Add transaction_index::HostFunctions with NO-OP impl to the polkadot-prepare/execute-worker

[bkontur]

Relates to: paritytech/polkadot-bulletin-chain#74
Similar issue for smoldot: paritytech/smoldot-archive#2182

Context

The pallet-transaction-storage pallet and its store function uses transaction index HostFunctions, e.g. sp_io::transaction_index::index(extrinsic_index, data.len() as u32, content_hash);. All our binaries (polkadot, polkadot-parachain, polkadot-omni-node) support these HostFunctions via sp_io::SubstrateHostFunctions.

Problem

When using this pallet within a parachain, the problem arises during parachain validation on the relay chain. The polkadot-execute / prepare-worker environment does not include these HostFunctions — resulting in the error shown below.

2025-11-19 09:51:12.068  WARN tokio-runtime-worker parachain::pvf: execution worker concluded, error occurred: candidate validation: invalid: worker reported: execute: Execution aborted due to trap: call
 to a missing function env:ext_transaction_index_index_version_1
WASM backtrace:
error while executing at wasm backtrace:
    0: 0x5f8de0 - bulletin_westend_runtime.wasm!sp_io::transaction_index::extern_host_function_impls::index::h35478cdbc56a306c
    1: 0x6bb403 - bulletin_westend_runtime.wasm!<wasm function 8748>
    2: 0x413640 - bulletin_westend_runtime.wasm!frame_support::storage::transactional::with_transaction::h79ce9a055b33819e
    3: 0x90389 - bulletin_westend_runtime.wasm!<pallet_transaction_storage::pallet::Call<T> as frame_support::traits::dispatch::UnfilteredDispatchable>::dispatch_bypass_filter::{{closure}}::h9dddca92896e
d49d
    4: 0x9ed1b - bulletin_westend_runtime.wasm!environmental::local_key::LocalKey<T>::with::h7e22e1a435c399fc
    5: 0x51407a - bulletin_westend_runtime.wasm!<bulletin_westend_runtime::RuntimeCall as frame_support::traits::dispatch::UnfilteredDispatchable>::dispatch_bypass_filter::h691bb264c7871775
    6: 0x5129d7 - bulletin_westend_runtime.wasm!<bulletin_westend_runtime::RuntimeCall as sp_runtime::traits::Dispatchable>::dispatch::h4935ba6fe14584db
    7: 0x35eed5 - bulletin_westend_runtime.wasm!<T as sp_runtime::traits::transaction_extension::dispatch_transaction::DispatchTransaction<Call>>::dispatch_transaction::h4c377a6a3677b5ef
    8: 0x3ce879 - bulletin_westend_runtime.wasm!<sp_runtime::generic::checked_extrinsic::CheckedExtrinsic<AccountId,Call,Extension> as sp_runtime::traits::Applyable>::apply::h92f77e6a58d26237
    9: 0x4a0135 - bulletin_westend_runtime.wasm!frame_executive::Executive<System,Block,Context,UnsignedValidator,AllPalletsWithSystem,COnRuntimeUpgrade>::do_apply_extrinsic::had25d7fd331d0474
   10: 0x49ed31 - bulletin_westend_runtime.wasm!frame_executive::Executive<System,Block,Context,UnsignedValidator,AllPalletsWithSystem,COnRuntimeUpgrade>::execute_block::hdb1b331a7c0334be
   11: 0x4e7237 - bulletin_westend_runtime.wasm!<cumulus_pallet_aura_ext::BlockExecutor<T,I> as frame_support::traits::misc::ExecuteBlock<Block>>::execute_block::h3c1578a9fc377780
   12: 0xa0f0d - bulletin_westend_runtime.wasm!environmental::local_key::LocalKey<T>::with::hac4bfb5192978ed0
   13: 0xde8b2 - bulletin_westend_runtime.wasm!cumulus_pallet_parachain_system::validate_block::implementation::validate_block::hc6a4c2b1a877fa32
   14: 0x446339 - bulletin_westend_runtime.wasm!validate_block
   15: 0x6b70cb - bulletin_westend_runtime.wasm!<wasm function 8248> artifact_id=ArtifactId { code_hash: 0x41ef24a292f50152812d6b39ce316a1a4bb71648c9bfba970c05b2c04038f0c7, executor_params_prep_hash: 0x5
0b16a713c0f8774ba3a0757c722b48c6eb4c1972f6e58c54fd0851f21a08633 } worker=Worker(1v1) worker_rip=false

Solution

This PR adds sp_io::transaction_index::HostFunctions as a no-op to the cumulus-pallet-parachain-system's validate_block.

[bkontur]

/cmd prdoc --audience runtime_dev node_dev --bump patch

[bkchr]

The proper way of doing this is that you override these host functions in validate_block/implementation.rs as done for the other host functions.

[bkontur]

The proper way of doing this is that you override these host functions in validate_block/implementation.rs as done for the other host functions.

@bkchr Ooooh, nice :) I had previously just followed the log error, and this is really better since it’s part of the runtime and not the binary. Thank you — tested and working :)

[bkontur]

aaah, "check compatibility" now hits the chopsticks issue: https://github.com/paritytech/polkadot-sdk/actions/runs/19652937174/job/56283788628#step:6:29, which is a smol-dot issue: paritytech/smoldot-archive#2182,
which is fixed and ready to be merged: paritytech/smoldot-archive#2189

cc: @tomaka please, please

[bkchr]

Could we please put this behind a feature. Otherwise all parachain nodes will require these host functions.

[bkontur]

Could we please put this behind a feature. Otherwise all parachain nodes will require these host functions.

Thank you, good point, fixed: 0f4c666

[paritytech-workflow-stopper]

All GitHub workflows were cancelled due to failure one of the required jobs.
Failed workflow url: https://github.com/paritytech/polkadot-sdk/actions/runs/19739906850
Failed job name: test-linux-stable-int

[bkontur]

merged as a part of #10662