This should silence the Win64 warnings (example https://cirrus-ci.com/task/5328746770071552?logs=ci#L3750) that don't consider assert(false) as an end of control flow:
script/sign.cpp: In function ‘bool SignStep(const SigningProvider&, const BaseSignatureCreator&, const CScript&, std::vector<std::vector<unsigned char> >&, TxoutType&, SigVersion, SignatureData&)’:
script/sign.cpp:247:13: warning: control reaches end of non-void function [-Wreturn-type]
script/standard.cpp: In function ‘bool ExtractDestination(const CScript&, CTxDestination&)’:
script/standard.cpp:215:26: warning: control reaches end of non-void function [-Wreturn-type]
policy/fees.cpp: In member function ‘unsigned int CBlockPolicyEstimator::HighestTargetTracked(FeeEstimateHorizon) const’:
./sync.h:232:104: warning: control reaches end of non-void function [-Wreturn-type]
qt/guiutil.cpp: In function ‘QString GUIUtil::ConnectionTypeToQString(ConnectionType, bool)’:
qt/guiutil.cpp:674:13: warning: control reaches end of non-void function [-Wreturn-type]
qt/peertablesortproxy.cpp: In member function ‘virtual bool PeerTableSortProxy::lessThan(const QModelIndex&, const QModelIndex&) const’:
qt/peertablesortproxy.cpp:21:132: warning: control reaches end of non-void function [-Wreturn-type]
Added a comment in the small functions where it seemed helpful.
