Tidy up Rust RoomVersion structs (#19766)

This is in prep for using the room versions more from Rust.

Main changes:
- Change it so each room version is defined as a delta to the last one.
This is a cosmetic change that makes it easier to ensure the room
version definitions are correct (as they're defined as deltas from
previous versions).
- Move constants to `RoomVersion` constants, like `RoomVersion::V1`, for
convenience.
- Change visibility of various attributes.

changelog.d/19766.misc

@@ -0,0 +1 @@
+Tidy up Rust `RoomVersion` structs.

rust/src/events/json_object.rs

@@ -34,7 +34,7 @@ use serde::{Deserialize, Serialize};
 /// 1. Fast access of top-level keys (e.g. `event.content["key"]`)
 /// 2. Pure Rust implementation.
 #[derive(Serialize, Deserialize, Clone, Default)]
-#[pyclass(mapping, frozen)]
+#[pyclass(mapping, frozen, skip_from_py_object)]
 #[serde(transparent)]
 pub struct JsonObject {
     object: Arc<BTreeMap<Box<str>, serde_json::Value>>,
@@ -197,7 +197,7 @@ impl JsonObject {
 /// of the object.
 ///
 /// This needs to both be iterable *and* operate like a set.
-#[pyclass(frozen)]
+#[pyclass(frozen, skip_from_py_object)]
 #[derive(Clone)]
 pub struct JsonObjectKeysView {
     object: JsonObject,
@@ -397,7 +397,7 @@ impl JsonObjectKeysView {
 
 /// Helper class returned by `JsonObject.values()` to act as a view into the
 /// values of the object.
-#[pyclass(frozen)]
+#[pyclass(frozen, skip_from_py_object)]
 #[derive(Clone)]
 pub struct JsonObjectValuesView {
     object: JsonObject,
@@ -440,7 +440,7 @@ impl JsonObjectValuesView {
 /// unless the values are unhashable. Since the values are immutable we could
 /// support it, but it's more work and nobody seems to actually use the set
 /// operations on `dict_items` in practice.
-#[pyclass(frozen)]
+#[pyclass(frozen, skip_from_py_object)]
 #[derive(Clone)]
 pub struct JsonObjectItemsView {
     object: JsonObject,

rust/src/room_versions.rs

@@ -14,7 +14,11 @@
 
 //! Rust implementation of room version definitions.
 
-use std::sync::{Arc, LazyLock, RwLock};
+use std::{
+    fmt::Display,
+    str::FromStr,
+    sync::{Arc, LazyLock, RwLock},
+};
 
 use pyo3::{
     exceptions::{PyKeyError, PyRuntimeError},
@@ -30,47 +34,47 @@ use pyo3::{
 /// 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.)
-#[pyclass(frozen)]
+#[pyclass(frozen, skip_from_py_object)]
 pub struct EventFormatVersions {}
 
 #[pymethods]
 impl EventFormatVersions {
     /// $id:server event id format: used for room v1 and v2
     #[classattr]
-    const ROOM_V1_V2: i32 = 1;
+    pub const ROOM_V1_V2: i32 = 1;
     /// MSC1659-style $hash event id format: used for room v3
     #[classattr]
-    const ROOM_V3: i32 = 2;
+    pub const ROOM_V3: i32 = 2;
     /// MSC1884-style $hash format: introduced for room v4
     #[classattr]
-    const ROOM_V4_PLUS: i32 = 3;
+    pub const ROOM_V4_PLUS: i32 = 3;
     /// MSC4291 room IDs as hashes: introduced for room HydraV11
     #[classattr]
-    const ROOM_V11_HYDRA_PLUS: i32 = 4;
+    pub const ROOM_V11_HYDRA_PLUS: i32 = 4;
     /// MSC4242 state DAGs: adds prev_state_events, removes auth_events
     #[classattr]
-    const ROOM_VMSC4242: i32 = 5;
+    pub const ROOM_VMSC4242: i32 = 5;
 }
 
 /// Enum to identify the state resolution algorithms.
-#[pyclass(frozen)]
+#[pyclass(frozen, skip_from_py_object)]
 pub struct StateResolutionVersions {}
 
 #[pymethods]
 impl StateResolutionVersions {
     /// Room v1 state res
     #[classattr]
-    const V1: i32 = 1;
+    pub const V1: i32 = 1;
     /// MSC1442 state res: room v2 and later
     #[classattr]
-    const V2: i32 = 2;
+    pub const V2: i32 = 2;
     /// MSC4297 state res
     #[classattr]
-    const V2_1: i32 = 3;
+    pub const V2_1: i32 = 3;
 }
 
 /// Room disposition constants.
-#[pyclass(frozen)]
+#[pyclass(frozen, skip_from_py_object)]
 pub struct RoomDisposition {}
 
