Temporary header file '/tmp/3nN3w8DxmX/dump1.h' with the following content will be compiled to create GCC translation unit dump:

  // add defines
  #define __STDC_VERSION__ 201710L
#define _FILE_OFFSET_BITS 64
#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/Fcitx5/Core/fcitx/action.h"
  #include "/usr/include/Fcitx5/Core/fcitx/addonfactory.h"
  #include "/usr/include/Fcitx5/Core/fcitx/addoninfo.h"
  #include "/usr/include/Fcitx5/Core/fcitx/addoninstance.h"
  #include "/usr/include/Fcitx5/Core/fcitx/addoninstance_details.h"
  #include "/usr/include/Fcitx5/Core/fcitx/addonloader.h"
  #include "/usr/include/Fcitx5/Core/fcitx/addonmanager.h"
  #include "/usr/include/Fcitx5/Core/fcitx/candidatelist.h"
  #include "/usr/include/Fcitx5/Core/fcitx/event.h"
  #include "/usr/include/Fcitx5/Core/fcitx/fcitxcore_export.h"
  #include "/usr/include/Fcitx5/Core/fcitx/focusgroup.h"
  #include "/usr/include/Fcitx5/Core/fcitx/globalconfig.h"
  #include "/usr/include/Fcitx5/Core/fcitx/icontheme.h"
  #include "/usr/include/Fcitx5/Core/fcitx/inputcontext.h"
  #include "/usr/include/Fcitx5/Core/fcitx/inputcontextmanager.h"
  #include "/usr/include/Fcitx5/Core/fcitx/inputcontextproperty.h"
  #include "/usr/include/Fcitx5/Core/fcitx/inputmethodengine.h"
  #include "/usr/include/Fcitx5/Core/fcitx/inputmethodentry.h"
  #include "/usr/include/Fcitx5/Core/fcitx/inputmethodgroup.h"
  #include "/usr/include/Fcitx5/Core/fcitx/inputmethodmanager.h"
  #include "/usr/include/Fcitx5/Core/fcitx/inputpanel.h"
  #include "/usr/include/Fcitx5/Core/fcitx/instance.h"
  #include "/usr/include/Fcitx5/Core/fcitx/menu.h"
  #include "/usr/include/Fcitx5/Core/fcitx/statusarea.h"
  #include "/usr/include/Fcitx5/Core/fcitx/surroundingtext.h"
  #include "/usr/include/Fcitx5/Core/fcitx/text.h"
  #include "/usr/include/Fcitx5/Core/fcitx/userinterface.h"
  #include "/usr/include/Fcitx5/Core/fcitx/userinterfacemanager.h"

  // add namespaces
  namespace fcitx{typedef int tmp_add_type_1;}
  fcitx::tmp_add_type_1 tmp_add_func_1(){return 0;};
  namespace fcitx{namespace filter{typedef int tmp_add_type_2;}}
  fcitx::filter::tmp_add_type_2 tmp_add_func_2(){return 0;};
  namespace fcitx{namespace fs{typedef int tmp_add_type_3;}}
  fcitx::fs::tmp_add_type_3 tmp_add_func_3(){return 0;};
  namespace fcitx{namespace stringutils{typedef int tmp_add_type_4;}}
  fcitx::stringutils::tmp_add_type_4 tmp_add_func_4(){return 0;};
  namespace fcitx{namespace stringutils{namespace details{typedef int tmp_add_type_5;}}}
  fcitx::stringutils::details::tmp_add_type_5 tmp_add_func_5(){return 0;};

  // add classes
  _G_fpos64_t* tmp_add_class_0;
  _G_fpos_t* tmp_add_class_1;
  _IO_cookie_io_functions_t* tmp_add_class_2;

The GCC parameters:
  gcc -fdump-lang-raw -fkeep-inline-functions -c -x c++ -fpermissive -w "/tmp/3nN3w8DxmX/dump1.h"  -I/usr/include/Fcitx5/Utils -I/usr/include/Fcitx5/Core -I/usr/include/Fcitx5/Config