From c155f0500e90882d41709fbdc1b37cb479ed6249 Mon Sep 17 00:00:00 2001
From: Marko Lindqvist <cazfi74@gmail.com>
Date: Sat, 4 Nov 2023 08:56:08 +0200
Subject: [PATCH 26/26] Meson: Add "zero-byte malloc()" check

See osdn #48936

Signed-off-by: Marko Lindqvist <cazfi74@gmail.com>
---
 gen_headers/meson_fc_config.h.in |  3 +++
 meson.build                      | 19 +++++++++++++++++++
 2 files changed, 22 insertions(+)

diff --git a/gen_headers/meson_fc_config.h.in b/gen_headers/meson_fc_config.h.in
index 9d1f90054a..315d330942 100644
--- a/gen_headers/meson_fc_config.h.in
+++ b/gen_headers/meson_fc_config.h.in
@@ -416,3 +416,6 @@
 
 /* Custom path to CA cert bundle */
 #mesondefine CUSTOM_CACERT_PATH
+
+/* It's ok to call malloc() for zero bytes */
+#mesondefine MALLOC_ZERO_OK
diff --git a/meson.build b/meson.build
index 0f69747888..cfed0f9e08 100644
--- a/meson.build
+++ b/meson.build
@@ -982,6 +982,25 @@ void me::top() { [=, this]() {}; };
   pub_conf_data.set('FREECIV_HAVE_CXX20_CAPTURE_THIS', 1)
 endif
 
+zbm = c_compiler.run('''
+#include <stdlib.h>
+int main()
+{
+  void *allocation = malloc(0);
+
+  if (allocation != NULL) {
+    free(allocation);
+  }
+
+  return (allocation == NULL);
+}''',
+     name: 'zero-byte malloc()',
+     args: ['-Werror', '-Wall'])
+
+if zbm.returncode() == 0
+  priv_conf_data.set('MALLOC_ZERO_OK', 1)
+endif
+
 configure_file(input : 'gen_headers/meson_fc_config.h.in',
                output : 'fc_config.h',
                configuration: priv_conf_data)
-- 
2.42.0