 #[pymethods]
@@ -94,18 +98,18 @@ impl PushRuleRoomFlag {
 
 /// An object which describes the unique attributes of a room version.
 #[pyclass(frozen, eq, hash, get_all, skip_from_py_object)]
-#[derive(Clone, Copy, PartialEq, Eq, Hash, PartialOrd, Ord)]
+#[derive(Clone, PartialEq, Eq, Hash, PartialOrd, Ord)]
 pub struct RoomVersion {
     /// The identifier for this version.
     pub identifier: &'static str,
-    /// One of the RoomDisposition constants.
+    /// One of the [`RoomDisposition`] constants.
     pub disposition: &'static str,
-    /// One of the EventFormatVersions constants.
+    /// One of the [`EventFormatVersions`] constants.
     pub event_format: i32,
-    /// One of the StateResolutionVersions constants.
+    /// One of the [`StateResolutionVersions`] constants.
     pub state_res: i32,
     pub enforce_key_validity: bool,
-    /// Before MSC2432, m.room.aliases had special auth rules and redaction rules.
+    /// Before MSC2432, `m.room.aliases` had special auth rules and redaction rules.
     pub special_case_aliases_auth: bool,
     /// Strictly enforce canonicaljson, do not allow:
     /// * Integers outside the range of [-2^53 + 1, 2^53 - 1]
@@ -159,459 +163,204 @@ pub struct RoomVersion {
     pub msc4242_state_dags: bool,
 }
 
-const ROOM_VERSION_V1: RoomVersion = RoomVersion {
-    identifier: "1",
-    disposition: RoomDisposition::STABLE,
-    event_format: EventFormatVersions::ROOM_V1_V2,
-    state_res: StateResolutionVersions::V1,
-    enforce_key_validity: false,
-    special_case_aliases_auth: true,
-    strict_canonicaljson: false,
-    limit_notifications_power_levels: false,
-    implicit_room_creator: false,
-    updated_redaction_rules: false,
-    restricted_join_rule: false,
-    restricted_join_rule_fix: false,
-    knock_join_rule: false,
-    msc3389_relation_redactions: false,
-    knock_restricted_join_rule: false,
-    enforce_int_power_levels: false,
-    msc3931_push_features: &[],
-    msc3757_enabled: false,
-    msc4289_creator_power_enabled: false,
-    msc4291_room_ids_as_hashes: false,
-    strict_event_byte_limits_room_versions: false,
-    msc4242_state_dags: false,
-};
+impl RoomVersion {
+    pub const V1: RoomVersion = RoomVersion {
+        identifier: "1",
+        disposition: RoomDisposition::STABLE,
+        event_format: EventFormatVersions::ROOM_V1_V2,
+        state_res: StateResolutionVersions::V1,
+        enforce_key_validity: false,
+        special_case_aliases_auth: true,
+        strict_canonicaljson: false,
+        limit_notifications_power_levels: false,
+        implicit_room_creator: false,
+        updated_redaction_rules: false,
+        restricted_join_rule: false,
+        restricted_join_rule_fix: false,
+        knock_join_rule: false,
+        msc3389_relation_redactions: false,
+        knock_restricted_join_rule: false,
+        enforce_int_power_levels: false,
+        msc3931_push_features: &[],
+        msc3757_enabled: false,
+        msc4289_creator_power_enabled: false,
+        msc4291_room_ids_as_hashes: false,
+        strict_event_byte_limits_room_versions: false,
+        msc4242_state_dags: false,
+    };
 
-const ROOM_VERSION_V2: RoomVersion = RoomVersion {
-    identifier: "2",
-    disposition: RoomDisposition::STABLE,
-    event_format: EventFormatVersions::ROOM_V1_V2,
-    state_res: StateResolutionVersions::V2,
-    enforce_key_validity: false,
-    special_case_aliases_auth: true,
-    strict_canonicaljson: false,
-    limit_notifications_power_levels: false,
-    implicit_room_creator: false,
-    updated_redaction_rules: false,
-    restricted_join_rule: false,
-    restricted_join_rule_fix: false,
-    knock_join_rule: false,
-    msc3389_relation_redactions: false,
-    knock_restricted_join_rule: false,
-    enforce_int_power_levels: false,
-    msc3931_push_features: &[],
-    msc3757_enabled: false,
-    msc4289_creator_power_enabled: false,
-    msc4291_room_ids_as_hashes: false,
-    strict_event_byte_limits_room_versions: false,
-    msc4242_state_dags: false,
-};
+    pub const V2: RoomVersion = RoomVersion {
+        identifier: "2",
+        state_res: StateResolutionVersions::V2,
+        ..Self::V1
+    };
 
-const ROOM_VERSION_V3: RoomVersion = RoomVersion {
-    identifier: "3",
-    disposition: RoomDisposition::STABLE,
-    event_format: EventFormatVersions::ROOM_V3,
-    state_res: StateResolutionVersions::V2,
-    enforce_key_validity: false,
-    special_case_aliases_auth: true,
-    strict_canonicaljson: false,
-    limit_notifications_power_levels: false,
-    implicit_room_creator: false,
-    updated_redaction_rules: false,
-    restricted_join_rule: false,
-    restricted_join_rule_fix: false,
-    knock_join_rule: false,
-    msc3389_relation_redactions: false,
-    knock_restricted_join_rule: false,
-    enforce_int_power_levels: false,
-    msc3931_push_features: &[],
-    msc3757_enabled: false,
-    msc4289_creator_power_enabled: false,
-    msc4291_room_ids_as_hashes: false,
-    strict_event_byte_limits_room_versions: false,
-    msc4242_state_dags: false,
-};
+    pub const V3: RoomVersion = RoomVersion {
+        identifier: "3",
+        event_format: EventFormatVersions::ROOM_V3,
+        ..Self::V2
+    };
 
