diff --git a/contrib/check-code.py b/contrib/check-code.py
--- a/contrib/check-code.py
+++ b/contrib/check-code.py
@@ -758,7 +758,7 @@
             preparefilters(filters)
 
 
-class norepeatlogger(object):
+class norepeatlogger:
     def __init__(self):
         self._lastseen = None
 
diff --git a/contrib/fuzz/mpatch_corpus.py b/contrib/fuzz/mpatch_corpus.py
--- a/contrib/fuzz/mpatch_corpus.py
+++ b/contrib/fuzz/mpatch_corpus.py
@@ -20,7 +20,7 @@
 
 if sys.version_info[0] < 3:
 
-    class py2reprhack(object):
+    class py2reprhack:
         def __repr__(self):
             """Py2 calls __repr__ for `bytes(foo)`, forward to __bytes__"""
             return self.__bytes__()
@@ -28,7 +28,7 @@
 
 else:
 
-    class py2reprhack(object):
+    class py2reprhack:
         """Not needed on py3."""
 
 
diff --git a/contrib/hgclient.py b/contrib/hgclient.py
--- a/contrib/hgclient.py
+++ b/contrib/hgclient.py
@@ -49,7 +49,7 @@
     return server
 
 
-class unixconnection(object):
+class unixconnection:
     def __init__(self, sockpath):
         self.sock = sock = socket.socket(socket.AF_UNIX)
         sock.connect(sockpath)
@@ -62,7 +62,7 @@
         self.sock.close()
 
 
-class unixserver(object):
+class unixserver:
     def __init__(self, sockpath, logpath=None, repopath=None):
         self.sockpath = sockpath
         cmdline = [b'hg', b'serve', b'--cmdserver', b'unix', b'-a', sockpath]
diff --git a/contrib/perf.py b/contrib/perf.py
--- a/contrib/perf.py
+++ b/contrib/perf.py
@@ -369,7 +369,7 @@
     return len
 
 
-class noop(object):
+class noop:
     """dummy context manager"""
 
     def __enter__(self):
@@ -413,7 +413,7 @@
         # available since 2.2 (or ae5f92e154d3)
         from mercurial import node
 
-        class defaultformatter(object):
+        class defaultformatter:
             """Minimized composition of baseformatter and plainformatter"""
 
             def __init__(self, ui, topic, opts):
@@ -652,7 +652,7 @@
 
     origvalue = getattr(obj, _sysstr(name))
 
-    class attrutil(object):
+    class attrutil:
         def set(self, newvalue):
             setattr(obj, _sysstr(name), newvalue)
 
@@ -2942,7 +2942,7 @@
     fm.end()
 
 
-class _faketr(object):
+class _faketr:
     def add(s, x, y, z=None):
         return None
 
diff --git a/contrib/testparseutil.py b/contrib/testparseutil.py
--- a/contrib/testparseutil.py
+++ b/contrib/testparseutil.py
@@ -79,7 +79,7 @@
 ####################
 
 
-class embeddedmatcher(object):  # pytype: disable=ignored-metaclass
+class embeddedmatcher:  # pytype: disable=ignored-metaclass
     """Base class to detect embedded code fragments in *.t test script"""
 
     __metaclass__ = abc.ABCMeta
@@ -156,7 +156,7 @@
     :ends: line number (1-origin), at which embedded code ends (exclusive)
     :code: extracted embedded code, which is single-stringified
 
-    >>> class ambigmatcher(object):
+    >>> class ambigmatcher:
     ...     # mock matcher class to examine implementation of
     ...     # "ambiguous matching" corner case
     ...     def __init__(self, desc, matchfunc):
diff --git a/doc/hgmanpage.py b/doc/hgmanpage.py
--- a/doc/hgmanpage.py
+++ b/doc/hgmanpage.py
@@ -112,7 +112,7 @@
         self.output = visitor.astext()
 
 
-class Table(object):
+class Table:
     def __init__(self):
         self._rows = []
         self._options = ['center']
@@ -312,7 +312,7 @@
         pass
 
     def list_start(self, node):
-        class enum_char(object):
+        class enum_char:
             enum_style = {
                 'bullet': '\\(bu',
                 'emdash': '\\(em',
diff --git a/hgdemandimport/demandimportpy2.py b/hgdemandimport/demandimportpy2.py
--- a/hgdemandimport/demandimportpy2.py
+++ b/hgdemandimport/demandimportpy2.py
@@ -54,7 +54,7 @@
         return importfunc(hgextname, globals, *args, **kwargs)
 
 
-class _demandmod(object):
+class _demandmod:
     """module demand-loader and proxy
 
     Specify 1 as 'level' argument at construction, to import module
diff --git a/hgdemandimport/demandimportpy3.py b/hgdemandimport/demandimportpy3.py
--- a/hgdemandimport/demandimportpy3.py
+++ b/hgdemandimport/demandimportpy3.py
@@ -54,7 +54,7 @@
                 super().exec_module(module)
 
 
-class LazyFinder(object):
+class LazyFinder:
     """A wrapper around a ``MetaPathFinder`` that makes loaders lazy.
 
     ``sys.meta_path`` finders have their ``find_spec()`` called to locate a
diff --git a/hgext/absorb.py b/hgext/absorb.py
--- a/hgext/absorb.py
+++ b/hgext/absorb.py
@@ -83,7 +83,7 @@
 defaultdict = collections.defaultdict
 
 
-class nullui(object):
+class nullui:
     """blank ui object doing nothing"""
 
     debugflag = False
@@ -97,7 +97,7 @@
         return nullfunc
 
 
-class emptyfilecontext(object):
+class emptyfilecontext:
     """minimal filecontext representing an empty file"""
 
     def __init__(self, repo):
@@ -277,7 +277,7 @@
     )
 
 
-class filefixupstate(object):
+class filefixupstate:
     """state needed to apply fixups to a single file
 
     internally, it keeps file contents of several revisions and a linelog.
@@ -655,7 +655,7 @@
             )
 
 
-class fixupstate(object):
+class fixupstate:
     """state needed to run absorb
 
     internally, it keeps paths and filefixupstates.
diff --git a/hgext/blackbox.py b/hgext/blackbox.py
--- a/hgext/blackbox.py
+++ b/hgext/blackbox.py
@@ -105,7 +105,7 @@
 _lastlogger = loggingutil.proxylogger()
 
 
-class blackboxlogger(object):
+class blackboxlogger:
     def __init__(self, ui, repo):
         self._repo = repo
         self._trackedevents = set(ui.configlist(b'blackbox', b'track'))
diff --git a/hgext/bugzilla.py b/hgext/bugzilla.py
--- a/hgext/bugzilla.py
+++ b/hgext/bugzilla.py
@@ -434,7 +434,7 @@
 )
 
 
-class bzaccess(object):
+class bzaccess:
     '''Base class for access to Bugzilla.'''
 
     def __init__(self, ui):
@@ -690,7 +690,7 @@
 # Bugzilla via XMLRPC interface.
 
 
-class cookietransportrequest(object):
+class cookietransportrequest:
     """A Transport request method that retains cookies over its lifetime.
 
     The regular xmlrpclib transports ignore cookies. Which causes
@@ -1095,7 +1095,7 @@
         pass
 
 
-class bugzilla(object):
+class bugzilla:
     # supported versions of bugzilla. different versions have
     # different schemas.
     _versions = {
diff --git a/hgext/convert/common.py b/hgext/convert/common.py
--- a/hgext/convert/common.py
+++ b/hgext/convert/common.py
@@ -34,7 +34,7 @@
     return d.encode('latin1')
 
 
-class _shlexpy3proxy(object):
+class _shlexpy3proxy:
     def __init__(self, l):
         self._l = l
 
@@ -127,7 +127,7 @@
 SKIPREV = b'SKIP'
 
 
-class commit(object):
+class commit:
     def __init__(
         self,
         author,
@@ -157,7 +157,7 @@
         self.ctx = ctx  # for hg to hg conversions
 
 
-class converter_source(object):
+class converter_source:
     """Conversion source interface"""
 
     def __init__(self, ui, repotype, path=None, revs=None):
@@ -307,7 +307,7 @@
         return True
 
 
-class converter_sink(object):
+class converter_sink:
     """Conversion sink (target) interface"""
 
     def __init__(self, ui, repotype, path):
@@ -403,7 +403,7 @@
         raise NotImplementedError
 
 
-class commandline(object):
+class commandline:
     def __init__(self, ui, command):
         self.ui = ui
         self.command = command
diff --git a/hgext/convert/convcmd.py b/hgext/convert/convcmd.py
--- a/hgext/convert/convcmd.py
+++ b/hgext/convert/convcmd.py
@@ -176,7 +176,7 @@
     raise error.Abort(_(b'%s: unknown repository type') % path)
 
 
-class progresssource(object):
+class progresssource:
     def __init__(self, ui, source, filecount):
         self.ui = ui
         self.source = source
@@ -198,7 +198,7 @@
         self.progress.complete()
 
 
-class converter(object):
+class converter:
     def __init__(self, ui, source, dest, revmapfile, opts):
 
         self.source = source
diff --git a/hgext/convert/cvsps.py b/hgext/convert/cvsps.py
--- a/hgext/convert/cvsps.py
+++ b/hgext/convert/cvsps.py
@@ -26,7 +26,7 @@
 )
 
 
-class logentry(object):
+class logentry:
     """Class logentry has the following attributes:
     .author    - author name as CVS knows it
     .branch    - name of branch this revision is on
@@ -577,7 +577,7 @@
     return log
 
 
-class changeset(object):
+class changeset:
     """Class changeset has the following attributes:
     .id        - integer identifying this changeset (list index)
     .author    - author name as CVS knows it
diff --git a/hgext/convert/filemap.py b/hgext/convert/filemap.py
--- a/hgext/convert/filemap.py
+++ b/hgext/convert/filemap.py
@@ -41,7 +41,7 @@
     return posixpath.normpath(path)
 
 
-class filemapper(object):
+class filemapper:
     """Map and filter filenames when importing.
     A name can be mapped to itself, a new name, or None (omit from new
     repository)."""
diff --git a/hgext/convert/git.py b/hgext/convert/git.py
--- a/hgext/convert/git.py
+++ b/hgext/convert/git.py
@@ -19,7 +19,7 @@
 from . import common
 
 
-class submodule(object):
+class submodule:
     def __init__(self, path, node, url):
         self.path = path
         self.node = node
diff --git a/hgext/convert/gnuarch.py b/hgext/convert/gnuarch.py
--- a/hgext/convert/gnuarch.py
+++ b/hgext/convert/gnuarch.py
@@ -27,7 +27,7 @@
 
 
 class gnuarch_source(common.converter_source, common.commandline):
-    class gnuarch_rev(object):
+    class gnuarch_rev:
         def __init__(self, rev):
             self.rev = rev
             self.summary = b''
diff --git a/hgext/convert/subversion.py b/hgext/convert/subversion.py
--- a/hgext/convert/subversion.py
+++ b/hgext/convert/subversion.py
@@ -180,7 +180,7 @@
     return optrev
 
 
-class changedpath(object):
+class changedpath:
     def __init__(self, p):
         self.copyfrom_path = p.copyfrom_path
         self.copyfrom_rev = p.copyfrom_rev
@@ -248,7 +248,7 @@
         get_log_child(ui.fout, *args)
 
 
-class logstream(object):
+class logstream:
     """Interruptible revision log iterator."""
 
     def __init__(self, stdout):
diff --git a/hgext/convert/transport.py b/hgext/convert/transport.py
--- a/hgext/convert/transport.py
+++ b/hgext/convert/transport.py
@@ -70,7 +70,7 @@
     pass
 
 
-class SvnRaTransport(object):
+class SvnRaTransport:
     """
     Open an ra connection to a Subversion repository.
     """
@@ -107,7 +107,7 @@
             self.ra = ra
             svn.ra.reparent(self.ra, self.svn_url.encode('utf8'))
 
-    class Reporter(object):
+    class Reporter:
         def __init__(self, reporter_data):
             self._reporter, self._baton = reporter_data
 
diff --git a/hgext/eol.py b/hgext/eol.py
--- a/hgext/eol.py
+++ b/hgext/eol.py
@@ -185,7 +185,7 @@
 }
 
 
-class eolfile(object):
+class eolfile:
     def __init__(self, ui, root, data):
         self._decode = {
             b'LF': b'to-lf',
diff --git a/hgext/extdiff.py b/hgext/extdiff.py
--- a/hgext/extdiff.py
+++ b/hgext/extdiff.py
@@ -695,7 +695,7 @@
     return dodiff(ui, repo, cmdline, pats, opts)
 
 
-class savedcmd(object):
+class savedcmd:
     """use external program to diff repository (or selected files)
 
     Show differences between revisions for the specified files, using
diff --git a/hgext/fastannotate/context.py b/hgext/fastannotate/context.py
--- a/hgext/fastannotate/context.py
+++ b/hgext/fastannotate/context.py
@@ -159,7 +159,7 @@
 _defaultdiffopthash = hashdiffopts(mdiff.defaultopts)
 
 
-class annotateopts(object):
+class annotateopts:
     """like mercurial.mdiff.diffopts, but is for annotate
 
     followrename: follow renames, like "hg annotate -f"
@@ -196,7 +196,7 @@
 defaultopts = annotateopts()
 
 
-class _annotatecontext(object):
+class _annotatecontext:
     """do not use this class directly as it does not use lock to protect
     writes. use "with annotatecontext(...)" instead.
     """
@@ -783,7 +783,7 @@
             pass
 
 
-class pathhelper(object):
+class pathhelper:
     """helper for getting paths for lockfile, linelog and revmap"""
 
     def __init__(self, repo, path, opts=defaultopts):
diff --git a/hgext/fastannotate/formatter.py b/hgext/fastannotate/formatter.py
--- a/hgext/fastannotate/formatter.py
+++ b/hgext/fastannotate/formatter.py
@@ -19,7 +19,7 @@
 
 # imitating mercurial.commands.annotate, not using the vanilla formatter since
 # the data structures are a bit different, and we have some fast paths.
-class defaultformatter(object):
+class defaultformatter:
     """the default formatter that does leftpad and support some common flags"""
 
     def __init__(self, ui, repo, opts):
diff --git a/hgext/fastannotate/revmap.py b/hgext/fastannotate/revmap.py
--- a/hgext/fastannotate/revmap.py
+++ b/hgext/fastannotate/revmap.py
@@ -48,7 +48,7 @@
 _hshlen = 20
 
 
-class revmap(object):
+class revmap:
     """trivial hg bin hash - linelog rev bidirectional map
 
     also stores a flag (uint8) for each revision, and track renames.
diff --git a/hgext/fastannotate/support.py b/hgext/fastannotate/support.py
--- a/hgext/fastannotate/support.py
+++ b/hgext/fastannotate/support.py
@@ -22,7 +22,7 @@
 )
 
 
-class _lazyfctx(object):
+class _lazyfctx:
     """delegates to fctx but do not construct fctx when unnecessary"""
 
     def __init__(self, repo, node, path):
diff --git a/hgext/fix.py b/hgext/fix.py
--- a/hgext/fix.py
+++ b/hgext/fix.py
@@ -903,7 +903,7 @@
     return names
 
 
-class Fixer(object):
+class Fixer:
     """Wraps the raw config values for a fixer with methods"""
 
     def __init__(
diff --git a/hgext/fsmonitor/__init__.py b/hgext/fsmonitor/__init__.py
--- a/hgext/fsmonitor/__init__.py
+++ b/hgext/fsmonitor/__init__.py
@@ -681,7 +681,7 @@
     )
 
 
-class poststatus(object):
+class poststatus:
     def __init__(self, startclock):
         self._startclock = pycompat.sysbytes(startclock)
 
@@ -756,7 +756,7 @@
             pass
 
 
-class state_update(object):
+class state_update:
     """This context manager is responsible for dispatching the state-enter
     and state-leave signals to the watchman service. The enter and leave
     methods can be invoked manually (for scenarios where context manager
diff --git a/hgext/fsmonitor/pywatchman/__init__.py b/hgext/fsmonitor/pywatchman/__init__.py
--- a/hgext/fsmonitor/pywatchman/__init__.py
+++ b/hgext/fsmonitor/pywatchman/__init__.py
@@ -301,7 +301,7 @@
         )
 
 
-class Transport(object):
+class Transport:
     """communication transport to the watchman server"""
 
     buf = None
@@ -346,7 +346,7 @@
             self.buf.append(b)
 
 
-class Codec(object):
+class Codec:
     """communication encoding for the watchman server"""
 
     transport = None
@@ -859,7 +859,7 @@
         self.transport.write(cmd + b"\n")
 
 
-class client(object):
+class client:
     """Handles the communication with the watchman service"""
 
     sockpath = None
diff --git a/hgext/fsmonitor/pywatchman/pybser.py b/hgext/fsmonitor/pywatchman/pybser.py
--- a/hgext/fsmonitor/pywatchman/pybser.py
+++ b/hgext/fsmonitor/pywatchman/pybser.py
@@ -93,7 +93,7 @@
     return ret
 
 
-class _bser_buffer(object):
+class _bser_buffer:
     def __init__(self, version):
         self.bser_version = version
         self.buf = ctypes.create_string_buffer(8192)
@@ -324,7 +324,7 @@
 # This is a quack-alike with the bserObjectType in bser.c
 # It provides by getattr accessors and getitem for both index
 # and name.
-class _BunserDict(object):
+class _BunserDict:
     __slots__ = ("_keys", "_values")
 
     def __init__(self, keys, values):
@@ -350,7 +350,7 @@
         return len(self._keys)
 
 
-class Bunser(object):
+class Bunser:
     def __init__(self, mutable=True, value_encoding=None, value_errors=None):
         self.mutable = mutable
         self.value_encoding = value_encoding
diff --git a/hgext/fsmonitor/state.py b/hgext/fsmonitor/state.py
--- a/hgext/fsmonitor/state.py
+++ b/hgext/fsmonitor/state.py
@@ -22,7 +22,7 @@
 _versionformat = b">I"
 
 
-class state(object):
+class state:
     def __init__(self, repo):
         self._vfs = repo.vfs
         self._ui = repo.ui
diff --git a/hgext/fsmonitor/watchmanclient.py b/hgext/fsmonitor/watchmanclient.py
--- a/hgext/fsmonitor/watchmanclient.py
+++ b/hgext/fsmonitor/watchmanclient.py
@@ -43,7 +43,7 @@
         super(WatchmanNoRoot, self).__init__(msg)
 
 
-class client(object):
+class client:
     def __init__(self, ui, root, timeout=1.0):
         err = None
         if not self._user:
diff --git a/hgext/git/__init__.py b/hgext/git/__init__.py
--- a/hgext/git/__init__.py
+++ b/hgext/git/__init__.py
@@ -47,7 +47,7 @@
 
 
 # TODO: extract an interface for this in core
-class gitstore(object):  # store.basicstore):
+class gitstore:  # store.basicstore):
     def __init__(self, path, vfstype):
         self.vfs = vfstype(path)
         self.opener = self.vfs
@@ -129,7 +129,7 @@
     return orig(requirements, storebasepath, vfstype)
 
 
-class gitfilestorage(object):
+class gitfilestorage:
     def file(self, path):
         if path[0:1] == b'/':
             path = path[1:]
@@ -161,7 +161,7 @@
 _BMS_PREFIX = 'refs/heads/'
 
 
-class gitbmstore(object):
+class gitbmstore:
     def __init__(self, gitrepo):
         self.gitrepo = gitrepo
         self._aclean = True
diff --git a/hgext/git/dirstate.py b/hgext/git/dirstate.py
--- a/hgext/git/dirstate.py
+++ b/hgext/git/dirstate.py
@@ -66,7 +66,7 @@
 
 
 @interfaceutil.implementer(intdirstate.idirstate)
-class gitdirstate(object):
+class gitdirstate:
     def __init__(self, ui, root, gitrepo):
         self._ui = ui
         self._root = os.path.dirname(root)
diff --git a/hgext/git/gitlog.py b/hgext/git/gitlog.py
--- a/hgext/git/gitlog.py
+++ b/hgext/git/gitlog.py
@@ -29,7 +29,7 @@
 pygit2 = gitutil.get_pygit2()
 
 
-class baselog(object):  # revlog.revlog):
+class baselog:  # revlog.revlog):
     """Common implementations between changelog and manifestlog."""
 
     def __init__(self, gr, db):
@@ -69,7 +69,7 @@
         return t is not None
 
 
-class baselogindex(object):
+class baselogindex:
     def __init__(self, log):
         self._log = log
 
diff --git a/hgext/git/manifest.py b/hgext/git/manifest.py
--- a/hgext/git/manifest.py
+++ b/hgext/git/manifest.py
@@ -15,7 +15,7 @@
 
 
 @interfaceutil.implementer(repository.imanifestdict)
-class gittreemanifest(object):
+class gittreemanifest:
     """Expose git trees (and optionally a builder's overlay) as a manifestdict.
 
