help: add help entry for internals.mergestate
This patch adds an entry for `internals.mergestate` as suggested
by @marmoute. Most of the help text is taken from `merge.mergestate`.
Differential Revision: https://phab.mercurial-scm.org/D6448
Differential Revision: https://phab.mercurial-scm.org/D6528
The active mergestate is stored in ``.hg/merge`` when a merge is triggered
by commands like ``hg merge``, ``hg rebase``, etc. until the merge is
completed or aborted to track the 3-way merge state of individual files.
The contents of the directory are:
Conflicting files
-----------------
The local version of the conflicting files are stored with their
filenames as the hash of their paths.
state
-----
This mergestate file record is used by hg version prior to 2.9.1
and contains less data than ``state2``. If there is no contradiction
with ``state2``, we can assume that both are written at the same time.
In this case, data from ``state2`` is used. Otherwise, we use ``state``.
We read/write both ``state`` and ``state2`` records to ensure backward
compatibility.
state2
------
This record stores a superset of data in ``state``, including new kinds
of records in the future.
Each record can contain arbitrary content and has an associated type. This
`type` should be a letter. If `type` is uppercase, the record is mandatory:
versions of Mercurial that don't support it should abort. If `type` is
lowercase, the record can be safely ignored.
Currently known records:
| * L: the node of the "local" part of the merge (hexified version)
| * O: the node of the "other" part of the merge (hexified version)
| * F: a file to be merged entry
| * C: a change/delete or delete/change conflict
| * D: a file that the external merge driver will merge internally
| (experimental)
| * P: a path conflict (file vs directory)
| * m: the external merge driver defined for this merge plus its run state
| (experimental)
| * f: a (filename, dictionary) tuple of optional values for a given file
| * X: unsupported mandatory record type (used in tests)
| * x: unsupported advisory record type (used in tests)
| * l: the labels for the parts of the merge.
Merge driver run states (experimental):
| * u: driver-resolved files unmarked -- needs to be run next time we're
| about to resolve or commit
| * m: driver-resolved files marked -- only needs to be run before commit
| * s: success/skipped -- does not need to be run any more
Merge record states (indexed by filename):
| * u: unresolved conflict
| * r: resolved conflict
| * pu: unresolved path conflict (file conflicts with directory)
| * pr: resolved path conflict
| * d: driver-resolved conflict
The resolve command transitions between 'u' and 'r' for conflicts and
'pu' and 'pr' for path conflicts.
This format is a list of arbitrary records of the form:
[type][length][content]
`type` is a single character, `length` is a 4 byte integer, and
`content` is an arbitrary byte sequence of length `length`.
Mercurial versions prior to 3.7 have a bug where if there are
unsupported mandatory merge records, attempting to clear out the merge
state with hg update --clean or similar aborts. The 't' record type
works around that by writing out what those versions treat as an
advisory record, but later versions interpret as special: the first
character is the 'real' record type and everything onwards is the data.