--- a/mercurial/configitems.py	Tue Apr 05 05:20:05 2022 +0200
+++ b/mercurial/configitems.py	Tue Mar 22 14:14:52 2022 +0100
@@ -1278,6 +1278,12 @@
 )
 coreconfigitem(
     b'format',
+    b'use-dirstate-v2.automatic-upgrade-of-mismatching-repositories',
+    default=False,
+    experimental=True,
+)
+coreconfigitem(
+    b'format',
     b'use-dirstate-tracked-hint',
     default=False,
     experimental=True,

--- a/mercurial/helptext/config.txt	Tue Apr 05 05:20:05 2022 +0200
+++ b/mercurial/helptext/config.txt	Tue Mar 22 14:14:52 2022 +0100
@@ -944,6 +944,24 @@
 
     For a more comprehensive guide, see :hg:`help internals.dirstate-v2`.
 
+``use-dirstate-v2.automatic-upgrade-of-mismatching-repositories``
+   When enabled, an automatic upgrade will be triggered when a repository format
+   does not match its `use-dirstate-v2` config.
+
+   This is an advanced behavior that most users will not need. We recommend you
+   don't use this unless you are a seasoned administrator of a Mercurial install
+   base.
+
+   Automatic upgrade means that any process accessing the repository will
+   upgrade the repository format to use `dirstate-v2`. This only triggers if a
+   change is needed. This also applies to operations that would have been
+   read-only (like hg status).
+
+   This configuration will apply for moves in any direction, either adding the
+   `dirstate-v2` format if `format.use-dirstate-v2=yes` or removing the
+   `dirstate-v2` requirement if `format.use-dirstate-v2=no`. So we recommend
+   setting both this value and `format.use-dirstate-v2` at the same time.
+
 ``use-dirstate-tracked-hint``
     Enable or disable the writing of "tracked key" file alongside the dirstate.
     (default to disabled)

--- a/mercurial/upgrade_utils/auto_upgrade.py	Tue Apr 05 05:20:05 2022 +0200
+++ b/mercurial/upgrade_utils/auto_upgrade.py	Tue Mar 22 14:14:52 2022 +0100
@@ -136,7 +136,64 @@
     return action
 
 
+def get_dirstate_v2_action(repo):
+    """return an automatic-upgrade action for `dirstate-v2` if applicable
+
+    If no action is needed, return None, otherwise return a callback to upgrade
+    or downgrade the repository according the configuration and repository
+    format.
+    """
+    ui = repo.ui
+    requirements = set(repo.requirements)
+    auto_upgrade_tracked_hint = ui.configbool(
+        b'format',
+        b'use-dirstate-v2.automatic-upgrade-of-mismatching-repositories',
+    )
+
+    action = None
+
+    if auto_upgrade_tracked_hint:
+        d2_config = ui.configbool(b'format', b'use-dirstate-v2')
+        d2_local = requirementsmod.DIRSTATE_V2_REQUIREMENT in requirements
+        if d2_config and not d2_local:
+            msg = _(
+                b"automatically upgrading repository to the `dirstate-v2`"
+                b" feature\n"
+            )
+            hint = (
+                b"(see `hg help config.format.use-dirstate-v2` for details)\n"
+            )
+
+            def action():
+                if not ui.quiet:
+                    ui.write_err(msg)
+                    ui.write_err(hint)
+                requirements.add(requirementsmod.DIRSTATE_V2_REQUIREMENT)
+                fake_op = AutoUpgradeOperation(requirements)
+                engine.upgrade_dirstate(repo.ui, repo, fake_op, b'v1', b'v2')
+
+        elif d2_local and not d2_config:
+            msg = _(
+                b"automatically downgrading repository from the `dirstate-v2`"
+                b" feature\n"
+            )
+            hint = (
+                b"(see `hg help config.format.use-dirstate-v2` for details)\n"
+            )
+
+            def action():
+                if not ui.quiet:
+                    ui.write_err(msg)
+                    ui.write_err(hint)
+                requirements.discard(requirementsmod.DIRSTATE_V2_REQUIREMENT)
+                fake_op = AutoUpgradeOperation(requirements)
+                engine.upgrade_dirstate(repo.ui, repo, fake_op, b'v2', b'v1')
+
+    return action
+
+
 AUTO_UPGRADE_ACTIONS = [
+    get_dirstate_v2_action,
     get_share_safe_action,
     get_tracked_hint_action,
 ]