-const ROOM_VERSION_V4: RoomVersion = RoomVersion {
-    identifier: "4",
-    disposition: RoomDisposition::STABLE,
-    event_format: EventFormatVersions::ROOM_V4_PLUS,
-    state_res: StateResolutionVersions::V2,
-    enforce_key_validity: false,
-    special_case_aliases_auth: true,
-    strict_canonicaljson: false,
-    limit_notifications_power_levels: false,
-    implicit_room_creator: false,
-    updated_redaction_rules: false,
-    restricted_join_rule: false,
-    restricted_join_rule_fix: false,
-    knock_join_rule: false,
-    msc3389_relation_redactions: false,
-    knock_restricted_join_rule: false,
-    enforce_int_power_levels: false,
-    msc3931_push_features: &[],
-    msc3757_enabled: false,
-    msc4289_creator_power_enabled: false,
-    msc4291_room_ids_as_hashes: false,
-    strict_event_byte_limits_room_versions: false,
-    msc4242_state_dags: false,
-};
+    pub const V4: RoomVersion = RoomVersion {
+        identifier: "4",
+        event_format: EventFormatVersions::ROOM_V4_PLUS,
+        ..Self::V3
+    };
 
-const ROOM_VERSION_V5: RoomVersion = RoomVersion {
-    identifier: "5",
-    disposition: RoomDisposition::STABLE,
-    event_format: EventFormatVersions::ROOM_V4_PLUS,
-    state_res: StateResolutionVersions::V2,
-    enforce_key_validity: true,
-    special_case_aliases_auth: true,
-    strict_canonicaljson: false,
-    limit_notifications_power_levels: false,
-    implicit_room_creator: false,
-    updated_redaction_rules: false,
-    restricted_join_rule: false,
-    restricted_join_rule_fix: false,
-    knock_join_rule: false,
-    msc3389_relation_redactions: false,
-    knock_restricted_join_rule: false,
-    enforce_int_power_levels: false,
-    msc3931_push_features: &[],
-    msc3757_enabled: false,
-    msc4289_creator_power_enabled: false,
-    msc4291_room_ids_as_hashes: false,
-    strict_event_byte_limits_room_versions: false,
-    msc4242_state_dags: false,
-};
+    pub const V5: RoomVersion = RoomVersion {
+        identifier: "5",
+        enforce_key_validity: true,
+        ..Self::V4
+    };
 
-const ROOM_VERSION_V6: RoomVersion = RoomVersion {
-    identifier: "6",
-    disposition: RoomDisposition::STABLE,
-    event_format: EventFormatVersions::ROOM_V4_PLUS,
-    state_res: StateResolutionVersions::V2,
-    enforce_key_validity: true,
-    special_case_aliases_auth: false,
-    strict_canonicaljson: true,
-    limit_notifications_power_levels: true,
-    implicit_room_creator: false,
-    updated_redaction_rules: false,
-    restricted_join_rule: false,
-    restricted_join_rule_fix: false,
-    knock_join_rule: false,
-    msc3389_relation_redactions: false,
-    knock_restricted_join_rule: false,
-    enforce_int_power_levels: false,
-    msc3931_push_features: &[],
-    msc3757_enabled: false,
-    msc4289_creator_power_enabled: false,
-    msc4291_room_ids_as_hashes: false,
-    strict_event_byte_limits_room_versions: false,
-    msc4242_state_dags: false,
-};
+    pub const V6: RoomVersion = RoomVersion {
+        identifier: "6",
+        special_case_aliases_auth: false,
+        strict_canonicaljson: true,
+        limit_notifications_power_levels: true,
+        ..Self::V5
+    };
 
-const ROOM_VERSION_V7: RoomVersion = RoomVersion {
-    identifier: "7",
-    disposition: RoomDisposition::STABLE,
-    event_format: EventFormatVersions::ROOM_V4_PLUS,
-    state_res: StateResolutionVersions::V2,
-    enforce_key_validity: true,
-    special_case_aliases_auth: false,
-    strict_canonicaljson: true,
-    limit_notifications_power_levels: true,
-    implicit_room_creator: false,
-    updated_redaction_rules: false,
-    restricted_join_rule: false,
-    restricted_join_rule_fix: false,
-    knock_join_rule: true,
-    msc3389_relation_redactions: false,
-    knock_restricted_join_rule: false,
-    enforce_int_power_levels: false,
-    msc3931_push_features: &[],
-    msc3757_enabled: false,
-    msc4289_creator_power_enabled: false,
-    msc4291_room_ids_as_hashes: false,
-    strict_event_byte_limits_room_versions: false,
-    msc4242_state_dags: false,
-};
+    pub const V7: RoomVersion = RoomVersion {
+        identifier: "7",
+        knock_join_rule: true,
+        ..Self::V6
+    };
 
