From e855c4cd1d5f87ae2a12c0e2620c0b747101c2bc Mon Sep 17 00:00:00 2001
From: badcw <badcw123@gmail.com>
Date: Mon, 17 Jan 2022 08:22:57 +0800
Subject: [PATCH] fix: Nil pointer when getting context's flagSet(#1325)
 (#1327)

* fix: Nil pointer when getting context's flagSet in UsageError function(#1325)

* test: add unit test for nil flagset in Context
---
 context.go      | 3 +++
 context_test.go | 2 ++
 2 files changed, 5 insertions(+)

diff --git a/context.go b/context.go
index 94cbb65909..da090e8256 100644
--- a/context.go
+++ b/context.go
@@ -151,6 +151,9 @@ func (ctx *Context) lookupFlag(name string) Flag {
 
 func (ctx *Context) lookupFlagSet(name string) *flag.FlagSet {
 	for _, c := range ctx.Lineage() {
+		if c.flagSet == nil {
+			continue
+		}
 		if f := c.flagSet.Lookup(name); f != nil {
 			return c.flagSet
 		}
diff --git a/context_test.go b/context_test.go
index b37876c033..84757063eb 100644
--- a/context_test.go
+++ b/context_test.go
@@ -112,6 +112,8 @@ func TestContext_String(t *testing.T) {
 	c := NewContext(nil, set, parentCtx)
 	expect(t, c.String("myflag"), "hello world")
 	expect(t, c.String("top-flag"), "hai veld")
+	c = NewContext(nil, nil, parentCtx)
+	expect(t, c.String("top-flag"), "hai veld")
 }
 
 func TestContext_Path(t *testing.T) {