typing: make `unionrepository` subclass `localrepository` while type checking

This is the same change as 9d4ad05bc91c made for `bundlerepository`, for the
same reasons.

Also, add a comment here to suppress the PyCharm warning that the superclass
constructor is not called, that is new now that there's a simulated superclass.
That lack of a call is by design- `makeunionrepository()` does magic that
PyCharm isn't aware of.  But PyCharm has been better at catching problems than
pytype in a lot of cases, so I'd like to reduce the bogus things it flags, to
make the real issues stand out.

mercurial/unionrepo.py

@@ -1,353 +1,360
 # unionrepo.py - repository class for viewing union of repository changesets
 #
 # Derived from bundlerepo.py
 # Copyright 2006, 2007 Benoit Boissinot <[e-mail]>
 # Copyright 2013 Unity Technologies, Mads Kiilerich <[e-mail]>
 #
 # This software may be used and distributed according to the terms of the
 # GNU General Public License version 2 or any later version.
 
 """Repository class for "in-memory pull" of one local repository to another,
 allowing operations like diff and log with revsets.
 """
 
 from __future__ import annotations
 
 import contextlib
-
+import typing
 
 from .i18n import _
 
 from . import (
     changelog,
     cmdutil,
     encoding,
     error,
     filelog,
     localrepo,
     manifest,
     mdiff,
     pathutil,
     revlog,
     util,
     vfs as vfsmod,
 )
 
 from .revlogutils import (
     constants as revlog_constants,
 )
 
 
 class unionrevlog(revlog.revlog):
     def __init__(self, opener, radix, revlog2, linkmapper):
         # How it works:
         # To retrieve a revision, we just need to know the node id so we can
         # look it up in revlog2.
         #
         # To differentiate a rev in the second revlog from a rev in the revlog,
         # we check revision against repotiprev.
         opener = vfsmod.readonlyvfs(opener)
         target = getattr(revlog2, 'target', None)
         if target is None:
             # a revlog wrapper, eg: the manifestlog that is not an actual revlog
             target = revlog2._revlog.target
         revlog.revlog.__init__(self, opener, target=target, radix=radix)
         self.revlog2 = revlog2
 
         n = len(self)
         self.repotiprev = n - 1
         self.bundlerevs = set()  # used by 'bundle()' revset expression
         for rev2 in self.revlog2:
             rev = self.revlog2.index[rev2]
             # rev numbers - in revlog2, very different from self.rev
             (
                 _start,
                 _csize,
                 rsize,
                 base,
                 linkrev,
                 p1rev,
                 p2rev,
                 node,
                 _sdo,
                 _sds,
                 _dcm,
                 _sdcm,
                 rank,
             ) = rev
             flags = _start & 0xFFFF
 
             if linkmapper is None:  # link is to same revlog
                 assert linkrev == rev2  # we never link back
                 link = n
             else:  # rev must be mapped from repo2 cl to unified cl by linkmapper
                 link = linkmapper(linkrev)
 
             if linkmapper is not None:  # link is to same revlog
                 base = linkmapper(base)
 
             this_rev = self.index.get_rev(node)
             if this_rev is not None:
                 # this happens for the common revlog revisions
                 self.bundlerevs.add(this_rev)
                 continue
 
             p1node = self.revlog2.node(p1rev)
             p2node = self.revlog2.node(p2rev)
 
             # TODO: it's probably wrong to set compressed length to -1, but
             # I have no idea if csize is valid in the base revlog context.
             e = (
                 flags,
                 -1,
                 rsize,
                 base,
                 link,
                 self.rev(p1node),
                 self.rev(p2node),
                 node,
                 0,  # sidedata offset
                 0,  # sidedata size
                 revlog_constants.COMP_MODE_INLINE,
                 revlog_constants.COMP_MODE_INLINE,
                 rank,
             )
             self.index.append(e)
             self.bundlerevs.add(n)
             n += 1
 
     @contextlib.contextmanager
     def reading(self):
         if 0 <= len(self.bundlerevs) < len(self.index):
             read_1 = super().reading
         else:
             read_1 = util.nullcontextmanager
         if 0 < len(self.bundlerevs):
             read_2 = self.revlog2.reading
         else:
             read_2 = util.nullcontextmanager
         with read_1(), read_2():
             yield
 
     def _chunk(self, rev):
         if rev <= self.repotiprev:
             return revlog.revlog._chunk(self, rev)
         return self.revlog2._chunk(self.node(rev))
 
     def revdiff(self, rev1, rev2):
         """return or calculate a delta between two revisions"""
         if rev1 > self.repotiprev and rev2 > self.repotiprev:
             return self.revlog2.revdiff(
                 self.revlog2.rev(self.node(rev1)),
                 self.revlog2.rev(self.node(rev2)),
             )
         elif rev1 <= self.repotiprev and rev2 <= self.repotiprev:
             return super(unionrevlog, self).revdiff(rev1, rev2)
 
         return mdiff.textdiff(self.rawdata(rev1), self.rawdata(rev2))
 
     def _revisiondata(self, nodeorrev, raw=False):
         if isinstance(nodeorrev, int):
             rev = nodeorrev
             node = self.node(rev)
         else:
             node = nodeorrev
             rev = self.rev(node)
 
         if rev > self.repotiprev:
             # work around manifestrevlog NOT being a revlog
             revlog2 = getattr(self.revlog2, '_revlog', self.revlog2)
             func = revlog2._revisiondata
         else:
             func = super(unionrevlog, self)._revisiondata
         return func(node, raw=raw)
 
     def addrevision(
         self,
         text,
         transaction,
         link,
         p1,
         p2,
         cachedelta=None,
         node=None,
         flags=revlog.REVIDX_DEFAULT_FLAGS,
         deltacomputer=None,
         sidedata=None,
     ):
         raise NotImplementedError
 
