Rename the `EventFormatVersions` enum values so that they line up with room version numbers. (#13706)

13 files changed, 47 insertions, 41 deletions

diff --git a/changelog.d/13706.misc b/changelog.d/13706.misc
new file mode 100644
index 0000000000..65c854c7a9
--- /dev/null
+++ b/changelog.d/13706.misc
@@ -0,0 +1 @@
+Rename the `EventFormatVersions` enum values so that they line up with room version numbers.
\ No newline at end of file
diff --git a/synapse/api/room_versions.py b/synapse/api/room_versions.py
index a0e4ab6db6..e37acb0f1e 100644
--- a/synapse/api/room_versions.py
+++ b/synapse/api/room_versions.py
@@ -19,18 +19,23 @@ import attr
 
 class EventFormatVersions:
     """This is an internal enum for tracking the version of the event format,
-    independently from the room version.
+    independently of the room version.
+
+    To reduce confusion, the event format versions are named after the room
+    versions that they were used or introduced in.
+    The concept of an 'event format version' is specific to Synapse (the
+    specification does not mention this term.)
     """
 
-    V1 = 1  # $id:server event id format
-    V2 = 2  # MSC1659-style $hash event id format: introduced for room v3
-    V3 = 3  # MSC1884-style $hash format: introduced for room v4
+    ROOM_V1_V2 = 1  # $id:server event id format: used for room v1 and v2
+    ROOM_V3 = 2  # MSC1659-style $hash event id format: used for room v3
+    ROOM_V4_PLUS = 3  # MSC1884-style $hash format: introduced for room v4
 
 
 KNOWN_EVENT_FORMAT_VERSIONS = {
-    EventFormatVersions.V1,
-    EventFormatVersions.V2,
-    EventFormatVersions.V3,
+    EventFormatVersions.ROOM_V1_V2,
+    EventFormatVersions.ROOM_V3,
+    EventFormatVersions.ROOM_V4_PLUS,
 }
 
