Temporary header file '/tmp/P1lk6zNEf6/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/opencv4/opencv2/imgcodecs/imgcodecs_c.h"
  #include "/usr/include/opencv4/opencv2/imgcodecs/ios.h"
  #include "/usr/include/opencv4/opencv2/imgcodecs/legacy/constants_c.h"
  #include "/usr/include/opencv4/opencv2/imgcodecs/macosx.h"
  #include "/usr/include/opencv4/opencv2/imgcodecs.hpp"

The GCC parameters:
  gcc -fdump-lang-raw -fkeep-inline-functions -c -x c++ -fpermissive -w "/tmp/P1lk6zNEf6/dump1.h"  -I/usr/include/opencv4 -I/usr/include/arm-linux-gnueabihf/opencv4/opencv2

In file included from /tmp/P1lk6zNEf6/dump1.h:12:
/usr/include/opencv4/opencv2/imgcodecs/imgcodecs_c.h:1:2: error: #error "This header with legacy C API declarations has been removed from OpenCV. Legacy constants are available from legacy/constants_c.h file."
    1 | #error "This header with legacy C API declarations has been removed from OpenCV. Legacy constants are available from legacy/constants_c.h file."
      |  ^~~~~
In file included from /tmp/P1lk6zNEf6/dump1.h:13:
/usr/include/opencv4/opencv2/imgcodecs/ios.h:44:9: fatal error: UIKit/UIKit.h: No such file or directory
   44 | #import <UIKit/UIKit.h>
      |         ^~~~~~~~~~~~~~~
compilation terminated.