Add nestif linter

Author: nakabonne

.golangci.example.yml

@@ -96,6 +96,9 @@ linters-settings:
   gocognit:
     # minimal code complexity to report, 30 by default (but we recommend 10-20)
     min-complexity: 10
+  nestif:
+    # minimal complexity of if statements to report, 5 by default
+    min-complexity: 4
   goconst:
     # minimal length of string constant, 3 by default
     min-len: 3

README.md

@@ -230,6 +230,7 @@ lll: Reports long lines [fast: true, auto-fix: false]
 maligned: Tool to detect Go structs that would take less memory if their fields were sorted [fast: true, auto-fix: false]
 misspell: Finds commonly misspelled English words in comments [fast: true, auto-fix: true]
 nakedret: Finds naked returns in functions greater than a specified function length [fast: true, auto-fix: false]
+nestif: Reports deeply nested if statements [fast: true, auto-fix: false]
 prealloc: Finds slice declarations that could potentially be preallocated [fast: true, auto-fix: false]
 rowserrcheck: checks whether Err of rows is checked successfully [fast: true, auto-fix: false]
 scopelint: Scopelint checks for unpinned variables in go programs [fast: true, auto-fix: false]
@@ -490,6 +491,7 @@ golangci-lint help linters
 - [goprintffuncname](https://github.com/jirfag/go-printf-func-name) - Checks that printf-like functions are named with `f` at the end
 - [gomnd](https://github.com/tommy-muehle/go-mnd) - An analyzer to detect magic numbers.
 - [godot](https://github.com/tetafro/godot) - Check if comments end in a period
+- [nestif](https://github.com/nakabonne/nestif) - Reports deeply nested if statements
 
 ## Configuration
 
@@ -708,6 +710,9 @@ linters-settings:
   gocognit:
     # minimal code complexity to report, 30 by default (but we recommend 10-20)
     min-complexity: 10
+  nestif:
+    # minimal complexity of if statements to report, 5 by default
+    min-complexity: 4
   goconst:
     # minimal length of string constant, 3 by default
     min-len: 3
@@ -1267,6 +1272,7 @@ Thanks to developers and authors of used linters:
 - [jirfag](https://github.com/jirfag)
 - [tommy-muehle](https://github.com/tommy-muehle)
 - [tetafro](https://github.com/tetafro)
+- [nakabonne](https://github.com/nakabonne)
 
 ## Changelog
 

go.mod

@@ -29,6 +29,7 @@ require (
 	github.com/mattn/go-colorable v0.1.4
 	github.com/mitchellh/go-homedir v1.1.0
 	github.com/mitchellh/go-ps v0.0.0-20190716172923-621e5597135b
+	github.com/nakabonne/nestif v0.3.0
 	github.com/pkg/errors v0.8.1
 	github.com/securego/gosec v0.0.0-20200103095621-79fbf3af8d83
 	github.com/shirou/gopsutil v0.0.0-20190901111213-e4ec7b275ada // v2.19.8

go.sum

@@ -183,6 +183,8 @@ github.com/mitchellh/mapstructure v1.1.2 h1:fmNYVwqnSfB9mZU6OS2O6GsXM+wcskZDuKQz
 github.com/mitchellh/mapstructure v1.1.2/go.mod h1:FVVH3fgwuzCH5S8UJGiWEs2h04kUh9fWfEaFds41c1Y=
 github.com/mozilla/tls-observatory v0.0.0-20190404164649-a3c1b6cfecfd/go.mod h1:SrKMQvPiws7F7iqYp8/TX+IhxCYhzr6N/1yb8cwHsGk=
 github.com/mwitkow/go-conntrack v0.0.0-20161129095857-cc309e4a2223/go.mod h1:qRWi+5nqEBWmkhHvq77mSJWrCKwh8bxhgT7d/eI7P4U=
+github.com/nakabonne/nestif v0.3.0 h1:+yOViDGhg8ygGrmII72nV9B/zGxY188TYpfolntsaPw=
+github.com/nakabonne/nestif v0.3.0/go.mod h1:dI314BppzXjJ4HsCnbo7XzrJHPszZsjnk5wEBSYHI2c=
 github.com/nbutton23/zxcvbn-go v0.0.0-20180912185939-ae427f1e4c1d h1:AREM5mwr4u1ORQBMvzfzBgpsctsbQikCVpvC+tX285E=
 github.com/nbutton23/zxcvbn-go v0.0.0-20180912185939-ae427f1e4c1d/go.mod h1:o96djdrsSGy3AWPyBgZMAGfxZNfgntdJG+11KU4QvbU=
 github.com/niemeyer/pretty v0.0.0-20200227124842-a10e7caefd8e h1:fD57ERR4JtEqsWbfPhv4DMiApHyliiK5xCTNVSPiaAs=

pkg/config/config.go

@@ -199,6 +199,7 @@ type LintersSettings struct {
 	Dogsled  DogsledSettings
 	Gocognit GocognitSettings
 	Godot    GodotSettings
+	Nestif   NestifSettings
 