-const ROOM_VERSION_V8: RoomVersion = RoomVersion {
-    identifier: "8",
-    disposition: RoomDisposition::STABLE,
-    event_format: EventFormatVersions::ROOM_V4_PLUS,
-    state_res: StateResolutionVersions::V2,
-    enforce_key_validity: true,
-    special_case_aliases_auth: false,
-    strict_canonicaljson: true,
-    limit_notifications_power_levels: true,
-    implicit_room_creator: false,
-    updated_redaction_rules: false,
-    restricted_join_rule: true,
-    restricted_join_rule_fix: false,
-    knock_join_rule: true,
-    msc3389_relation_redactions: false,
-    knock_restricted_join_rule: false,
-    enforce_int_power_levels: false,
-    msc3931_push_features: &[],
-    msc3757_enabled: false,
-    msc4289_creator_power_enabled: false,
-    msc4291_room_ids_as_hashes: false,
-    strict_event_byte_limits_room_versions: false,
-    msc4242_state_dags: false,
-};
+    pub const V8: RoomVersion = RoomVersion {
+        identifier: "8",
+        restricted_join_rule: true,
+        ..Self::V7
+    };
 
-const ROOM_VERSION_V9: RoomVersion = RoomVersion {
-    identifier: "9",
-    disposition: RoomDisposition::STABLE,
-    event_format: EventFormatVersions::ROOM_V4_PLUS,
-    state_res: StateResolutionVersions::V2,
-    enforce_key_validity: true,
-    special_case_aliases_auth: false,
-    strict_canonicaljson: true,
-    limit_notifications_power_levels: true,
-    implicit_room_creator: false,
-    updated_redaction_rules: false,
-    restricted_join_rule: true,
-    restricted_join_rule_fix: true,
-    knock_join_rule: true,
-    msc3389_relation_redactions: false,
-    knock_restricted_join_rule: false,
-    enforce_int_power_levels: false,
-    msc3931_push_features: &[],
-    msc3757_enabled: false,
-    msc4289_creator_power_enabled: false,
-    msc4291_room_ids_as_hashes: false,
-    strict_event_byte_limits_room_versions: false,
-    msc4242_state_dags: false,
-};
+    pub const V9: RoomVersion = RoomVersion {
+        identifier: "9",
+        restricted_join_rule_fix: true,
+        ..Self::V8
+    };
 
-const ROOM_VERSION_V10: RoomVersion = RoomVersion {
-    identifier: "10",
-    disposition: RoomDisposition::STABLE,
-    event_format: EventFormatVersions::ROOM_V4_PLUS,
-    state_res: StateResolutionVersions::V2,
-    enforce_key_validity: true,
-    special_case_aliases_auth: false,
-    strict_canonicaljson: true,
-    limit_notifications_power_levels: true,
-    implicit_room_creator: false,
-    updated_redaction_rules: false,
-    restricted_join_rule: true,
-    restricted_join_rule_fix: true,
-    knock_join_rule: true,
-    msc3389_relation_redactions: false,
-    knock_restricted_join_rule: true,
-    enforce_int_power_levels: true,
-    msc3931_push_features: &[],
-    msc3757_enabled: false,
-    msc4289_creator_power_enabled: false,
-    msc4291_room_ids_as_hashes: false,
-    strict_event_byte_limits_room_versions: false,
-    msc4242_state_dags: false,
-};
+    pub const V10: RoomVersion = RoomVersion {
+        identifier: "10",
+        knock_restricted_join_rule: true,
+        enforce_int_power_levels: true,
+        ..Self::V9
+    };
 
-/// MSC3389 (Redaction changes for events with a relation) based on room version "10".
-const ROOM_VERSION_MSC3389V10: RoomVersion = RoomVersion {
-    identifier: "org.matrix.msc3389.10",
-    disposition: RoomDisposition::UNSTABLE,
-    event_format: EventFormatVersions::ROOM_V4_PLUS,
-    state_res: StateResolutionVersions::V2,
-    enforce_key_validity: true,
-    special_case_aliases_auth: false,
-    strict_canonicaljson: true,
-    limit_notifications_power_levels: true,
-    implicit_room_creator: false,
-    updated_redaction_rules: false,
-    restricted_join_rule: true,
-    restricted_join_rule_fix: true,
-    knock_join_rule: true,
-    msc3389_relation_redactions: true, // Changed from v10
-    knock_restricted_join_rule: true,
-    enforce_int_power_levels: true,
-    msc3931_push_features: &[],
-    msc3757_enabled: false,
-    msc4289_creator_power_enabled: false,
-    msc4291_room_ids_as_hashes: false,
-    strict_event_byte_limits_room_versions: true,
-    msc4242_state_dags: false,
-};
+    /// MSC3389 (Redaction changes for events with a relation) based on room version "10".
+    pub const MSC3389V10: RoomVersion = RoomVersion {
+        identifier: "org.matrix.msc3389.10",
+        disposition: RoomDisposition::UNSTABLE,
+        msc3389_relation_redactions: true,
+        strict_event_byte_limits_room_versions: true,
+        ..Self::V10
+    };
 
