From e8994dfe170b979d5298abed658cc1a71a2d0417 Mon Sep 17 00:00:00 2001
From: Peter Hutterer <peter.hutterer@who-t.net>
Date: Thu, 6 Nov 2025 09:07:25 +1000
Subject: [PATCH] util: add handling for an auto type

Because sometimes it's much easier and more readable, e.g.
 auto eis_device = eis_touchscreen_get_device(...)

Part-of: <https://gitlab.freedesktop.org/libinput/libei/-/merge_requests/373>
---
 meson.build       | 9 +++++++++
 src/util-macros.h | 4 ++++
 2 files changed, 13 insertions(+)

diff --git a/meson.build b/meson.build
index 4ab047f..cccab65 100644
--- a/meson.build
+++ b/meson.build
@@ -74,6 +74,15 @@ if cc.has_function('memfd_create', prefix: '#define _GNU_SOURCE\n#include <sys/m
     config_h.set10('HAVE_MEMFD_CREATE', true)
 endif
 
+code = '''
+#include <time.h>
+
+void func() { auto foo = gmtime(NULL); foo->tm_sec = 0; }
+'''
+if cc.compiles(code, name: 'has C23 auto keyword')
+    config_h.set('HAVE_C23_AUTO', '1')
+endif
+
 dep_math = cc.find_library('m', required: false)
 dep_epoll = dependency('epoll-shim', required: false)
 dep_libxkbcommon = dependency('xkbcommon', required: false)
diff --git a/src/util-macros.h b/src/util-macros.h
index f3ee5b1..369ca58 100644
--- a/src/util-macros.h
+++ b/src/util-macros.h
@@ -31,6 +31,10 @@
 #include <unistd.h>
 #include <stdio.h>
 
+#ifndef HAVE_C23_AUTO
+#define auto __auto_type
+#endif
+
 #define ARRAY_LENGTH(a) (sizeof (a) / sizeof (a)[0])
 #define ARRAY_FOR_EACH(_arr, _elem) \
 	for (size_t _i = 0; _i < ARRAY_LENGTH(_arr) && (_elem = &_arr[_i]); _i++)