cognitive-complexity: handle direct recursion (#1149)

Author: alexandear

rule/cognitive_complexity.go

@@ -67,7 +67,9 @@ func (w cognitiveComplexityLinter) lintCognitiveComplexity() {
 	f := w.file
 	for _, decl := range f.AST.Decls {
 		if fn, ok := decl.(*ast.FuncDecl); ok && fn.Body != nil {
-			v := cognitiveComplexityVisitor{}
+			v := cognitiveComplexityVisitor{
+				name: fn.Name,
+			}
 			c := v.subTreeComplexity(fn.Body)
 			if c > w.maxComplexity {
 				w.onFailure(lint.Failure{
@@ -82,6 +84,7 @@ func (w cognitiveComplexityLinter) lintCognitiveComplexity() {
 }
 
 type cognitiveComplexityVisitor struct {
+	name         *ast.Ident
 	complexity   int
 	nestingLevel int
 }
@@ -125,8 +128,15 @@ func (v *cognitiveComplexityVisitor) Visit(n ast.Node) ast.Visitor {
 		if n.Label != nil {
 			v.complexity++
 		}
+	case *ast.CallExpr:
+		if ident, ok := n.Fun.(*ast.Ident); ok {
+			if ident.Obj == v.name.Obj && ident.Name == v.name.Name {
+				// called by same function directly (direct recursion)
+				v.complexity++
+				return nil
+			}
+		}
 	}
-	// TODO handle (at least) direct recursion
 
 	return v
 }

testdata/cognitive_complexity.go

@@ -281,3 +281,13 @@ func (m *Migrator) MigrateIfNeeded(target *EtcdVersionPair) error { // MATCH /fu
 
 // no regression test for issue #451
 func myFunc()
+
+// Recursive functions
+func Walk(t *Tree, ch chan int) { // MATCH /function Walk has cognitive complexity 3 (> max enabled 0)/
+	if t == nil { // +1
+		return
+	}
+	Walk(t.Left, ch) // +1
+	ch <- t.Value
+	Walk(t.Right, ch) // +1
+}