[darcs-devel] [issue1077] wish: whatsnew sanity check (nothing new before == nothing new after)

[Eric Kow]

New submission from Eric Kow <kowey at darcs.net>:

This is a request for comment as well as a wish.  

Perhaps darcs whatsnew should have the following sanity check: if there is
nothing new before I pull or apply patches, there is nothing new after I apply
them.  We can't do much more checking than that (because if there are changes to
the pending patch, they would need to be commuted), but I suspect that this very
simple case could give us some early warning about potential pending patch bugs.

I'm not sure if this should be tolerant or not.  If the sanity check fails, do
we want a "Bug in darcs" or do we just want a big warning?

The context is that I have been thinking about Claus and his battles with
http://bugs.darcs.net/issue693 and http://bugs.darcs.net/issue1034 this morning.
 One of his insights is that it is a pity we can't reason backwards about why
mysterious bugs happen.  Our inability to do this is partly because darcs
doesn't record the fact that things go wrong (e.g. having to tolerantly apply
patches, issue1010)... but sometimes darcs /can't/ in general know that
something has gone wrong (for example, with pending patch bugs).  The invariant
I propose is a just special case where we actually have a clear definition of
"wrong"... so maybe we should exploit it.

----------
messages: 6024
nosy: claus.reinke, dagit, kowey
priority: feature
status: unread
title: wish: whatsnew sanity check (nothing new before == nothing new after)
topic: ThePendingPatch

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