[PATCH 1 of 2 V2] debug: add debugexplainunstable that explains instabilities

[Yuya Nishihara]

On Wed, 14 Mar 2018 19:07:16 +0800, Anton Shestakov wrote:
> On Wed, 28 Feb 2018 00:44:49 +0900
> Yuya Nishihara <yuya at tcha.org> wrote:
> 
> > On Tue, 27 Feb 2018 21:11:17 +0800, Anton Shestakov wrote:
> > > On Tue, 27 Feb 2018 20:45:21 +0900
> > > Yuya Nishihara <yuya at tcha.org> wrote:
> > > 
> > > > On Mon, 26 Feb 2018 22:05:26 +0800, Anton Shestakov wrote:
> > > > > # HG changeset patch
> > > > > # User Anton Shestakov <av6 at dwimlabs.net>
> > > > > # Date 1519649041 -28800
> > > > > #      Mon Feb 26 20:44:01 2018 +0800
> > > > > # Node ID 0aa1728931cc2c2c7d6ee0f18e0618fc17add42a
> > > > > # Parent  aefb75730ea34f545f0756bf8441fc9ae07bf8dc
> > > > > debug: add debugexplainunstable that explains instabilities  
> > > > 
> > > > > diff --git a/mercurial/obsolete.py b/mercurial/obsolete.py
> > > > > --- a/mercurial/obsolete.py
> > > > > +++ b/mercurial/obsolete.py
> > > > > @@ -1039,3 +1039,35 @@ def createmarkers(repo, relations, flag=
> > > > >                                   date=date, metadata=localmetadata,
> > > > >                                   ui=repo.ui)
> > > > >              repo.filteredrevcache.clear()
> > > > > +
> > > > > +def explainunstable(repo, ctx):  
> > > > 
> > > > I think this is an obs"util" function.
> > > 
> > > I thought so too, but then I noticed that explainunstable() uses
> > > `bumpedfix`, which is a constant defined and documented with a pretty
> > > long comment in obsolete.py, and the only other use of it is
> > > incidentally also in obsolete.py, in a function that computes all
> > > phase-divergent changesets (_computephasedivergentset). Its code is
> > > very similar to what explainunstable function uses to explain the
> > > corresponding instability. So I feel that it's fine to put this function
> > > in the same file with the related code. Even if that file is
> > > obsutil.py, but then quite a bit of code from obsolete.py would need to
> > > be moved there too.
> > 
> > Thanks for considering it deeply. I don't have strong opinion, but it seems
> > we're slowly moving non-core parts out of obsolete.py, and templating stuff
> > would be non-core.
> > 
> > Boris, do you have any preference?
> 
> I actually tried to move this function to obsutil, and that required
> moving bumpedfix to obsutil too, otherwise there would be a circular
> import to resolve (because obsolete, naturally, imports obsutil). But
> then I noticed that moving bumpedfix to obsutil breaks evolve extension,
> because it expects to find obsolete.bumpedfix.

Boris?

I think it's okay to move bumpedfix to obsutil.py and re-export by
obsolete.py.

> Importing bumpedfix into
> obsolete directly (from obsutil import ...) to save evolve from
> breaking, in turn, raises a warning because there's only a handful of
> modules that are allowed in direct imports (e.g. from node import hex
> is allowed).

'bumpedfix = obsutil.bumpedfix' should work.