Use "system" include type for all dependencies and add header test

Things get confused when these flags differ across projects, so universally
use "system" for external dependencies and test for header warnings only in
the project that owns them.

5 files changed, 75 insertions, 3 deletions

diff --git a/NEWS b/NEWS
index 6890053..594b4ba 100644
--- a/NEWS
+++ b/NEWS
@@ -1,3 +1,9 @@
+suil (0.10.23) unstable; urgency=medium
+
+  * Add header warnings test
+
+ -- David Robillard <d@drobilla.net>  Mon, 20 Jan 2025 18:06:58 +0000
+
 suil (0.10.22) stable; urgency=medium
 
   * Add support for X11 in Qt6
diff --git a/meson.build b/meson.build
index 3ededac..e785109 100644
--- a/meson.build
+++ b/meson.build
@@ -1,4 +1,4 @@
-# Copyright 2021-2022 David Robillard <d@drobilla.net>
+# Copyright 2021-2025 David Robillard <d@drobilla.net>
 # SPDX-License-Identifier: 0BSD OR ISC
 
 project(
@@ -12,7 +12,7 @@ project(
   ],
   license: 'ISC',
   meson_version: '>= 0.56.0',
-  version: '0.10.22',
+  version: '0.10.23',
 )
 
 suil_src_root = meson.current_source_dir()
@@ -203,7 +203,12 @@ endif
 
 dl_dep = cc.find_library('dl', required: false)
 
-lv2_dep = dependency('lv2', fallback: 'lv2', version: '>= 1.18.4')
+lv2_dep = dependency(
+  'lv2',
+  fallback: 'lv2',
+  include_type: 'system',
+  version: '>= 1.18.4',
+)
 
 x11_dep = dependency(
   'x11',
@@ -466,6 +471,14 @@ if qt6_dep.found()
   )
 endif
 
+#########
+# Tests #
+#########
+
+if not get_option('tests').disabled()
+  subdir('test/headers')
+endif
+
 ########
 # Lint #
 ########
diff --git a/test/headers/.clang-tidy b/test/headers/.clang-tidy
new file mode 100644
index 0000000..c0f1613
--- /dev/null
+++ b/test/headers/.clang-tidy
@@ -0,0 +1,13 @@
+# Copyright 2020-2025 David Robillard <d@drobilla.net>
+# SPDX-License-Identifier: 0BSD OR ISC
+
+Checks: >
+  *,
+  -altera-*,
+  -llvmlibc-*,
+CheckOptions:
+  - key:   readability-function-cognitive-complexity.Threshold
+    value: '0'
+WarningsAsErrors: '*'
+HeaderFilterRegex: '.*'
+FormatStyle: file
diff --git a/test/headers/meson.build b/test/headers/meson.build
new file mode 100644
index 0000000..191159c
--- /dev/null
+++ b/test/headers/meson.build
@@ -0,0 +1,27 @@
+# Copyright 2020-2025 David Robillard <d@drobilla.net>
+# SPDX-License-Identifier: 0BSD OR ISC
+
+header_c_suppressions = []
+
+if get_option('warning_level') == 'everything'
+  if cc.get_id() == 'clang'
+    if not meson.is_cross_build()
+      header_c_suppressions += ['-Wno-poison-system-directories']
+    endif
+  endif
+endif
+
+if cc.get_id() == 'clang'
+  header_c_suppressions += ['-Wno-nullability-extension']
+endif
+
+test(
+  'headers',
+  executable(
+    'test_headers',
+    files('test_headers.c'),
+    c_args: header_c_suppressions,
+    dependencies: suil_dep,
+  ),
+  suite: 'unit',
+)
diff --git a/test/headers/test_headers.c b/test/headers/test_headers.c
new file mode 100644
index 0000000..f79c9c6
--- /dev/null
+++ b/test/headers/test_headers.c
@@ -0,0 +1,13 @@
+// Copyright 2022-2025 David Robillard <d@drobilla.net>
+// SPDX-License-Identifier: ISC
+
+#include <suil/suil.h> // IWYU pragma: keep
+
+#if defined(__GNUC__)
+__attribute__((const))
+#endif
+int
+main(void)
+{
+  return 0;
+}