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Re: mergeinfo assertion in trunk Re: 'svn switch' now requires --ignore-ancestry?

From: Paul Burba <ptburba_at_gmail.com>
Date: Mon, 25 Apr 2011 11:56:30 -0400

On Sat, Apr 23, 2011 at 5:21 AM, Daniel Shahaf <d.s_at_daniel.shahaf.name> wrote:
> On Sat, 23 Apr 2011 07:15 +1000, "Daniel Becroft" <djcbecroft_at_gmail.com> wrote:
>> Hi,
>> I've just updated to trunk_at_1096029, and have noticed the following change in
>> behavior.
>> Previously, any reproduction script I write has the following pattern:
>> svn checkout <url> workingcopy
>> > pushd workingcopy
>> > svn mkdir trunk
>> > svn commit
>> > svn switch <url>/trunk .
>> >
>> This used to work fine. But now I'm getting the following error messages:
>> subversion/svn/switch-cmd.c:184: (apr_err=195012)
>> > svn: E195012: Path '.' does not share common version control ancestry with
>> > the requested switch location.  Use --ignore-ancestry to disable this check.
>> > subversion/libsvn_client/switch.c:201: (apr_err=195012)
>> > svn: E195012: 'file:///home/djcbecroft/dev/sandpit/repository/trunk' shares
>> > no common ancestry with '/home/djcbecroft/dev/sandpit/workingcopy'
>> >
>> As the error message suggests, using --ignore-ancestry works fine. I don't
>> think this is required, though, as the paths share a common ancestry
>> already.
> I've not read the whole thread, but tweaking your recipe I've just run into an assertion in a case I expected to work:
> [[[
> % rm -rf wc1 r1
> % $svnadmin create r1
> % $svn co file://$PWD/r1 wc1
> Checked out revision 0.
> % cd wc1
> % $svn cp . trunk
> svn: E200007: Cannot copy path '/tmp/svn/wc1' into its own child '/tmp/svn/wc1/trunk'
> % $svn cp ^/ ^/trunk -mm

Hi Daniel,

Should we even allow a copy of r0? What exactly does it mean and how
is it useful?

The assert you see here happens because mergeinfo has no concept of r0
as a valid change. When we try this switch without using
--ignore-ancestry, switch.c:switch_internal() calls
svn_client__get_youngest_common_ancestor looking for common ancestor
of ^/trunk_at_1 and ^/@0. svn_client__get_youngest_common_ancestor()
uses svn_client__get_history_as_mergeinfo() to convert ^/trunk_at_1 and
/^@0 to svn_mergeinfo_t.

Unfortunately svn_client__get_history_as_mergeinfo() does this
conversion by using svn_mergeinfo__mergeinfo_from_segments() to covert
svn_location_segment_t's into mergeinfo.
svn_location_segment_t.range_start can be the same as
svn_location_segment_t.range_end, but when
svn_mergeinfo__mergeinfo_from_segments converts these to
svn_merge_range_t, it enforces the rule that svn_merge_range_t.start <
svn_merge_range_t.end (see

So we end up with a bogus rangelist that later trips the assert when
svn_client__get_youngest_common_ancestor() sends it to the
svn_rangelist_intersect API.

Unsure how to address this. We could tweak
svn_client__get_youngest_common_ancestor() to handle this edge case,
but I wonder if preventing copies of r0 in the first place is
something to consider too.


> Committed revision 1.
> % $svn sw ^/trunk
> subversion/libsvn_subr/mergeinfo.c:800: (apr_err=235000)
> svn: E235000: In file 'subversion/libsvn_subr/mergeinfo.c' line 800: assertion failed (IS_VALID_FORWARD_RANGE(first))
> zsh: abort      $svn sw ^/trunk
> ]]]
Received on 2011-04-25 17:57:00 CEST

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