On Friday, 26 February 2016 at 18:19:57 UTC, Steven Schveighoffer
wrote:
The idea is that ldc and gdc will get plenty of warning if
something breaks.
As stated, this in itself would be utterly useless. Right now,
you can be absolutely certain that the AST semantics will change
in between each DMD release. Sometimes in obvious ways because
fields are removed and so on, but much more often silently and in
a hard-to-track-down fashion because the structure of the AST or
the interpretation of certain node properties changes.
In other words, we don't need any warning that something breaks,
because we already know it will. The people that need the warning
are the authors of the breaking front-end commits, so that they
can properly document the changes and make sure they are
acceptable for the other backends (right now, you typically have
to reverse-engineer that from the DMD glue layer changes).
Ideally, of course, no such changes would be merged without
making sure that all the backends have already been adapted for
them first.
— David
