From bf94da4667789c94296c32cb038e5238d314157b Mon Sep 17 00:00:00 2001
From: Ivan Ivanov <ivan.ivanov@ft.com>
Date: Sun, 1 May 2022 20:07:12 +0300
Subject: [PATCH 1/2] Fix gocognit output when a function has generic receiver
 type

recvString func in gocognit returns BADRECV when the function's receiver is a
generic type.

Implement recvString in two variants in order to keep the code
compatible with go versions less than 1.18
---
 gocognit.go    | 12 ------------
 recv.go        | 30 ++++++++++++++++++++++++++++++
 recv_pre118.go | 20 ++++++++++++++++++++
 3 files changed, 50 insertions(+), 12 deletions(-)
 create mode 100644 recv.go
 create mode 100644 recv_pre118.go

diff --git a/gocognit.go b/gocognit.go
index 418c163..1d539ee 100644
--- a/gocognit.go
+++ b/gocognit.go
@@ -49,18 +49,6 @@ func funcName(fn *ast.FuncDecl) string {
 	return fn.Name.Name
 }
 
-// recvString returns a string representation of recv of the
-// form "T", "*T", or "BADRECV" (if not a proper receiver type).
-func recvString(recv ast.Expr) string {
-	switch t := recv.(type) {
-	case *ast.Ident:
-		return t.Name
-	case *ast.StarExpr:
-		return "*" + recvString(t.X)
-	}
-	return "BADRECV"
-}
-
 // Complexity calculates the cognitive complexity of a function.
 func Complexity(fn *ast.FuncDecl) int {
 	v := complexityVisitor{
diff --git a/recv.go b/recv.go
new file mode 100644
index 0000000..b2e8b6a
--- /dev/null
+++ b/recv.go
@@ -0,0 +1,30 @@
+//go:build go1.18
+// +build go1.18
+
+package gocognit
+
+import (
+	"go/ast"
+	"strings"
+)
+
+// recvString returns a string representation of recv of the
+// form "T", "*T", Type[T], Type[T, V], or "BADRECV" (if not a proper receiver type).
+func recvString(recv ast.Expr) string {
+	switch t := recv.(type) {
+	case *ast.Ident:
+		return t.Name
+	case *ast.StarExpr:
+		return "*" + recvString(t.X)
+	case *ast.IndexExpr:
+		return recvString(t.X) + "[" + recvString(t.Index) + "]"
+	case *ast.IndexListExpr:
+		targs := make([]string, len(t.Indices))
+		for i, exp := range t.Indices {
+			targs[i] = recvString(exp)
+		}
+
+		return recvString(t.X) + "[" + strings.Join(targs, ", ") + "]"
+	}
+	return "BADRECV"
+}
diff --git a/recv_pre118.go b/recv_pre118.go
new file mode 100644
index 0000000..9e0ebfd
--- /dev/null
+++ b/recv_pre118.go
@@ -0,0 +1,20 @@
+//go:build !go1.18
+// +build !go1.18
+
+package gocognit
+
+import (
+	"go/ast"
+)
+
+// recvString returns a string representation of recv of the
+// form "T", "*T", or "BADRECV" (if not a proper receiver type).
+func recvString(recv ast.Expr) string {
+	switch t := recv.(type) {
+	case *ast.Ident:
+		return t.Name
+	case *ast.StarExpr:
+		return "*" + recvString(t.X)
+	}
+	return "BADRECV"
+}

From c660021124c82f8c675246d4c3cf32f180556193 Mon Sep 17 00:00:00 2001
From: Ivan Ivanov <ruski9606@gmail.com>
Date: Fri, 1 Jul 2022 15:28:59 +0300
Subject: [PATCH 2/2] Add unit test for methods with generic receivers

---
 gocognit118_test.go | 17 +++++++++++++++++
 testdata/src/c/c.go | 36 ++++++++++++++++++++++++++++++++++++
 2 files changed, 53 insertions(+)
 create mode 100644 gocognit118_test.go
 create mode 100644 testdata/src/c/c.go

diff --git a/gocognit118_test.go b/gocognit118_test.go
new file mode 100644
index 0000000..51d396d
--- /dev/null
+++ b/gocognit118_test.go
@@ -0,0 +1,17 @@
+//go:build go1.18
+// +build go1.18
+
+package gocognit_test
+
+import (
+	"testing"
+
+	"github.com/uudashr/gocognit"
+	"golang.org/x/tools/go/analysis/analysistest"
+)
+
+func TestAnalyzer_Generics(t *testing.T) {
+	testdata := analysistest.TestData()
+	gocognit.Analyzer.Flags.Set("over", "0")
+	analysistest.Run(t, testdata, gocognit.Analyzer, "c")
+}
diff --git a/testdata/src/c/c.go b/testdata/src/c/c.go
new file mode 100644
index 0000000..5a75c99
--- /dev/null
+++ b/testdata/src/c/c.go
@@ -0,0 +1,36 @@
+package testdata
+
+type Node[T any] struct {
+}
+
+func (n *Node[T]) String() string { // want "cognitive complexity 1 of func \\(\\*Node\\[T\\]\\)\\.String is high \\(> 0\\)"
+	if n != nil { // +1
+		return "Node"
+	}
+
+	return ""
+} // total complexity = 1
+
+type Pair[K any, V any] struct {
+	Key   K
+	Value V
+}
+
+func (p *Pair[K, V]) String() string { // want "cognitive complexity 1 of func \\(\\*Pair\\[K, V\\]\\)\\.String is high \\(> 0\\)"
+	if p != nil { // +1
+		return "Pair"
+	}
+
+	return ""
+} // total complexity = 1
+
+type Triple[K any, V any, T any] struct {
+}
+
+func (t *Triple[K, V, T]) String() string { // want "cognitive complexity 1 of func \\(\\*Triple\\[K, V, T\\]\\)\\.String is high \\(> 0\\)"
+	if t != nil { // +1 `
+		return "Triple"
+	}
+
+	return ""
+} // total complexity = 1