[Monotone-devel] Re: propagate failure: usage constaint

[graydon hoare]

Peter Simons wrote:
> When trying to propagate the changes made in one branch to
> another, I get the following error:
>
>   monotone: matched 5 del/add pairs as deltas
>   monotone: file sets 'left adds' and 'right dels' do not intersect
>   monotone: file sets 'left dels' and 'right adds' do not intersect
>   monotone: file sets 'left move sources' and 'right adds' do not intersect
>   monotone: file sets 'left adds' and 'right move sources' do not intersect
>   monotone: file sets 'left move sources' and 'right dels' do not intersect
>   monotone: file sets 'left dels' and 'right move sources' do not intersect
>   monotone: conflict: file sets 'left move sources' and 'right deltas' intersect
>   monotone: commands.cc:562: usage constraint 'N(merge3(ancestor_map, left_map, 
> right_map, app, merger, merged_map, left_renames.mapping, 
> right_renames.mapping))' violated
>   monotone: db.execute("ROLLBACK")
>   monotone: misuse: failed to 3-way merge manifests 
> 73675ed451bf404b83dca9c7b302f504740b6a07 and 
> 7d0968adbf00b12e0b1400cbfa1f1af617ab4583 via ancestor 
> 47cc4f6a2761d7c1f11fa8200444b2484f0f9fcf
>
> Can anyone give me a hint how to fix this?

sure. tree layout merging is immature. it's complaining that you have a 
delta on one edge applying to a file which was moved on another edge. 
this is considered a tree layout conflict (possibly incorrectly; I wrote 
a pretty much ad-hoc selection of conditions which count as tree layout 
conflicts).

your options for correcting it are either:

 - look at "monotone diff 47cc 7d09" and
           "monotone diff 47cc 7367"
   and try to work out which delta and move are conflicting,
   then move the file to its old location, merge, and move it back.

 - insert some new logic before the conflict detection phase
   (around diff_patch.cc:1110) to change the delta to apply to the
   new filename.

 - remark at how this seems like a fundamental missing feature, then
   pause for a while, while I go and implement it myself :(

-graydon