[[nodiscard]]

[l0rinc]

Temporarily Annotated

• Validation/mempool/block helpers: AcceptToMemoryPool, ProcessNewPackage, CheckFinalTxAtTip, CalculateLockPointsAtTip, CheckSequenceLocksAtTip, CScriptCheck::operator(), CheckBlock, TestBlockValidity, HasValidProofOfWork, IsBlockMutated,
  CalculateClaimedHeadersWork, CheckInputScripts, CalculatePrevHeights, CheckInputsFromMempoolAndCache, MemPoolAccept::*, ApplyTxInUndo, CheckBlockHeader, CheckMerkleRoot, CheckWitnessMalleation, ContextualCheckBlockHeader, ContextualCheckBlock,
  GetSynchronizationState.
• Chainstate/manager APIs: ResizeCoinsCaches, FlushStateToDisk, ActivateBestChain, DisconnectBlock, ConnectBlock, DisconnectTip, PreciousBlock, InvalidateBlock, ReplayBlocks, LoadGenesisBlock, LoadChainTip, GetCoinsCacheSizeState,
  ActivateBestChainStep, ConnectTip, FindMostWorkChain, RollforwardBlock, NotifyHeaderTip, AcceptBlockHeader, MaybeValidateSnapshot, ProcessNewBlock, ProcessNewBlockHeaders, AcceptBlock, LoadBlockIndex, LoadAssumeutxoChainstate,
  ValidatedSnapshotCleanup, GetHistoricalBlockRange, ActivateBestChains, BlocksAheadOfTip.
• Direct validation callees: BlockManager::{LoadBlockIndex, FindUndoPos, LoadBlockIndexDB, LookupBlockIndex, WriteBlockUndo, WriteBlock, CheckBlockDataAvailability, IsBlockPruned, DeletePruneLock, ReadBlock, ReadRawBlock, ReadBlockUndo},
  CCoinsViewCache::SpendCoin, CheckTransaction, sequence-lock helpers, PoW helpers, and policy/package/RBF/TRUC/ephemeral standardness helpers.

Diagnostics

Diagnostic	Classification	Action
ProcessNewBlock ignored in net processing	intentional but unclear	Store result and debug-log false at src/net_processing.cpp:3429.
LoadGenesisBlock ignored after reindex	likely bug	Fatal error and return if retry fails at src/node/blockstorage.cpp:1299.
PreciousBlock ignored in RPC	suspicious	Check bool plus state at src/rpc/blockchain.cpp:1720.
InvalidateBlock ignored in RPC	likely bug	Check bool plus state; genesis invalidation now returns invalid state at src/validation.cpp:3521, with regression test at src/test/blockchain_tests.cpp:127.
ActivateBestChain ignored in invalidate/reconsider RPC	suspicious	Check bool plus state at src/rpc/blockchain.cpp:1743.
ProcessNewBlockHeaders ignored in submitheader	intentional but unclear	Throw if false with otherwise valid state at src/rpc/mining.cpp:1138.
FlushStateToDisk(PERIODIC) ignored after mempool/package admission	suspicious	Log warning, do not change admission result, at src/validation.cpp:1800 and src/validation.cpp:1834.
FlushStateToDisk(NONE) ignored in AcceptBlock	likely bug	Return false on flush/prune failure at src/validation.cpp:4386.
ResizeCoinsCaches ignored in snapshot activation	likely bug	Return util::Error at src/validation.cpp:5656.
ResizeCoinsCaches ignored in cache rebalance	intentional but unclear	Added logging helper at src/validation.cpp:6084.
SpendCoin, DeletePruneLock, NotifyHeaderTip, MaybeValidateSnapshot	harmless	Removed exploratory annotations.
Test/bench ignored returns from retained annotations	harmless/test harness	Converted to BOOST_REQUIRE, Assert, explicit tolerated false, or benchmark sink.

Annotations Kept
Kept [[nodiscard]] on the high-signal validation, chainstate, blockstorage I/O, consensus tx, PoW, package/policy/RBF/TRUC, and mempool acceptance return values in validation.h, validation.cpp, node/blockstorage.h, consensus/*, pow.h, and policy/
*.

Annotations Removed
Removed exploratory [[nodiscard]] from CCoinsViewCache::SpendCoin, BlockManager::DeletePruneLock, ChainstateManager::NotifyHeaderTip, ChainstateManager::MaybeValidateSnapshot, and GetSynchronizationState.

Verification

• cmake --build build-ubsan -j2: PASS before changes, PASS final.
• Annotated production rebuild initially failed as intended with ignored-result diagnostics; after fixes, cmake --build build-ubsan --target bitcoind bitcoin-cli bitcoin-chainstate libbitcoinkernel -j2: PASS.
• cmake --build build-ubsan --target test_bitcoin -j2: PASS.
• Focused unit tests passed: chainstate_write_tests, validation_chainstate_tests, validation_chainstatemanager_tests, blockchain_tests/invalidate_block, interfaces_tests/findCommonAncestor, transaction_tests/tx_valid, validation_block_tests/
  processnewblock_signals_ordering.
• git diff --check: PASS.
• Note: test_bitcoin in this UBSan build emits pre-existing sanitizer reports in crypto/secp256k1 startup paths; focused test exit statuses were still pass. One combined Boost filter command failed with “no test cases matching filter” and was
  rerun as separate tests.

Open Questions

• Whether InvalidateBlock(genesis) should use a different BlockValidationResult or RPC error code than the current invalid-state/database-error path.
• Whether periodic mempool flush failure should ever affect AcceptToMemoryPool / package admission results, instead of warning only.
• Whether MaybeRebalanceCaches() should become fallible rather than logging ResizeCoinsCaches failures.
• Whether maintainers prefer landing the retained broad [[nodiscard]] annotations together or splitting validation/blockstorage/policy groups.