meson: Add more tests for system includes

test cases/linuxlike/16 isystem includes/global_include/my_global_lib/my_global.h

@@ -0,0 +1,7 @@
+#pragma once
+
+#include <stdbool.h>
+
+/* Attempt to trigger -Wsizeof-array-div */
+extern int arr1[10];
+const int C0 = sizeof(arr1) / sizeof(short);

test cases/linuxlike/16 isystem includes/local_include1/my_local1_lib/my_local1.h

@@ -0,0 +1,7 @@
+#pragma once
+
+#include <stdbool.h>
+
+/* Attempt to trigger -Wsizeof-array-div */
+extern int arr1[10];
+const int C1 = sizeof(arr1) / sizeof(short);

test cases/linuxlike/16 isystem includes/main.c

@@ -0,0 +1,6 @@
+#include <my_global_lib/my_global.h>
+#include <my_local1_lib/my_local1.h>
+
+int main() {
+	return C0 + C1;
+}

test cases/linuxlike/16 isystem includes/meson.build

@@ -0,0 +1,23 @@
+project('isystem includes', 'c', default_options : 'werror=true')
+
+cc = meson.get_compiler('c')
+
+# Canary warning to check suppression in system headers. Chosen randomly from GCC docs.
+incwarg = '-Wsizeof-array-div'
+
+add_project_dependencies(
+  declare_dependency(
+    include_directories: include_directories('global_include', is_system: true),
+  ),
+  language: ['c'],
+)
+
+local_inc_dep1 = declare_dependency(
+  include_directories: 'local_include1',
+).as_system().partial_dependency(includes : true)
+
+if cc.has_argument(incwarg)
+  executable('main', 'main.c', c_args: incwarg, dependencies: local_inc_dep1)
+else
+  error('MESON_SKIP_TEST compiler does not support emitting canary warning.')
+endif