     Very similar to mercurial.manifest.treemanifest.
@@ -258,7 +258,7 @@
 
 
 @interfaceutil.implementer(repository.imanifestrevisionstored)
-class gittreemanifestctx(object):
+class gittreemanifestctx:
     def __init__(self, repo, gittree):
         self._repo = repo
         self._tree = gittree
@@ -279,7 +279,7 @@
 
 
 @interfaceutil.implementer(repository.imanifestrevisionwritable)
-class memgittreemanifestctx(object):
+class memgittreemanifestctx:
     def __init__(self, repo, tree):
         self._repo = repo
         self._tree = tree
diff --git a/hgext/githelp.py b/hgext/githelp.py
--- a/hgext/githelp.py
+++ b/hgext/githelp.py
@@ -122,7 +122,7 @@
     return args, opts
 
 
-class Command(object):
+class Command:
     def __init__(self, name):
         self.name = name
         self.args = []
@@ -163,7 +163,7 @@
         return AndCommand(self, other)
 
 
-class AndCommand(object):
+class AndCommand:
     def __init__(self, left, right):
         self.left = left
         self.right = right
diff --git a/hgext/gpg.py b/hgext/gpg.py
--- a/hgext/gpg.py
+++ b/hgext/gpg.py
@@ -64,7 +64,7 @@
 help.CATEGORY_NAMES[_HELP_CATEGORY] = b'Signing changes (GPG)'
 
 
-class gpg(object):
+class gpg:
     def __init__(self, path, key=None):
         self.path = path
         self.key = (key and b" --local-user \"%s\"" % key) or b""
diff --git a/hgext/histedit.py b/hgext/histedit.py
--- a/hgext/histedit.py
+++ b/hgext/histedit.py
@@ -351,7 +351,7 @@
     return b''.join([b'# %s\n' % l if l else b'#\n' for l in lines])
 
 
-class histeditstate(object):
+class histeditstate:
     def __init__(self, repo):
         self.repo = repo
         self.actions = None
@@ -490,7 +490,7 @@
         return self.repo.vfs.exists(b'histedit-state')
 
 
-class histeditaction(object):
+class histeditaction:
     def __init__(self, state, node):
         self.state = state
         self.repo = state.repo
@@ -1142,7 +1142,7 @@
     return struct.unpack(b'hh', fcntl.ioctl(1, termios.TIOCGWINSZ, b'    '))
 
 
-class histeditrule(object):
+class histeditrule:
     def __init__(self, ui, ctx, pos, action=b'pick'):
         self.ui = ui
         self.ctx = ctx
@@ -1242,7 +1242,7 @@
     return line[: n - 2] + b' >'
 
 
-class _chistedit_state(object):
+class _chistedit_state:
     def __init__(
         self,
         repo,
diff --git a/hgext/infinitepush/__init__.py b/hgext/infinitepush/__init__.py
--- a/hgext/infinitepush/__init__.py
+++ b/hgext/infinitepush/__init__.py
@@ -286,7 +286,7 @@
     return remotebookmark
 
 
-class bundlestore(object):
+class bundlestore:
     def __init__(self, repo):
         self._repo = repo
         storetype = self._repo.ui.config(b'infinitepush', b'storetype')
diff --git a/hgext/infinitepush/bundleparts.py b/hgext/infinitepush/bundleparts.py
--- a/hgext/infinitepush/bundleparts.py
+++ b/hgext/infinitepush/bundleparts.py
@@ -101,7 +101,7 @@
         return
 
 
-class copiedpart(object):
+class copiedpart:
     """a copy of unbundlepart content that can be consumed later"""
 
     def __init__(self, part):
diff --git a/hgext/infinitepush/indexapi.py b/hgext/infinitepush/indexapi.py
--- a/hgext/infinitepush/indexapi.py
+++ b/hgext/infinitepush/indexapi.py
@@ -6,7 +6,7 @@
 # GNU General Public License version 2 or any later version.
 
 
-class indexapi(object):
+class indexapi:
     """Class that manages access to infinitepush index.
 
     This class is a context manager and all write operations (like
diff --git a/hgext/infinitepush/store.py b/hgext/infinitepush/store.py
--- a/hgext/infinitepush/store.py
+++ b/hgext/infinitepush/store.py
@@ -25,7 +25,7 @@
     pass
 
 
-class abstractbundlestore(object):  # pytype: disable=ignored-metaclass
+class abstractbundlestore:  # pytype: disable=ignored-metaclass
     """Defines the interface for bundle stores.
 
     A bundle store is an entity that stores raw bundle data. It is a simple
@@ -56,7 +56,7 @@
         """
 
 
-class filebundlestore(object):
+class filebundlestore:
     """bundle store in filesystem
 
     meant for storing bundles somewhere on disk and on network filesystems
diff --git a/hgext/journal.py b/hgext/journal.py
--- a/hgext/journal.py
+++ b/hgext/journal.py
@@ -282,7 +282,7 @@
     __str__ = encoding.strmethod(__bytes__)
 
 
-class journalstorage(object):
+class journalstorage:
     """Storage for journal entries
 
     Entries are divided over two files; one with entries that pertain to the
diff --git a/hgext/keyword.py b/hgext/keyword.py
--- a/hgext/keyword.py
+++ b/hgext/keyword.py
@@ -235,7 +235,7 @@
     return modified, added
 
 
-class kwtemplater(object):
+class kwtemplater:
     """
     Sets up keyword templates, corresponding keyword regex, and
     provides keyword substitution functions.
diff --git a/hgext/largefiles/basestore.py b/hgext/largefiles/basestore.py
--- a/hgext/largefiles/basestore.py
+++ b/hgext/largefiles/basestore.py
@@ -41,7 +41,7 @@
         return b"%s: %s" % (urlutil.hidepassword(self.url), self.detail)
 
 
-class basestore(object):
+class basestore:
     def __init__(self, ui, repo, url):
         self.ui = ui
         self.repo = repo
diff --git a/hgext/largefiles/lfutil.py b/hgext/largefiles/lfutil.py
--- a/hgext/largefiles/lfutil.py
+++ b/hgext/largefiles/lfutil.py
@@ -756,7 +756,7 @@
     return match
 
 
-class automatedcommithook(object):
+class automatedcommithook:
     """Stateful hook to update standins at the 1st commit of resuming
 
     For efficiency, updating standins in the working directory should
diff --git a/hgext/largefiles/overrides.py b/hgext/largefiles/overrides.py
--- a/hgext/largefiles/overrides.py
+++ b/hgext/largefiles/overrides.py
@@ -492,7 +492,7 @@
     large = opts.pop('large', False)
     if large:
 
-        class fakerepo(object):
+        class fakerepo:
             dirstate = lfutil.openlfdirstate(ui, repo)
 
         orig(ui, fakerepo, *pats, **opts)
diff --git a/hgext/lfs/blobstore.py b/hgext/lfs/blobstore.py
--- a/hgext/lfs/blobstore.py
+++ b/hgext/lfs/blobstore.py
@@ -108,7 +108,7 @@
         return None  # progress is handled by the worker client
 
 
-class local(object):
+class local:
     """Local blobstore for large file contents.
 
     This blobstore is used both as a cache and as a staging area for large blobs
@@ -306,7 +306,7 @@
         return None
 
 
-class _gitlfsremote(object):
+class _gitlfsremote:
     def __init__(self, repo, url):
         ui = repo.ui
         self.ui = ui
@@ -642,7 +642,7 @@
                 getattr(h, "close_all", lambda: None)()
 
 
-class _dummyremote(object):
+class _dummyremote:
     """Dummy store storing blobs to temp directory."""
 
     def __init__(self, repo, url):
@@ -661,7 +661,7 @@
                 tostore.download(p.oid(), fp, None)
 
 
-class _nullremote(object):
+class _nullremote:
     """Null store storing blobs to /dev/null."""
 
     def __init__(self, repo, url):
@@ -674,7 +674,7 @@
         pass
 
 
-class _promptremote(object):
+class _promptremote:
     """Prompt user to set lfs.url when accessed."""
 
     def __init__(self, repo, url):
diff --git a/hgext/logtoprocess.py b/hgext/logtoprocess.py
--- a/hgext/logtoprocess.py
+++ b/hgext/logtoprocess.py
@@ -44,7 +44,7 @@
 testedwith = b'ships-with-hg-core'
 
 
-class processlogger(object):
+class processlogger:
     """Map log events to external commands
 
     Arguments are passed on as environment variables.
diff --git a/hgext/mq.py b/hgext/mq.py
--- a/hgext/mq.py
+++ b/hgext/mq.py
@@ -150,7 +150,7 @@
 except KeyError:
     # note: load is lazy so we could avoid the try-except,
     # but I (marmoute) prefer this explicit code.
-    class dummyui(object):
+    class dummyui:
         def debug(self, msg):
             pass
 
@@ -183,7 +183,7 @@
 normname = util.normpath
 
 
-class statusentry(object):
+class statusentry:
     def __init__(self, node, name):
         self.node, self.name = node, name
 
@@ -293,7 +293,7 @@
     return lines
 
 
-class patchheader(object):
+class patchheader:
     def __init__(self, pf, plainmode=False):
         def eatdiff(lines):
             while lines:
@@ -495,7 +495,7 @@
     pass
 
 
-class queue(object):
+class queue:
     def __init__(self, ui, baseui, path, patchdir=None):
         self.basepath = path
         try:
diff --git a/hgext/notify.py b/hgext/notify.py
--- a/hgext/notify.py
+++ b/hgext/notify.py
@@ -314,7 +314,7 @@
 }
 
 
-class notifier(object):
+class notifier:
     '''email notification class.'''
 
     def __init__(self, ui, repo, hooktype):
diff --git a/hgext/phabricator.py b/hgext/phabricator.py
--- a/hgext/phabricator.py
+++ b/hgext/phabricator.py
@@ -668,7 +668,7 @@
     return output.getvalue()
 
 
-class DiffChangeType(object):
+class DiffChangeType:
     ADD = 1
     CHANGE = 2
     DELETE = 3
@@ -679,7 +679,7 @@
     MULTICOPY = 8
 
 
-class DiffFileType(object):
+class DiffFileType:
     TEXT = 1
     IMAGE = 2
     BINARY = 3
@@ -700,7 +700,7 @@
 
 
 @attr.s
-class phabchange(object):
+class phabchange:
     """Represents a Differential change, owns Differential hunks and owned by a
     Differential diff.  Each one represents one file in a diff.
     """
@@ -741,7 +741,7 @@
 
 
 @attr.s
-class phabdiff(object):
+class phabdiff:
     """Represents a Differential diff, owns Differential changes.  Corresponds
     to a commit.
     """
diff --git a/hgext/rebase.py b/hgext/rebase.py
--- a/hgext/rebase.py
+++ b/hgext/rebase.py
@@ -159,7 +159,7 @@
     )
 
 
-class rebaseruntime(object):
+class rebaseruntime:
     """This class is a container for rebase runtime state"""
 
     def __init__(self, repo, ui, inmemory=False, dryrun=False, opts=None):
diff --git a/hgext/releasenotes.py b/hgext/releasenotes.py
--- a/hgext/releasenotes.py
+++ b/hgext/releasenotes.py
@@ -77,7 +77,7 @@
 BULLET_SECTION = _(b'Other Changes')
 
 
-class parsedreleasenotes(object):
+class parsedreleasenotes:
     def __init__(self):
         self.sections = {}
 
@@ -170,7 +170,7 @@
                 self.addnontitleditem(section, paragraphs)
 
 
-class releasenotessections(object):
+class releasenotessections:
     def __init__(self, ui, repo=None):
         if repo:
             sections = util.sortdict(DEFAULT_SECTIONS)
diff --git a/hgext/remotefilelog/basepack.py b/hgext/remotefilelog/basepack.py
--- a/hgext/remotefilelog/basepack.py
+++ b/hgext/remotefilelog/basepack.py
@@ -63,7 +63,7 @@
     PACKOPENMODE = b'rb'
 
 
-class _cachebackedpacks(object):
+class _cachebackedpacks:
     def __init__(self, packs, cachesize):
         self._packs = set(packs)
         self._lrucache = util.lrucachedict(cachesize)
@@ -109,7 +109,7 @@
         self._lastpack = None
 
 
-class basepackstore(object):
+class basepackstore:
     # Default cache size limit for the pack files.
     DEFAULTCACHESIZE = 100
 
@@ -267,7 +267,7 @@
         return newpacks
 
 
-class versionmixin(object):
+class versionmixin:
     # Mix-in for classes with multiple supported versions
     VERSION = None
     SUPPORTED_VERSIONS = [2]
@@ -526,7 +526,7 @@
         self.idxfp.write(struct.pack(b'!BB', self.VERSION, config))
 
 
-class indexparams(object):
+class indexparams:
     __slots__ = (
         'fanoutprefix',
         'fanoutstruct',
diff --git a/hgext/remotefilelog/basestore.py b/hgext/remotefilelog/basestore.py
--- a/hgext/remotefilelog/basestore.py
+++ b/hgext/remotefilelog/basestore.py
@@ -19,7 +19,7 @@
 )
 
 
-class basestore(object):
+class basestore:
     def __init__(self, repo, path, reponame, shared=False):
         """Creates a remotefilelog store object for the given repo name.
 
@@ -412,7 +412,7 @@
         )
 
 
-class baseunionstore(object):
+class baseunionstore:
     def __init__(self, *args, **kwargs):
         # If one of the functions that iterates all of the stores is about to
         # throw a KeyError, try this many times with a full refresh between
diff --git a/hgext/remotefilelog/connectionpool.py b/hgext/remotefilelog/connectionpool.py
--- a/hgext/remotefilelog/connectionpool.py
+++ b/hgext/remotefilelog/connectionpool.py
@@ -15,7 +15,7 @@
 _sshv1peer = sshpeer.sshv1peer
 
 
-class connectionpool(object):
+class connectionpool:
     def __init__(self, repo):
         self._repo = repo
         self._pool = dict()
@@ -65,7 +65,7 @@
             del pathpool[:]
 
 
-class connection(object):
+class connection:
     def __init__(self, pool, peer):
         self._pool = pool
         self.peer = peer
diff --git a/hgext/remotefilelog/contentstore.py b/hgext/remotefilelog/contentstore.py
--- a/hgext/remotefilelog/contentstore.py
+++ b/hgext/remotefilelog/contentstore.py
@@ -17,7 +17,7 @@
 )
 
 
-class ChainIndicies(object):
+class ChainIndicies:
     """A static class for easy reference to the delta chain indicies."""
 
