Struct Field Addition Flagged as Incompatible Upgrade

[yashnaman]

npx @openzeppelin/upgrades-core@1.41.0 validate --contract Pool --referenceBuildInfoDirs out-v1/build-info-v1 --reference build-info-v1:pool

I'm using upgrades-core 'svalidate command to compare two versions of the Pool contract. The only change between the versions is an addition to a struct:

• The Pool contract has a single state variable: a struct named PoolState.
• I added a uint256 variable at the end of the PoolState struct.

Expected Behavior:

Since the new field is appended to the end of the struct and there is no other state after the struct, this should not cause any storage layout issues.

Observed Behavior:

Despite the safe change, I get the following error:

src/Pool.sol:9: Upgraded `pool` to an incompatible type
  - Bad upgrade to struct PoolState
  - In struct PoolState
    - Added `additionalUint256`

Why is this considered an incompatible upgrade?
Is this a false positive, or is there something I'm missing about how OpenZeppelin detects unsafe changes to structs?

[ericglau]

Thanks for reporting this. This appears to be a false positive and is the same as issue #1136

I'll close this as a duplicate.