-/// MSC1767 (Extensible Events) based on room version "10".
-const ROOM_VERSION_MSC1767V10: RoomVersion = RoomVersion {
-    identifier: "org.matrix.msc1767.10",
-    disposition: RoomDisposition::UNSTABLE,
-    event_format: EventFormatVersions::ROOM_V4_PLUS,
-    state_res: StateResolutionVersions::V2,
-    enforce_key_validity: true,
-    special_case_aliases_auth: false,
-    strict_canonicaljson: true,
-    limit_notifications_power_levels: true,
-    implicit_room_creator: false,
-    updated_redaction_rules: false,
-    restricted_join_rule: true,
-    restricted_join_rule_fix: true,
-    knock_join_rule: true,
-    msc3389_relation_redactions: false,
-    knock_restricted_join_rule: true,
-    enforce_int_power_levels: true,
-    msc3931_push_features: &[PushRuleRoomFlag::EXTENSIBLE_EVENTS],
-    msc3757_enabled: false,
-    msc4289_creator_power_enabled: false,
-    msc4291_room_ids_as_hashes: false,
-    strict_event_byte_limits_room_versions: false,
-    msc4242_state_dags: false,
-};
+    /// MSC1767 (Extensible Events) based on room version "10".
+    pub const MSC1767V10: RoomVersion = RoomVersion {
+        identifier: "org.matrix.msc1767.10",
+        disposition: RoomDisposition::UNSTABLE,
+        msc3931_push_features: &[PushRuleRoomFlag::EXTENSIBLE_EVENTS],
+        ..Self::V10
+    };
 
-/// MSC3757 (Restricting who can overwrite a state event) based on room version "10".
-const ROOM_VERSION_MSC3757V10: RoomVersion = RoomVersion {
-    identifier: "org.matrix.msc3757.10",
-    disposition: RoomDisposition::UNSTABLE,
-    event_format: EventFormatVersions::ROOM_V4_PLUS,
-    state_res: StateResolutionVersions::V2,
-    enforce_key_validity: true,
-    special_case_aliases_auth: false,
-    strict_canonicaljson: true,
-    limit_notifications_power_levels: true,
-    implicit_room_creator: false,
-    updated_redaction_rules: false,
-    restricted_join_rule: true,
-    restricted_join_rule_fix: true,
-    knock_join_rule: true,
-    msc3389_relation_redactions: false,
-    knock_restricted_join_rule: true,
-    enforce_int_power_levels: true,
-    msc3931_push_features: &[],
-    msc3757_enabled: true,
-    msc4289_creator_power_enabled: false,
-    msc4291_room_ids_as_hashes: false,
-    strict_event_byte_limits_room_versions: false,
-    msc4242_state_dags: false,
-};
+    /// MSC3757 (Restricting who can overwrite a state event) based on room version "10".
+    pub const MSC3757V10: RoomVersion = RoomVersion {
+        identifier: "org.matrix.msc3757.10",
+        disposition: RoomDisposition::UNSTABLE,
+        msc3757_enabled: true,
+        ..Self::V10
+    };
 
-const ROOM_VERSION_V11: RoomVersion = RoomVersion {
-    identifier: "11",
-    disposition: RoomDisposition::STABLE,
-    event_format: EventFormatVersions::ROOM_V4_PLUS,
-    state_res: StateResolutionVersions::V2,
-    enforce_key_validity: true,
-    special_case_aliases_auth: false,
-    strict_canonicaljson: true,
-    limit_notifications_power_levels: true,
-    implicit_room_creator: true,   // Used by MSC3820
-    updated_redaction_rules: true, // Used by MSC3820
-    restricted_join_rule: true,
-    restricted_join_rule_fix: true,
-    knock_join_rule: true,
-    msc3389_relation_redactions: false,
-    knock_restricted_join_rule: true,
-    enforce_int_power_levels: true,
-    msc3931_push_features: &[],
-    msc3757_enabled: false,
-    msc4289_creator_power_enabled: false,
-    msc4291_room_ids_as_hashes: false,
-    strict_event_byte_limits_room_versions: true, // Changed from v10
-    msc4242_state_dags: false,
-};
+    pub const V11: RoomVersion = RoomVersion {
+        identifier: "11",
+        implicit_room_creator: true,   // Used by MSC3820
+        updated_redaction_rules: true, // Used by MSC3820
+        strict_event_byte_limits_room_versions: true,
+        ..Self::V10
+    };
 