     def addgroup(
         self,
         deltas,
         linkmapper,
         transaction,
         alwayscache=False,
         addrevisioncb=None,
         duplicaterevisioncb=None,
         debug_info=None,
         delta_base_reuse_policy=None,
     ):
         raise NotImplementedError
 
     def strip(self, minlink, transaction):
         raise NotImplementedError
 
     def checksize(self):
         raise NotImplementedError
 
 
 class unionchangelog(unionrevlog, changelog.changelog):
     def __init__(self, opener, opener2):
         changelog.changelog.__init__(self, opener)
         linkmapper = None
         changelog2 = changelog.changelog(opener2)
         unionrevlog.__init__(self, opener, self.radix, changelog2, linkmapper)
 
 
 class unionmanifest(unionrevlog, manifest.manifestrevlog):
     repotiprev: int
     revlog2: manifest.ManifestRevlog
 
     def __init__(self, nodeconstants, opener, opener2, linkmapper):
         # XXX manifestrevlog is not actually a revlog , so mixing it with
         # bundlerevlog is not a good idea.
         manifest.manifestrevlog.__init__(self, nodeconstants, opener)
         manifest2 = manifest.manifestrevlog(nodeconstants, opener2)
         unionrevlog.__init__(
             self, opener, self._revlog.radix, manifest2, linkmapper
         )
 
 
 class unionfilelog(filelog.filelog):
     _revlog: unionrevlog
     repotiprev: int
     revlog2: revlog.revlog
 
     def __init__(self, opener, path, opener2, linkmapper, repo):
         filelog.filelog.__init__(self, opener, path)
         filelog2 = filelog.filelog(opener2, path)
         self._revlog = unionrevlog(
             opener, self._revlog.radix, filelog2._revlog, linkmapper
         )
         self._repo = repo
         self.repotiprev = self._revlog.repotiprev
         self.revlog2 = self._revlog.revlog2
 
     def iscensored(self, rev):
         """Check if a revision is censored."""
         if rev <= self.repotiprev:
             return filelog.filelog.iscensored(self, rev)
         node = self.node(rev)
         return self.revlog2.iscensored(self.revlog2.rev(node))
 
 
 class unionpeer(localrepo.localpeer):
     def canpush(self):
         return False
 
 
-class unionrepository:
+_union_repo_baseclass = object
+
+if typing.TYPE_CHECKING:
+    _union_repo_baseclass = localrepo.localrepository
+
+
+class unionrepository(_union_repo_baseclass):
     """Represents the union of data in 2 repositories.
 
     Instances are not usable if constructed directly. Use ``instance()``
     or ``makeunionrepository()`` to create a usable instance.
     """
 
+    # noinspection PyMissingConstructor
     def __init__(self, repo2, url):
         self.repo2 = repo2
         self._url = url
 
         self.ui.setconfig(b'phases', b'publish', False, b'unionrepo')
 
     @localrepo.unfilteredpropertycache
     def changelog(self):
         return unionchangelog(self.svfs, self.repo2.svfs)
 
     @localrepo.unfilteredpropertycache
     def manifestlog(self):
         rootstore = unionmanifest(
             self.nodeconstants,
             self.svfs,
             self.repo2.svfs,
             self.unfiltered()._clrev,
         )
         return manifest.manifestlog(
             self.svfs, self, rootstore, self.narrowmatch()
         )
 
     def _clrev(self, rev2):
         """map from repo2 changelog rev to temporary rev in self.changelog"""
         node = self.repo2.changelog.node(rev2)
         return self.changelog.rev(node)
 
     def url(self):
         return self._url
 
     def file(self, f):
         return unionfilelog(
             self.svfs, f, self.repo2.svfs, self.unfiltered()._clrev, self
         )
 
     def close(self):
         self.repo2.close()
 
     def cancopy(self):
         return False
 
     def peer(self, path=None, remotehidden=False):
         return unionpeer(self, path=None, remotehidden=remotehidden)
 
     def getcwd(self):
         return encoding.getcwd()  # always outside the repo
 
 
 def instance(ui, path, create, intents=None, createopts=None):
     if create:
         raise error.Abort(_(b'cannot create new union repository'))
     parentpath = ui.config(b"bundle", b"mainreporoot")
     if not parentpath:
         # try to find the correct path to the working directory repo
         parentpath = cmdutil.findrepo(encoding.getcwd())
         if parentpath is None:
             parentpath = b''
     if parentpath:
         # Try to make the full path relative so we get a nice, short URL.
         # In particular, we don't want temp dir names in test outputs.
         cwd = encoding.getcwd()
         if parentpath == cwd:
             parentpath = b''
         else:
             cwd = pathutil.normasprefix(cwd)
             if parentpath.startswith(cwd):
                 parentpath = parentpath[len(cwd) :]
     if path.startswith(b'union:'):
         s = path.split(b":", 1)[1].split(b"+", 1)
         if len(s) == 1:
             repopath, repopath2 = parentpath, s[0]
         else:
             repopath, repopath2 = s
     else:
         repopath, repopath2 = parentpath, path
 
     return makeunionrepository(ui, repopath, repopath2)
 
 
 def makeunionrepository(ui, repopath1, repopath2):
     """Make a union repository object from 2 local repo paths."""
     repo1 = localrepo.instance(ui, repopath1, create=False)
     repo2 = localrepo.instance(ui, repopath2, create=False)
 
     url = b'union:%s+%s' % (
         util.expandpath(repopath1),
         util.expandpath(repopath2),
     )
 
     class derivedunionrepository(unionrepository, repo1.__class__):
         pass
 
     repo = repo1
     repo.__class__ = derivedunionrepository
     unionrepository.__init__(repo1, repo2, url)
 
     return repo