From c5642697e7e51a5984fd7574f4e3723f42ee9ed5 Mon Sep 17 00:00:00 2001
From: fanquake <fanquake@gmail.com>
Date: Tue, 13 Jul 2021 15:08:44 +0800
Subject: [PATCH] build: fail with a useful error message if pkg-config isn't
 available

---
 m4/libevent_openssl.m4 | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/m4/libevent_openssl.m4 b/m4/libevent_openssl.m4
index 178cf387..1adc583f 100644
--- a/m4/libevent_openssl.m4
+++ b/m4/libevent_openssl.m4
@@ -1,6 +1,9 @@
 dnl ######################################################################
 dnl OpenSSL support
 AC_DEFUN([LIBEVENT_OPENSSL], [
+
+m4_ifndef([PKG_PROG_PKG_CONFIG], [AC_MSG_ERROR([PKG_PROG_PKG_CONFIG not found. Please install pkg-config and re-run autogen.sh])])
+
 PKG_PROG_PKG_CONFIG([0.15.0])
 
 case "$host_os" in
-- 
2.50.1