foo.cc: In function ‘bool leap(int)’:
foo.cc:6:18: warning: suggest parentheses around ‘&&’ within ‘||’ [-Wparentheses]
    6 |         if(y%4==0&&y%100!=0||y%400==0)return true;
      |            ~~~~~~^~~~~~~~~~
foo.cc: In function ‘int main()’:
foo.cc:29:9: warning: this ‘while’ clause does not guard... [-Wmisleading-indentation]
   29 |         while(day>365+leap(y));
      |         ^~~~~
foo.cc:30:9: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the ‘while’
   30 |         {
      |         ^