     # The filename of this revision delta
@@ -229,7 +229,7 @@
         self._threaddata.metacache = (node, meta)
 
 
-class remotecontentstore(object):
+class remotecontentstore:
     def __init__(self, ui, fileservice, shared):
         self._fileservice = fileservice
         # type(shared) is usually remotefilelogcontentstore
@@ -274,7 +274,7 @@
         pass
 
 
-class manifestrevlogstore(object):
+class manifestrevlogstore:
     def __init__(self, repo):
         self._store = repo.store
         self._svfs = repo.svfs
diff --git a/hgext/remotefilelog/debugcommands.py b/hgext/remotefilelog/debugcommands.py
--- a/hgext/remotefilelog/debugcommands.py
+++ b/hgext/remotefilelog/debugcommands.py
@@ -81,7 +81,7 @@
         os.remove(temppath)
     r = filelog.filelog(repo.svfs, b'temprevlog')
 
-    class faket(object):
+    class faket:
         def add(self, a, b, c):
             pass
 
diff --git a/hgext/remotefilelog/fileserverclient.py b/hgext/remotefilelog/fileserverclient.py
--- a/hgext/remotefilelog/fileserverclient.py
+++ b/hgext/remotefilelog/fileserverclient.py
@@ -139,7 +139,7 @@
     peer.__class__ = remotefilepeer
 
 
-class cacheconnection(object):
+class cacheconnection:
     """The connection for communicating with the remote cache. Performs
     gets and sets by communicating with an external process that has the
     cache-specific implementation.
@@ -302,7 +302,7 @@
     pipeo.flush()
 
 
-class fileserverclient(object):
+class fileserverclient:
     """A client for requesting files from the remote file server."""
 
     def __init__(self, repo):
@@ -517,7 +517,7 @@
             # returns cache misses.  This enables tests to run easily
             # and may eventually allow us to be a drop in replacement
             # for the largefiles extension.
-            class simplecache(object):
+            class simplecache:
                 def __init__(self):
                     self.missingids = []
                     self.connected = True
diff --git a/hgext/remotefilelog/metadatastore.py b/hgext/remotefilelog/metadatastore.py
--- a/hgext/remotefilelog/metadatastore.py
+++ b/hgext/remotefilelog/metadatastore.py
@@ -141,7 +141,7 @@
         )
 
 
-class remotemetadatastore(object):
+class remotemetadatastore:
     def __init__(self, ui, fileservice, shared):
         self._fileservice = fileservice
         self._shared = shared
diff --git a/hgext/remotefilelog/remotefilelog.py b/hgext/remotefilelog/remotefilelog.py
--- a/hgext/remotefilelog/remotefilelog.py
+++ b/hgext/remotefilelog/remotefilelog.py
@@ -27,7 +27,7 @@
 )
 
 
-class remotefilelognodemap(object):
+class remotefilelognodemap:
     def __init__(self, filename, store):
         self._filename = filename
         self._store = store
@@ -42,7 +42,7 @@
         return node
 
 
-class remotefilelog(object):
+class remotefilelog:
 
     _generaldelta = True
     _flagserrorclass = error.RevlogError
diff --git a/hgext/remotefilelog/remotefilelogserver.py b/hgext/remotefilelog/remotefilelogserver.py
--- a/hgext/remotefilelog/remotefilelogserver.py
+++ b/hgext/remotefilelog/remotefilelogserver.py
@@ -93,7 +93,7 @@
         b'x_rfl_getfile', b'file node', permission=b'pull'
     )(getfile)
 
-    class streamstate(object):
+    class streamstate:
         match = None
         shallowremote = False
         noflatmf = False
diff --git a/hgext/remotefilelog/repack.py b/hgext/remotefilelog/repack.py
--- a/hgext/remotefilelog/repack.py
+++ b/hgext/remotefilelog/repack.py
@@ -498,7 +498,7 @@
     return keepkeys
 
 
-class repacker(object):
+class repacker:
     """Class for orchestrating the repack of data and history information into a
     new format.
     """
@@ -819,7 +819,7 @@
         return sortednodes
 
 
-class repackledger(object):
+class repackledger:
     """Storage for all the bookkeeping that happens during a repack. It contains
     the list of revisions being repacked, what happened to each revision, and
     which source store contained which revision originally (for later cleanup).
@@ -867,7 +867,7 @@
         self.created.add(value)
 
 
-class repackentry(object):
+class repackentry:
     """Simple class representing a single revision entry in the repackledger."""
 
     __slots__ = (
diff --git a/hgext/remotenames.py b/hgext/remotenames.py
--- a/hgext/remotenames.py
+++ b/hgext/remotenames.py
@@ -176,7 +176,7 @@
     items = iteritems
 
 
-class remotenames(object):
+class remotenames:
     """
     This class encapsulates all the remotenames state. It also contains
     methods to access that state in convenient ways. Remotenames are lazy
diff --git a/hgext/schemes.py b/hgext/schemes.py
--- a/hgext/schemes.py
+++ b/hgext/schemes.py
@@ -67,7 +67,7 @@
 _partre = re.compile(br'{(\d+)\}')
 
 
-class ShortRepository(object):
+class ShortRepository:
     def __init__(self, url, scheme, templater):
         self.scheme = scheme
         self.templater = templater
diff --git a/hgext/sqlitestore.py b/hgext/sqlitestore.py
--- a/hgext/sqlitestore.py
+++ b/hgext/sqlitestore.py
@@ -264,7 +264,7 @@
 
 
 @attr.s
-class revisionentry(object):
+class revisionentry:
     rid = attr.ib()
     rev = attr.ib()
     node = attr.ib()
@@ -278,7 +278,7 @@
 
 @interfaceutil.implementer(repository.irevisiondelta)
 @attr.s(slots=True)
-class sqliterevisiondelta(object):
+class sqliterevisiondelta:
     node = attr.ib()
     p1node = attr.ib()
     p2node = attr.ib()
@@ -294,14 +294,14 @@
 
 @interfaceutil.implementer(repository.iverifyproblem)
 @attr.s(frozen=True)
-class sqliteproblem(object):
+class sqliteproblem:
     warning = attr.ib(default=None)
     error = attr.ib(default=None)
     node = attr.ib(default=None)
 
 
 @interfaceutil.implementer(repository.ifilestorage)
-class sqlitefilestore(object):
+class sqlitefilestore:
     """Implements storage for an individual tracked path."""
 
     def __init__(self, db, path, compression):
@@ -1249,7 +1249,7 @@
 
 
 @interfaceutil.implementer(repository.ilocalrepositoryfilestorage)
-class sqlitefilestorage(object):
+class sqlitefilestorage:
     """Repository file storage backed by SQLite."""
 
     def file(self, path):
diff --git a/hgext/transplant.py b/hgext/transplant.py
--- a/hgext/transplant.py
+++ b/hgext/transplant.py
@@ -75,13 +75,13 @@
 )
 
 
-class transplantentry(object):
+class transplantentry:
     def __init__(self, lnode, rnode):
         self.lnode = lnode
         self.rnode = rnode
 
 
-class transplants(object):
+class transplants:
     def __init__(self, path=None, transplantfile=None, opener=None):
         self.path = path
         self.transplantfile = transplantfile
@@ -128,7 +128,7 @@
             self.dirty = True
 
 
-class transplanter(object):
+class transplanter:
     def __init__(self, ui, repo, opts):
         self.ui = ui
         self.repo = repo
diff --git a/hgext/zeroconf/Zeroconf.py b/hgext/zeroconf/Zeroconf.py
--- a/hgext/zeroconf/Zeroconf.py
+++ b/hgext/zeroconf/Zeroconf.py
@@ -231,7 +231,7 @@
 # implementation classes
 
 
-class DNSEntry(object):
+class DNSEntry:
     """A DNS entry"""
 
     def __init__(self, name, type, clazz):
@@ -506,7 +506,7 @@
         return self.toString(b"%s:%s" % (self.server, self.port))
 
 
-class DNSIncoming(object):
+class DNSIncoming:
     """Object representation of an incoming DNS packet"""
 
     def __init__(self, data):
@@ -702,7 +702,7 @@
         return result
 
 
-class DNSOutgoing(object):
+class DNSOutgoing:
     """Object representation of an outgoing packet"""
 
     def __init__(self, flags, multicast=1):
@@ -864,7 +864,7 @@
         return b''.join(self.data)
 
 
-class DNSCache(object):
+class DNSCache:
     """A cache of DNS entries"""
 
     def __init__(self):
@@ -982,7 +982,7 @@
         self.condition.release()
 
 
-class Listener(object):
+class Listener:
     """A Listener is used by this module to listen on the multicast
     group to which DNS messages are sent, allowing the implementation
     to cache information as it arrives.
@@ -1127,7 +1127,7 @@
                 event(self.zeroconf)
 
 
-class ServiceInfo(object):
+class ServiceInfo:
     """Service information"""
 
     def __init__(
@@ -1386,7 +1386,7 @@
         return result
 
 
-class Zeroconf(object):
+class Zeroconf:
     """Implementation of Zeroconf Multicast DNS Service Discovery
 
     Supports registration, unregistration, queries and browsing.
diff --git a/hgext/zeroconf/__init__.py b/hgext/zeroconf/__init__.py
--- a/hgext/zeroconf/__init__.py
+++ b/hgext/zeroconf/__init__.py
@@ -158,7 +158,7 @@
 # listen
 
 
-class listener(object):
+class listener:
     def __init__(self):
         self.found = {}
 
diff --git a/i18n/polib.py b/i18n/polib.py
--- a/i18n/polib.py
+++ b/i18n/polib.py
@@ -42,7 +42,7 @@
 except ImportError:
     # replacement of io.open() for python < 2.6
     # we use codecs instead
-    class io(object):
+    class io:
         @staticmethod
         def open(fpath, mode='r', encoding=None):
             return codecs.open(fpath, mode, encoding)
@@ -816,7 +816,7 @@
 # class _BaseEntry {{{
 
 
-class _BaseEntry(object):
+class _BaseEntry:
     """
     Base class for :class:`~polib.POEntry` and :class:`~polib.MOEntry` classes.
     This class should **not** be instanciated directly.
@@ -1227,7 +1227,7 @@
 # class _POFileParser {{{
 
 
-class _POFileParser(object):
+class _POFileParser:
     """
     A finite state machine to parse efficiently and correctly po
     file format.
@@ -1706,7 +1706,7 @@
 # class _MOFileParser {{{
 
 
-class _MOFileParser(object):
+class _MOFileParser:
     """
     A class to parse binary mo files.
     """
diff --git a/mercurial/ancestor.py b/mercurial/ancestor.py
--- a/mercurial/ancestor.py
+++ b/mercurial/ancestor.py
@@ -146,7 +146,7 @@
     return deepest(gca)
 
 
-class incrementalmissingancestors(object):
+class incrementalmissingancestors:
     """persistent state used to calculate missing ancestors incrementally
 
     Although similar in spirit to lazyancestors below, this is a separate class
@@ -316,7 +316,7 @@
             see(p2)
 
 
-class lazyancestors(object):
+class lazyancestors:
     def __init__(self, pfunc, revs, stoprev=0, inclusive=False):
         """Create a new object generating ancestors for the given revs. Does
         not generate revs lower than stoprev.
diff --git a/mercurial/archival.py b/mercurial/archival.py
--- a/mercurial/archival.py
+++ b/mercurial/archival.py
@@ -132,7 +132,7 @@
     return out.getvalue()
 
 
-class tarit(object):
+class tarit:
     """write archive to tar file or stream.  can write uncompressed,
     or compress with gzip or bzip2."""
 
@@ -193,7 +193,7 @@
             self.fileobj.close()
 
 
-class zipit(object):
+class zipit:
     """write archive to zip file or stream.  can write uncompressed,
     or compressed with deflate."""
 
@@ -240,7 +240,7 @@
         self.z.close()
 
 
-class fileit(object):
+class fileit:
     '''write archive as files in directory.'''
 
     def __init__(self, name, mtime):
diff --git a/mercurial/bookmarks.py b/mercurial/bookmarks.py
--- a/mercurial/bookmarks.py
+++ b/mercurial/bookmarks.py
@@ -58,7 +58,7 @@
     return fp
 
 
-class bmstore(object):
+class bmstore:
     r"""Storage for bookmarks.
 
     This object should do all bookmark-related reads and writes, so
diff --git a/mercurial/branchmap.py b/mercurial/branchmap.py
--- a/mercurial/branchmap.py
+++ b/mercurial/branchmap.py
@@ -62,7 +62,7 @@
 unpack_from = struct.unpack_from
 
 
-class BranchMapCache(object):
+class BranchMapCache:
     """mapping of filtered views of repo with their branchcache"""
 
     def __init__(self):
@@ -169,7 +169,7 @@
         return b'branch cache'
 
 
-class branchcache(object):
+class branchcache:
     """A dict like object that hold branches heads cache.
 
     This cache is used to avoid costly computations to determine all the
@@ -631,7 +631,7 @@
 _rbccloseflag = 0x80000000
 
 
-class revbranchcache(object):
+class revbranchcache:
     """Persistent cache, mapping from revision number to branch name and close.
     This is a low level cache, independent of filtering.
 
diff --git a/mercurial/bundle2.py b/mercurial/bundle2.py
--- a/mercurial/bundle2.py
+++ b/mercurial/bundle2.py
@@ -251,7 +251,7 @@
     return _decorator
 
 
-class unbundlerecords(object):
+class unbundlerecords:
     """keep record of what happens during and unbundle
 
     New records are added using `records.add('cat', obj)`. Where 'cat' is a
@@ -299,7 +299,7 @@
     __bool__ = __nonzero__
 
 
-class bundleoperation(object):
+class bundleoperation:
     """an object that represents a single bundling process
 
     Its purpose is to carry unbundle-related objects and states.
@@ -379,7 +379,7 @@
         return op
 
 
-class partiterator(object):
+class partiterator:
     def __init__(self, repo, op, unbundler):
         self.repo = repo
         self.op = op
@@ -626,7 +626,7 @@
 bundlepriority = [b'HG10GZ', b'HG10BZ', b'HG10UN']
 
 
-class bundle20(object):
+class bundle20:
     """represent an outgoing bundle2 container
 
     Use the `addparam` method to add stream level parameter. and `newpart` to
@@ -750,7 +750,7 @@
         return salvaged
 
 
-class unpackermixin(object):
+class unpackermixin:
     """A mixin to extract bytes and struct data from a stream"""
 
     def __init__(self, fp):
@@ -983,7 +983,7 @@
         unbundler._compressed = True
 
 
-class bundlepart(object):
+class bundlepart:
     """A bundle2 part contains application level payload
 
     The part `type` is used to route the part to the application level
@@ -1273,7 +1273,7 @@
         )
 
 
-class interruptoperation(object):
+class interruptoperation:
     """A limited operation to be use by part handler during interruption
 
     It only have access to an ui object.
diff --git a/mercurial/bundlecaches.py b/mercurial/bundlecaches.py
--- a/mercurial/bundlecaches.py
+++ b/mercurial/bundlecaches.py
@@ -21,7 +21,7 @@
 
 
 @attr.s
-class bundlespec(object):
+class bundlespec:
     compression = attr.ib()
     wirecompression = attr.ib()
     version = attr.ib()
@@ -343,7 +343,7 @@
     return newentries
 
 
-class clonebundleentry(object):
+class clonebundleentry:
     """Represents an item in a clone bundles manifest.
 
     This rich class is needed to support sorting since sorted() in Python 3
diff --git a/mercurial/bundlerepo.py b/mercurial/bundlerepo.py
--- a/mercurial/bundlerepo.py
+++ b/mercurial/bundlerepo.py
@@ -270,7 +270,7 @@
     return filespos
 
 
-class bundlerepository(object):
+class bundlerepository:
     """A repository instance that is a union of a local repo and a bundle.
 
     Instances represent a read-only repository composed of a local repository
@@ -550,7 +550,7 @@
     return repo
 
 
-class bundletransactionmanager(object):
+class bundletransactionmanager:
     def transaction(self):
         return None
 
diff --git a/mercurial/cffi/osutil.py b/mercurial/cffi/osutil.py
--- a/mercurial/cffi/osutil.py
+++ b/mercurial/cffi/osutil.py
@@ -33,7 +33,7 @@
     attrkinds[lib.VFIFO] = statmod.S_IFIFO
     attrkinds[lib.VSOCK] = statmod.S_IFSOCK
 
-    class stat_res(object):
+    class stat_res:
         def __init__(self, st_mode, st_mtime, st_size):
             self.st_mode = st_mode
             self.st_mtime = st_mtime
diff --git a/mercurial/changegroup.py b/mercurial/changegroup.py
--- a/mercurial/changegroup.py
+++ b/mercurial/changegroup.py
@@ -105,7 +105,7 @@
                 os.unlink(cleanup)
 
 
-class cg1unpacker(object):
+class cg1unpacker:
     """Unpacker for cg1 changegroup streams.
 
     A changegroup unpacker handles the framing of the revision data in
@@ -691,7 +691,7 @@
         )
 
 
-class headerlessfixup(object):
+class headerlessfixup:
     def __init__(self, fh, h):
         self._h = h
         self._fh = fh
@@ -1003,7 +1003,7 @@
         progress.complete()
 
 
-class cgpacker(object):
+class cgpacker:
     def __init__(
         self,
         repo,
diff --git a/mercurial/changelog.py b/mercurial/changelog.py
--- a/mercurial/changelog.py
+++ b/mercurial/changelog.py
@@ -91,7 +91,7 @@
     return b'\n'.join([l.rstrip() for l in desc.splitlines()]).strip(b'\n')
 
 
-class appender(object):
+class appender:
     """the changelog index must be updated last on disk, so we use this class
     to delay writes to it"""
 
@@ -161,7 +161,7 @@
         return self.fp.__exit__(*args)
 
 
-class _divertopener(object):
+class _divertopener:
     def __init__(self, opener, target):
         self._opener = opener
         self._target = target
@@ -188,7 +188,7 @@
 
 
 @attr.s
-class _changelogrevision(object):
+class _changelogrevision:
     # Extensions might modify _defaultextra, so let the constructor below pass
     # it in
     extra = attr.ib()
@@ -204,7 +204,7 @@
     branchinfo = attr.ib(default=(_defaultextra[b'branch'], False))
 
 
-class changelogrevision(object):
+class changelogrevision:
     """Holds results of a parsed changelog revision.
 
     Changelog revisions consist of multiple pieces of data, including
diff --git a/mercurial/chgserver.py b/mercurial/chgserver.py
--- a/mercurial/chgserver.py
+++ b/mercurial/chgserver.py
@@ -196,7 +196,7 @@
     return _hashlist(pycompat.maplist(trystat, paths))[:12]
 
 
-class hashstate(object):
+class hashstate:
     """a structure storing confighash, mtimehash, paths used for mtimehash"""
 
     def __init__(self, confighash, mtimehash, mtimepaths):
@@ -292,7 +292,7 @@
     return (newui, newlui)
 
 
-class channeledsystem(object):
+class channeledsystem:
     """Propagate ui.system() request in the following format:
 
     payload length (unsigned int),
@@ -623,7 +623,7 @@
     return b'%s-%s' % (os.path.join(dirname, basename), hashstr)
 
 
-class chgunixservicehandler(object):
+class chgunixservicehandler:
     """Set of operations for chg services"""
 
     pollinterval = 1  # [sec]
diff --git a/mercurial/cmdutil.py b/mercurial/cmdutil.py
--- a/mercurial/cmdutil.py
+++ b/mercurial/cmdutil.py
@@ -666,7 +666,7 @@
     return commit(ui, repo, recordinwlock, pats, opts)
 
 
-class dirnode(object):
+class dirnode:
     """
     Represent a directory in user working copy with information required for
     the purpose of tersing its status.
@@ -832,7 +832,7 @@
 
 
 @attr.s(frozen=True)
-class morestatus(object):
+class morestatus:
     reporoot = attr.ib()
     unfinishedop = attr.ib()
     unfinishedmsg = attr.ib()
@@ -1343,7 +1343,7 @@
     return not pat or pat == b'-'
 
 
-class _unclosablefile(object):
+class _unclosablefile:
     def __init__(self, fp):
         self._fp = fp
 
diff --git a/mercurial/commandserver.py b/mercurial/commandserver.py
--- a/mercurial/commandserver.py
+++ b/mercurial/commandserver.py
@@ -39,7 +39,7 @@
 )
 
 
-class channeledoutput(object):
+class channeledoutput:
     """
     Write data to out in the following format:
 
@@ -68,7 +68,7 @@
         return getattr(self.out, attr)
 
 
-class channeledmessage(object):
+class channeledmessage:
     """
     Write encoded message and metadata to out in the following format:
 
@@ -97,7 +97,7 @@
         return getattr(self._cout, attr)
 
 
-class channeledinput(object):
+class channeledinput:
     """
     Read data from in_.
 