--- a/rust/rhg/src/main.rs	Tue Apr 05 05:20:05 2022 +0200
+++ b/rust/rhg/src/main.rs	Tue Mar 22 14:14:52 2022 +0100
@@ -736,6 +736,11 @@
         ("format", "use-dirstate-tracked-hint"),
         requirements::DIRSTATE_TRACKED_HINT_V1,
     ),
+    (
+        ("use-dirstate-v2", "automatic-upgrade-of-mismatching-repositories"),
+        ("format", "use-dirstate-v2"),
+        requirements::DIRSTATE_V2_REQUIREMENT,
+    ),
 ];
 
 /// Mercurial allows users to automatically upgrade their repository.

--- a/tests/test-help.t	Tue Apr 05 05:20:05 2022 +0200
+++ b/tests/test-help.t	Tue Mar 22 14:14:52 2022 +0100
@@ -1600,6 +1600,8 @@
   
       "use-dirstate-v2"
   
+      "use-dirstate-v2.automatic-upgrade-of-mismatching-repositories"
+  
       "use-dirstate-tracked-hint"
   
       "use-dirstate-tracked-hint.automatic-upgrade-of-mismatching-repositories"

--- a/tests/test-upgrade-repo.t	Tue Apr 05 05:20:05 2022 +0200
+++ b/tests/test-upgrade-repo.t	Tue Mar 22 14:14:52 2022 +0100
@@ -1994,3 +1994,70 @@
   dirstate-v2:         no
 
   $ cd ..
+
+Test automatic upgrade/downgrade
+================================
+
+
+For dirstate v2
+---------------
+
+create an initial repository
+
+  $ hg init auto-upgrade \
+  >     --config format.use-dirstate-v2=no \
+  >     --config format.use-dirstate-tracked-hint=yes \
+  >     --config format.use-share-safe=no
+  $ hg debugbuilddag -R auto-upgrade --new-file .+5
+  $ hg -R auto-upgrade update
+  6 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  $ hg debugformat -R auto-upgrade | grep dirstate-v2
+  dirstate-v2:         no
+
+upgrade it to dirstate-v2 automatically
+
+  $ hg status -R auto-upgrade \
+  >     --config format.use-dirstate-v2.automatic-upgrade-of-mismatching-repositories=yes \
+  >     --config format.use-dirstate-v2=yes
+  automatically upgrading repository to the `dirstate-v2` feature
+  (see `hg help config.format.use-dirstate-v2` for details)
+  $ hg debugformat -R auto-upgrade | grep dirstate-v2
+  dirstate-v2:        yes
+
+downgrade it from dirstate-v2 automatically
+
+  $ hg status -R auto-upgrade \
+  >     --config format.use-dirstate-v2.automatic-upgrade-of-mismatching-repositories=yes \
+  >     --config format.use-dirstate-v2=no
+  automatically downgrading repository from the `dirstate-v2` feature
+  (see `hg help config.format.use-dirstate-v2` for details)
+  $ hg debugformat -R auto-upgrade | grep dirstate-v2
+  dirstate-v2:         no
+
+
+For multiple change at the same time
+------------------------------------
+
+  $ hg debugformat -R auto-upgrade | egrep '(dirstate-v2|tracked|share-safe)'
+  dirstate-v2:         no
+  tracked-hint:       yes
+  share-safe:          no
+
+  $ hg status -R auto-upgrade \
+  >     --config format.use-dirstate-v2.automatic-upgrade-of-mismatching-repositories=yes \
+  >     --config format.use-dirstate-v2=yes \
+  >     --config format.use-dirstate-tracked-hint.automatic-upgrade-of-mismatching-repositories=yes \
+  >     --config format.use-dirstate-tracked-hint=no\
+  >     --config format.use-share-safe.automatic-upgrade-of-mismatching-repositories=yes \
+  >     --config format.use-share-safe=yes
+  automatically upgrading repository to the `dirstate-v2` feature
+  (see `hg help config.format.use-dirstate-v2` for details)
+  automatically upgrading repository to the `share-safe` feature
+  (see `hg help config.format.use-share-safe` for details)
+  automatically downgrading repository from the `tracked-hint` feature
+  (see `hg help config.format.use-dirstate-tracked-hint` for details)
+  $ hg debugformat -R auto-upgrade | egrep '(dirstate-v2|tracked|share-safe)'
+  dirstate-v2:        yes
+  tracked-hint:        no
+  share-safe:         yes
+