/in/foo.cc: In function 'int main()':
/in/foo.cc:7:8: error: unable to find numeric literal operator 'operator""\U0000ff1b'
    7 | return 0；
      |        ^~~
/in/foo.cc:7:8: note: use '-fext-numeric-literals' to enable more built-in suffixes
/in/foo.cc:7:11: error: expected ';' before '}' token
    7 | return 0；
      |           ^
      |           ;
    8 | }
      | ~