- workaround for https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=280210
- code uses the c11 feature stdatomic.h while it uses --std=c99
- add FreeBSD TUN support: include src/tun_freebsd.c in the platform build

--- meson.build.orig	2026-07-30 03:39:06 UTC
+++ meson.build
@@ -5,7 +5,7 @@ project('libRIST', 'c',
 
 project('libRIST', 'c',
 	version: '0.2.20',
-	default_options: ['c_std=c99', 'warning_level=3', 'libdir=lib'],
+	default_options: ['c_std=c11', 'warning_level=3', 'libdir=lib'],
         meson_version: '>= 0.51.0')
 
 cc = meson.get_compiler('c')
@@ -158,6 +158,8 @@ void test(void) {
 		platform_files += 'src/tun_darwin.c'
 		test_args += '-D_DARWIN_C_SOURCE'
 		add_project_arguments('-D_DARWIN_C_SOURCE', language: 'c')
+	elif host_machine.system() == 'freebsd'
+		platform_files += 'src/tun_freebsd.c'
 	elif host_machine.system() == 'gnu'
 		test_args += '-D_GNU_SOURCE'
 		add_project_arguments('-D_GNU_SOURCE', language: 'c')
@@ -426,7 +428,7 @@ if get_option('static_analyze')
 if get_option('static_analyze')
 	run_target('cppcheck', command : ['cppcheck',
 									  '--quiet',
-									  '--std=c99',
+									  '--std=c11',
 									  '--suppressions-list=' + join_paths(librist_src_root, 'common/configs/cppcheck-suppressions.txt'),
 									  '--project=' + join_paths(meson.build_root(),
 									  'compile_commands.json')])