From 1d70fbe4c83d6439716a054f6c074202c534a425 Mon Sep 17 00:00:00 2001
From: Philipp Stephani <phst@google.com>
Date: Sat, 1 Aug 2020 20:59:09 +0200
Subject: [PATCH] * src/alloc.c (resize_string_data): Adjust string bytes
 (Bug#42540)

---
 src/alloc.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/src/alloc.c b/src/alloc.c
index 5b9c6e4eb1f..f203061161b 100644
--- a/src/alloc.c
+++ b/src/alloc.c
@@ -1947,6 +1947,9 @@ resize_string_data (Lisp_Object string, ptrdiff_t cidx_byte,
       /* No need to reallocate, as the size change falls within the
 	 alignment slop.  */
       XSTRING (string)->u.s.size_byte = new_nbytes;
+#ifdef GC_CHECK_STRING_BYTES
+      SDATA_NBYTES (old_sdata) = new_nbytes;
+#endif
       new_charaddr = data + cidx_byte;
       memmove (new_charaddr + new_clen, new_charaddr + clen,
 	       nbytes - (cidx_byte + (clen - 1)));
-- 
2.39.2