https://github.com/libsdl-org/autoconf/commit/486065814804c3335091260924ce583cd614eff7
From 486065814804c3335091260924ce583cd614eff7 Mon Sep 17 00:00:00 2001
From: Paul Eggert <[EMAIL REDACTED]>
Date: Sun, 15 May 2022 22:14:57 -0700
Subject: [PATCH] Work around AT&T 3b1 bug
* lib/m4sugar/m4sh.m4: Work around bug in ancient sed.
Problem reported by Alain Knaff [sr#110654] for AT&T 3b1.
The Autoconf manual says this sed bug also occurs for
RISC/OS and IRIX 5.3.
---
lib/m4sugar/m4sh.m4 | 2 ++
1 file changed, 2 insertions(+)
diff --git a/lib/m4sugar/m4sh.m4 b/lib/m4sugar/m4sh.m4
index e6067ecf..8323eb1d 100644
--- a/lib/m4sugar/m4sh.m4
+++ b/lib/m4sugar/m4sh.m4
@@ -1221,6 +1221,8 @@ dnl Eggert wrote the scripts with optimization help from Paolo Bonzini).
/[$]LINENO/=
' <$as_myself |
sed '
+ t clear
+ :clear
s/[$]LINENO.*/&-/
t lineno
b