckCfg = &m.cfg.LintersSettings.Wrapcheck
 		nlreturnCfg = &m.cfg.LintersSettings.Nlreturn
 	}
@@ -511,30 +513,35 @@ func (m Manager) GetAllSupportedLinterConfigs() []*linter.Config {
 			WithPresets(linter.PresetStyle).
 			WithURL("https://github.com/ldez/tagliatelle"),
 		linter.NewConfig(golinters.NewErrName()).
+			WithSince("v1.42.0").
 			WithPresets(linter.PresetStyle).
 			WithLoadForGoAnalysis().
-			WithURL("https://github.com/Antonboom/errname").
-			WithSince("v1.42.0"),
+			WithURL("https://github.com/Antonboom/errname"),
 		linter.NewConfig(golinters.NewIreturn(ireturnCfg)).
 			WithSince("v1.43.0").
 			WithPresets(linter.PresetStyle).
 			WithLoadForGoAnalysis().
 			WithURL("https://github.com/butuzov/ireturn"),
 		linter.NewConfig(golinters.NewNilNil(nilNilCfg)).
+			WithSince("v1.43.0").
 			WithPresets(linter.PresetStyle).
 			WithLoadForGoAnalysis().
-			WithURL("https://github.com/Antonboom/nilnil").
-			WithSince("v1.43.0"),
+			WithURL("https://github.com/Antonboom/nilnil"),
 		linter.NewConfig(golinters.NewTenv(tenvCfg)).
 			WithSince("v1.43.0").
 			WithPresets(linter.PresetStyle).
 			WithLoadForGoAnalysis().
 			WithURL("https://github.com/sivchari/tenv"),
 		linter.NewConfig(golinters.NewContextCheck()).
+			WithSince("v1.43.0").
 			WithPresets(linter.PresetBugs).
 			WithLoadForGoAnalysis().
-			WithURL("https://github.com/sylvia7788/contextcheck").
-			WithSince("v1.43.0"),
+			WithURL("https://github.com/sylvia7788/contextcheck"),
+		linter.NewConfig(golinters.NewVarnamelen(varnamelenCfg)).
+			WithSince("v1.43.0").
+			WithPresets(linter.PresetStyle).
+			WithLoadForGoAnalysis().
+			WithURL("https://github.com/blizzy78/varnamelen"),
 
 		// nolintlint must be last because it looks at the results of all the previous linters for unused nolint directives
 		linter.NewConfig(golinters.NewNoLintLint()).

test/testdata/varnamelen.go

@@ -0,0 +1,17 @@
+//args: -Evarnamelen
+package testdata
+
+import "math"
+
+func varnamelen() {
+	x := math.MinInt8 // ERROR "variable name 'x' is too short for the scope of its usage"
+	x++
+	x++
+	x++
+	x++
+	x++
+	x++
+	x++
+	x++
+	x++
+}