add varnamelen linter

.golangci.example.yml

@@ -633,6 +633,22 @@ 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
+      - ctx
+
   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 v0.2.0
 	github.com/bombsimon/wsl/v3 v3.3.0
 	github.com/butuzov/ireturn v0.1.0
 	github.com/charithe/durationcheck v0.0.8
@@ -86,7 +87,7 @@ require (
 	github.com/uudashr/gocognit v1.0.5
 	github.com/valyala/quicktemplate v1.6.3
 	github.com/yeya24/promlinter v0.1.0
-	golang.org/x/tools v0.1.5
+	golang.org/x/tools v0.1.6
 	gopkg.in/yaml.v3 v3.0.0-20210107192922-496545a6307b
 	honnef.co/go/tools v0.2.1
 	mvdan.cc/gofumpt v0.1.1

pkg/config/linters_settings.go

@@ -134,6 +134,7 @@ type LintersSettings struct {
 	Unparam          UnparamSettings
 	Unused           StaticCheckSettings
 	Varcheck         VarCheckSettings
+	Varnamelen       VarnamelenSettings
 	Whitespace       WhitespaceSettings
 	Wrapcheck        WrapcheckSettings
 	WSL              WSLSettings
@@ -467,6 +468,14 @@ 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 +1,48 @@
+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": boolString(settings.CheckReceiver),
+			"checkReturn":   boolString(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,
+	)
+}
+
+func boolString(b bool) string {
+	if b {
+		return "true"
+	}
+	return "false"
+}

pkg/lint/lintersdb/manager.go

@@ -119,6 +119,7 @@ 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
 
 	if m.cfg != nil {
@@ -142,6 +143,7 @@ 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
 	}
 
@@ -520,6 +522,11 @@ func (m Manager) GetAllSupportedLinterConfigs() []*linter.Config {
 			WithLoadForGoAnalysis().
 			WithURL("https://github.com/Antonboom/nilnil").
 			WithSince("v1.43.0"),
+		linter.NewConfig(golinters.NewVarnamelen(varnamelenCfg)).
+			WithPresets(linter.PresetStyle).
+			WithLoadForGoAnalysis().
+			WithURL("https://github.com/blizzy78/varnamelen").
+			WithSince("v1.43.0"),
 
 		// 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 +1,15 @@
+//args: -Evarnamelen
+package testdata
+
+func varnamelen() {
+	x := 1 // ERROR "variable name 'x' is too short for the scope of its usage"
+	x++
+	x++
+	x++
+	x++
+	x++
+	x++
+	x++
+	x++
+	x++
+}