@@ -200,7 +200,7 @@
     )
 
 
-class server(object):
+class server:
     """
     Listens for commands on fin, runs them and writes the output on a channel
     based stream to fout.
@@ -450,7 +450,7 @@
         u.setlogger(b'cmdserver', logger)
 
 
-class pipeservice(object):
+class pipeservice:
     def __init__(self, ui, repo, opts):
         self.ui = ui
         self.repo = repo
@@ -525,7 +525,7 @@
                 raise
 
 
-class unixservicehandler(object):
+class unixservicehandler:
     """Set of pluggable operations for unix-mode services
 
     Almost all methods except for createcmdserver() are called in the main
@@ -559,7 +559,7 @@
         return server(self.ui, repo, fin, fout, prereposetups)
 
 
-class unixforkingservice(object):
+class unixforkingservice:
     """
     Listens on unix domain socket and forks server per connection
     """
diff --git a/mercurial/config.py b/mercurial/config.py
--- a/mercurial/config.py
+++ b/mercurial/config.py
@@ -18,7 +18,7 @@
 )
 
 
-class config(object):
+class config:
     def __init__(self, data=None):
         self._current_source_level = 0
         self._data = {}
diff --git a/mercurial/configitems.py b/mercurial/configitems.py
--- a/mercurial/configitems.py
+++ b/mercurial/configitems.py
@@ -29,7 +29,7 @@
         knownitems.update(items)
 
 
-class configitem(object):
+class configitem:
     """represent a known config item
 
     :section: the official config section where to find this item,
diff --git a/mercurial/context.py b/mercurial/context.py
--- a/mercurial/context.py
+++ b/mercurial/context.py
@@ -51,7 +51,7 @@
 propertycache = util.propertycache
 
 
-class basectx(object):
+class basectx:
     """A basectx object represents the common logic for its children:
     changectx: read-only context that is already present in the repo,
     workingctx: a context that represents the working directory and can
@@ -796,7 +796,7 @@
         return self.walk(match)
 
 
-class basefilectx(object):
+class basefilectx:
     """A filecontext object represents the common logic for its children:
     filectx: read-only access to a filerevision that is already present
              in the repo,
@@ -3104,7 +3104,7 @@
         return scmutil.status(modified, added, removed, [], [], [], [])
 
 
-class arbitraryfilectx(object):
+class arbitraryfilectx:
     """Allows you to use filectx-like functions on a file in an arbitrary
     location on disk, possibly not in the working directory.
     """
diff --git a/mercurial/copies.py b/mercurial/copies.py
--- a/mercurial/copies.py
+++ b/mercurial/copies.py
@@ -887,7 +887,7 @@
             copy[dst] = src
 
 
-class branch_copies(object):
+class branch_copies:
     """Information about copies made on one side of a merge/graft.
 
     "copy" is a mapping from destination name -> source name,
diff --git a/mercurial/crecord.py b/mercurial/crecord.py
--- a/mercurial/crecord.py
+++ b/mercurial/crecord.py
@@ -82,7 +82,7 @@
     return curses and ui.interface(b"chunkselector") == b"curses"
 
 
-class patchnode(object):
+class patchnode:
     """abstract class for patch graph nodes
     (i.e. patchroot, header, hunk, hunkline)
     """
@@ -601,7 +601,7 @@
     """
     chunkselector = curseschunkselector(headerlist, ui, operation)
 
-    class dummystdscr(object):
+    class dummystdscr:
         def clear(self):
             pass
 
@@ -628,7 +628,7 @@
 }
 
 
-class curseschunkselector(object):
+class curseschunkselector:
     def __init__(self, headerlist, ui, operation=None):
         # put the headers into a patch object
         self.headerlist = patch(headerlist)
diff --git a/mercurial/dagop.py b/mercurial/dagop.py
--- a/mercurial/dagop.py
+++ b/mercurial/dagop.py
@@ -271,7 +271,7 @@
                 break
 
 
-class subsetparentswalker(object):
+class subsetparentswalker:
     r"""Scan adjacent ancestors in the graph given by the subset
 
     This computes parent-child relations in the sub graph filtered by
@@ -647,7 +647,7 @@
 
 
 @attr.s(slots=True, frozen=True)
-class annotateline(object):
+class annotateline:
     fctx = attr.ib()
     lineno = attr.ib()
     # Whether this annotation was the result of a skip-annotate.
@@ -656,7 +656,7 @@
 
 
 @attr.s(slots=True, frozen=True)
-class _annotatedfile(object):
+class _annotatedfile:
     # list indexed by lineno - 1
     fctxs = attr.ib()
     linenos = attr.ib()
diff --git a/mercurial/dirstate.py b/mercurial/dirstate.py
--- a/mercurial/dirstate.py
+++ b/mercurial/dirstate.py
@@ -90,7 +90,7 @@
 
 
 @interfaceutil.implementer(intdirstate.idirstate)
-class dirstate(object):
+class dirstate:
     def __init__(
         self,
         opener,
diff --git a/mercurial/dirstatemap.py b/mercurial/dirstatemap.py
--- a/mercurial/dirstatemap.py
+++ b/mercurial/dirstatemap.py
@@ -34,7 +34,7 @@
 rangemask = 0x7FFFFFFF
 
 
-class _dirstatemapcommon(object):
+class _dirstatemapcommon:
     """
     Methods that are identical for both implementations of the dirstatemap
     class, with and without Rust extensions enabled.
diff --git a/mercurial/dirstateutils/docket.py b/mercurial/dirstateutils/docket.py
--- a/mercurial/dirstateutils/docket.py
+++ b/mercurial/dirstateutils/docket.py
@@ -28,7 +28,7 @@
 )
 
 
-class DirstateDocket(object):
+class DirstateDocket:
     data_filename_pattern = b'dirstate.%s'
 
     def __init__(self, parents, data_size, tree_metadata, uuid):
diff --git a/mercurial/dirstateutils/v2.py b/mercurial/dirstateutils/v2.py
--- a/mercurial/dirstateutils/v2.py
+++ b/mercurial/dirstateutils/v2.py
@@ -125,7 +125,7 @@
 
 
 @attr.s
-class Node(object):
+class Node:
     path = attr.ib()
     entry = attr.ib()
     parent = attr.ib(default=None)
diff --git a/mercurial/discovery.py b/mercurial/discovery.py
--- a/mercurial/discovery.py
+++ b/mercurial/discovery.py
@@ -73,7 +73,7 @@
     return (list(common), anyinc, heads or list(srvheads))
 
 
-class outgoing(object):
+class outgoing:
     """Represents the result of a findcommonoutgoing() call.
 
     Members:
diff --git a/mercurial/dispatch.py b/mercurial/dispatch.py
--- a/mercurial/dispatch.py
+++ b/mercurial/dispatch.py
@@ -53,7 +53,7 @@
 )
 
 
-class request(object):
+class request:
     def __init__(
         self,
         args,
@@ -557,7 +557,7 @@
     return r.sub(lambda x: replacemap[x.group()], cmd)
 
 
-class cmdalias(object):
+class cmdalias:
     def __init__(self, ui, name, definition, cmdtable, source):
         self.name = self.cmd = name
         self.cmdname = b''
@@ -740,7 +740,7 @@
                 raise
 
 
-class lazyaliasentry(object):
+class lazyaliasentry:
     """like a typical command entry (func, opts, help), but is lazy"""
 
     def __init__(self, ui, name, definition, cmdtable, source):
diff --git a/mercurial/encoding.py b/mercurial/encoding.py
--- a/mercurial/encoding.py
+++ b/mercurial/encoding.py
@@ -510,7 +510,7 @@
     return u + ellipsis
 
 
-class normcasespecs(object):
+class normcasespecs:
     """what a platform's normcase does to ASCII strings
 
     This is specified per platform, and should be consistent with what normcase
diff --git a/mercurial/error.py b/mercurial/error.py
--- a/mercurial/error.py
+++ b/mercurial/error.py
@@ -39,7 +39,7 @@
     return b'(%s)' % b', '.join(b"'%s'" % pycompat.bytestr(a) for a in exc.args)
 
 
-class Hint(object):
+class Hint:
     """Mix-in to provide a hint of an error
 
     This should come first in the inheritance list to consume a hint and
diff --git a/mercurial/exchange.py b/mercurial/exchange.py
--- a/mercurial/exchange.py
+++ b/mercurial/exchange.py
@@ -222,7 +222,7 @@
     return forcebundle1 or not op.remote.capable(b'bundle2')
 
 
-class pushoperation(object):
+class pushoperation:
     """A object that represent a single push operation
 
     Its purpose is to carry push related state and very common operations.
@@ -1371,7 +1371,7 @@
                 pushop.bkresult = 1
 
 
-class pulloperation(object):
+class pulloperation:
     """A object that represent a single pull operation
 
     It purpose is to carry pull related state and very common operation.
diff --git a/mercurial/extensions.py b/mercurial/extensions.py
--- a/mercurial/extensions.py
+++ b/mercurial/extensions.py
@@ -621,7 +621,7 @@
         raise AttributeError("type '%s' has no property '%s'" % (cls, propname))
 
 
-class wrappedfunction(object):
+class wrappedfunction:
     '''context manager for temporarily wrapping a function'''
 
     def __init__(self, container, funcname, wrapper):
diff --git a/mercurial/exthelper.py b/mercurial/exthelper.py
--- a/mercurial/exthelper.py
+++ b/mercurial/exthelper.py
@@ -20,7 +20,7 @@
 from hgdemandimport import tracing
 
 
-class exthelper(object):
+class exthelper:
     """Helper for modular extension setup
 
     A single helper should be instantiated for each module of an
diff --git a/mercurial/fancyopts.py b/mercurial/fancyopts.py
--- a/mercurial/fancyopts.py
+++ b/mercurial/fancyopts.py
@@ -204,7 +204,7 @@
     return parsedopts, parsedargs
 
 
-class customopt(object):  # pytype: disable=ignored-metaclass
+class customopt:  # pytype: disable=ignored-metaclass
     """Manage defaults and mutations for any type of opt."""
 
     __metaclass__ = abc.ABCMeta
diff --git a/mercurial/filelog.py b/mercurial/filelog.py
--- a/mercurial/filelog.py
+++ b/mercurial/filelog.py
@@ -24,7 +24,7 @@
 
 
 @interfaceutil.implementer(repository.ifilestorage)
-class filelog(object):
+class filelog:
     def __init__(self, opener, path):
         self._revlog = revlog.revlog(
             opener,
diff --git a/mercurial/filemerge.py b/mercurial/filemerge.py
--- a/mercurial/filemerge.py
+++ b/mercurial/filemerge.py
@@ -84,7 +84,7 @@
 )
 
 
-class absentfilectx(object):
+class absentfilectx:
     """Represents a file that's ostensibly in a context but is actually not
     present in it.
 
diff --git a/mercurial/fileset.py b/mercurial/fileset.py
--- a/mercurial/fileset.py
+++ b/mercurial/fileset.py
@@ -503,7 +503,7 @@
 }
 
 
-class matchctx(object):
+class matchctx:
     def __init__(self, basectx, ctx, cwd, badfn=None):
         self._basectx = basectx
         self.ctx = ctx
diff --git a/mercurial/formatter.py b/mercurial/formatter.py
--- a/mercurial/formatter.py
+++ b/mercurial/formatter.py
@@ -144,7 +144,7 @@
     return isinstance(obj, (type(None), bool, int, int, float, bytes))
 
 
-class _nullconverter(object):
+class _nullconverter:
     '''convert non-primitive data types to be processed by formatter'''
 
     # set to True if context object should be stored as item
@@ -175,7 +175,7 @@
         return list(data)
 
 
-class baseformatter(object):
+class baseformatter:
 
     # set to True if the formater output a strict format that does not support
     # arbitrary output in the stream.
@@ -297,7 +297,7 @@
     return data
 
 
-class _plainconverter(object):
+class _plainconverter:
     '''convert non-primitive data types to text'''
 
     storecontext = False
@@ -452,7 +452,7 @@
         self._out.write(b"\n]\n")
 
 
-class _templateconverter(object):
+class _templateconverter:
     '''convert non-primitive data types to be processed by templater'''
 
     storecontext = True
@@ -541,7 +541,7 @@
 
 
 @attr.s(frozen=True)
-class templatespec(object):
+class templatespec:
     ref = attr.ib()
     tmpl = attr.ib()
     mapfile = attr.ib()
diff --git a/mercurial/graphmod.py b/mercurial/graphmod.py
--- a/mercurial/graphmod.py
+++ b/mercurial/graphmod.py
@@ -358,7 +358,7 @@
 
 
 @attr.s
-class asciistate(object):
+class asciistate:
     """State of ascii() graph rendering"""
 
     seen = attr.ib(init=False, default=attr.Factory(list))
diff --git a/mercurial/grep.py b/mercurial/grep.py
--- a/mercurial/grep.py
+++ b/mercurial/grep.py
@@ -35,7 +35,7 @@
         yield linenum, mstart - lstart, mend - lstart, body[lstart:lend]
 
 
-class linestate(object):
+class linestate:
     def __init__(self, line, linenum, colstart, colend):
         self.line = line
         self.linenum = linenum
@@ -79,7 +79,7 @@
                 yield (b'+', b[i])
 
 
-class grepsearcher(object):
+class grepsearcher:
     """Search files and revisions for lines matching the given pattern
 
     Options:
diff --git a/mercurial/hg.py b/mercurial/hg.py
--- a/mercurial/hg.py
+++ b/mercurial/hg.py
@@ -1534,7 +1534,7 @@
 ]
 
 
-class cachedlocalrepo(object):
+class cachedlocalrepo:
     """Holds a localrepository that can be cached and reused."""
 
     def __init__(self, repo):
diff --git a/mercurial/hgweb/__init__.py b/mercurial/hgweb/__init__.py
--- a/mercurial/hgweb/__init__.py
+++ b/mercurial/hgweb/__init__.py
@@ -54,7 +54,7 @@
     return hgwebdir_mod.hgwebdir(config, baseui=baseui)
 
 
-class httpservice(object):
+class httpservice:
     def __init__(self, ui, app, opts):
         self.ui = ui
         self.app = app
diff --git a/mercurial/hgweb/common.py b/mercurial/hgweb/common.py
--- a/mercurial/hgweb/common.py
+++ b/mercurial/hgweb/common.py
@@ -115,7 +115,7 @@
         self.message = message
 
 
-class continuereader(object):
+class continuereader:
     """File object wrapper to handle HTTP 100-continue.
 
     This is used by servers so they automatically handle Expect: 100-continue
diff --git a/mercurial/hgweb/hgweb_mod.py b/mercurial/hgweb/hgweb_mod.py
--- a/mercurial/hgweb/hgweb_mod.py
+++ b/mercurial/hgweb/hgweb_mod.py
@@ -110,7 +110,7 @@
     return templateutil.mappinglist(reversed(breadcrumb))
 
 
-class requestcontext(object):
+class requestcontext:
     """Holds state/context for an individual request.
 
     Servers can be multi-threaded. Holding state on the WSGI application
@@ -235,7 +235,7 @@
         return self.res.sendresponse()
 
 
-class hgweb(object):
+class hgweb:
     """HTTP server for individual repositories.
 
     Instances of this class serve HTTP responses for a particular
diff --git a/mercurial/hgweb/hgwebdir_mod.py b/mercurial/hgweb/hgwebdir_mod.py
--- a/mercurial/hgweb/hgwebdir_mod.py
+++ b/mercurial/hgweb/hgwebdir_mod.py
@@ -268,7 +268,7 @@
     return templateutil.mappinggenerator(_indexentriesgen, args=args)
 
 
-class hgwebdir(object):
+class hgwebdir:
     """HTTP server for multiple repositories.
 
     Given a configuration, different repositories will be served depending
diff --git a/mercurial/hgweb/request.py b/mercurial/hgweb/request.py
--- a/mercurial/hgweb/request.py
+++ b/mercurial/hgweb/request.py
@@ -21,7 +21,7 @@
 )
 
 
-class multidict(object):
+class multidict:
     """A dict like object that can store multiple values for a key.
 
     Used to store parsed request parameters.
@@ -81,7 +81,7 @@
 
 
 @attr.s(frozen=True)
-class parsedrequest(object):
+class parsedrequest:
     """Represents a parsed WSGI request.
 
     Contains both parsed parameters as well as a handle on the input stream.
@@ -355,7 +355,7 @@
     )
 
 
-class offsettrackingwriter(object):
+class offsettrackingwriter:
     """A file object like object that is append only and tracks write count.
 
     Instances are bound to a callable. This callable is called with data
@@ -388,7 +388,7 @@
         return self._offset
 
 
-class wsgiresponse(object):
+class wsgiresponse:
     """Represents a response to a WSGI request.
 
     A response consists of a status line, headers, and a body.
diff --git a/mercurial/hgweb/server.py b/mercurial/hgweb/server.py
--- a/mercurial/hgweb/server.py
+++ b/mercurial/hgweb/server.py
@@ -52,7 +52,7 @@
     return urlreq.unquote(path), query
 
 
-class _error_logger(object):
+class _error_logger:
     def __init__(self, handler):
         self.handler = handler
 
@@ -343,7 +343,7 @@
         _mixin = socketserver.ForkingMixIn
     else:
 
-        class _mixin(object):
+        class _mixin:
             pass
 
 
diff --git a/mercurial/hgweb/webcommands.py b/mercurial/hgweb/webcommands.py
--- a/mercurial/hgweb/webcommands.py
+++ b/mercurial/hgweb/webcommands.py
@@ -46,7 +46,7 @@
 commands = {}
 
 
-class webcommand(object):
+class webcommand:
     """Decorator used to register a web command handler.
 
     The decorator takes as its positional arguments the name/path the
diff --git a/mercurial/hgweb/webutil.py b/mercurial/hgweb/webutil.py
--- a/mercurial/hgweb/webutil.py
+++ b/mercurial/hgweb/webutil.py
@@ -99,7 +99,7 @@
         step *= 10
 
 
-class revnav(object):
+class revnav:
     def __init__(self, repo):
         """Navigation generation object
 
diff --git a/mercurial/hgweb/wsgiheaders.py b/mercurial/hgweb/wsgiheaders.py
--- a/mercurial/hgweb/wsgiheaders.py
+++ b/mercurial/hgweb/wsgiheaders.py
@@ -29,7 +29,7 @@
         return param
 
 
-class Headers(object):
+class Headers:
     """Manage a collection of HTTP response headers"""
 
     def __init__(self, headers=None):
diff --git a/mercurial/httpconnection.py b/mercurial/httpconnection.py
--- a/mercurial/httpconnection.py
+++ b/mercurial/httpconnection.py
@@ -26,7 +26,7 @@
 urlreq = util.urlreq
 
 # moved here from url.py to avoid a cycle
-class httpsendfile(object):
+class httpsendfile:
     """This is a wrapper around the objects returned by python's "open".
 
     Its purpose is to send file-like objects via HTTP.
diff --git a/mercurial/httppeer.py b/mercurial/httppeer.py
--- a/mercurial/httppeer.py
+++ b/mercurial/httppeer.py
@@ -62,7 +62,7 @@
     return result
 
 
-class _multifile(object):
+class _multifile:
     def __init__(self, *fileobjs):
         for f in fileobjs:
             if not util.safehasattr(f, b'length'):
diff --git a/mercurial/interfaces/repository.py b/mercurial/interfaces/repository.py
--- a/mercurial/interfaces/repository.py
+++ b/mercurial/interfaces/repository.py
@@ -388,7 +388,7 @@
 
 
 @interfaceutil.implementer(ipeerbase)
-class peer(object):
+class peer:
     """Base class for peer repositories."""
 
     limitedarguments = False
diff --git a/mercurial/interfaces/util.py b/mercurial/interfaces/util.py
--- a/mercurial/interfaces/util.py
+++ b/mercurial/interfaces/util.py
@@ -20,11 +20,11 @@
     implementer = zi.implementer
 else:
 
-    class Attribute(object):
+    class Attribute:
         def __init__(self, __name__, __doc__=b''):
             pass
 
-    class Interface(object):
+    class Interface:
         def __init__(
             self, name, bases=(), attrs=None, __doc__=None, __module__=None
         ):
diff --git a/mercurial/keepalive.py b/mercurial/keepalive.py
--- a/mercurial/keepalive.py
+++ b/mercurial/keepalive.py
@@ -107,7 +107,7 @@
 DEBUG = None
 
 
-class ConnectionManager(object):
+class ConnectionManager:
     """
     The connection manager must be able to:
       * keep track of all existing
@@ -170,7 +170,7 @@
             return dict(self._hostmap)
 
 
-class KeepAliveHandler(object):
+class KeepAliveHandler:
     def __init__(self, timeout=None):
         self._cm = ConnectionManager()
         self._timeout = timeout
@@ -789,7 +789,7 @@
     global DEBUG
     dbbackup = DEBUG
 
-    class FakeLogger(object):
+    class FakeLogger:
         def debug(self, msg, *args):
             print(msg % args)
 
diff --git a/mercurial/linelog.py b/mercurial/linelog.py
--- a/mercurial/linelog.py
+++ b/mercurial/linelog.py
@@ -33,7 +33,7 @@
 
 
 @attr.s
-class lineinfo(object):
+class lineinfo:
     # Introducing revision of this line.
     rev = attr.ib()
     # Line number for this line in its introducing revision.
@@ -43,7 +43,7 @@
 
 
 @attr.s
-class annotateresult(object):
+class annotateresult:
     rev = attr.ib()
     lines = attr.ib()
     _eof = attr.ib()
@@ -52,7 +52,7 @@
         return iter(self.lines)
 
 
-class _llinstruction(object):  # pytype: disable=ignored-metaclass
+class _llinstruction:  # pytype: disable=ignored-metaclass
 
     __metaclass__ = abc.ABCMeta
 
@@ -233,7 +233,7 @@
     raise NotImplementedError(b'Unimplemented opcode %r' % opcode)
 
 
-class linelog(object):
+class linelog:
     """Efficient cache for per-line history information."""
 
     def __init__(self, program=None, maxrev=0):
diff --git a/mercurial/localrepo.py b/mercurial/localrepo.py
--- a/mercurial/localrepo.py
+++ b/mercurial/localrepo.py
@@ -251,7 +251,7 @@
 
 
 @interfaceutil.implementer(repository.ipeercommandexecutor)
-class localcommandexecutor(object):
+class localcommandexecutor:
     def __init__(self, peer):
         self._peer = peer
         self._sent = False
@@ -1215,7 +1215,7 @@
 
 
 @interfaceutil.implementer(repository.ilocalrepositoryfilestorage)
-class revlogfilestorage(object):
+class revlogfilestorage:
     """File storage when using revlogs."""
 
     def file(self, path):
@@ -1226,7 +1226,7 @@
 
 
 @interfaceutil.implementer(repository.ilocalrepositoryfilestorage)
-class revlognarrowfilestorage(object):
+class revlognarrowfilestorage:
     """File storage when using revlogs and narrow files."""
 
     def file(self, path):
@@ -1259,7 +1259,7 @@
 
 
 @interfaceutil.implementer(repository.ilocalrepositorymain)
-class localrepository(object):
+class localrepository:
     """Main class for representing local repositories.
 
     All local repositories are instances of this class.
@@ -2044,7 +2044,7 @@
 
         # This simplifies its cache management by having one decorated
         # function (this one) and the rest simply fetch things from it.
-        class tagscache(object):
+        class tagscache:
             def __init__(self):
                 # These two define the set of tags for this repository. tags
                 # maps tag name to node; tagtypes maps tag name to 'global' or
@@ -3912,7 +3912,7 @@
     #
     # But we have to allow the close() method because some constructors
     # of repos call close() on repo references.
-    class poisonedrepository(object):
+    class poisonedrepository:
         def __getattribute__(self, item):
             if item == 'close':
                 return object.__getattribute__(self, item)
diff --git a/mercurial/lock.py b/mercurial/lock.py
--- a/mercurial/lock.py
+++ b/mercurial/lock.py
@@ -173,7 +173,7 @@
     return l
 
 
-class lock(object):
+class lock:
     """An advisory lock held by one process to control access to a set
     of files.  Non-cooperating processes or incorrectly written scripts
     can ignore Mercurial's locking scheme and stomp all over the
diff --git a/mercurial/logcmdutil.py b/mercurial/logcmdutil.py
--- a/mercurial/logcmdutil.py
+++ b/mercurial/logcmdutil.py
@@ -227,7 +227,7 @@
             )
 
 
-class changesetdiffer(object):
+class changesetdiffer:
     """Generate diff of changeset with pre-configured filtering functions"""
 
     def _makefilematcher(self, ctx):
@@ -261,7 +261,7 @@
     return b' '.join(labels)
 
 
-class changesetprinter(object):
+class changesetprinter:
     '''show changeset information when templating not requested.'''
 
     def __init__(self, ui, repo, differ=None, diffopts=None, buffered=False):
@@ -706,7 +706,7 @@
 
 
 @attr.s
-class walkopts(object):
+class walkopts:
     """Options to configure a set of revisions and file matcher factory
     to scan revision/file history
     """
diff --git a/mercurial/loggingutil.py b/mercurial/loggingutil.py
--- a/mercurial/loggingutil.py
+++ b/mercurial/loggingutil.py
@@ -73,7 +73,7 @@
     return b'*' in tracked or event in tracked
 
 
-class filelogger(object):
+class filelogger:
     """Basic logger backed by physical file with optional rotation"""
 
     def __init__(self, vfs, name, tracked, maxfiles=0, maxsize=0):
@@ -104,7 +104,7 @@
             )
 
 
-class fileobjectlogger(object):
+class fileobjectlogger:
     """Basic logger backed by file-like object"""
 
     def __init__(self, fp, tracked):
@@ -129,7 +129,7 @@
             )
 
 
-class proxylogger(object):
+class proxylogger:
     """Forward log events to another logger to be set later"""
 
     def __init__(self):
diff --git a/mercurial/lsprof.py b/mercurial/lsprof.py
--- a/mercurial/lsprof.py
+++ b/mercurial/lsprof.py
@@ -22,7 +22,7 @@
     return Stats(p.getstats())
 
 
-class Stats(object):
+class Stats:
     """XXX docstring"""
 
     def __init__(self, data):
diff --git a/mercurial/lsprofcalltree.py b/mercurial/lsprofcalltree.py
--- a/mercurial/lsprofcalltree.py
+++ b/mercurial/lsprofcalltree.py
@@ -26,7 +26,7 @@
         )
 
 
-class KCacheGrind(object):
+class KCacheGrind:
     def __init__(self, profiler):
         self.data = profiler.getstats()
         self.out_file = None
diff --git a/mercurial/manifest.py b/mercurial/manifest.py
--- a/mercurial/manifest.py
+++ b/mercurial/manifest.py
@@ -84,7 +84,7 @@
     return b''.join(lines)
 
 
-class lazymanifestiter(object):
+class lazymanifestiter:
     def __init__(self, lm):
         self.pos = 0
         self.lm = lm
@@ -107,7 +107,7 @@
     __next__ = next
 
 
-class lazymanifestiterentries(object):
+class lazymanifestiterentries:
     def __init__(self, lm):
         self.lm = lm
         self.pos = 0
@@ -158,7 +158,7 @@
 _manifestflags = {b'', b'l', b't', b'x'}
 
 
-class _lazymanifest(object):
+class _lazymanifest:
     """A pure python manifest backed by a byte string.  It is supplimented with
     internal lists as it is modified, until it is compacted back to a pure byte
     string.
@@ -473,7 +473,7 @@
 
 
 @interfaceutil.implementer(repository.imanifestdict)
-class manifestdict(object):
+class manifestdict:
     def __init__(self, nodelen, data=b''):
         self._nodelen = nodelen
         self._lm = _lazymanifest(nodelen, data)
@@ -796,7 +796,7 @@
 
 
 @interfaceutil.implementer(repository.imanifestdict)
-class treemanifest(object):
+class treemanifest:
     def __init__(self, nodeconstants, dir=b'', text=b''):
         self._dir = dir
         self.nodeconstants = nodeconstants
@@ -1550,7 +1550,7 @@
 
 
 @interfaceutil.implementer(repository.imanifeststorage)
-class manifestrevlog(object):
+class manifestrevlog:
     """A revlog that stores manifest texts. This is responsible for caching the
     full-text manifest contents.
     """
@@ -1908,7 +1908,7 @@
 
 
 @interfaceutil.implementer(repository.imanifestlog)
-class manifestlog(object):
+class manifestlog:
     """A collection class representing the collection of manifest snapshots
     referenced by commits in the repository.
 
@@ -2007,7 +2007,7 @@
 
 
 @interfaceutil.implementer(repository.imanifestrevisionwritable)
-class memmanifestctx(object):
+class memmanifestctx:
     def __init__(self, manifestlog):
         self._manifestlog = manifestlog
         self._manifestdict = manifestdict(manifestlog.nodeconstants.nodelen)
@@ -2037,7 +2037,7 @@
 
 
 @interfaceutil.implementer(repository.imanifestrevisionstored)
-class manifestctx(object):
+class manifestctx:
     """A class representing a single revision of a manifest, including its
     contents, its parent revs, and its linkrev.
     """
@@ -2117,7 +2117,7 @@
 
 
 @interfaceutil.implementer(repository.imanifestrevisionwritable)
-class memtreemanifestctx(object):
+class memtreemanifestctx:
     def __init__(self, manifestlog, dir=b''):
         self._manifestlog = manifestlog
         self._dir = dir
@@ -2152,7 +2152,7 @@
 
 
 @interfaceutil.implementer(repository.imanifestrevisionstored)
-class treemanifestctx(object):
+class treemanifestctx:
     def __init__(self, manifestlog, dir, node):
         self._manifestlog = manifestlog
         self._dir = dir
diff --git a/mercurial/match.py b/mercurial/match.py
--- a/mercurial/match.py
+++ b/mercurial/match.py
@@ -382,7 +382,7 @@
     return kindpats
 
 
-class basematcher(object):
+class basematcher:
     def __init__(self, badfn=None):
         if badfn is not None:
             self.bad = badfn
@@ -659,7 +659,7 @@
 # This is basically a reimplementation of pathutil.dirs that stores the
 # children instead of just a count of them, plus a small optional optimization
 # to avoid some directories we don't need.
-class _dirchildren(object):
+class _dirchildren:
     def __init__(self, paths, onlyinclude=None):
         self._dirs = {}
         self._onlyinclude = onlyinclude or []
diff --git a/mercurial/mdiff.py b/mercurial/mdiff.py
--- a/mercurial/mdiff.py
+++ b/mercurial/mdiff.py
@@ -37,7 +37,7 @@
 
 
 # TODO: this looks like it could be an attrs, which might help pytype
-class diffopts(object):
+class diffopts:
     """context is the number of context lines
     text treats all files as text
     showfunc enables diff -p output
diff --git a/mercurial/merge.py b/mercurial/merge.py
--- a/mercurial/merge.py
+++ b/mercurial/merge.py
@@ -66,7 +66,7 @@
     )
 
 
-class _unknowndirschecker(object):
+class _unknowndirschecker:
     """
     Look for any unknown files or directories that may have a path conflict
     with a file.  If any path prefix of the file exists as a file or link,
@@ -537,7 +537,7 @@
             raise error.StateError(msg % f)
 
 
-class mergeresult(object):
+class mergeresult:
     """An object representing result of merging manifests.
 
     It has information about what actions need to be performed on dirstate
@@ -1467,7 +1467,7 @@
 
 
 @attr.s(frozen=True)
-class updateresult(object):
+class updateresult:
     updatedcount = attr.ib()
     mergedcount = attr.ib()
     removedcount = attr.ib()
diff --git a/mercurial/mergestate.py b/mercurial/mergestate.py
--- a/mercurial/mergestate.py
+++ b/mercurial/mergestate.py
@@ -100,7 +100,7 @@
 CHANGE_MODIFIED = b'modified'
 
 
-class MergeAction(object):
+class MergeAction:
     """represent an "action" merge need to take for a given file
 
     Attributes:
@@ -194,7 +194,7 @@
 )
 
 
-class _mergestate_base(object):
+class _mergestate_base:
     """track 3-way merge state of individual files
 
     The merge state is stored on disk when needed. Two files are used: one with
diff --git a/mercurial/metadata.py b/mercurial/metadata.py
--- a/mercurial/metadata.py
+++ b/mercurial/metadata.py
@@ -22,7 +22,7 @@
 )
 
 
-class ChangingFiles(object):
+class ChangingFiles:
     """A class recording the changes made to files by a changeset
 
     Actions performed on files are gathered into 3 sets:
diff --git a/mercurial/namespaces.py b/mercurial/namespaces.py
--- a/mercurial/namespaces.py
+++ b/mercurial/namespaces.py
@@ -16,7 +16,7 @@
         return [val]
 
 
-class namespaces(object):
+class namespaces:
     """provides an interface to register and operate on multiple namespaces. See
     the namespace class below for details on the namespace object.
 
@@ -124,7 +124,7 @@
         raise KeyError(_(b'no such name: %s') % name)
 
 
-class namespace(object):
+class namespace:
     """provides an interface to a namespace
 
     Namespaces are basically generic many-to-many mapping between some
diff --git a/mercurial/node.py b/mercurial/node.py
--- a/mercurial/node.py
+++ b/mercurial/node.py
@@ -31,7 +31,7 @@
 wdirrev = 0x7FFFFFFF
 
 
-class sha1nodeconstants(object):
+class sha1nodeconstants:
     nodelen = 20
 
     # In hex, this is '0000000000000000000000000000000000000000'
diff --git a/mercurial/obsolete.py b/mercurial/obsolete.py
--- a/mercurial/obsolete.py
+++ b/mercurial/obsolete.py
@@ -541,7 +541,7 @@
             )
 
 
-class obsstore(object):
+class obsstore:
     """Store obsolete markers
 
     Markers can be accessed with two mappings:
diff --git a/mercurial/obsutil.py b/mercurial/obsutil.py
--- a/mercurial/obsutil.py
+++ b/mercurial/obsutil.py
@@ -56,7 +56,7 @@
 usingsha256 = 2
 
 
-class marker(object):
+class marker:
     """Wrap obsolete marker raw data"""
 
     def __init__(self, repo, data):
diff --git a/mercurial/parser.py b/mercurial/parser.py
--- a/mercurial/parser.py
+++ b/mercurial/parser.py
@@ -25,7 +25,7 @@
 from .utils import stringutil
 
 
-class parser(object):
+class parser:
     def __init__(self, elements, methods=None):
         self._elements = elements
         self._methods = methods
@@ -415,7 +415,7 @@
         return inst.message
 
 
-class alias(object):
+class alias:
     """Parsed result of alias"""
 
     def __init__(self, name, args, err, replacement):
@@ -429,7 +429,7 @@
         self.warned = False
 
 
-class basealiasrules(object):
+class basealiasrules:
     """Parsing and expansion rule set of aliases
 
     This is a helper for fileset/revset/template aliases. A concrete rule set
diff --git a/mercurial/patch.py b/mercurial/patch.py
--- a/mercurial/patch.py
+++ b/mercurial/patch.py
@@ -149,7 +149,7 @@
     def remainder(cur):
         yield chunk(cur)
 
-    class fiter(object):
+    class fiter:
         def __init__(self, fp):
             self.fp = fp
 
@@ -342,7 +342,7 @@
     return data
 
 
-class patchmeta(object):
+class patchmeta:
     """Patched file metadata
 
     'op' is the performed operation within ADD, DELETE, RENAME, MODIFY
@@ -435,7 +435,7 @@
     return gitpatches
 
 
-class linereader(object):
+class linereader:
     # simple class to allow pushing lines back into the input stream
     def __init__(self, fp):
         self.fp = fp
@@ -456,7 +456,7 @@
         return iter(self.readline, b'')
 
 
-class abstractbackend(object):
+class abstractbackend:
     def __init__(self, ui):
         self.ui = ui
 
@@ -592,7 +592,7 @@
         return sorted(self.changed)
 
 
-class filestore(object):
+class filestore:
     def __init__(self, maxsize=None):
         self.opener = None
         self.files = {}
@@ -681,7 +681,7 @@
 eolmodes = [b'strict', b'crlf', b'lf', b'auto']
 
 
-class patchfile(object):
+class patchfile:
     def __init__(self, ui, gp, backend, store, eolmode=b'strict'):
         self.fname = gp.path
         self.eolmode = eolmode
@@ -914,7 +914,7 @@
         return len(self.rej)
 
 
-class header(object):
+class header:
     """patch header"""
 
     diffgit_re = re.compile(b'diff --git a/(.*) b/(.*)$')
@@ -994,7 +994,7 @@
         )
 
 
-class recordhunk(object):
+class recordhunk:
     """patch hunk
 
     XXX shouldn't we merge this with the other hunk class?
@@ -1349,7 +1349,7 @@
     )
 
 
-class hunk(object):
+class hunk:
     def __init__(self, desc, num, lr, context):
         self.number = num
         self.desc = desc
@@ -1577,7 +1577,7 @@
         return old, oldstart, new, newstart
 
 
-class binhunk(object):
+class binhunk:
     """A binary patch file."""
 
     def __init__(self, lr, fname):
@@ -1758,7 +1758,7 @@
     +9
     """
 
-    class parser(object):
+    class parser:
         """patch parsing state machine"""
 
         def __init__(self):
diff --git a/mercurial/pathutil.py b/mercurial/pathutil.py
--- a/mercurial/pathutil.py
+++ b/mercurial/pathutil.py
@@ -31,7 +31,7 @@
     return encoding.hfsignoreclean(s.lower())
 
 
-class pathauditor(object):
+class pathauditor:
     """ensure that a filesystem path contains no banned components.
     the following properties of a path are checked:
 
@@ -314,7 +314,7 @@
     yield b''
 
 
-class dirs(object):
+class dirs:
     '''a multiset of directory names from a set of file paths'''
 
     def __init__(self, map, only_tracked=False):
diff --git a/mercurial/phases.py b/mercurial/phases.py
--- a/mercurial/phases.py
+++ b/mercurial/phases.py
@@ -343,7 +343,7 @@
         data.insert(low + 1, (pycompat.xrange(rev, rev + 1), t))
 
 
-class phasecache(object):
+class phasecache:
     def __init__(self, repo, phasedefaults, _load=True):
         # type: (localrepo.localrepository, Optional[Phasedefaults], bool) -> None
         if _load:
@@ -879,7 +879,7 @@
     return publicheads, draftroots
 
 
-class remotephasessummary(object):
+class remotephasessummary:
     """summarize phase information on the remote side
 
     :publishing: True is the remote is publishing
diff --git a/mercurial/posix.py b/mercurial/posix.py
--- a/mercurial/posix.py
+++ b/mercurial/posix.py
@@ -664,7 +664,7 @@
     pass
 
 
-class cachestat(object):
+class cachestat:
     def __init__(self, path):
         self.stat = os.stat(path)
 
diff --git a/mercurial/profiling.py b/mercurial/profiling.py
--- a/mercurial/profiling.py
+++ b/mercurial/profiling.py
@@ -173,7 +173,7 @@
         statprof.display(fp, data=data, format=displayformat, **kwargs)
 
 
-class profile(object):
+class profile:
     """Start profiling.
 
     Profiling is active when the context manager is active. When the context
@@ -231,7 +231,7 @@
                 self._fp = open(path, b'wb')
             elif pycompat.iswindows:
                 # parse escape sequence by win32print()
-                class uifp(object):
+                class uifp:
                     def __init__(self, ui):
                         self._ui = ui
 
diff --git a/mercurial/progress.py b/mercurial/progress.py
--- a/mercurial/progress.py
+++ b/mercurial/progress.py
@@ -84,7 +84,7 @@
             raise
 
 
-class progbar(object):
+class progbar:
     def __init__(self, ui):
         self.ui = ui
         self._refreshlock = threading.Lock()
diff --git a/mercurial/pure/osutil.py b/mercurial/pure/osutil.py
--- a/mercurial/pure/osutil.py
+++ b/mercurial/pure/osutil.py
@@ -220,7 +220,7 @@
             err.errno, '%s: %s' % (encoding.strfromlocal(name), err.strerror)
         )
 
-    class posixfile(object):
+    class posixfile:
         """a file object aiming for POSIX-like semantics
 
         CPython's open() returns a file that was opened *without* setting the
diff --git a/mercurial/pure/parsers.py b/mercurial/pure/parsers.py
--- a/mercurial/pure/parsers.py
+++ b/mercurial/pure/parsers.py
@@ -63,7 +63,7 @@
 
 
 @attr.s(slots=True, init=False)
-class DirstateItem(object):
+class DirstateItem:
     """represent a dirstate entry
 
     It hold multiple attributes
@@ -560,7 +560,7 @@
     return int(q & 0xFFFF)
 
 
-class BaseIndexObject(object):
+class BaseIndexObject:
     # Can I be passed to an algorithme implemented in Rust ?
     rust_ext_compat = 0
     # Format of an index entry according to Python's `struct` language
diff --git a/mercurial/pvec.py b/mercurial/pvec.py
--- a/mercurial/pvec.py
+++ b/mercurial/pvec.py
@@ -180,7 +180,7 @@
     return pvec(util.b85encode(bs))
 
 
-class pvec(object):
+class pvec:
     def __init__(self, hashorctx):
         if isinstance(hashorctx, bytes):
             self._bs = hashorctx
diff --git a/mercurial/pycompat.py b/mercurial/pycompat.py
--- a/mercurial/pycompat.py
+++ b/mercurial/pycompat.py
@@ -163,7 +163,7 @@
 
     __bytes__() should be called if provided:
 
-    >>> class bytesable(object):
+    >>> class bytesable:
     ...     def __bytes__(self):
     ...         return b'bytes'
     >>> bytestr(bytesable())
diff --git a/mercurial/registrar.py b/mercurial/registrar.py
--- a/mercurial/registrar.py
+++ b/mercurial/registrar.py
@@ -21,7 +21,7 @@
 configitem = configitems.getitemregister
 
 
-class _funcregistrarbase(object):
+class _funcregistrarbase:
     """Base of decorator to register a function for specific purpose
 
     This decorator stores decorated functions into own dict 'table'.
diff --git a/mercurial/repair.py b/mercurial/repair.py
--- a/mercurial/repair.py
+++ b/mercurial/repair.py
@@ -379,7 +379,7 @@
     return [c.node() for c in repo.set(b'roots(%ld)', tostrip)]
 
 
-class stripcallback(object):
+class stripcallback:
     """used as a transaction postclose callback"""
 
     def __init__(self, ui, repo, backup, topic):
diff --git a/mercurial/repocache.py b/mercurial/repocache.py
--- a/mercurial/repocache.py
+++ b/mercurial/repocache.py
@@ -19,7 +19,7 @@
 )
 
 
-class repoloader(object):
+class repoloader:
     """Load repositories in background thread
 
     This is designed for a forking server. A cached repo cannot be obtained
diff --git a/mercurial/repoview.py b/mercurial/repoview.py
--- a/mercurial/repoview.py
+++ b/mercurial/repoview.py
@@ -261,7 +261,7 @@
     return cl
 
 
-class filteredchangelogmixin(object):
+class filteredchangelogmixin:
     def tiprev(self):
         """filtered version of revlog.tiprev"""
         for i in pycompat.xrange(len(self) - 1, -2, -1):
@@ -361,7 +361,7 @@
         return super(filteredchangelogmixin, self).flags(rev)
 
 
-class repoview(object):
+class repoview:
     """Provide a read/write view of a repo through a filtered changelog
 
     This object is used to access a filtered version of a repository without
diff --git a/mercurial/revlog.py b/mercurial/revlog.py
--- a/mercurial/revlog.py
+++ b/mercurial/revlog.py
@@ -171,7 +171,7 @@
 
 @interfaceutil.implementer(repository.irevisiondelta)
 @attr.s(slots=True)
-class revlogrevisiondelta(object):
+class revlogrevisiondelta:
     node = attr.ib()
     p1node = attr.ib()
     p2node = attr.ib()
@@ -187,7 +187,7 @@
 
 @interfaceutil.implementer(repository.iverifyproblem)
 @attr.s(frozen=True)
-class revlogproblem(object):
+class revlogproblem:
     warning = attr.ib(default=None)
     error = attr.ib(default=None)
     node = attr.ib(default=None)
@@ -237,7 +237,7 @@
 )
 
 
-class revlog(object):
+class revlog:
     """
     the underlying revision storage object
 
@@ -1042,7 +1042,7 @@
         heads = [self.rev(n) for n in heads]
 
         # we want the ancestors, but inclusive
-        class lazyset(object):
+        class lazyset:
             def __init__(self, lazyvalues):
                 self.addedvalues = set()
                 self.lazyvalues = lazyvalues
diff --git a/mercurial/revlogutils/__init__.py b/mercurial/revlogutils/__init__.py
--- a/mercurial/revlogutils/__init__.py
+++ b/mercurial/revlogutils/__init__.py
@@ -62,7 +62,7 @@
 
 
 @attr.s(slots=True, frozen=True)
-class revisioninfo(object):
+class revisioninfo:
     """Information about a revision that allows building its fulltext
     node:       expected hash of the revision
     p1, p2:     parent revs of the revision
diff --git a/mercurial/revlogutils/deltas.py b/mercurial/revlogutils/deltas.py
--- a/mercurial/revlogutils/deltas.py
+++ b/mercurial/revlogutils/deltas.py
@@ -38,7 +38,7 @@
 LIMIT_DELTA2TEXT = 2
 
 
-class _testrevlog(object):
+class _testrevlog:
     """minimalist fake revlog to use in doctests"""
 
     def __init__(self, data, density=0.5, mingap=0, snapshot=()):
@@ -544,7 +544,7 @@
 
 
 @attr.s(slots=True, frozen=True)
-class _deltainfo(object):
+class _deltainfo:
     distance = attr.ib()
     deltalen = attr.ib()
     data = attr.ib()
@@ -927,7 +927,7 @@
         yield (prev,)
 
 
-class deltacomputer(object):
+class deltacomputer:
     def __init__(self, revlog):
         self.revlog = revlog
 
diff --git a/mercurial/revlogutils/docket.py b/mercurial/revlogutils/docket.py
--- a/mercurial/revlogutils/docket.py
+++ b/mercurial/revlogutils/docket.py
@@ -99,7 +99,7 @@
 S_OLD_UID = struct.Struct('>BL')
 
 
-class RevlogDocket(object):
+class RevlogDocket:
     """metadata associated with revlog"""
 
     def __init__(
diff --git a/mercurial/revlogutils/nodemap.py b/mercurial/revlogutils/nodemap.py
--- a/mercurial/revlogutils/nodemap.py
+++ b/mercurial/revlogutils/nodemap.py
@@ -113,7 +113,7 @@
     tr.addfinalize(callback_id, lambda tr: persist_nodemap(tr, revlog))
 
 
-class _NoTransaction(object):
+class _NoTransaction:
     """transaction like object to update the nodemap outside a transaction"""
 
     def __init__(self):
@@ -304,7 +304,7 @@
 S_HEADER = struct.Struct(">BQQQQ")
 
 
-class NodeMapDocket(object):
+class NodeMapDocket:
     """metadata associated with persistent nodemap data
 
     The persistent data may come from disk or be on their way to disk.
diff --git a/mercurial/revlogutils/randomaccessfile.py b/mercurial/revlogutils/randomaccessfile.py
--- a/mercurial/revlogutils/randomaccessfile.py
+++ b/mercurial/revlogutils/randomaccessfile.py
@@ -23,7 +23,7 @@
     return (n & (n - 1) == 0) and n != 0
 
 
-class randomaccessfile(object):
+class randomaccessfile:
     """Accessing arbitrary chuncks of data within a file, with some caching"""
 
     def __init__(
diff --git a/mercurial/scmutil.py b/mercurial/scmutil.py
--- a/mercurial/scmutil.py
+++ b/mercurial/scmutil.py
@@ -62,7 +62,7 @@
 
 
 @attr.s(slots=True, repr=False)
-class status(object):
+class status:
     """Struct with a list of files per status.
 
     The 'deleted', 'unknown' and 'ignored' properties are only
@@ -323,7 +323,7 @@
     return abort, warn
 
 
-class casecollisionauditor(object):
+class casecollisionauditor:
     def __init__(self, ui, abort, dirstate):
         self._ui = ui
         self._abort = abort
@@ -1019,7 +1019,7 @@
     return origvfs.join(filepath)
 
 
-class _containsnode(object):
+class _containsnode:
     """proxy __contains__(node) to container.__contains__ which accepts revs"""
 
     def __init__(self, repo, revcontainer):
@@ -1567,7 +1567,7 @@
             fp.write(b"%s\n" % r)
 
 
-class filecachesubentry(object):
+class filecachesubentry:
     def __init__(self, path, stat):
         self.path = path
         self.cachestat = None
@@ -1623,7 +1623,7 @@
                 raise
 
 
-class filecacheentry(object):
+class filecacheentry:
     def __init__(self, paths, stat=True):
         self._entries = []
         for path in paths:
@@ -1641,7 +1641,7 @@
             entry.refresh()
 
 
-class filecache(object):
+class filecache:
     """A property like decorator that tracks files under .hg/ for updates.
 
     On first access, the files defined as arguments are stat()ed and the
@@ -1798,7 +1798,7 @@
     return data
 
 
-class progress(object):
+class progress:
     def __init__(self, ui, updatebar, topic, unit=b"", total=None):
         self.ui = ui
         self.pos = 0
@@ -1863,7 +1863,7 @@
     return ui.configbool(b'format', b'generaldelta')
 
 
-class simplekeyvaluefile(object):
+class simplekeyvaluefile:
     """A simple file with key=value lines
 
     Keys must be alphanumerics and start with a letter, values must not
diff --git a/mercurial/setdiscovery.py b/mercurial/setdiscovery.py
--- a/mercurial/setdiscovery.py
+++ b/mercurial/setdiscovery.py
@@ -106,7 +106,7 @@
     return set(sample[:desiredlen])
 
 
-class partialdiscovery(object):
+class partialdiscovery:
     """an object representing ongoing discovery
 
     Feed with data from the remote repository, this object keep track of the
diff --git a/mercurial/shelve.py b/mercurial/shelve.py
--- a/mercurial/shelve.py
+++ b/mercurial/shelve.py
@@ -68,7 +68,7 @@
 shelveuser = b'shelve@localhost'
 
 
-class ShelfDir(object):
+class ShelfDir:
     def __init__(self, repo, for_backups=False):
         if for_backups:
             self.vfs = vfsmod.vfs(repo.vfs.join(backupdir))
@@ -101,7 +101,7 @@
         return sorted(info, reverse=True)
 
 
-class Shelf(object):
+class Shelf:
     """Represents a shelf, including possibly multiple files storing it.
 
     Old shelves will have a .patch and a .hg file. Newer shelves will
@@ -213,7 +213,7 @@
             self.vfs.tryunlink(self.name + b'.' + ext)
 
 
-class shelvedstate(object):
+class shelvedstate:
     """Handle persistence during unshelving operations.
 
     Handles saving and restoring a shelved state. Ensures that different
diff --git a/mercurial/simplemerge.py b/mercurial/simplemerge.py
--- a/mercurial/simplemerge.py
+++ b/mercurial/simplemerge.py
@@ -62,7 +62,7 @@
         return True
 
 
-class Merge3Text(object):
+class Merge3Text:
     """3-way merge of texts.
 
     Given strings BASE, OTHER, THIS, tries to produce a combined text
@@ -468,7 +468,7 @@
     return lines
 
 
-class MergeInput(object):
+class MergeInput:
     def __init__(self, fctx, label=None, label_detail=None):
         self.fctx = fctx
         self.label = label
diff --git a/mercurial/smartset.py b/mercurial/smartset.py
--- a/mercurial/smartset.py
+++ b/mercurial/smartset.py
@@ -20,7 +20,7 @@
     return pycompat.sysbytes(type(o).__name__).lstrip(b'_')
 
 
-class abstractsmartset(object):
+class abstractsmartset:
     def __nonzero__(self):
         """True if the smartset is not empty"""
         raise NotImplementedError()
diff --git a/mercurial/sshpeer.py b/mercurial/sshpeer.py
--- a/mercurial/sshpeer.py
+++ b/mercurial/sshpeer.py
@@ -47,7 +47,7 @@
                 display(_(b"remote: "), l, b'\n')
 
 
-class doublepipe(object):
+class doublepipe:
     """Operate a side-channel pipe in addition of a main one
 
     The side-channel pipe contains server output to be forwarded to the user
diff --git a/mercurial/state.py b/mercurial/state.py
--- a/mercurial/state.py
+++ b/mercurial/state.py
@@ -39,7 +39,7 @@
         assert t
 
 
-class cmdstate(object):
+class cmdstate:
     """a wrapper class to store the state of commands like `rebase`, `graft`,
     `histedit`, `shelve` etc. Extensions can also use this to write state files.
 