 	Custom map[string]CustomLinterSettings
 }
@@ -280,6 +281,10 @@ type GodotSettings struct {
 	CheckAll bool `mapstructure:"check-all"`
 }
 
+type NestifSettings struct {
+	MinComplexity int `mapstructure:"min-complexity"`
+}
+
 //nolint:gomnd
 var defaultLintersSettings = LintersSettings{
 	Lll: LllSettings{
@@ -319,6 +324,9 @@ var defaultLintersSettings = LintersSettings{
 		ForceCuddleErrCheckAndAssign:     false,
 		ForceCaseTrailingWhitespaceLimit: 0,
 	},
+	Nestif: NestifSettings{
+		MinComplexity: 5,
+	},
 }
 
 type CustomLinterSettings struct {

pkg/golinters/nestif.go

@@ -0,0 +1,65 @@
+package golinters
+
+import (
+	"sort"
+	"sync"
+
+	"github.com/nakabonne/nestif"
+	"golang.org/x/tools/go/analysis"
+
+	"github.com/golangci/golangci-lint/pkg/golinters/goanalysis"
+	"github.com/golangci/golangci-lint/pkg/lint/linter"
+	"github.com/golangci/golangci-lint/pkg/result"
+)
+
+const nestifName = "nestif"
+
+func NewNestif() *goanalysis.Linter {
+	var mu sync.Mutex
+	var resIssues []goanalysis.Issue
+
+	analyzer := &analysis.Analyzer{
+		Name: goanalysis.TheOnlyAnalyzerName,
+		Doc:  goanalysis.TheOnlyanalyzerDoc,
+	}
+	return goanalysis.NewLinter(
+		nestifName,
+		"Reports deeply nested if statements",
+		[]*analysis.Analyzer{analyzer},
+		nil,
+	).WithContextSetter(func(lintCtx *linter.Context) {
+		analyzer.Run = func(pass *analysis.Pass) (interface{}, error) {
+			checker := &nestif.Checker{
+				MinComplexity: lintCtx.Settings().Nestif.MinComplexity,
+			}
+			var issues []nestif.Issue
+			for _, f := range pass.Files {
+				issues = append(issues, checker.Check(f, pass.Fset)...)
+			}
+			if len(issues) == 0 {
+				return nil, nil
+			}
+
+			sort.Slice(issues, func(i, j int) bool {
+				return issues[i].Complexity > issues[j].Complexity
+			})
+
+			res := make([]goanalysis.Issue, 0, len(issues))
+			for _, i := range issues {
+				res = append(res, goanalysis.NewIssue(&result.Issue{ //nolint:scopelint
+					Pos:        i.Pos,
+					Text:       i.Message,
+					FromLinter: nestifName,
+				}, pass))
+			}
+
+			mu.Lock()
+			resIssues = append(resIssues, res...)
+			mu.Unlock()
+
+			return nil, nil
+		}
+	}).WithIssuesReporter(func(*linter.Context) []goanalysis.Issue {
+		return resIssues
+	}).WithLoadMode(goanalysis.LoadModeSyntax)
+}

pkg/lint/lintersdb/manager.go

@@ -250,6 +250,9 @@ func (m Manager) GetAllSupportedLinterConfigs() []*linter.Config {
 		linter.NewConfig(golinters.NewGodot()).
 			WithPresets(linter.PresetStyle).
 			WithURL("https://github.com/tetafro/godot"),
+		linter.NewConfig(golinters.NewNestif()).
+			WithPresets(linter.PresetComplexity).
+			WithURL("https://github.com/nakabonne/nestif"),
 	}
 
 	isLocalRun := os.Getenv("GOLANGCI_COM_RUN") == ""

test/testdata/nestif.go

@@ -0,0 +1,47 @@
+//args: -Enestif
+//config: linters-settings.nestif.min-complexity=1
+package testdata
+
+func _() {
+	var b1, b2, b3, b4 bool
+
+	if b1 { // ERROR "`if b1` is deeply nested \(complexity: 1\)"
+		if b2 { // +1
+		}
+	}
+
+	if b1 { // ERROR "`if b1` is deeply nested \(complexity: 3\)"
+		if b2 { // +1
+			if b3 { // +2
+			}
+		}
+	}
+
+	if b1 { // ERROR "`if b1` is deeply nested \(complexity: 5\)"
+		if b2 { // +1
+		} else if b3 { // +1
+			if b4 { // +2
+			}
+		} else { // +1
+		}
+	}
+
+	if b1 { // ERROR "`if b1` is deeply nested \(complexity: 9\)"
+		if b2 { // +1
+			if b3 { // +2
+			}
+		}
+
+		if b2 { // +1
+			if b3 { // +2
+				if b4 { // +3
+				}
+			}
+		}
+	}
+
+	if b1 == b2 == b3 { // ERROR "`if b1 == b2 == b3` is deeply nested \(complexity: 1\)"
+		if b4 { // +1
+		}
+	}
+}