resolve: use "other" changeset from merge state (issue4163) We can use the "other" data from the recorded merge state instead of inferring what the other could be from working copy parent. This will allow resolve to fulfil its duty even when the second parent have been dropped. Most direct benefit is fixing a regression in backout.

merge: add "other" file node in the merge state file This data is mostly redundant with the "other" changeset node (+ other changeset file path). However, more data never hurt. The old format do not store it so this require some dancing to add and remove it on demand.

merge: infer the "other" changeset when falling back to v1 format When we have to fallback to the old version of the file, we infer the "other" from current working directory parent. The same way it is currently done in the resolve command. This is know to have shortcoming… but we cannot do better from the data contained in the old file format. This is actually the motivation to add this new file format.

merge: record the "other" node in merge state We need to record the merge we were merging with. This solve multiple bug with resolve when dropping the second parent after a merge. This happen a lot when doing special merge (overriding the ancestor). Backout, shelve, rebase, etc. can takes advantage of it. This changeset just add the information in the merge state. We'll use it in the resolve process in a later changeset.

merge: introduce new format for the state file This new format will allow us to address common bugs while doing special merge (graft, backout, rebase…) and record user choice during conflict resolution. The format is open so we can add more record for future usage. This file still store hexified version of node to help human willing to debug it by hand. The overhead or oversize are not expected be an issue. The old format is still used. It will be written to disk along side the newer format. And at parse time we detect if the data from old version of the mergestate are different from the one in the new version file. If its the same, both have most likely be written at the same time and you can trust the extra data from the new file. If it differs, the old file have been written by an older version of mercurial that did not knew about the new file. In that case we use the content of the old file.

merge: change the merge state serialisation to use a record based logic The format of the file is unchanged. But we are preparing a new file with a new format that would be record based. So we change all the read/write logic to handle a list of record until a very low level. This will allow simple plugging of the new format in the current code.

merge: move merge state file path into a constant We are about to change the format. Having the file path in a single place make it easier to update the filename for the new version.

revset: changed spanset __add__ implementation to work lazily $ time hg log -qr "first(0:tip or draft())" ... real 0m1.032s user 0m0.841s sys 0m0.179s $ time ./hg log -qr "first(0:tip or draft())" ... real 0m0.378s user 0m0.291s sys 0m0.085s

revset: changed lazyset __add__ implementation to work lazily Performance Benchmarking: $ time hg log -qr "first(author(mpm) or branch(default))" 0:9117c6561b0b real 0m3.875s user 0m3.818s sys 0m0.051s $ time ./hg log -qr "first(author(mpm) or branch(default))" 0:9117c6561b0b real 0m0.213s user 0m0.174s sys 0m0.038s

obsstore: add a __len__ method We can already use "for mark in store:" it make sense to allow "len(store)" too.