`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
```
} else {
        WalletLogPrintf("Rescan completed in %15dms\n", GetTimeMillis() - start_time);
    }
    return result;
}
void CWallet::ReacceptWalletTransactions(interfaces::Chain::Lock& locked_chain)
{
    
    if (!fBroadcastTransactions)
        return;
    std::map<int64_t, CWalletTx*> mapSorted;
    
    for (std::pair<const uint256, CWalletTx>& item : mapWallet)
    {
        const uint256& wtxid = item.first;
        CWalletTx& wtx = item.second;
        assert(wtx.GetHash() == wtxid);
        int nDepth = wtx.GetDepthInMainChain(locked_chain);
        if (!wtx.IsCoinBase() && (nDepth == 0 && !wtx.isAbandoned())) {
            mapSorted.insert(std::make_pair(wtx.nOrderPos, &wtx));
        }
    }
    
    for (const std::pair<const int64_t, CWalletTx*>& item : mapSorted) {
        CWalletTx& wtx = *(item.second);
        CValidationState state;
        wtx.AcceptToMemoryPool(locked_chain, state);
    }
}
bool CWalletTx::RelayWalletTransaction(interfaces::Chain::Lock& locked_chain)