Temporary header file '/tmp/DDwHv7D8Ps/dump1.h' with the following content will be compiled to create GCC translation unit dump:

  // add defines
  #define __STDC_VERSION__ 201710L
#define _TIME_BITS 64
#define _FILE_OFFSET_BITS 64
#define _GXX_NULLPTR_T
#define CLUTTER_ENABLE_COMPOSITOR_API 1
#define _REGEX_NELTS(n)
#define _Atomic
#define PACKED

  // add includes
  #include "/usr/include/libimagequant.h"

  // add classes
  liq_color* tmp_add_class_0;
  liq_histogram_entry* tmp_add_class_1;
  liq_palette* tmp_add_class_2;

The GCC parameters:
  gcc -fdump-lang-raw -fkeep-inline-functions -c -x c++ -fpermissive -w "/tmp/DDwHv7D8Ps/dump1.h"