Temporary header file '/tmp/UR_ZmyvS0B/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/capnp/any.h"
  #include "/usr/include/capnp/blob.h"
  #include "/usr/include/capnp/c++.capnp.h"
  #include "/usr/include/capnp/capability.h"
  #include "/usr/include/capnp/common.h"
  #include "/usr/include/capnp/compat/json.capnp.h"
  #include "/usr/include/capnp/compat/json.h"
  #include "/usr/include/capnp/compat/std-iterator.h"
  #include "/usr/include/capnp/compat/websocket-rpc.h"
  #include "/usr/include/capnp/dynamic.h"
  #include "/usr/include/capnp/endian.h"
  #include "/usr/include/capnp/ez-rpc.h"
  #include "/usr/include/capnp/generated-header-support.h"
  #include "/usr/include/capnp/layout.h"
  #include "/usr/include/capnp/list.h"
  #include "/usr/include/capnp/membrane.h"
  #include "/usr/include/capnp/message.h"
  #include "/usr/include/capnp/orphan.h"
  #include "/usr/include/capnp/persistent.capnp.h"
  #include "/usr/include/capnp/pointer-helpers.h"
  #include "/usr/include/capnp/pretty-print.h"
  #include "/usr/include/capnp/raw-schema.h"
  #include "/usr/include/capnp/rpc-prelude.h"
  #include "/usr/include/capnp/rpc-twoparty.capnp.h"
  #include "/usr/include/capnp/rpc-twoparty.h"
  #include "/usr/include/capnp/rpc.capnp.h"
  #include "/usr/include/capnp/rpc.h"
  #include "/usr/include/capnp/schema-lite.h"
  #include "/usr/include/capnp/schema-loader.h"
  #include "/usr/include/capnp/schema-parser.h"
  #include "/usr/include/capnp/schema.capnp.h"
  #include "/usr/include/capnp/schema.h"
  #include "/usr/include/capnp/serialize-async.h"
  #include "/usr/include/capnp/serialize-packed.h"
  #include "/usr/include/capnp/serialize-text.h"
  #include "/usr/include/capnp/serialize.h"
  #include "/usr/include/capnp/stream.capnp.h"
  #include "/usr/include/kj/arena.h"
  #include "/usr/include/kj/array.h"
  #include "/usr/include/kj/async-inl.h"
  #include "/usr/include/kj/async-io.h"
  #include "/usr/include/kj/async-prelude.h"
  #include "/usr/include/kj/async-queue.h"
  #include "/usr/include/kj/async.h"
  #include "/usr/include/kj/common.h"
  #include "/usr/include/kj/compat/gtest.h"
  #include "/usr/include/kj/compat/gzip.h"
  #include "/usr/include/kj/compat/http.h"
  #include "/usr/include/kj/compat/readiness-io.h"
  #include "/usr/include/kj/compat/tls.h"
  #include "/usr/include/kj/compat/url.h"
  #include "/usr/include/kj/debug.h"
  #include "/usr/include/kj/encoding.h"
  #include "/usr/include/kj/exception.h"
  #include "/usr/include/kj/filesystem.h"
  #include "/usr/include/kj/function.h"
  #include "/usr/include/kj/hash.h"
  #include "/usr/include/kj/io.h"
  #include "/usr/include/kj/list.h"
  #include "/usr/include/kj/main.h"
  #include "/usr/include/kj/map.h"
  #include "/usr/include/kj/memory.h"
  #include "/usr/include/kj/mutex.h"
  #include "/usr/include/kj/one-of.h"
  #include "/usr/include/kj/parse/char.h"
  #include "/usr/include/kj/parse/common.h"
  #include "/usr/include/kj/refcount.h"
  #include "/usr/include/kj/source-location.h"
  #include "/usr/include/kj/std/iostream.h"
  #include "/usr/include/kj/string-tree.h"
  #include "/usr/include/kj/string.h"
  #include "/usr/include/kj/table.h"
  #include "/usr/include/kj/test.h"
  #include "/usr/include/kj/thread.h"
  #include "/usr/include/kj/threadlocal.h"
  #include "/usr/include/kj/time.h"
  #include "/usr/include/kj/timer.h"
  #include "/usr/include/kj/tuple.h"
  #include "/usr/include/kj/units.h"
  #include "/usr/include/kj/vector.h"
  #include "/usr/include/kj/windows-sanity.h"

  // add namespaces
  namespace capnp{typedef int tmp_add_type_1;}
  capnp::tmp_add_type_1 tmp_add_func_1(){return 0;};
  namespace capnp{namespace annotations{typedef int tmp_add_type_2;}}
  capnp::annotations::tmp_add_type_2 tmp_add_func_2(){return 0;};
  namespace capnp{namespace json{typedef int tmp_add_type_3;}}
  capnp::json::tmp_add_type_3 tmp_add_func_3(){return 0;};
  namespace capnp{namespace rpc{typedef int tmp_add_type_4;}}
  capnp::rpc::tmp_add_type_4 tmp_add_func_4(){return 0;};
  namespace capnp{namespace rpc{namespace twoparty{typedef int tmp_add_type_5;}}}
  capnp::rpc::twoparty::tmp_add_type_5 tmp_add_func_5(){return 0;};
  namespace capnp{namespace schema{typedef int tmp_add_type_6;}}
  capnp::schema::tmp_add_type_6 tmp_add_func_6(){return 0;};
  namespace capnp{namespace schemas{typedef int tmp_add_type_7;}}
  capnp::schemas::tmp_add_type_7 tmp_add_func_7(){return 0;};
  namespace kj{typedef int tmp_add_type_8;}
  kj::tmp_add_type_8 tmp_add_func_8(){return 0;};
  namespace kj{namespace parse{typedef int tmp_add_type_9;}}
  kj::parse::tmp_add_type_9 tmp_add_func_9(){return 0;};
  namespace kj{namespace std{typedef int tmp_add_type_10;}}
  kj::std::tmp_add_type_10 tmp_add_func_10(){return 0;};
  namespace capnp{namespace _{typedef int tmp_add_type_11;}}
  capnp::_::tmp_add_type_11 tmp_add_func_11(){return 0;};
  namespace kj{namespace _{typedef int tmp_add_type_12;}}
  kj::_::tmp_add_type_12 tmp_add_func_12(){return 0;};
  namespace kj{namespace parse{namespace _{typedef int tmp_add_type_13;}}}
  kj::parse::_::tmp_add_type_13 tmp_add_func_13(){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;
  gzFile_s* tmp_add_class_3;
  gz_header_s* tmp_add_class_4;
  z_stream_s* tmp_add_class_5;

The GCC parameters:
  gcc -fdump-lang-raw -fkeep-inline-functions -c -x c++ -fpermissive -w "/tmp/UR_ZmyvS0B/dump1.h"  -I/usr/include/capnp