foo.cc: In function 'int main()':
foo.cc:8:2: warning: this 'for' clause does not guard... [-Wmisleading-indentation]
  for(int i=m1;i<m2;i++)
  ^~~
foo.cc:10:3: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'for'
   gd=gd-d1+d2;
   ^~
foo.cc:10:8: warning: 'gd' may be used uninitialized in this function [-Wmaybe-uninitialized]
   gd=gd-d1+d2;
      ~~^~~