Added support for indirect recursion

gocognit.go

@@ -66,6 +66,7 @@ func Complexity(fn *ast.FuncDecl) int {
 	v := complexityVisitor{
 		name: fn.Name,
 	}
+
 	ast.Walk(&v, fn)
 	return v.complexity
 }
@@ -300,8 +301,11 @@ func (v *complexityVisitor) visitBinaryExpr(n *ast.BinaryExpr) ast.Visitor {
 func (v *complexityVisitor) visitCallExpr(n *ast.CallExpr) ast.Visitor {
 	if name, ok := n.Fun.(*ast.Ident); ok {
 		if name.Obj == v.name.Obj && name.Name == v.name.Name {
-			// called by same function (recursion)
+			// called by same function directly (direct recursion)
 			v.incComplexity()
+		} else if fnDecl, ok := name.Obj.Decl.(*ast.FuncDecl); ok {
+			// called by same function indirectly (indirect recursion)
+			ast.Walk(v, fnDecl)
 		}
 	}
 	return v

testdata/src/a/a.go

@@ -6,6 +6,10 @@ import (
 	"io"
 )
 
+func HelloWorld() string {
+	return "Hello, World!"
+} // total complexity = 0
+
 func SimpleCond(n int) string { // want "cognitive complexity 1 of func SimpleCond is high \\(> 0\\)"
 	if n == 100 { // +1
 		return "a hundred"
@@ -112,14 +116,35 @@ OUT:
 	return total
 } // Cognitive complexity = 7
 
-func Fact(n int) int { // want "cognitive complexity 3 of func Fact is high \\(> 0\\)"
+func FactRec(n int) int { // want "cognitive complexity 3 of func FactRec is high \\(> 0\\)"
+	if n <= 1 { // +1
+		return 1
+	} else { // +1
+		return n * FactRec(n-1) // +1
+	}
+} // total complexity = 3
+
+func FactRecIndirect(n int) int { // want "cognitive complexity 3 of func FactRecIndirect is high \\(> 0\\)"
 	if n <= 1 { // +1
 		return 1
 	} else { // +1
-		return n * Fact(n-1) // +1
+		return factRecIndirect0(n) // +0 +1, due to indirect call to FactRecIndirect
 	}
 } // total complexity = 3
 
+func factRecIndirect0(n int) int { // want "cognitive complexity 3 of func factRecIndirect0 is high \\(> 0\\)"
+	return n * FactRecIndirect(n-1) // +0 +3 due to inderect call to factRecIndirect0
+} // total complexity = 3
+
+func FactLoop(n int) int { // want "cognitive complexity 1 of func FactLoop is high \\(> 0\\)"
+	total := 1
+	for n > 0 { // +1
+		total *= n
+		n--
+	}
+	return total
+} // total complexity = 1
+
 func DumpVal(w io.Writer, i interface{}) error { // want "cognitive complexity 1 of func DumpVal is high \\(> 0\\)"
 	switch v := i.(type) { // +1
 	case int:

testdata/src/b/b.go

@@ -6,6 +6,10 @@ import (
 	"io"
 )
 
+func HelloWorld() string {
+	return "Hello, World!"
+} // total complexity = 0
+
 func SimpleCond(n int) string {
 	if n == 100 { // +1
 		return "a hundred"
@@ -112,14 +116,35 @@ OUT:
 	return total
 } // Cognitive complexity = 7
 
-func Fact(n int) int {
+func FactRec(n int) int {
+	if n <= 1 { // +1
+		return 1
+	} else { // +1
+		return n * FactRec(n-1) // +1
+	}
+} // total complexity = 3
+
+func FactRecIndirect(n int) int {
 	if n <= 1 { // +1
 		return 1
 	} else { // +1
-		return n * Fact(n-1) // +1
+		return factRecIndirect0(n) // +0 +1, due to indirect call to FactRecIndirect
 	}
 } // total complexity = 3
 
+func factRecIndirect0(n int) int {
+	return n * FactRecIndirect(n-1) // +0 +3 due to inderect call to factRecIndirect0
+} // total complexity = 3
+
+func FactLoop(n int) int {
+	total := 1
+	for n > 0 { // +1
+		total *= n
+		n--
+	}
+	return total
+} // total complexity = 1
+
 func DumpVal(w io.Writer, i interface{}) error {
 	switch v := i.(type) { // +1
 	case int: