/in/foo.cc: In function 'void Concat(char*, int*)':
/in/foo.cc:7:2: warning: this 'for' clause does not guard... [-Wmisleading-indentation]
  for (i = 0; s[i] != 0; i++);
  ^~~
/in/foo.cc:8:2: note: ...this statement, but the latter is misleadingly indented as if it is guarded by the 'for'
  {
  ^
/in/foo.cc:12:13: warning: array subscript has type 'char' [-Wchar-subscripts]
       a[s[i]]++;
             ^