Temporary header file '/tmp/C8vScwC9jy/dump1.h' with the following content will be compiled to create GCC translation unit dump:

  // add defines
  #define __STDC_VERSION__ 201710L
#define _GXX_NULLPTR_T
#define CLUTTER_ENABLE_COMPOSITOR_API 1
#define _REGEX_NELTS(n)
#define _Atomic
#define PACKED
#define getaddrinfo_a(a,b,c,d)

  // add includes
  #include "/usr/include/gwenhywfar5/gwen-gui-gtk3/gtk3_gui.h"

The GCC parameters:
  gcc -fdump-lang-raw -fkeep-inline-functions -c -x c++ -fpermissive -w "/tmp/C8vScwC9jy/dump1.h"  -I/usr/include/gwenhywfar5

In file included from /tmp/C8vScwC9jy/dump1.h:12:
/usr/include/gwenhywfar5/gwen-gui-gtk3/gtk3_gui.h:14:10: fatal error: gtk/gtk.h: No such file or directory
   14 | #include <gtk/gtk.h>
      |          ^~~~~~~~~~~
compilation terminated.