From 24b3f138b027a23b553f4baec4d907a52b6c8cd5 Mon Sep 17 00:00:00 2001
From: Aki Tuomi <aki.tuomi@open-xchange.com>
Date: Thu, 4 Sep 2025 08:46:06 +0300
Subject: [PATCH] m4: Fix how pcre2_substitute_callout_block is checked

The old way was very wrong
---
 m4/want_pcre.m4 | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/m4/want_pcre.m4 b/m4/want_pcre.m4
index f013aaad82..692a673177 100644
--- a/m4/want_pcre.m4
+++ b/m4/want_pcre.m4
@@ -14,7 +14,12 @@ AC_DEFUN([DOVECOT_WANT_PCRE], [
   AS_IF([test "$have_pcre" != "no"], [
     old_CFLAGS="$CFLAGS"
     CFLAGS="$CFLAGS $LIBPCRE_CFLAGS"
-    AC_CHECK_FUNCS([pcre2_substitute_callout_block])
+    AC_CHECK_DECL([pcre2_substitute_callout_block],
+      AC_DEFINE(HAVE_PCRE2_SUBSTITUTE_CALLOUT_BLOCK,,
+        [Define if you have pcre2_substitute_callout_block]),,
+      [[#define PCRE2_CODE_UNIT_WIDTH 0]]
+      [[#include <pcre2.h>]]
+    )
     CFLAGS="$old_CFLAGS"
     AC_DEFINE(HAVE_LIBPCRE,, [Define if you have libpcre2 backed regular expressions])
   ])
-- 
2.47.3