`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
```
{
    {
        LOCK(cs_wallet);
        for (std::pair<const uint256, CWalletTx>& item : mapWallet)
            item.second.MarkDirty();
    }
}
bool CWallet::MarkReplaced(const uint256& originalHash, const uint256& newHash)
{
    LOCK(cs_wallet);
    auto mi = mapWallet.find(originalHash);
    
    assert(mi != mapWallet.end());
    CWalletTx& wtx = (*mi).second;
    
    assert(wtx.mapValue.count("replaced_by_txid") == 0);
    wtx.mapValue["replaced_by_txid"] = newHash.ToString();
    WalletBatch batch(*database, "r+");
    bool success = true;
    if (!batch.WriteTx(wtx)) {
        WalletLogPrintf("%s: Updating batch tx %s failed\n", __func__, wtx.GetHash().ToString());
        success = false;
    }
    NotifyTransactionChanged(this, originalHash, CT_UPDATED);
    return success;
}
bool CWallet::AddToWallet(const CWalletTx& wtxIn, bool fFlushOnClose)