Metadata changed but version did not

[Slesarew]

Describe the bug

Today I've fetched Acala metadata through rpc call from public node and received different response then last Thursday. Apparently, some pallets changed. Yet, spec_version is still the same as before. This breaks Signer functionality and is unsafe.

Expected Behavior

Metadata should always be uniquely identified by spec_name and spec_version, any changes in metadata should be reflected with version bump.

There should be some mechanism to prevent this in future. I've reported similar bug in Polkadot and Kusama previously and those were fixed and covered with tests somehow, I do not know the details.

Current Behavior

CollateralCurrencyIds value is different in 2 places

Steps to Reproduce

1. Fetch metadata from current block
2. Fetch metadata from previous blocks
3. Compare

I used to keep a log of metadata, but only for 3 networks and I do not do it anymore.

Additional context

• Node version: 2064

Code to check metadata diff:

 let acala_meta_old = RuntimeMetadataV14::decode(&mut &acala_old[5..]).unwrap();    
 let acala_meta_new = RuntimeMetadataV14::decode(&mut &acala_new[5..]).unwrap();

 for pallet_old in acala_meta_old.pallets.iter() {
        let index = pallet_old.index;
        for pallet_new in acala_meta_new.pallets.iter() {
            if pallet_new.index == pallet_old.index {
                if pallet_new != pallet_old {
                    println!("pallet name new: {}", pallet_new.name);
                    println!("in new:\n{:?}", pallet_new);
                    println!("in old:\n{:?}", pallet_old);
                }
            }
        }
    }

Observed diff:

pallet name new: Honzon
in new:
PalletMetadata { name: "Honzon", storage: Some(PalletStorageMetadata { prefix: "Honzon", entries: [StorageEntryMetadata { name: "Authorization", modifier: Optional, ty: Map { hashers: [Twox64Concat, Blake2_128Concat], key: UntrackedSymbol { id: 537, marker: PhantomData }, value: UntrackedSymbol { id: 6, marker: PhantomData } }, default: [0], docs: [] }] }), calls: Some(PalletCallMetadata { ty: UntrackedSymbol { id: 308, marker: PhantomData } }), event: Some(PalletEventMetadata { ty: UntrackedSymbol { id: 150, marker: PhantomData } }), constants: [PalletConstantMetadata { name: "DepositPerAuthorization", ty: UntrackedSymbol { id: 6, marker: PhantomData }, value: [0, 192, 101, 67, 172, 3, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0], docs: [] }, PalletConstantMetadata { name: "CollateralCurrencyIds", ty: UntrackedSymbol { id: 59, marker: PhantomData }, value: [20, 0, 0, 0, 3, 0, 2, 3, 0, 0, 0, 0, 4, 13, 0, 0, 0], docs: [] }], error: Some(PalletErrorMetadata { ty: UntrackedSymbol { id: 538, marker: PhantomData } }), index: 102 }
in old:
PalletMetadata { name: "Honzon", storage: Some(PalletStorageMetadata { prefix: "Honzon", entries: [StorageEntryMetadata { name: "Authorization", modifier: Optional, ty: Map { hashers: [Twox64Concat, Blake2_128Concat], key: UntrackedSymbol { id: 537, marker: PhantomData }, value: UntrackedSymbol { id: 6, marker: PhantomData } }, default: [0], docs: [] }] }), calls: Some(PalletCallMetadata { ty: UntrackedSymbol { id: 308, marker: PhantomData } }), event: Some(PalletEventMetadata { ty: UntrackedSymbol { id: 150, marker: PhantomData } }), constants: [PalletConstantMetadata { name: "DepositPerAuthorization", ty: UntrackedSymbol { id: 6, marker: PhantomData }, value: [0, 192, 101, 67, 172, 3, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0], docs: [] }, PalletConstantMetadata { name: "CollateralCurrencyIds", ty: UntrackedSymbol { id: 59, marker: PhantomData }, value: [16, 0, 0, 0, 3, 0, 2, 4, 13, 0, 0, 0], docs: [] }], error: Some(PalletErrorMetadata { ty: UntrackedSymbol { id: 538, marker: PhantomData } }), index: 102 }
pallet name new: EmergencyShutdown
in new:
PalletMetadata { name: "EmergencyShutdown", storage: Some(PalletStorageMetadata { prefix: "EmergencyShutdown", entries: [StorageEntryMetadata { name: "IsShutdown", modifier: Default, ty: Plain(UntrackedSymbol { id: 126, marker: PhantomData }), default: [0], docs: [] }, StorageEntryMetadata { name: "CanRefund", modifier: Default, ty: Plain(UntrackedSymbol { id: 126, marker: PhantomData }), default: [0], docs: [] }] }), calls: Some(PalletCallMetadata { ty: UntrackedSymbol { id: 314, marker: PhantomData } }), event: Some(PalletEventMetadata { ty: UntrackedSymbol { id: 154, marker: PhantomData } }), constants: [PalletConstantMetadata { name: "CollateralCurrencyIds", ty: UntrackedSymbol { id: 59, marker: PhantomData }, value: [20, 0, 0, 0, 3, 0, 2, 3, 0, 0, 0, 0, 4, 13, 0, 0, 0], docs: [] }], error: Some(PalletErrorMetadata { ty: UntrackedSymbol { id: 542, marker: PhantomData } }), index: 105 }
in old:
PalletMetadata { name: "EmergencyShutdown", storage: Some(PalletStorageMetadata { prefix: "EmergencyShutdown", entries: [StorageEntryMetadata { name: "IsShutdown", modifier: Default, ty: Plain(UntrackedSymbol { id: 126, marker: PhantomData }), default: [0], docs: [] }, StorageEntryMetadata { name: "CanRefund", modifier: Default, ty: Plain(UntrackedSymbol { id: 126, marker: PhantomData }), default: [0], docs: [] }] }), calls: Some(PalletCallMetadata { ty: UntrackedSymbol { id: 314, marker: PhantomData } }), event: Some(PalletEventMetadata { ty: UntrackedSymbol { id: 154, marker: PhantomData } }), constants: [PalletConstantMetadata { name: "CollateralCurrencyIds", ty: UntrackedSymbol { id: 59, marker: PhantomData }, value: [16, 0, 0, 0, 3, 0, 2, 4, 13, 0, 0, 0], docs: [] }], error: Some(PalletErrorMetadata { ty: UntrackedSymbol { id: 542, marker: PhantomData } }), index: 105 }

[xlc]

Thanks for the report. We have incorrectly annotated a non constant as a constant and hence this issue. Will fix it in next runtime upgrade.