 
@@ -92,7 +97,7 @@ class RoomVersions:
     V1 = RoomVersion(
         "1",
         RoomDisposition.STABLE,
-        EventFormatVersions.V1,
+        EventFormatVersions.ROOM_V1_V2,
         StateResolutionVersions.V1,
         enforce_key_validity=False,
         special_case_aliases_auth=True,
@@ -110,7 +115,7 @@ class RoomVersions:
     V2 = RoomVersion(
         "2",
         RoomDisposition.STABLE,
-        EventFormatVersions.V1,
+        EventFormatVersions.ROOM_V1_V2,
         StateResolutionVersions.V2,
         enforce_key_validity=False,
         special_case_aliases_auth=True,
@@ -128,7 +133,7 @@ class RoomVersions:
     V3 = RoomVersion(
         "3",
         RoomDisposition.STABLE,
-        EventFormatVersions.V2,
+        EventFormatVersions.ROOM_V3,
         StateResolutionVersions.V2,
         enforce_key_validity=False,
         special_case_aliases_auth=True,
@@ -146,7 +151,7 @@ class RoomVersions:
     V4 = RoomVersion(
         "4",
         RoomDisposition.STABLE,
-        EventFormatVersions.V3,
+        EventFormatVersions.ROOM_V4_PLUS,
         StateResolutionVersions.V2,
         enforce_key_validity=False,
         special_case_aliases_auth=True,
@@ -164,7 +169,7 @@ class RoomVersions:
     V5 = RoomVersion(
         "5",
         RoomDisposition.STABLE,
-        EventFormatVersions.V3,
+        EventFormatVersions.ROOM_V4_PLUS,
         StateResolutionVersions.V2,
         enforce_key_validity=True,
         special_case_aliases_auth=True,
@@ -182,7 +187,7 @@ class RoomVersions:
     V6 = RoomVersion(
         "6",
         RoomDisposition.STABLE,
-        EventFormatVersions.V3,
+        EventFormatVersions.ROOM_V4_PLUS,
         StateResolutionVersions.V2,
         enforce_key_validity=True,
         special_case_aliases_auth=False,
@@ -200,7 +205,7 @@ class RoomVersions:
     MSC2176 = RoomVersion(
         "org.matrix.msc2176",
         RoomDisposition.UNSTABLE,
-        EventFormatVersions.V3,
+        EventFormatVersions.ROOM_V4_PLUS,
         StateResolutionVersions.V2,
         enforce_key_validity=True,
         special_case_aliases_auth=False,
@@ -218,7 +223,7 @@ class RoomVersions:
     V7 = RoomVersion(
         "7",
         RoomDisposition.STABLE,
-        EventFormatVersions.V3,
+        EventFormatVersions.ROOM_V4_PLUS,
         StateResolutionVersions.V2,
         enforce_key_validity=True,
         special_case_aliases_auth=False,
@@ -236,7 +241,7 @@ class RoomVersions:
     V8 = RoomVersion(
         "8",
         RoomDisposition.STABLE,
-        EventFormatVersions.V3,
+        EventFormatVersions.ROOM_V4_PLUS,
         StateResolutionVersions.V2,
         enforce_key_validity=True,
         special_case_aliases_auth=False,
@@ -254,7 +259,7 @@ class RoomVersions:
     V9 = RoomVersion(
         "9",
         RoomDisposition.STABLE,
-        EventFormatVersions.V3,
+        EventFormatVersions.ROOM_V4_PLUS,
         StateResolutionVersions.V2,
         enforce_key_validity=True,
         special_case_aliases_auth=False,
@@ -272,7 +277,7 @@ class RoomVersions:
     MSC3787 = RoomVersion(
         "org.matrix.msc3787",
         RoomDisposition.UNSTABLE,
-        EventFormatVersions.V3,
+        EventFormatVersions.ROOM_V4_PLUS,
         StateResolutionVersions.V2,
         enforce_key_validity=True,
         special_case_aliases_auth=False,
@@ -290,7 +295,7 @@ class RoomVersions:
     V10 = RoomVersion(
         "10",
         RoomDisposition.STABLE,
-        EventFormatVersions.V3,
+        EventFormatVersions.ROOM_V4_PLUS,
         StateResolutionVersions.V2,
         enforce_key_validity=True,
         special_case_aliases_auth=False,
@@ -308,7 +313,7 @@ class RoomVersions:
     MSC2716v4 = RoomVersion(
         "org.matrix.msc2716v4",
         RoomDisposition.UNSTABLE,
-        EventFormatVersions.V3,
+        EventFormatVersions.ROOM_V4_PLUS,
         StateResolutionVersions.V2,
         enforce_key_validity=True,
         special_case_aliases_auth=False,
diff --git a/synapse/event_auth.py b/synapse/event_auth.py
index 389b0c5d53..c7d5ef92fc 100644
--- a/synapse/event_auth.py
+++ b/synapse/event_auth.py
@@ -109,7 +109,7 @@ def validate_event_for_room_version(event: "EventBase") -> None:
         if not is_invite_via_3pid:
             raise AuthError(403, "Event not signed by sender's server")
 
-    if event.format_version in (EventFormatVersions.V1,):
+    if event.format_version in (EventFormatVersions.ROOM_V1_V2,):
         # Only older room versions have event IDs to check.
         event_id_domain = get_domain_from_id(event.event_id)
 
@@ -716,7 +716,7 @@ def check_redaction(
     if user_level >= redact_level:
         return False
 
-    if room_version_obj.event_format == EventFormatVersions.V1:
+    if room_version_obj.event_format == EventFormatVersions.ROOM_V1_V2:
         redacter_domain = get_domain_from_id(event.event_id)
         if not isinstance(event.redacts, str):
             return False
diff --git a/synapse/events/__init__.py b/synapse/events/__init__.py
index 39ad2793d9..b2c9119fd0 100644
--- a/synapse/events/__init__.py
+++ b/synapse/events/__init__.py
@@ -442,7 +442,7 @@ class EventBase(metaclass=abc.ABCMeta):
 
 
 class FrozenEvent(EventBase):
-    format_version = EventFormatVersions.V1  # All events of this type are V1
+    format_version = EventFormatVersions.ROOM_V1_V2  # All events of this type are V1
 
     def __init__(
         self,
@@ -490,7 +490,7 @@ class FrozenEvent(EventBase):
 
 
 class FrozenEventV2(EventBase):
-    format_version = EventFormatVersions.V2  # All events of this type are V2
+    format_version = EventFormatVersions.ROOM_V3  # All events of this type are V2
 
     def __init__(
         self,
@@ -567,7 +567,7 @@ class FrozenEventV2(EventBase):
 class FrozenEventV3(FrozenEventV2):
     """FrozenEventV3, which differs from FrozenEventV2 only in the event_id format"""
 
-    format_version = EventFormatVersions.V3  # All events of this type are V3
+    format_version = EventFormatVersions.ROOM_V4_PLUS  # All events of this type are V3
 
     @property
     def event_id(self) -> str:
@@ -597,11 +597,11 @@ def _event_type_from_format_version(
         `FrozenEvent`
     """
 
-    if format_version == EventFormatVersions.V1:
+    if format_version == EventFormatVersions.ROOM_V1_V2:
         return FrozenEvent
-    elif format_version == EventFormatVersions.V2:
+    elif format_version == EventFormatVersions.ROOM_V3:
         return FrozenEventV2
-    elif format_version == EventFormatVersions.V3:
+    elif format_version == EventFormatVersions.ROOM_V4_PLUS:
         return FrozenEventV3
     else:
         raise Exception("No event format %r" % (format_version,))
diff --git a/synapse/events/builder.py b/synapse/events/builder.py
index 17f624b68f..746bd3978d 100644
--- a/synapse/events/builder.py
+++ b/synapse/events/builder.py
@@ -137,7 +137,7 @@ class EventBuilder:
         # The types of auth/prev events changes between event versions.
         prev_events: Union[List[str], List[Tuple[str, Dict[str, str]]]]
         auth_events: Union[List[str], List[Tuple[str, Dict[str, str]]]]
-        if format_version == EventFormatVersions.V1:
+        if format_version == EventFormatVersions.ROOM_V1_V2:
             auth_events = await self._store.add_event_hashes(auth_event_ids)
             prev_events = await self._store.add_event_hashes(prev_event_ids)
         else:
@@ -253,7 +253,7 @@ def create_local_event_from_event_dict(
 
     time_now = int(clock.time_msec())
 
-    if format_version == EventFormatVersions.V1:
+    if format_version == EventFormatVersions.ROOM_V1_V2:
         event_dict["event_id"] = _create_event_id(clock, hostname)
 
     event_dict["origin"] = hostname
diff --git a/synapse/events/validator.py b/synapse/events/validator.py
index 27c8beba25..a6f0104396 100644
--- a/synapse/events/validator.py
+++ b/synapse/events/validator.py
@@ -45,7 +45,7 @@ class EventValidator:
         """
         self.validate_builder(event)
 
-        if event.format_version == EventFormatVersions.V1:
+        if event.format_version == EventFormatVersions.ROOM_V1_V2:
             EventID.from_string(event.event_id)
 
         required = [
diff --git a/synapse/federation/federation_base.py b/synapse/federation/federation_base.py
index 4269a98db2..abe2c1971a 100644
--- a/synapse/federation/federation_base.py
+++ b/synapse/federation/federation_base.py
@@ -194,7 +194,7 @@ async def _check_sigs_on_pdu(
     # event id's domain (normally only the case for joins/leaves), and add additional
     # checks. Only do this if the room version has a concept of event ID domain
     # (ie, the room version uses old-style non-hash event IDs).
-    if room_version.event_format == EventFormatVersions.V1:
+    if room_version.event_format == EventFormatVersions.ROOM_V1_V2:
         event_domain = get_domain_from_id(pdu.event_id)
         if event_domain != sender_domain:
             try:
diff --git a/synapse/federation/federation_client.py b/synapse/federation/federation_client.py
index 7ee2974bb1..4a4289ee7c 100644
--- a/synapse/federation/federation_client.py
+++ b/synapse/federation/federation_client.py
@@ -1190,7 +1190,7 @@ class FederationClient(FederationBase):
             # Otherwise, consider it a legitimate error and raise.
             err = e.to_synapse_error()
             if self._is_unknown_endpoint(e, err):
-                if room_version.event_format != EventFormatVersions.V1:
+                if room_version.event_format != EventFormatVersions.ROOM_V1_V2:
                     raise SynapseError(
                         400,
                         "User's homeserver does not support this room version",
diff --git a/synapse/storage/databases/main/event_federation.py b/synapse/storage/databases/main/event_federation.py
index c836078da6..e687f87eca 100644
--- a/synapse/storage/databases/main/event_federation.py
+++ b/synapse/storage/databases/main/event_federation.py
@@ -1606,7 +1606,7 @@ class EventFederationWorkerStore(SignatureWorkerStore, EventsWorkerStore, SQLBas
                 logger.info("Invalid prev_events for %s", event_id)
                 continue
 
-            if room_version.event_format == EventFormatVersions.V1:
+            if room_version.event_format == EventFormatVersions.ROOM_V1_V2:
                 for prev_event_tuple in prev_events:
                     if (
                         not isinstance(prev_event_tuple, list)
diff --git a/synapse/storage/databases/main/events_worker.py b/synapse/storage/databases/main/events_worker.py
index 9b997c304d..84f17a9945 100644
--- a/synapse/storage/databases/main/events_worker.py
+++ b/synapse/storage/databases/main/events_worker.py
@@ -1156,7 +1156,7 @@ class EventsWorkerStore(SQLBaseStore):
             if format_version is None:
                 # This means that we stored the event before we had the concept
                 # of a event format version, so it must be a V1 event.
-                format_version = EventFormatVersions.V1
+                format_version = EventFormatVersions.ROOM_V1_V2
 
             room_version_id = row.room_version_id
 
@@ -1186,10 +1186,10 @@ class EventsWorkerStore(SQLBaseStore):
                 #
                 # So, the following approximations should be adequate.
 
-                if format_version == EventFormatVersions.V1:
+                if format_version == EventFormatVersions.ROOM_V1_V2:
                     # if it's event format v1 then it must be room v1 or v2
                     room_version = RoomVersions.V1
-                elif format_version == EventFormatVersions.V2:
+                elif format_version == EventFormatVersions.ROOM_V3:
                     # if it's event format v2 then it must be room v3
                     room_version = RoomVersions.V3
                 else:
diff --git a/tests/storage/databases/main/test_events_worker.py b/tests/storage/databases/main/test_events_worker.py
index 46d829b062..67401272ac 100644
--- a/tests/storage/databases/main/test_events_worker.py
+++ b/tests/storage/databases/main/test_events_worker.py
@@ -254,7 +254,7 @@ class DatabaseOutageTestCase(unittest.HomeserverTestCase):
                         "room_id": self.room_id,
                         "json": json.dumps(event_json),
                         "internal_metadata": "{}",
-                        "format_version": EventFormatVersions.V3,
+                        "format_version": EventFormatVersions.ROOM_V4_PLUS,
                     },
                 )
             )
diff --git a/tests/storage/test_event_federation.py b/tests/storage/test_event_federation.py
index d92a9ac5b7..a6679e1312 100644
--- a/tests/storage/test_event_federation.py
+++ b/tests/storage/test_event_federation.py
@@ -513,7 +513,7 @@ class EventFederationWorkerStoreTestCase(tests.unittest.HomeserverTestCase):
 
         def prev_event_format(prev_event_id: str) -> Union[Tuple[str, dict], str]:
             """Account for differences in prev_events format across room versions"""
-            if room_version.event_format == EventFormatVersions.V1:
+            if room_version.event_format == EventFormatVersions.ROOM_V1_V2:
                 return prev_event_id, {}
 
             return prev_event_id
diff --git a/tests/test_event_auth.py b/tests/test_event_auth.py
index e42d7b9ba0..f4d9fba0a1 100644
--- a/tests/test_event_auth.py
+++ b/tests/test_event_auth.py
@@ -821,7 +821,7 @@ def _alias_event(room_version: RoomVersion, sender: str, **kwargs) -> EventBase:
 def _build_auth_dict_for_room_version(
     room_version: RoomVersion, auth_events: Iterable[EventBase]
 ) -> List:
-    if room_version.event_format == EventFormatVersions.V1:
+    if room_version.event_format == EventFormatVersions.ROOM_V1_V2:
         return [(e.event_id, "not_used") for e in auth_events]
     else:
         return [e.event_id for e in auth_events]
@@ -871,7 +871,7 @@ event_count = 0
 
 def _maybe_get_event_id_dict_for_room_version(room_version: RoomVersion) -> dict:
     """If this room version needs it, generate an event id"""
-    if room_version.event_format != EventFormatVersions.V1:
+    if room_version.event_format != EventFormatVersions.ROOM_V1_V2:
         return {}
 
     global event_count