/in/foo.cc: In function 'bign& operator++(bign&, int)':
/in/foo.cc:258:12: warning: reference to local variable 't' returned [-Wreturn-local-addr]
  258 |     return t;
      |            ^
/in/foo.cc:256:10: note: declared here
  256 |     bign t=a;
      |          ^
/in/foo.cc: In function 'bign& operator--(bign&, int)':
/in/foo.cc:269:12: warning: reference to local variable 't' returned [-Wreturn-local-addr]
  269 |     return t;
      |            ^
/in/foo.cc:267:10: note: declared here
  267 |     bign t=a;
      |          ^