@@ -102,7 +102,7 @@
         return self._repo.vfs.exists(self.fname)
 
 
-class _statecheck(object):
+class _statecheck:
     """a utility class that deals with multistep operations like graft,
     histedit, bisect, update etc and check whether such commands
     are in an unfinished conditition or not and return appropriate message
diff --git a/mercurial/statichttprepo.py b/mercurial/statichttprepo.py
--- a/mercurial/statichttprepo.py
+++ b/mercurial/statichttprepo.py
@@ -34,7 +34,7 @@
 urlreq = util.urlreq
 
 
-class httprangereader(object):
+class httprangereader:
     def __init__(self, url, opener):
         # we assume opener has HTTPRangeHandler
         self.url = url
diff --git a/mercurial/statprof.py b/mercurial/statprof.py
--- a/mercurial/statprof.py
+++ b/mercurial/statprof.py
@@ -154,7 +154,7 @@
 ## Collection data structures
 
 
-class ProfileState(object):
+class ProfileState:
     def __init__(self, frequency=None):
         self.reset(frequency)
         self.track = b'cpu'
@@ -202,7 +202,7 @@
 state = ProfileState()
 
 
-class CodeSite(object):
+class CodeSite:
     cache = {}
 
     __slots__ = ('path', 'lineno', 'function', 'source')
@@ -260,7 +260,7 @@
         return '%s:%s' % (self.filename(), self.function)
 
 
-class Sample(object):
+class Sample:
     __slots__ = ('stack', 'time')
 
     def __init__(self, stack, time):
@@ -434,7 +434,7 @@
 ## Reporting API
 
 
-class SiteStats(object):
+class SiteStats:
     def __init__(self, site):
         self.site = site
         self.selfcount = 0
@@ -708,7 +708,7 @@
 
 
 def display_hotpath(data, fp, limit=0.05, **kwargs):
-    class HotNode(object):
+    class HotNode:
         def __init__(self, site):
             self.site = site
             self.count = 0
diff --git a/mercurial/store.py b/mercurial/store.py
--- a/mercurial/store.py
+++ b/mercurial/store.py
@@ -455,7 +455,7 @@
 FILETYPE_OTHER = FILEFLAGS_OTHER
 
 
-class basicstore(object):
+class basicstore:
     '''base class for local repository stores'''
 
     def __init__(self, path, vfstype):
@@ -601,7 +601,7 @@
         return [b'requires', b'00changelog.i'] + [b'store/' + f for f in _data]
 
 
-class fncache(object):
+class fncache:
     # the filename used to be partially encoded
     # hence the encodedir/decodedir dance
     def __init__(self, vfs):
diff --git a/mercurial/streamclone.py b/mercurial/streamclone.py
--- a/mercurial/streamclone.py
+++ b/mercurial/streamclone.py
@@ -516,7 +516,7 @@
     nodemap.post_stream_cleanup(repo)
 
 
-class streamcloneapplier(object):
+class streamcloneapplier:
     """Class to manage applying streaming clone bundles.
 
     We need to wrap ``applybundlev1()`` in a dedicated type to enable bundle
diff --git a/mercurial/subrepo.py b/mercurial/subrepo.py
--- a/mercurial/subrepo.py
+++ b/mercurial/subrepo.py
@@ -220,7 +220,7 @@
 # subrepo classes need to implement the following abstract class:
 
 
-class abstractsubrepo(object):
+class abstractsubrepo:
     def __init__(self, ctx, path):
         """Initialize abstractsubrepo part
 
diff --git a/mercurial/tags.py b/mercurial/tags.py
--- a/mercurial/tags.py
+++ b/mercurial/tags.py
@@ -684,7 +684,7 @@
 _fnodesmissingrec = b'\xff' * 24
 
 
-class hgtagsfnodescache(object):
+class hgtagsfnodescache:
     """Persistent cache mapping revisions to .hgtags filenodes.
 
     The cache is an array of records. Each item in the array corresponds to
diff --git a/mercurial/templater.py b/mercurial/templater.py
--- a/mercurial/templater.py
+++ b/mercurial/templater.py
@@ -626,7 +626,7 @@
     return s[1:-1]
 
 
-class resourcemapper(object):  # pytype: disable=ignored-metaclass
+class resourcemapper:  # pytype: disable=ignored-metaclass
     """Mapper of internal template resources"""
 
     __metaclass__ = abc.ABCMeta
@@ -663,7 +663,7 @@
         return {}
 
 
-class engine(object):
+class engine:
     """template expansion engine.
 
     template expansion works like this. a map file contains key=value
@@ -919,7 +919,7 @@
     return cache, tmap, aliases
 
 
-class loader(object):
+class loader:
     """Load template fragments optionally from a map file"""
 
     def __init__(self, cache, aliases):
@@ -994,7 +994,7 @@
         return syms
 
 
-class templater(object):
+class templater:
     def __init__(
         self,
         filters=None,
diff --git a/mercurial/templateutil.py b/mercurial/templateutil.py
--- a/mercurial/templateutil.py
+++ b/mercurial/templateutil.py
@@ -31,7 +31,7 @@
     pass
 
 
-class wrapped(object):  # pytype: disable=ignored-metaclass
+class wrapped:  # pytype: disable=ignored-metaclass
     """Object requiring extra conversion prior to displaying or processing
     as value
 
@@ -108,7 +108,7 @@
         """
 
 
-class mappable(object):  # pytype: disable=ignored-metaclass
+class mappable:  # pytype: disable=ignored-metaclass
     """Object which can be converted to a single template mapping"""
 
     __metaclass__ = abc.ABCMeta
diff --git a/mercurial/ui.py b/mercurial/ui.py
--- a/mercurial/ui.py
+++ b/mercurial/ui.py
@@ -169,7 +169,7 @@
     return pycompat.rapply(pycompat.bytesurl, maybestr)
 
 
-class httppasswordmgrdbproxy(object):
+class httppasswordmgrdbproxy:
     """Delays loading urllib2 until it's needed."""
 
     def __init__(self):
@@ -207,7 +207,7 @@
 _reqexithandlers = []
 
 
-class ui(object):
+class ui:
     def __init__(self, src=None):
         """Create a fresh new ui object if no src given
 
diff --git a/mercurial/unionrepo.py b/mercurial/unionrepo.py
--- a/mercurial/unionrepo.py
+++ b/mercurial/unionrepo.py
@@ -209,7 +209,7 @@
         return False
 
 
-class unionrepository(object):
+class unionrepository:
     """Represents the union of data in 2 repositories.
 
     Instances are not usable if constructed directly. Use ``instance()``
diff --git a/mercurial/upgrade_utils/actions.py b/mercurial/upgrade_utils/actions.py
--- a/mercurial/upgrade_utils/actions.py
+++ b/mercurial/upgrade_utils/actions.py
@@ -45,7 +45,7 @@
 OPTIMISATION = b'optimization'
 
 
-class improvement(object):
+class improvement:
     """Represents an improvement that can be made as part of an upgrade."""
 
     ### The following attributes should be defined for each subclass:
@@ -684,7 +684,7 @@
     return newactions
 
 
-class UpgradeOperation(object):
+class UpgradeOperation:
     """represent the work to be done during an upgrade"""
 
     def __init__(
diff --git a/mercurial/url.py b/mercurial/url.py
--- a/mercurial/url.py
+++ b/mercurial/url.py
@@ -50,7 +50,7 @@
     return s
 
 
-class passwordmgr(object):
+class passwordmgr:
     def __init__(self, ui, passwddb):
         self.ui = ui
         self.passwddb = passwddb
diff --git a/mercurial/urllibcompat.py b/mercurial/urllibcompat.py
--- a/mercurial/urllibcompat.py
+++ b/mercurial/urllibcompat.py
@@ -17,7 +17,7 @@
 _sysstr = pycompat.sysstr
 
 
-class _pycompatstub(object):
+class _pycompatstub:
     def __init__(self):
         self._aliases = {}
 
diff --git a/mercurial/util.py b/mercurial/util.py
--- a/mercurial/util.py
+++ b/mercurial/util.py
@@ -231,7 +231,7 @@
     assert k in DIGESTS
 
 
-class digester(object):
+class digester:
     """helper to compute digests.
 
     This helper can be used to compute one or more digests given their name.
@@ -279,7 +279,7 @@
         return None
 
 
-class digestchecker(object):
+class digestchecker:
     """file handle wrapper that additionally checks content against a given
     size and digests.
 
@@ -329,7 +329,7 @@
 _chunksize = 4096
 
 
-class bufferedinputpipe(object):
+class bufferedinputpipe:
     """a manually buffered input pipe
 
     Python will not let us use buffered IO and lazy reading with 'polling' at
@@ -457,7 +457,7 @@
         raise
 
 
-class fileobjectproxy(object):
+class fileobjectproxy:
     """A proxy around file objects that tells a watcher when events occur.
 
     This type is intended to only be used for testing purposes. Think hard
@@ -693,7 +693,7 @@
 }
 
 
-class socketproxy(object):
+class socketproxy:
     """A proxy around a socket that tells a watcher when events occur.
 
     This is like ``fileobjectproxy`` except for sockets.
@@ -816,7 +816,7 @@
         )
 
 
-class baseproxyobserver(object):
+class baseproxyobserver:
     def __init__(self, fh, name, logdata, logdataapis):
         self.fh = fh
         self.name = name
@@ -1256,7 +1256,7 @@
     return f
 
 
-class cow(object):
+class cow:
     """helper class to make copy-on-write easier
 
     Call preparewrite before doing any writes.
@@ -1349,7 +1349,7 @@
     """
 
 
-class transactional(object):  # pytype: disable=ignored-metaclass
+class transactional:  # pytype: disable=ignored-metaclass
     """Base class for making a transactional type into a context manager."""
 
     __metaclass__ = abc.ABCMeta
@@ -1400,7 +1400,7 @@
     yield enter_result
 
 
-class _lrucachenode(object):
+class _lrucachenode:
     """A node in a doubly linked list.
 
     Holds a reference to nodes on either side as well as a key-value
@@ -1424,7 +1424,7 @@
         self.cost = 0
 
 
-class lrucachedict(object):
+class lrucachedict:
     """Dict that caches most recent accesses and sets.
 
     The dict consists of an actual backing dict - indexed by original
@@ -1755,7 +1755,7 @@
     return f
 
 
-class propertycache(object):
+class propertycache:
     def __init__(self, func):
         self.func = func
         self.name = func.__name__
@@ -2214,7 +2214,7 @@
     _re2 = False
 
 
-class _re(object):
+class _re:
     def _checkre2(self):
         global _re2
         global _re2_input
@@ -2416,7 +2416,7 @@
     return temp
 
 
-class filestat(object):
+class filestat:
     """help to exactly detect change of a file
 
     'stat' attribute is result of 'os.stat()' if specified 'path'
@@ -2522,7 +2522,7 @@
         return not self == other
 
 
-class atomictempfile(object):
+class atomictempfile:
     """writable file object that atomically updates a file
 
     All writes will go to a temporary copy of the original file. Call
@@ -2665,7 +2665,7 @@
         fp.write(text)
 
 
-class chunkbuffer(object):
+class chunkbuffer:
     """Allow arbitrary sized chunks of data to be efficiently read from an
     iterator over chunks of arbitrary size."""
 
@@ -2770,7 +2770,7 @@
         yield s
 
 
-class cappedreader(object):
+class cappedreader:
     """A file object proxy that allows reading up to N bytes.
 
     Given a source file object, instances of this type allow reading up to
@@ -2858,7 +2858,7 @@
 )
 
 
-class transformingwriter(object):
+class transformingwriter:
     """Writable file wrapper to transform data by function"""
 
     def __init__(self, fp, encode):
@@ -2966,7 +2966,7 @@
 
 
 @attr.s
-class timedcmstats(object):
+class timedcmstats:
     """Stats information produced by the timedcm context manager on entering."""
 
     # the starting value of the timer as a float (meaning and resulution is
@@ -3067,7 +3067,7 @@
         raise error.ParseError(_(b"couldn't parse size: %s") % s)
 
 
-class hooks(object):
+class hooks:
     """A collection of hook functions that can be used to extend a
     function's behavior. Hooks are called in lexicographic order,
     based on the names of their sources."""
diff --git a/mercurial/utils/cborutil.py b/mercurial/utils/cborutil.py
--- a/mercurial/utils/cborutil.py
+++ b/mercurial/utils/cborutil.py
@@ -483,7 +483,7 @@
         return self
 
 
-class sansiodecoder(object):
+class sansiodecoder:
     """A CBOR decoder that doesn't perform its own I/O.
 
     To use, construct an instance and feed it segments containing
@@ -976,7 +976,7 @@
         return l
 
 
-class bufferingdecoder(object):
+class bufferingdecoder:
     """A CBOR decoder that buffers undecoded input.
 
     This is a glorified wrapper around ``sansiodecoder`` that adds a buffering
diff --git a/mercurial/utils/compression.py b/mercurial/utils/compression.py
--- a/mercurial/utils/compression.py
+++ b/mercurial/utils/compression.py
@@ -32,7 +32,7 @@
 )
 
 
-class propertycache(object):
+class propertycache:
     def __init__(self, func):
         self.func = func
         self.name = func.__name__
@@ -47,7 +47,7 @@
         obj.__dict__[self.name] = value
 
 
-class compressormanager(object):
+class compressormanager:
     """Holds registrations of various compression engines.
 
     This class essentially abstracts the differences between compression
@@ -219,7 +219,7 @@
 compengines = compressormanager()
 
 
-class compressionengine(object):
+class compressionengine:
     """Base class for compression engines.
 
     Compression engines must implement the interface defined by this class.
@@ -338,7 +338,7 @@
         raise NotImplementedError()
 
 
-class _CompressedStreamReader(object):
+class _CompressedStreamReader:
     def __init__(self, fh):
         if safehasattr(fh, 'unbufferedread'):
             self._reader = fh.unbufferedread
@@ -482,7 +482,7 @@
     def decompressorreader(self, fh):
         return _GzipCompressedStreamReader(fh)
 
-    class zlibrevlogcompressor(object):
+    class zlibrevlogcompressor:
         def __init__(self, level=None):
             self._level = level
 
@@ -626,7 +626,7 @@
     def decompressorreader(self, fh):
         return fh
 
-    class nooprevlogcompressor(object):
+    class nooprevlogcompressor:
         def compress(self, data):
             return None
 
@@ -698,7 +698,7 @@
     def decompressorreader(self, fh):
         return _ZstdCompressedStreamReader(fh, self._module)
 
-    class zstdrevlogcompressor(object):
+    class zstdrevlogcompressor:
         def __init__(self, zstd, level=3):
             # TODO consider omitting frame magic to save 4 bytes.
             # This writes content sizes into the frame header. That is
@@ -782,7 +782,7 @@
 
     # We need to format the docstring. So use a dummy object/type to hold it
     # rather than mutating the original.
-    class docobject(object):
+    class docobject:
         pass
 
     for name in compengines:
diff --git a/mercurial/utils/procutil.py b/mercurial/utils/procutil.py
--- a/mercurial/utils/procutil.py
+++ b/mercurial/utils/procutil.py
@@ -59,7 +59,7 @@
         raise IOError(errno.EBADF, 'Bad file descriptor')
 
 
-class LineBufferedWrapper(object):
+class LineBufferedWrapper:
     def __init__(self, orig):
         self.orig = orig
 
@@ -98,7 +98,7 @@
     return stream
 
 
-class WriteAllWrapper(object):
+class WriteAllWrapper:
     def __init__(self, orig):
         self.orig = orig
 
@@ -193,7 +193,7 @@
     return _(b"killed by signal %d") % -code
 
 
-class _pfile(object):
+class _pfile:
     """File-like wrapper for a stream opened by subprocess.Popen()"""
 
     def __init__(self, proc, fp):
diff --git a/mercurial/utils/stringutil.py b/mercurial/utils/stringutil.py
--- a/mercurial/utils/stringutil.py
+++ b/mercurial/utils/stringutil.py
@@ -496,7 +496,7 @@
 
 
 @attr.s(hash=True)
-class mailmapping(object):
+class mailmapping:
     """Represents a username/email key or value in
     a mailmap file"""
 
diff --git a/mercurial/utils/urlutil.py b/mercurial/utils/urlutil.py
--- a/mercurial/utils/urlutil.py
+++ b/mercurial/utils/urlutil.py
@@ -54,7 +54,7 @@
         )
 
 
-class url(object):
+class url:
     r"""Reliable URL parser.
 
     This parses URLs and provides attributes for the following
@@ -832,7 +832,7 @@
     return new_paths
 
 
-class path(object):
+class path:
     """Represents an individual path and its configuration."""
 
     def __init__(
diff --git a/mercurial/verify.py b/mercurial/verify.py
--- a/mercurial/verify.py
+++ b/mercurial/verify.py
@@ -54,7 +54,7 @@
 )
 
 
-class verifier(object):
+class verifier:
     def __init__(self, repo, level=None):
         self.repo = repo.unfiltered()
         self.ui = repo.ui
diff --git a/mercurial/vfs.py b/mercurial/vfs.py
--- a/mercurial/vfs.py
+++ b/mercurial/vfs.py
@@ -46,7 +46,7 @@
         checkandavoid()
 
 
-class abstractvfs(object):
+class abstractvfs:
     """Abstract base class; cannot be instantiated"""
 
     # default directory separator for vfs
@@ -606,7 +606,7 @@
         return self.vfs.join(path, *insidef)
 
 
-class closewrapbase(object):
+class closewrapbase:
     """Base class of wrapper, which hooks closing
 
     Do not instantiate outside of the vfs layer.
@@ -652,7 +652,7 @@
         self._closer.close(self._origfh)
 
 
-class backgroundfilecloser(object):
+class backgroundfilecloser:
     """Coordinates background closing of file handles on multiple threads."""
 
     def __init__(self, ui, expectedcount=-1):
diff --git a/mercurial/windows.py b/mercurial/windows.py
--- a/mercurial/windows.py
+++ b/mercurial/windows.py
@@ -53,7 +53,7 @@
 umask = 0o022
 
 
-class mixedfilemodewrapper(object):
+class mixedfilemodewrapper:
     """Wraps a file handle when it is opened in read/write mode.
 
     fopen() and fdopen() on Windows have a specific-to-Windows requirement
@@ -130,7 +130,7 @@
         return self._fp.readlines(*args, **kwargs)
 
 
-class fdproxy(object):
+class fdproxy:
     """Wraps osutil.posixfile() to override the name attribute to reflect the
     underlying file name.
     """
@@ -214,7 +214,7 @@
     return encoding.unitolocal(pw)
 
 
-class winstdout(object):
+class winstdout:
     """Some files on Windows misbehave.
 
     When writing to a broken pipe, EINVAL instead of EPIPE may be raised.
@@ -658,7 +658,7 @@
     return False
 
 
-class cachestat(object):
+class cachestat:
     def __init__(self, path):
         pass
 
diff --git a/mercurial/wireprotoframing.py b/mercurial/wireprotoframing.py
--- a/mercurial/wireprotoframing.py
+++ b/mercurial/wireprotoframing.py
@@ -134,7 +134,7 @@
 
 
 @attr.s(slots=True)
-class frameheader(object):
+class frameheader:
     """Represents the data in a frame header."""
 
     length = attr.ib()
@@ -146,7 +146,7 @@
 
 
 @attr.s(slots=True, repr=False)
-class frame(object):
+class frame:
     """Represents a parsed frame."""
 
     requestid = attr.ib()
@@ -589,7 +589,7 @@
     )
 
 
-class bufferingcommandresponseemitter(object):
+class bufferingcommandresponseemitter:
     """Helper object to emit command response frames intelligently.
 
     Raw command response data is likely emitted in chunks much smaller
@@ -699,7 +699,7 @@
 # mechanism.
 
