tests: add check to make sure -bad lib headers are C++ compiler clean

Only non-internal libs without external deps for now.

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/6440>

subprojects/gst-plugins-bad/tests/check/libs/gstlibscpp.cc

@@ -0,0 +1,78 @@
+/* GStreamer
+ * Copyright (C) 2024 Tim-Philipp Müller <tim centricular net>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
+ * Boston, MA 02110-1301, USA.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include <gst/gst.h>
+#include <gst/check/gstcheck.h>
+
+#include <gst/analytics/analytics.h>
+
+#include <gst/audio/gstnonstreamaudiodecoder.h>
+#include <gst/audio/gstplanaraudioadapter.h>
+
+#include <gst/basecamerabinsrc/gstbasecamerasrc.h>
+#include <gst/basecamerabinsrc/gstcamerabinpreview.h>
+/*
+#include <gst/codecparsers/x>
+#include <gst/codecs/x>
+#include <gst/cuda/x>
+*/
+#include <gst/insertbin/gstinsertbin.h>
+#include <gst/interfaces/photography.h>
+#include <gst/mpegts/mpegts.h>
+#include <gst/mse/mse.h>
+/*
+#include <gst/opencv/x>
+*/
+#include <gst/play/play.h>
+#include <gst/player/player.h>
+// #include <gst/sctp/x>
+#include <gst/transcoder/gsttranscoder.h>
+/*
+#include <gst/va/x>
+#include <gst/vulkan/x>
+#include <gst/wayland/x>
+*/
+#include <gst/webrtc/webrtc.h>
+
+/* we mostly just want to make sure that our library headers don't
+ * contain anything a C++ compiler might not like */
+GST_START_TEST (test_nothing)
+{
+  gst_init (NULL, NULL);
+}
+
+GST_END_TEST;
+
+static Suite *
+libscpp_suite (void)
+{
+  Suite *s = suite_create ("BadLibsCpp");
+  TCase *tc_chain = tcase_create ("C++ bad libs header tests");
+
+  suite_add_tcase (s, tc_chain);
+  tcase_add_test (tc_chain, test_nothing);
+
+  return s;
+}
+
+GST_CHECK_MAIN (libscpp);

subprojects/gst-plugins-bad/tests/check/meson.build

@@ -114,6 +114,13 @@ base_tests = [
   [['libs/cudamemory.c'], not gstcuda_dep.found(), [gstcuda_dep, gstcuda_stub_dep]],
 ]
 
+# Make sure our headers are C++ clean
+if add_languages('cpp', native: false, required: false)
+  base_tests += [
+    [['libs/gstlibscpp.cc'], false ],
+  ]
+endif
+
 # FIXME: unistd dependency, unstable or not tested yet on windows
 if host_machine.system() != 'windows'
   base_tests += [