From d93e68a44b063a2d0b939d88649bd57b7614c063 Mon Sep 17 00:00:00 2001
From: bahtya <bahtyar153@qq.com>
Date: Sun, 5 Apr 2026 10:20:29 +0800
Subject: [PATCH] Fix BoolWithInverseFlag.String() panic when FlagStringer
 returns no tab

When FlagStringer returns a string without a tab character,
strings.Index returns -1, causing out[i:] to panic with index out of
range. Add guard to return the string as-is when no tab is found.

Fixes #2303
---
 flag_bool_with_inverse.go | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/flag_bool_with_inverse.go b/flag_bool_with_inverse.go
index 272dd98fec..edbd2b7063 100644
--- a/flag_bool_with_inverse.go
+++ b/flag_bool_with_inverse.go
@@ -171,6 +171,9 @@ func (bif *BoolWithInverseFlag) String() string {
 	out := FlagStringer(bif)
 
 	i := strings.Index(out, "\t")
+	if i == -1 {
+		return out
+	}
 
 	prefix := "--"