gistfile1.txt

C:\Users\Tony\dev\perl\git>type mbsurr.c
#include <windows.h>
#include <stdio.h>
#include <string.h>

char mbcs[] = "\xED\xA0\x81"; // D801

int main() {

  wchar_t out[20];
  int len = MultiByteToWideChar(CP_UTF8, 0, mbcs, strlen(mbcs), out, 20);
  printf("len %d error %lu\n", len, (unsigned long)GetLastError());
  for (int i = 0; i < len; ++i) {
    printf("%04x\n", out[i]);
  }
}

C:\Users\Tony\dev\perl\git>cl mbsurr.c
Microsoft (R) C/C++ Optimizing Compiler Version 19.43.34808 for x64
Copyright (C) Microsoft Corporation.  All rights reserved.

mbsurr.c
Microsoft (R) Incremental Linker Version 14.43.34808.0
Copyright (C) Microsoft Corporation.  All rights reserved.

/out:mbsurr.exe
mbsurr.obj

C:\Users\Tony\dev\perl\git>mbsurr
len 2 error 0
fffd
fffd