Bump module serialization format to v2

CHANGELOG.md

@@ -21,6 +21,8 @@ and this project adheres to
 ### Fixed
 
 - cosmwasm-vm: Fix `AddAssign` implementation of `GasInfo`.
+- cosmwasm-vm: Bump `MODULE_SERIALIZATION_VERSION` to "v2" because the module
+  serialization format changed between Wasmer 2.0.0 and 2.1.x.
 
 ## [1.0.0-beta4] - 2021-12-23
 

packages/vm/src/modules/file_system_cache.rs

@@ -14,7 +14,23 @@ use crate::errors::{VmError, VmResult};
 /// The string is used as a folder and should be named in a way that is
 /// easy to interprete for system admins. It should allow easy clearing
 /// of old versions.
-const MODULE_SERIALIZATION_VERSION: &str = "v1";
+///
+/// See https://github.com/wasmerio/wasmer/issues/2781 for more information
+/// on Wasmer's module stability concept.
+///
+/// ## Version history:
+/// - **v1**:<br>
+///   cosmwasm_vm < 1.0.0-beta5. This is working well up to Wasmer 2.0.0 as
+///   [in wasmvm 1.0.0-beta2](https://github.com/CosmWasm/wasmvm/blob/v1.0.0-beta2/libwasmvm/Cargo.lock#L1412-L1413)
+///   and [wasmvm 0.16.3](https://github.com/CosmWasm/wasmvm/blob/v0.16.3/libwasmvm/Cargo.lock#L1408-L1409).
+///   Versions that ship with Wasmer 2.1.x such [as wasmvm 1.0.0-beta3](https://github.com/CosmWasm/wasmvm/blob/v1.0.0-beta3/libwasmvm/Cargo.lock#L1534-L1535)
+///   to [wasmvm 1.0.0-beta5](https://github.com/CosmWasm/wasmvm/blob/v1.0.0-beta5/libwasmvm/Cargo.lock#L1530-L1531)
+///   are broken, i.e. they will crash when reading older v1 modules.
+/// - **v2**:<br>
+///   Version for cosmwasm_vm 1.0.0-beta5 / wasmvm 1.0.0-beta6 that ships with Wasmer 2.1.1.
+/// - **v3**:<br>
+///   Version for Wasmer 2.2.0 which contains a [module breaking change to 2.1.x](https://github.com/wasmerio/wasmer/pull/2747).
+const MODULE_SERIALIZATION_VERSION: &str = "v2";
 
 /// Representation of a directory that contains compiled Wasm artifacts.
 pub struct FileSystemCache {
@@ -173,7 +189,7 @@ mod tests {
         let module = compile(&wasm, None, &[]).unwrap();
         cache.store(&checksum, &module).unwrap();
 
-        let file_path = format!("{}/v1/{}", tmp_dir.path().to_string_lossy(), checksum);
+        let file_path = format!("{}/v2/{}", tmp_dir.path().to_string_lossy(), checksum);
         let serialized_module = fs::read(file_path).unwrap();
         assert_eq!(serialized_module.len(), 1040);
     }