main.d(217): Error: module `M.Q` from file M\Q.d conflicts with another module Q from file M\Q.d

the line is simply

import Q : foo;

the problem is that it should have been

import M.Q : foo;

There is no module Q.

The error message is in error! There is no other module.

the module is named

module M.Q;

where M is a subdirectory. This is probably suppose to be module Q; but everything works out.

The error message could be more accurate(took me a min to figure out what was going on).