`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
```
{
    return strprintf("COutput(%s, %d, %d) [%s]", tx->GetHash().ToString(), i, nDepth, FormatMoney(tx->tx->vout[i].nValue));
}
std::vector<CKeyID> GetAffectedKeys(const CScript& spk, const SigningProvider& provider)
{
    std::vector<CScript> dummy;
    FlatSigningProvider out;
    InferDescriptor(spk, provider)->Expand(0, DUMMY_SIGNING_PROVIDER, dummy, out);
    std::vector<CKeyID> ret;
    for (const auto& entry : out.pubkeys) {
        ret.push_back(entry.first);
    }
    return ret;
}
const CWalletTx* CWallet::GetWalletTx(const uint256& hash) const
{
    LOCK(cs_wallet);
    std::map<uint256, CWalletTx>::const_iterator it = mapWallet.find(hash);
    if (it == mapWallet.end())
        return nullptr;
    return &(it->second);
}
CPubKey CWallet::GenerateNewKey(WalletBatch &batch, bool internal)