 
-class identityencoder(object):
+class identityencoder:
     """Encoder for the "identity" stream encoding profile."""
 
     def __init__(self, ui):
@@ -715,7 +715,7 @@
         return b''
 
 
-class identitydecoder(object):
+class identitydecoder:
     """Decoder for the "identity" stream encoding profile."""
 
     def __init__(self, ui, extraobjs):
@@ -728,7 +728,7 @@
         return data
 
 
-class zlibencoder(object):
+class zlibencoder:
     def __init__(self, ui):
         import zlib
 
@@ -749,7 +749,7 @@
         return res
 
 
-class zlibdecoder(object):
+class zlibdecoder:
     def __init__(self, ui, extraobjs):
         import zlib
 
@@ -764,7 +764,7 @@
         return self._decompressor.decompress(data)
 
 
-class zstdbaseencoder(object):
+class zstdbaseencoder:
     def __init__(self, level):
         from . import zstd
 
@@ -792,7 +792,7 @@
         super(zstd8mbencoder, self).__init__(3)
 
 
-class zstdbasedecoder(object):
+class zstdbasedecoder:
     def __init__(self, maxwindowsize):
         from . import zstd
 
@@ -842,7 +842,7 @@
     STREAM_ENCODERS_ORDER.append(b'identity')
 
 
-class stream(object):
+class stream:
     """Represents a logical unidirectional series of frames."""
 
     def __init__(self, streamid, active=False):
@@ -995,7 +995,7 @@
 }
 
 
-class serverreactor(object):
+class serverreactor:
     """Holds state of a server handling frame-based protocol requests.
 
     This class is the "brain" of the unified frame-based protocol server
@@ -1683,7 +1683,7 @@
         return self._makeerrorresult(_(b'server already errored'))
 
 
-class commandrequest(object):
+class commandrequest:
     """Represents a request to run a command."""
 
     def __init__(self, requestid, name, args, datafh=None, redirect=None):
@@ -1695,7 +1695,7 @@
         self.state = b'pending'
 
 
-class clientreactor(object):
+class clientreactor:
     """Holds state of a client issuing frame-based protocol requests.
 
     This is like ``serverreactor`` but for client-side state.
diff --git a/mercurial/wireprotoserver.py b/mercurial/wireprotoserver.py
--- a/mercurial/wireprotoserver.py
+++ b/mercurial/wireprotoserver.py
@@ -56,7 +56,7 @@
 
 
 @interfaceutil.implementer(wireprototypes.baseprotocolhandler)
-class httpv1protocolhandler(object):
+class httpv1protocolhandler:
     def __init__(self, req, ui, checkperm):
         self._req = req
         self._ui = ui
@@ -374,7 +374,7 @@
 
 
 @interfaceutil.implementer(wireprototypes.baseprotocolhandler)
-class sshv1protocolhandler(object):
+class sshv1protocolhandler:
     """Handler for requests services via version 1 of SSH protocol."""
 
     def __init__(self, ui, fin, fout):
@@ -520,7 +520,7 @@
             )
 
 
-class sshserver(object):
+class sshserver:
     def __init__(self, ui, repo, logfh=None):
         self._ui = ui
         self._repo = repo
diff --git a/mercurial/wireprototypes.py b/mercurial/wireprototypes.py
--- a/mercurial/wireprototypes.py
+++ b/mercurial/wireprototypes.py
@@ -39,14 +39,14 @@
 }
 
 
-class bytesresponse(object):
+class bytesresponse:
     """A wire protocol response consisting of raw bytes."""
 
     def __init__(self, data):
         self.data = data
 
 
-class ooberror(object):
+class ooberror:
     """wireproto reply: failure of a batch of operation
 
     Something failed during a batch call. The error message is stored in
@@ -57,7 +57,7 @@
         self.message = message
 
 
-class pushres(object):
+class pushres:
     """wireproto reply: success with simple integer return
 
     The call was successful and returned an integer contained in `self.res`.
@@ -68,7 +68,7 @@
         self.output = output
 
 
-class pusherr(object):
+class pusherr:
     """wireproto reply: failure
 
     The call failed. The `self.res` attribute contains the error message.
@@ -79,7 +79,7 @@
         self.output = output
 
 
-class streamres(object):
+class streamres:
     """wireproto reply: binary stream
 
     The call was successful and the result is a stream.
@@ -96,7 +96,7 @@
         self.prefer_uncompressed = prefer_uncompressed
 
 
-class streamreslegacy(object):
+class streamreslegacy:
     """wireproto reply: uncompressed binary stream
 
     The call was successful and the result is a stream.
@@ -243,7 +243,7 @@
         """
 
 
-class commandentry(object):
+class commandentry:
     """Represents a declared wire protocol command."""
 
     def __init__(
@@ -406,7 +406,7 @@
 
 
 @attr.s
-class encodedresponse(object):
+class encodedresponse:
     """Represents response data that is already content encoded.
 
     Wire protocol version 2 only.
@@ -420,7 +420,7 @@
 
 
 @attr.s
-class alternatelocationresponse(object):
+class alternatelocationresponse:
     """Represents a response available at an alternate location.
 
     Instances are sent in place of actual response objects when the server
@@ -439,7 +439,7 @@
 
 
 @attr.s
-class indefinitebytestringresponse(object):
+class indefinitebytestringresponse:
     """Represents an object to be encoded to an indefinite length bytestring.
 
     Instances are initialized from an iterable of chunks, with each chunk being
diff --git a/mercurial/wireprotov1peer.py b/mercurial/wireprotov1peer.py
--- a/mercurial/wireprotov1peer.py
+++ b/mercurial/wireprotov1peer.py
@@ -109,7 +109,7 @@
 
 
 @interfaceutil.implementer(repository.ipeercommandexecutor)
-class peerexecutor(object):
+class peerexecutor:
     def __init__(self, peer):
         self._peer = peer
         self._sent = False
diff --git a/mercurial/worker.py b/mercurial/worker.py
--- a/mercurial/worker.py
+++ b/mercurial/worker.py
@@ -68,7 +68,7 @@
     return threading.current_thread() == threading.main_thread()
 
 
-class _blockingreader(object):
+class _blockingreader:
     def __init__(self, wrapped):
         self._wrapped = wrapped
 
diff --git a/setup.py b/setup.py
--- a/setup.py
+++ b/setup.py
@@ -213,7 +213,7 @@
     return p.returncode, out, err
 
 
-class hgcommand(object):
+class hgcommand:
     def __init__(self, cmd, env):
         self.cmd = cmd
         self.env = env
@@ -1528,7 +1528,7 @@
     # the cygwinccompiler package is not available on some Python
     # distributions like the ones from the optware project for Synology
     # DiskStation boxes
-    class HackedMingw32CCompiler(object):
+    class HackedMingw32CCompiler:
         pass
 
 
diff --git a/tests/drawdag.py b/tests/drawdag.py
--- a/tests/drawdag.py
+++ b/tests/drawdag.py
@@ -265,7 +265,7 @@
     return dict(edges)
 
 
-class simplefilectx(object):
+class simplefilectx:
     def __init__(self, path, data):
         self._data = data
         self._path = path
diff --git a/tests/dumbhttp.py b/tests/dumbhttp.py
--- a/tests/dumbhttp.py
+++ b/tests/dumbhttp.py
@@ -37,7 +37,7 @@
         sys.stderr.flush()
 
 
-class simplehttpservice(object):
+class simplehttpservice:
     def __init__(self, host, port):
         self.address = (host, port)
 
diff --git a/tests/httpserverauth.py b/tests/httpserverauth.py
--- a/tests/httpserverauth.py
+++ b/tests/httpserverauth.py
@@ -16,7 +16,7 @@
     return parsed
 
 
-class digestauthserver(object):
+class digestauthserver:
     def __init__(self):
         self._user_hashes = {}
 
diff --git a/tests/mocktime.py b/tests/mocktime.py
--- a/tests/mocktime.py
+++ b/tests/mocktime.py
@@ -2,7 +2,7 @@
 import time
 
 
-class mocktime(object):
+class mocktime:
     def __init__(self, increment):
         self.time = 0
         self.increment = [float(s) for s in increment.split()]
diff --git a/tests/run-tests.py b/tests/run-tests.py
--- a/tests/run-tests.py
+++ b/tests/run-tests.py
@@ -171,7 +171,7 @@
     # Windows lacks os.environb, for instance.  A proxy over the real thing
     # instead of a copy allows the environment to be updated via bytes on
     # all platforms.
-    class environbytes(object):
+    class environbytes:
         def __init__(self, strenv):
             self.__len__ = strenv.__len__
             self.clear = strenv.clear
@@ -2983,7 +2983,7 @@
     testdescs.sort(key=sortkey)
 
 
-class TestRunner(object):
+class TestRunner:
     """Holds context for executing tests.
 
     Tests rely on a lot of state. This object holds it for them.
diff --git a/tests/simplestorerepo.py b/tests/simplestorerepo.py
--- a/tests/simplestorerepo.py
+++ b/tests/simplestorerepo.py
@@ -70,7 +70,7 @@
 
 @interfaceutil.implementer(repository.irevisiondelta)
 @attr.s(slots=True)
-class simplestorerevisiondelta(object):
+class simplestorerevisiondelta:
     node = attr.ib()
     p1node = attr.ib()
     p2node = attr.ib()
@@ -84,14 +84,14 @@
 
 @interfaceutil.implementer(repository.iverifyproblem)
 @attr.s(frozen=True)
-class simplefilestoreproblem(object):
+class simplefilestoreproblem:
     warning = attr.ib(default=None)
     error = attr.ib(default=None)
     node = attr.ib(default=None)
 
 
 @interfaceutil.implementer(repository.ifilestorage)
-class filestorage(object):
+class filestorage:
     """Implements storage for a tracked path.
 
     Data is stored in the VFS in a directory corresponding to the tracked
diff --git a/tests/test-absorb-filefixupstate.py b/tests/test-absorb-filefixupstate.py
--- a/tests/test-absorb-filefixupstate.py
+++ b/tests/test-absorb-filefixupstate.py
@@ -3,7 +3,7 @@
 from hgext import absorb
 
 
-class simplefctx(object):
+class simplefctx:
     def __init__(self, content):
         self.content = content
 
diff --git a/tests/test-ancestor.py b/tests/test-ancestor.py
--- a/tests/test-ancestor.py
+++ b/tests/test-ancestor.py
@@ -62,7 +62,7 @@
     return ancs
 
 
-class naiveincrementalmissingancestors(object):
+class naiveincrementalmissingancestors:
     def __init__(self, ancs, bases):
         self.ancs = ancs
         self.bases = set(bases)
diff --git a/tests/test-batching.py b/tests/test-batching.py
--- a/tests/test-batching.py
+++ b/tests/test-batching.py
@@ -20,7 +20,7 @@
 
 
 # equivalent of repo.repository
-class thing(object):
+class thing:
     def hello(self):
         return b"Ready."
 
@@ -107,7 +107,7 @@
 # server side
 
 # equivalent of wireproto's global functions
-class server(object):
+class server:
     def __init__(self, local):
         self.local = local
 
diff --git a/tests/test-check-interfaces.py b/tests/test-check-interfaces.py
--- a/tests/test-check-interfaces.py
+++ b/tests/test-check-interfaces.py
@@ -80,7 +80,7 @@
 
 
 # Facilitates testing localpeer.
-class dummyrepo(object):
+class dummyrepo:
     def __init__(self):
         self.ui = uimod.ui()
         self._wanted_sidedata = set()
@@ -92,7 +92,7 @@
         pass
 
 
-class dummyopener(object):
+class dummyopener:
     handlers = []
 
 
@@ -108,7 +108,7 @@
         pass
 
 
-class dummypipe(object):
+class dummypipe:
     def close(self):
         pass
 
diff --git a/tests/test-extensions-wrapfunction.py b/tests/test-extensions-wrapfunction.py
--- a/tests/test-extensions-wrapfunction.py
+++ b/tests/test-extensions-wrapfunction.py
@@ -16,7 +16,7 @@
 wrappers = [genwrapper(i) for i in range(5)]
 
 
-class dummyclass(object):
+class dummyclass:
     def getstack(self):
         return ['orig']
 
@@ -67,7 +67,7 @@
 print('context manager', dummy.getstack())
 
 # Wrap callable object which has no __name__
-class callableobj(object):
+class callableobj:
     def __call__(self):
         return ['orig']
 
diff --git a/tests/test-fastannotate-revmap.py b/tests/test-fastannotate-revmap.py
--- a/tests/test-fastannotate-revmap.py
+++ b/tests/test-fastannotate-revmap.py
@@ -169,7 +169,7 @@
     os.unlink(path2)
 
 
-class fakefctx(object):
+class fakefctx:
     def __init__(self, node, path=None):
         self._node = node
         self._path = path
diff --git a/tests/test-filecache.py b/tests/test-filecache.py
--- a/tests/test-filecache.py
+++ b/tests/test-filecache.py
@@ -35,11 +35,11 @@
     xrange = range
 
 
-class fakerepo(object):
+class fakerepo:
     def __init__(self):
         self._filecache = {}
 
-    class fakevfs(object):
+    class fakevfs:
         def join(self, p):
             return p
 
diff --git a/tests/test-hashutil.py b/tests/test-hashutil.py
--- a/tests/test-hashutil.py
+++ b/tests/test-hashutil.py
@@ -12,7 +12,7 @@
     sha1dc = None
 
 
-class hashertestsbase(object):
+class hashertestsbase:
     def test_basic_hash(self):
         h = self.hasher()
         h.update(b'foo')
diff --git a/tests/test-lock.py b/tests/test-lock.py
--- a/tests/test-lock.py
+++ b/tests/test-lock.py
@@ -35,7 +35,7 @@
         return super(lockwrapper, self)._getpid() + self._pidoffset
 
 
-class teststate(object):
+class teststate:
     def __init__(self, testcase, dir, pidoffset=0):
         self._testcase = testcase
         self._acquirecalled = False
diff --git a/tests/test-manifest.py b/tests/test-manifest.py
--- a/tests/test-manifest.py
+++ b/tests/test-manifest.py
@@ -74,7 +74,7 @@
 )
 
 
-class basemanifesttests(object):
+class basemanifesttests:
     def parsemanifest(self, text):
         raise NotImplementedError('parsemanifest not implemented by test case')
 
diff --git a/tests/test-remotefilelog-datapack.py b/tests/test-remotefilelog-datapack.py
--- a/tests/test-remotefilelog-datapack.py
+++ b/tests/test-remotefilelog-datapack.py
@@ -35,7 +35,7 @@
 )
 
 
-class datapacktestsbase(object):
+class datapacktestsbase:
     def __init__(self, datapackreader, paramsavailable):
         self.datapackreader = datapackreader
         self.paramsavailable = paramsavailable
diff --git a/tests/test-revlog-raw.py b/tests/test-revlog-raw.py
--- a/tests/test-revlog-raw.py
+++ b/tests/test-revlog-raw.py
@@ -19,7 +19,7 @@
 )
 
 
-class _NoTransaction(object):
+class _NoTransaction:
     """transaction like object to update the nodemap outside a transaction"""
 
     def __init__(self):
@@ -150,7 +150,7 @@
     code path, which is not covered by "appendrev" alone.
     """
 
-    class dummychangegroup(object):
+    class dummychangegroup:
         @staticmethod
         def deltachunk(pnode):
             pnode = pnode or rlog.nullid
diff --git a/tests/test-rust-discovery.py b/tests/test-rust-discovery.py
--- a/tests/test-rust-discovery.py
+++ b/tests/test-rust-discovery.py
@@ -31,12 +31,12 @@
 )
 
 
-class fakechangelog(object):
+class fakechangelog:
     def __init__(self, idx):
         self.index = idx
 
 
-class fakerepo(object):
+class fakerepo:
     def __init__(self, idx):
         """Just make so that self.changelog.index is the given idx."""
         self.changelog = fakechangelog(idx)
diff --git a/tests/test-simplekeyvaluefile.py b/tests/test-simplekeyvaluefile.py
--- a/tests/test-simplekeyvaluefile.py
+++ b/tests/test-simplekeyvaluefile.py
@@ -7,7 +7,7 @@
 )
 
 
-class mockfile(object):
+class mockfile:
     def __init__(self, name, fs):
         self.name = name
         self.fs = fs
@@ -25,7 +25,7 @@
         return self.fs.contents[self.name]
 
 
-class mockvfs(object):
+class mockvfs:
     def __init__(self):
         self.contents = {}
 
diff --git a/tests/test-sshserver.py b/tests/test-sshserver.py
--- a/tests/test-sshserver.py
+++ b/tests/test-sshserver.py
@@ -38,12 +38,12 @@
     return wireprotoserver.sshserver(ui, repo)
 
 
-class mockrepo(object):
+class mockrepo:
     def __init__(self, ui):
         self.ui = ui
 
 
-class mockui(object):
+class mockui:
     def __init__(self, inbytes):
         self.fin = io.BytesIO(inbytes)
         self.fout = io.BytesIO()
diff --git a/tests/test-wireproto.py b/tests/test-wireproto.py
--- a/tests/test-wireproto.py
+++ b/tests/test-wireproto.py
@@ -14,7 +14,7 @@
 stringio = util.stringio
 
 
-class proto(object):
+class proto:
     def __init__(self, args):
         self.args = args
         self.name = 'dummyproto'
@@ -76,7 +76,7 @@
         return {b'name': mangle(name)}, unmangle
 
 
-class serverrepo(object):
+class serverrepo:
     def __init__(self, ui):
         self.ui = ui
 
diff --git a/tests/testlib/badserverext.py b/tests/testlib/badserverext.py
--- a/tests/testlib/badserverext.py
+++ b/tests/testlib/badserverext.py
@@ -90,7 +90,7 @@
 )
 
 
-class ConditionTracker(object):
+class ConditionTracker:
     def __init__(
         self,
         close_after_recv_bytes,
@@ -256,7 +256,7 @@
 
 
 # We can't adjust __class__ on a socket instance. So we define a proxy type.
-class socketproxy(object):
+class socketproxy:
     __slots__ = ('_orig', '_logfp', '_cond')
 
     def __init__(self, obj, logfp, condition_tracked):
@@ -300,7 +300,7 @@
 
 
 # We can't adjust __class__ on socket._fileobject, so define a proxy.
-class fileobjectproxy(object):
+class fileobjectproxy:
     __slots__ = ('_orig', '_logfp', '_cond')
 
     def __init__(self, obj, logfp, condition_tracked):