From e37a2e54ab7229b332c903ed380297b99963e429 Mon Sep 17 00:00:00 2001
From: nicm <nicm>
Date: Wed, 8 Jul 2026 11:04:51 +0000
Subject: [PATCH] Fix regsub with anchor at start of pattern, GitHub issue
 5341.

---
 regsub.c | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/regsub.c b/regsub.c
index 62d750d8a..9e33a88ab 100644
--- a/regsub.c
+++ b/regsub.c
@@ -90,6 +90,15 @@ regsub(const char *pattern, const char *with, const char *text, int flags)
 		 */
 		regsub_copy(&buf, &len, text, last, m[0].rm_so + start);
 
+		/* For anchored patterns, replace the first match only. */
+		if (*pattern == '^') {
+			regsub_expand(&buf, &len, with, text + start, m,
+			    nitems(m));
+			last = start + m[0].rm_eo;
+			regsub_copy(&buf, &len, text, last, end);
+			break;
+		}
+
 		/*
 		 * If the last match was empty and this one isn't (it is either
 		 * later or has matched text), expand this match. If it is
@@ -109,12 +118,6 @@ regsub(const char *pattern, const char *with, const char *text, int flags)
 			start += m[0].rm_eo + 1;
 			empty = 1;
 		}
-
-		/* Stop now if anchored to start. */
-		if (*pattern == '^') {
-			regsub_copy(&buf, &len, text, start, end);
-			break;
-		}
 	}
 	buf[len] = '\0';