[Bug 4199 - Warn on case-changing rename on Windows]

[Matt Harbison]

On Thu, 19 Nov 2015 08:09:04 -0500, Piotr Listkiewicz  
<piotr.listkiewicz at gmail.com> wrote:

> Hi,
> i would like to work on this issue but i don't get what is valid
> solution to this problem from discussion. Should hg warn
> when user want to add file with same name without removing
> file that only differs in case?

Based on comment #5 in the bug, I think it does this already.

> What about
> 'hg rename NAME.XYZ name.xyz' - should it warn or not?

I'd say no, because only one or the other exists at any given time.  The  
reporter apparently got into trouble by using rename (OK), but then  
explicitly committing only the new file (bad).  That effectively turns the  
rename into a copy I guess.  I'm not sure how valid that transformation  
is- maybe commit can check if only part of a rename is being committed,  
and abort?  (Maybe with a (BC) flag?  Get other's opinions before spending  
time on that.  At least this would avoid case collision checking on  
commit.)

Note that comment #5 mentions `hg copy` not giving a warning- that you can  
probably fix separately.

> Another
> option is aborting the commit which would cause case-folding name
> collision. And lastly how can i check if hg is running in case-sensitive
> system or not?

See util.checkcase().

It looks like the ui.portablefilenames setting changes behaviors for  
different scenarios, including case collisions, so you'll want to keep  
that in mind too.  See how cmdutil.add() uses  
scmutil.checkportabilityalert() and scmutil.casecollisionauditor().