From ed5a8e8880f4572673406391d200d36589319641 Mon Sep 17 00:00:00 2001
From: Lavanya  Verma <108087018+lverma14@users.noreply.github.com>
Date: Wed, 3 Apr 2024 00:22:39 -0700
Subject: [PATCH] Fix nil ptr bug in checkGenerated (#159)

Currently, while checking if a file contains generated code, if the file
doesn't contain any package comment,
 we run into a nil pointer dereference error.
```
package example
... // rest of the logic
```
**Why**
This happens due to missing nil check in the `checkGenerated` function
before iterating `ast.File.Doc.List` ([pkg
ref](https://pkg.go.dev/go/ast#File))
```
for _, comm := range f.Doc.List { // nil pointer error when f.Doc is nil
```
This commit adds a nil pointer check in `checkGenerated` to continue
with the rest of the logic only if there's a package comment.
---
 main.go      | 3 +++
 main_test.go | 4 ++++
 2 files changed, 7 insertions(+)

diff --git a/main.go b/main.go
index 8959fa5..77b38c8 100644
--- a/main.go
+++ b/main.go
@@ -355,6 +355,9 @@ func checkGeneratedCode(f *ast.File) bool {
 	if ast.IsGenerated(f) {
 		return true
 	}
+	if f.Doc == nil {
+		return false
+	}
 	for _, comm := range f.Doc.List {
 		if strings.Contains(comm.Text, "@generated") {
 			return true
diff --git a/main_test.go b/main_test.go
index 5994f9b..5f38da8 100644
--- a/main_test.go
+++ b/main_test.go
@@ -252,6 +252,10 @@ func TestCheckGeneratedCode(t *testing.T) {
 				},
 			},
 		},
+		{
+			name: "non-generated code with no package comment",
+			file: &ast.File{},
+		},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {