retronym/xsbt — comment on commit 067917a0fb6ad221ed1be8081e1f457260532de2
File: compile/api/SameAPI.scala line 49
By harrah:

This seems fragile. I assume that empirically it doesn't cause a macro client to be recompiled everytime. If that is true, it is probably because of shortcuts that check information in Source. That is supposed to be an optimization, but would now be necessary for correctness. So, if the intention is to _not_ recompile a client every time regardless of whether the macro source file was recompiled, perhaps just a comment that the Compilation shortcut check on Source is necessary for macros.