`LockAnnotation lock(::cs_main)` is a guarantee to the compiler thread analysis that `::cs_main` is locked (when it couldn't be determined otherwise).

Despite being annotated with the locking guarantee ...

https://github.com/bitcoin/bitcoin/blob/65526fc8666fef35ef908dbc225f706bef642c7e/src/interfaces/chain.cpp#L134-L138

... `getTipLocator()` reads `chainActive` (via `::ChainActive()`) without holding `cs_main`.

This can be verified by adding the following `AssertLockHeld(cs_main)`:

```
$ git diff
diff --git a/src/interfaces/chain.cpp b/src/interfaces/chain.cpp
index 59623284d..9fc693a0f 100644
--- a/src/interfaces/chain.cpp
+++ b/src/interfaces/chain.cpp
@@ -134,6 +134,7 @@ class LockImpl : public Chain::Lock
     CBlockLocator getTipLocator() override
     {
         LockAnnotation lock(::cs_main);
+        AssertLockHeld(::cs_main);
         return ::ChainActive().GetLocator();
     }
     Optional<int> findLocatorFork(const CBlockLocator& locator) override
$ make check
../build-aux/test-driver: line 107: 12881 Aborted                 "$@" > $log_file 2>&1
FAIL: qt/test/test_bitcoin-qt
```
for (const CTxOut& txout: tx.vout) {
                
                for (const auto& keyid : GetAffectedKeys(txout.scriptPubKey, *this)) {
                    std::map<CKeyID, int64_t>::const_iterator mi = m_pool_key_to_index.find(keyid);
                    if (mi != m_pool_key_to_index.end()) {
                        WalletLogPrintf("%s: Detected a used keypool key, mark all keypool key up to this key as used\n", __func__);
                        MarkReserveKeysAsUsed(mi->second);
                        if (!TopUpKeyPool()) {
                            WalletLogPrintf("%s: Topping up keypool failed (locked wallet)\n", __func__);
                        }
                    }
                }
            }
            CWalletTx wtx(this, ptx);
            
            if (!block_hash.IsNull())
                wtx.SetMerkleBranch(block_hash, posInBlock);
            return AddToWallet(wtx, false);
        }
    }
    return false;
}
bool CWallet::TransactionCanBeAbandoned(const uint256& hashTx) const
{
    auto locked_chain = chain().lock();
    LOCK(cs_wallet);
    const CWalletTx* wtx = GetWalletTx(hashTx);
    return wtx && !wtx->isAbandoned() && wtx->GetDepthInMainChain(*locked_chain) == 0 && !wtx->InMempool();
}
void CWallet::MarkInputsDirty(const CTransactionRef& tx)