`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);
    m_wallet_flags = overwriteFlags;
    if (((overwriteFlags & g_known_wallet_flags) >> 32) ^ (overwriteFlags >> 32)) {
        
        return false;
    }
    if (!memonly && !WalletBatch(*database).WriteWalletFlags(m_wallet_flags)) {
        throw std::runtime_error(std::string(__func__) + ": writing wallet flags failed");
    }
    return true;
}
int64_t CWalletTx::GetTxTime() const
{
    int64_t n = nTimeSmart;
    return n ? n : nTimeReceived;
}
bool CWallet::DummySignInput(CTxIn &tx_in, const CTxOut &txout, bool use_max_sig) const
{
    
    const CScript& scriptPubKey = txout.scriptPubKey;
    SignatureData sigdata;
    if (!ProduceSignature(*this, use_max_sig ? DUMMY_MAXIMUM_SIGNATURE_CREATOR : DUMMY_SIGNATURE_CREATOR, scriptPubKey, sigdata)) {
        return false;
    }
    UpdateInput(tx_in, sigdata);
    return true;
}
bool CWallet::DummySignTx(CMutableTransaction &txNew, const std::vector<CTxOut> &txouts, bool use_max_sig) const