-/// MSC3757 (Restricting who can overwrite a state event) based on room version "11".
-const ROOM_VERSION_MSC3757V11: RoomVersion = RoomVersion {
-    identifier: "org.matrix.msc3757.11",
-    disposition: RoomDisposition::UNSTABLE,
-    event_format: EventFormatVersions::ROOM_V4_PLUS,
-    state_res: StateResolutionVersions::V2,
-    enforce_key_validity: true,
-    special_case_aliases_auth: false,
-    strict_canonicaljson: true,
-    limit_notifications_power_levels: true,
-    implicit_room_creator: true,   // Used by MSC3820
-    updated_redaction_rules: true, // Used by MSC3820
-    restricted_join_rule: true,
-    restricted_join_rule_fix: true,
-    knock_join_rule: true,
-    msc3389_relation_redactions: false,
-    knock_restricted_join_rule: true,
-    enforce_int_power_levels: true,
-    msc3931_push_features: &[],
-    msc3757_enabled: true,
-    msc4289_creator_power_enabled: false,
-    msc4291_room_ids_as_hashes: false,
-    strict_event_byte_limits_room_versions: true,
-    msc4242_state_dags: false,
-};
+    /// MSC3757 (Restricting who can overwrite a state event) based on room version "11".
+    pub const MSC3757V11: RoomVersion = RoomVersion {
+        identifier: "org.matrix.msc3757.11",
+        disposition: RoomDisposition::UNSTABLE,
+        msc3757_enabled: true,
+        ..Self::V11
+    };
 
-const ROOM_VERSION_HYDRA_V11: RoomVersion = RoomVersion {
-    identifier: "org.matrix.hydra.11",
-    disposition: RoomDisposition::UNSTABLE,
-    event_format: EventFormatVersions::ROOM_V11_HYDRA_PLUS,
-    state_res: StateResolutionVersions::V2_1, // Changed from v11
-    enforce_key_validity: true,
-    special_case_aliases_auth: false,
-    strict_canonicaljson: true,
-    limit_notifications_power_levels: true,
-    implicit_room_creator: true,   // Used by MSC3820
-    updated_redaction_rules: true, // Used by MSC3820
-    restricted_join_rule: true,
-    restricted_join_rule_fix: true,
-    knock_join_rule: true,
-    msc3389_relation_redactions: false,
-    knock_restricted_join_rule: true,
-    enforce_int_power_levels: true,
-    msc3931_push_features: &[],
-    msc3757_enabled: false,
-    msc4289_creator_power_enabled: true, // Changed from v11
-    msc4291_room_ids_as_hashes: true,    // Changed from v11
-    strict_event_byte_limits_room_versions: true,
-    msc4242_state_dags: false,
-};
+    pub const HYDRA_V11: RoomVersion = RoomVersion {
+        identifier: "org.matrix.hydra.11",
+        disposition: RoomDisposition::UNSTABLE,
+        event_format: EventFormatVersions::ROOM_V11_HYDRA_PLUS,
+        state_res: StateResolutionVersions::V2_1,
+        msc4289_creator_power_enabled: true,
+        msc4291_room_ids_as_hashes: true,
+        ..Self::V11
+    };
 
-const ROOM_VERSION_V12: RoomVersion = RoomVersion {
-    identifier: "12",
-    disposition: RoomDisposition::STABLE,
-    event_format: EventFormatVersions::ROOM_V11_HYDRA_PLUS,
-    state_res: StateResolutionVersions::V2_1, // Changed from v11
-    enforce_key_validity: true,
-    special_case_aliases_auth: false,
-    strict_canonicaljson: true,
-    limit_notifications_power_levels: true,
-    implicit_room_creator: true,   // Used by MSC3820
-    updated_redaction_rules: true, // Used by MSC3820
-    restricted_join_rule: true,
-    restricted_join_rule_fix: true,
-    knock_join_rule: true,
-    msc3389_relation_redactions: false,
-    knock_restricted_join_rule: true,
-    enforce_int_power_levels: true,
-    msc3931_push_features: &[],
-    msc3757_enabled: false,
-    msc4289_creator_power_enabled: true, // Changed from v11
-    msc4291_room_ids_as_hashes: true,    // Changed from v11
-    strict_event_byte_limits_room_versions: true,
-    msc4242_state_dags: false,
-};
+    pub const V12: RoomVersion = RoomVersion {
+        identifier: "12",
+        disposition: RoomDisposition::STABLE,
+        event_format: EventFormatVersions::ROOM_V11_HYDRA_PLUS,
+        state_res: StateResolutionVersions::V2_1,
+        msc4289_creator_power_enabled: true,
+        msc4291_room_ids_as_hashes: true,
+        ..Self::V11
+    };
 
