Subrepos and diff command

Eric ROSHAN EISNER eric.d.eisner at gmail.com
Fri Oct 21 11:47:20 CDT 2011


On Fri, Oct 21, 2011 at 09:07, Patrick Mézard <pmezard at gmail.com> wrote:

> Le 21/10/11 17:56, Eric ROSHAN EISNER a écrit :
> > On Fri, Oct 21, 2011 at 07:30, Patrick Mézard <pmezard at gmail.com<mailto:
> pmezard at gmail.com>> wrote:
> >
> >     I have some questions after looking at "Issue3056 - hg diff/status -
> subrepo files not listed on revision where subrepo was added". With the
> following setup (one modified subrepo being added):
> >
> >      $ hg init sub
> >      $ echo b > sub/b
> >      $ hg -R sub add sub/b
> >      $ hg -R sub ci -m "addb"
> >      $ hg init repo
> >      $ cd repo
> >      $ hg clone ../sub sub
> >      $ echo sub = sub > .hgsub
> >      $ hg add .hgsub
> >      $ echo b >> sub/b
> >
> >     1- Should "hg diff -S" display the changes to sub/b ?
> >
> >     I guess it should, it is the whole point of -S.
> >
> >     2- Say we commit this change as revision 0. Should "hg diff -S
> --change 0" display the changes to sub/b ?
> >
> >     Yes for consistency with [1].
> >
> >     No because it is undefined : we know the subrepo was introduced at
> revision 1, we do not know the use start adding it while being at revision 0
> and committed it recursively.
> >
> >     3- Say we modify "sub" 3 times with as many recursive commits. Should
> "hg diff -S -r null:3" display the changes to sub/b and which ones ?
> >
> >
> > The transparent thing to do is show the file diffs as if these files were
> directly tracked by the main repo. Since these files were unknown in rev 0
> and known in rev 3, diff -S should show them all adding their full contents
> from /dev/null. Before you wrote this I had been under the impression that
> diff -S and status -S already did this.
> >
> > Either way the subdiffs are useless for patching purposes (as any new
> commit made with them will conflict with .hgsubstate).
>
> Then how do you address [1]? Display a diff of sub/b against /dev/null
> instead of the actual change in the subrepo?
>
> If you do that, you do not know what you are committing in the subrepo
> unless you ask the subrepo yourself.


Well you're doing two different things with the recursive commit, so I think
it's reasonable to ask the two repos separately to get the two different
answers.

  $ hg diff -S # effect on root repo
  ---/dev/null
  +++sub/b
  +b
  +b
  $ cd sub
  $ hg diff # effect on sub repo
  ---sub/b
  +++sub/b
  b
  +b
  $ hg commit -m b2 # manual recursive commit
  $ cd ..
  $ hg diff -S
  ---/dev/null
  +++sub/b
  +b
  +b

Importantly, it is consistent that a diff -S in the root repo gives the same
result before and after the inner commit, because they end up with the same
contents. I agree this is a bit confusing, but it reflects the confusing
nature of recursive commit.
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