From 97e6ad49a4604e7e4ca04da2aaafc63cbd5d29d8 Mon Sep 17 00:00:00 2001
From: Jean Boussier <jean.boussier@gmail.com>
Date: Mon, 24 Feb 2025 14:42:09 +0100
Subject: [PATCH] Reuse the backref if it isn't marked as busy.

[Misc #20652]
---
 re.c | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/re.c b/re.c
index 4f7afb6b0b..5d365edb63 100644
--- a/re.c
+++ b/re.c
@@ -1813,11 +1813,20 @@ rb_reg_search_set_match(VALUE re, VALUE str, long pos, int reverse, int set_back
         return ONIG_MISMATCH;
     }
 
-    VALUE match;
-    if (set_match && RTEST(*set_match)) {
+    VALUE match = Qnil;
+    if (set_match) {
         match = *set_match;
     }
-    else {
+
+    if (NIL_P(match)) {
+        match = rb_backref_get();
+    }
+
+    if (!NIL_P(match) && FL_TEST(match, MATCH_BUSY)) {
+        match = Qnil;
+    }
+
+    if (NIL_P(match)) {
         match = match_alloc(rb_cMatch);
     }