-const ROOM_VERSION_MSC4242V12: RoomVersion = RoomVersion {
-    identifier: "org.matrix.msc4242.12",
-    disposition: RoomDisposition::UNSTABLE,
-    event_format: EventFormatVersions::ROOM_VMSC4242,
-    state_res: StateResolutionVersions::V2_1,
-    enforce_key_validity: true,
-    special_case_aliases_auth: false,
-    strict_canonicaljson: true,
-    limit_notifications_power_levels: true,
-    implicit_room_creator: true,
-    updated_redaction_rules: true,
-    restricted_join_rule: true,
-    restricted_join_rule_fix: true,
-    knock_join_rule: true,
-    msc3389_relation_redactions: false,
-    knock_restricted_join_rule: true,
-    enforce_int_power_levels: true,
-    msc3931_push_features: &[],
-    msc3757_enabled: false,
-    msc4289_creator_power_enabled: true,
-    msc4291_room_ids_as_hashes: true,
-    strict_event_byte_limits_room_versions: true,
-    msc4242_state_dags: true,
-};
+    pub const MSC4242V12: RoomVersion = RoomVersion {
+        identifier: "org.matrix.msc4242.12",
+        disposition: RoomDisposition::UNSTABLE,
+        event_format: EventFormatVersions::ROOM_VMSC4242,
+        msc4242_state_dags: true,
+        ..Self::V12
+    };
+}
+
+impl Display for RoomVersion {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        self.identifier.fmt(f)
+    }
+}
+
+impl FromStr for &'static RoomVersion {
+    type Err = anyhow::Error;
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        match s {
+            "1" => Ok(&RoomVersion::V1),
+            "2" => Ok(&RoomVersion::V2),
+            "3" => Ok(&RoomVersion::V3),
+            "4" => Ok(&RoomVersion::V4),
+            "5" => Ok(&RoomVersion::V5),
+            "6" => Ok(&RoomVersion::V6),
+            "7" => Ok(&RoomVersion::V7),
+            "8" => Ok(&RoomVersion::V8),
+            "9" => Ok(&RoomVersion::V9),
+            "10" => Ok(&RoomVersion::V10),
+            "11" => Ok(&RoomVersion::V11),
+            "12" => Ok(&RoomVersion::V12),
+            "org.matrix.msc1767.10" => Ok(&RoomVersion::MSC1767V10),
+            "org.matrix.msc3389.10" => Ok(&RoomVersion::MSC3389V10),
+            "org.matrix.msc3757.10" => Ok(&RoomVersion::MSC3757V10),
+            "org.matrix.msc3757.11" => Ok(&RoomVersion::MSC3757V11),
+            "org.matrix.hydra.11" => Ok(&RoomVersion::HYDRA_V11),
+            "org.matrix.msc4242.12" => Ok(&RoomVersion::MSC4242V12),
+            _ => Err(anyhow::anyhow!("Unknown room version: {}", s)),
+        }
+    }
+}
+
+impl<'py> IntoPyObject<'py> for &RoomVersion {
+    type Target = RoomVersion;
+
+    type Output = Bound<'py, RoomVersion>;
+
+    type Error = PyErr;
+
+    fn into_pyobject(self, py: Python<'py>) -> Result<Self::Output, Self::Error> {
+        self.clone().into_pyobject(py)
+    }
+}
 
 /// Helper class for managing the known room versions, and providing dict-like
 /// access to them for Python.
@@ -652,7 +401,7 @@ impl KnownRoomVersionsMapping {
             return Ok(());
         }
 
-        versions.push(*version.get());
+        versions.push(version.get().clone());
         Ok(())
     }
 
@@ -666,7 +415,7 @@ impl KnownRoomVersionsMapping {
         versions
             .iter()
             .find(|v| v.identifier == key)
-            .copied()
+            .cloned()
             .ok_or_else(|| PyKeyError::new_err(key.to_string()))
     }
 
@@ -698,7 +447,7 @@ impl KnownRoomVersionsMapping {
         // like a Set *and* has a stable ordering). We don't depend on this, so
         // for simplicity we just return a list of the items.
         let versions = self.versions.read().unwrap();
-        Ok(versions.iter().map(|v| (v.identifier, *v)).collect())
+        Ok(versions.iter().map(|v| (v.identifier, v.clone())).collect())
     }
 
     #[pyo3(signature = (key, default=None))]
@@ -715,8 +464,8 @@ impl KnownRoomVersionsMapping {
         };
 
         let versions = self.versions.read().unwrap();
-        if let Some(version) = versions.iter().find(|v| v.identifier == key).copied() {
-            return Ok(Some(version.into_bound_py_any(py)?));
+        if let Some(version) = versions.iter().find(|v| v.identifier == key) {
+            return Ok(Some(version.clone().into_bound_py_any(py)?));
         }
 
         Ok(default)
@@ -757,21 +506,21 @@ impl<'py> IntoPyObject<'py> for &KnownRoomVersionsMapping {
 /// support all experimental room versions.
 static KNOWN_ROOM_VERSIONS: LazyLock<KnownRoomVersionsMapping> = LazyLock::new(|| {
     let vec = vec![
-        ROOM_VERSION_V1,
-        ROOM_VERSION_V2,
-        ROOM_VERSION_V3,
-        ROOM_VERSION_V4,
-        ROOM_VERSION_V5,
-        ROOM_VERSION_V6,
-        ROOM_VERSION_V7,
-        ROOM_VERSION_V8,
-        ROOM_VERSION_V9,
-        ROOM_VERSION_V10,
-        ROOM_VERSION_V11,
-        ROOM_VERSION_V12,
-        ROOM_VERSION_MSC3757V10,
-        ROOM_VERSION_MSC3757V11,
-        ROOM_VERSION_HYDRA_V11,
+        RoomVersion::V1,
+        RoomVersion::V2,
+        RoomVersion::V3,
+        RoomVersion::V4,
+        RoomVersion::V5,
+        RoomVersion::V6,
+        RoomVersion::V7,
+        RoomVersion::V8,
+        RoomVersion::V9,
+        RoomVersion::V10,
+        RoomVersion::V11,
+        RoomVersion::V12,
+        RoomVersion::MSC3757V10,
+        RoomVersion::MSC3757V11,
+        RoomVersion::HYDRA_V11,
     ];
 
