@jonasschnelli wrote in #14979:
> #14573 broke < