Add "grouper" linter (#2497)

Author: leonklingele

Diff for: .golangci.example.yml

@@ -806,6 +806,35 @@ linters-settings:
       - unusedresult
       - unusedwrite
 
+  grouper:
+    # Require the use of a single global 'const' declaration only.
+    # Default: false
+    const-require-single-const: true
+    # Require the use of grouped global 'const' declarations.
+    # Default: false
+    const-require-grouping: true
+
+    # Require the use of a single 'import' declaration only.
+    # Default: false
+    import-require-single-import: true
+    # Require the use of grouped 'import' declarations.
+    # Default: false
+    import-require-grouping: true
+
+    # Require the use of a single global 'type' declaration only.
+    # Default: false
+    type-require-single-type: true
+    # Require the use of grouped global 'type' declarations.
+    # Default: false
+    type-require-grouping: true
+
+    # Require the use of a single global 'var' declaration only.
+    # Default: false
+    var-require-single-var: true
+    # Require the use of grouped global 'var' declarations.
+    # Default: false
+    var-require-grouping: true
+
   ifshort:
     # Maximum length of variable declaration measured in number of lines, after which linter won't suggest using short syntax.
     # Has higher priority than max-decl-chars.

Diff for: go.mod

@@ -50,6 +50,7 @@ require (
 	github.com/kyoh86/exportloopref v0.1.8
 	github.com/ldez/gomoddirectives v0.2.2
 	github.com/ldez/tagliatelle v0.3.0
+	github.com/leonklingele/grouper v1.1.0
 	github.com/maratori/testpackage v1.0.1
 	github.com/matoous/godox v0.0.0-20210227103229-6504466cf951 // v1.0
 	github.com/mattn/go-colorable v0.1.12

Diff for: go.sum

@@ -131,6 +131,7 @@ type LintersSettings struct {
 	Gosec            GoSecSettings
 	Gosimple         StaticCheckSettings
 	Govet            GovetSettings
+	Grouper          GrouperSettings
 	Ifshort          IfshortSettings
 	ImportAs         ImportAsSettings
 	Ireturn          IreturnSettings
@@ -376,6 +377,17 @@ func (cfg GovetSettings) Validate() error {
 	return nil
 }
 
+type GrouperSettings struct {
+	ConstRequireSingleConst   bool `mapstructure:"const-require-single-const"`
+	ConstRequireGrouping      bool `mapstructure:"const-require-grouping"`
+	ImportRequireSingleImport bool `mapstructure:"import-require-single-import"`
+	ImportRequireGrouping     bool `mapstructure:"import-require-grouping"`
+	TypeRequireSingleType     bool `mapstructure:"type-require-single-type"`
+	TypeRequireGrouping       bool `mapstructure:"type-require-grouping"`
+	VarRequireSingleVar       bool `mapstructure:"var-require-single-var"`
+	VarRequireGrouping        bool `mapstructure:"var-require-grouping"`
+}
+
 type IfshortSettings struct {
 	MaxDeclLines int `mapstructure:"max-decl-lines"`
 	MaxDeclChars int `mapstructure:"max-decl-chars"`

Diff for: pkg/config/linters_settings.go

@@ -0,0 +1,32 @@
+package golinters
+
+import (
+	grouper "github.com/leonklingele/grouper/pkg/analyzer"
+	"golang.org/x/tools/go/analysis"
+
+	"github.com/golangci/golangci-lint/pkg/config"
+	"github.com/golangci/golangci-lint/pkg/golinters/goanalysis"
+)
+
+func NewGrouper(settings *config.GrouperSettings) *goanalysis.Linter {
+	linterCfg := map[string]map[string]interface{}{}
+	if settings != nil {
+		linterCfg["grouper"] = map[string]interface{}{
+			"const-require-single-const":   settings.ConstRequireSingleConst,
+			"const-require-grouping":       settings.ConstRequireGrouping,
+			"import-require-single-import": settings.ImportRequireSingleImport,
+			"import-require-grouping":      settings.ImportRequireGrouping,
+			"type-require-single-type":     settings.TypeRequireSingleType,
+			"type-require-grouping":        settings.TypeRequireGrouping,
+			"var-require-single-var":       settings.VarRequireSingleVar,
+			"var-require-grouping":         settings.VarRequireGrouping,
+		}
+	}
+
+	return goanalysis.NewLinter(
+		"grouper",
+		"An analyzer to analyze expression groups.",
+		[]*analysis.Analyzer{grouper.New()},
+		linterCfg,
+	).WithLoadMode(goanalysis.LoadModeSyntax)
+}

Diff for: pkg/golinters/grouper.go

@@ -112,6 +112,7 @@ func (m Manager) GetAllSupportedLinterConfigs() []*linter.Config {
 	var gosecCfg *config.GoSecSettings
 	var gosimpleCfg *config.StaticCheckSettings
 	var govetCfg *config.GovetSettings
+	var grouperCfg *config.GrouperSettings
 	var ifshortCfg *config.IfshortSettings
 	var importAsCfg *config.ImportAsSettings
 	var ireturnCfg *config.IreturnSettings
@@ -143,6 +144,7 @@ func (m Manager) GetAllSupportedLinterConfigs() []*linter.Config {
 		gosecCfg = &m.cfg.LintersSettings.Gosec
 		gosimpleCfg = &m.cfg.LintersSettings.Gosimple
 		govetCfg = &m.cfg.LintersSettings.Govet
+		grouperCfg = &m.cfg.LintersSettings.Grouper
 		ifshortCfg = &m.cfg.LintersSettings.Ifshort
 		importAsCfg = &m.cfg.LintersSettings.ImportAs
 		ireturnCfg = &m.cfg.LintersSettings.Ireturn
@@ -415,6 +417,11 @@ func (m Manager) GetAllSupportedLinterConfigs() []*linter.Config {
 			WithAlternativeNames("vet", "vetshadow").
 			WithURL("https://golang.org/cmd/vet/"),
 
+		linter.NewConfig(golinters.NewGrouper(grouperCfg)).
+			WithSince("v1.44.0").
+			WithPresets(linter.PresetStyle).
+			WithURL("https://github.com/leonklingele/grouper"),
+
 		linter.NewConfig(golinters.NewIfshort(ifshortCfg)).
 			WithSince("v1.36.0").
 			WithPresets(linter.PresetStyle).