     KnownRoomVersionsMapping {
@@ -783,82 +532,82 @@ static KNOWN_ROOM_VERSIONS: LazyLock<KnownRoomVersionsMapping> = LazyLock::new(|
 ///
 /// This should contain all room versions that we know about.
 #[pyclass(frozen)]
-pub struct RoomVersions {}
+struct RoomVersions {}
 
 #[pymethods]
 #[allow(non_snake_case)]
 impl RoomVersions {
     #[classattr]
     fn V1(py: Python<'_>) -> PyResult<Py<PyAny>> {
-        ROOM_VERSION_V1.into_py_any(py)
+        RoomVersion::V1.into_py_any(py)
     }
     #[classattr]
     fn V2(py: Python<'_>) -> PyResult<Py<PyAny>> {
-        ROOM_VERSION_V2.into_py_any(py)
+        RoomVersion::V2.into_py_any(py)
     }
     #[classattr]
     fn V3(py: Python<'_>) -> PyResult<Py<PyAny>> {
-        ROOM_VERSION_V3.into_py_any(py)
+        RoomVersion::V3.into_py_any(py)
     }
     #[classattr]
     fn V4(py: Python<'_>) -> PyResult<Py<PyAny>> {
-        ROOM_VERSION_V4.into_py_any(py)
+        RoomVersion::V4.into_py_any(py)
     }
     #[classattr]
     fn V5(py: Python<'_>) -> PyResult<Py<PyAny>> {
-        ROOM_VERSION_V5.into_py_any(py)
+        RoomVersion::V5.into_py_any(py)
     }
     #[classattr]
     fn V6(py: Python<'_>) -> PyResult<Py<PyAny>> {
-        ROOM_VERSION_V6.into_py_any(py)
+        RoomVersion::V6.into_py_any(py)
     }
     #[classattr]
     fn V7(py: Python<'_>) -> PyResult<Py<PyAny>> {
-        ROOM_VERSION_V7.into_py_any(py)
+        RoomVersion::V7.into_py_any(py)
     }
     #[classattr]
     fn V8(py: Python<'_>) -> PyResult<Py<PyAny>> {
-        ROOM_VERSION_V8.into_py_any(py)
+        RoomVersion::V8.into_py_any(py)
     }
     #[classattr]
     fn V9(py: Python<'_>) -> PyResult<Py<PyAny>> {
-        ROOM_VERSION_V9.into_py_any(py)
+        RoomVersion::V9.into_py_any(py)
     }
     #[classattr]
     fn V10(py: Python<'_>) -> PyResult<Py<PyAny>> {
-        ROOM_VERSION_V10.into_py_any(py)
+        RoomVersion::V10.into_py_any(py)
     }
     #[classattr]
     fn MSC1767v10(py: Python<'_>) -> PyResult<Py<PyAny>> {
-        ROOM_VERSION_MSC1767V10.into_py_any(py)
+        RoomVersion::MSC1767V10.into_py_any(py)
     }
     #[classattr]
     fn MSC3389v10(py: Python<'_>) -> PyResult<Py<PyAny>> {
-        ROOM_VERSION_MSC3389V10.into_py_any(py)
+        RoomVersion::MSC3389V10.into_py_any(py)
     }
     #[classattr]
     fn MSC3757v10(py: Python<'_>) -> PyResult<Py<PyAny>> {
-        ROOM_VERSION_MSC3757V10.into_py_any(py)
+        RoomVersion::MSC3757V10.into_py_any(py)
     }
     #[classattr]
     fn V11(py: Python<'_>) -> PyResult<Py<PyAny>> {
-        ROOM_VERSION_V11.into_py_any(py)
+        RoomVersion::V11.into_py_any(py)
     }
     #[classattr]
     fn MSC3757v11(py: Python<'_>) -> PyResult<Py<PyAny>> {
-        ROOM_VERSION_MSC3757V11.into_py_any(py)
+        RoomVersion::MSC3757V11.into_py_any(py)
     }
     #[classattr]
     fn HydraV11(py: Python<'_>) -> PyResult<Py<PyAny>> {
-        ROOM_VERSION_HYDRA_V11.into_py_any(py)
+        RoomVersion::HYDRA_V11.into_py_any(py)
     }
     #[classattr]
     fn V12(py: Python<'_>) -> PyResult<Py<PyAny>> {
-        ROOM_VERSION_V12.into_py_any(py)
+        RoomVersion::V12.into_py_any(py)
     }
     #[classattr]
     fn MSC4242v12(py: Python<'_>) -> PyResult<Py<PyAny>> {
-        ROOM_VERSION_MSC4242V12.into_py_any(py)
+        RoomVersion::MSC4242V12.into_py_any(py)
     }
 }