foo.cc: In function ‘bool operator<(const Data&, const Data&)’:
foo.cc:32:17: warning: this ‘if’ clause does not guard... [-Wmisleading-indentation]
   32 |                 if(a.y==b.y)
      |                 ^~
foo.cc:35:25: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the ‘if’
   35 |                         return a.m<b.m;
      |                         ^~~~~~