Temporary header file '/tmp/ou_ITUwVgi/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
#ifdef __cplusplus
// C17 compat layer
#define _Alignof(type) alignof(type)
#endif
#define getaddrinfo_a(a,b,c,d)

  // add includes
  #include "/usr/include/octomap/AbstractOcTree.h"
  #include "/usr/include/octomap/AbstractOccupancyOcTree.h"
  #include "/usr/include/octomap/ColorOcTree.h"
  #include "/usr/include/octomap/CountingOcTree.h"
  #include "/usr/include/octomap/MCTables.h"
  #include "/usr/include/octomap/MapCollection.h"
  #include "/usr/include/octomap/MapCollection.hxx"
  #include "/usr/include/octomap/MapNode.h"
  #include "/usr/include/octomap/MapNode.hxx"
  #include "/usr/include/octomap/OcTree.h"
  #include "/usr/include/octomap/OcTreeBase.h"
  #include "/usr/include/octomap/OcTreeBaseImpl.h"
  #include "/usr/include/octomap/OcTreeBaseImpl.hxx"
  #include "/usr/include/octomap/OcTreeDataNode.h"
  #include "/usr/include/octomap/OcTreeDataNode.hxx"
  #include "/usr/include/octomap/OcTreeIterator.hxx"
  #include "/usr/include/octomap/OcTreeKey.h"
  #include "/usr/include/octomap/OcTreeNode.h"
  #include "/usr/include/octomap/OcTreeStamped.h"
  #include "/usr/include/octomap/OccupancyOcTreeBase.h"
  #include "/usr/include/octomap/OccupancyOcTreeBase.hxx"
  #include "/usr/include/octomap/Pointcloud.h"
  #include "/usr/include/octomap/ScanGraph.h"
  #include "/usr/include/octomap/math/Pose6D.h"
  #include "/usr/include/octomap/math/Quaternion.h"
  #include "/usr/include/octomap/math/Utils.h"
  #include "/usr/include/octomap/math/Vector3.h"
  #include "/usr/include/octomap/octomap.h"
  #include "/usr/include/octomap/octomap_deprecated.h"
  #include "/usr/include/octomap/octomap_timing.h"
  #include "/usr/include/octomap/octomap_types.h"
  #include "/usr/include/octomap/octomap_utils.h"

  // add namespaces
  namespace octomap{typedef int tmp_add_type_1;}
  octomap::tmp_add_type_1 tmp_add_func_1(){return 0;};
  namespace octomath{typedef int tmp_add_type_2;}
  octomath::tmp_add_type_2 tmp_add_func_2(){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;
  itimerval* tmp_add_class_3;

The GCC parameters:
  gcc -fdump-lang-raw -fkeep-inline-functions -c -x c++ -fpermissive -w "/tmp/ou_ITUwVgi/dump1.h"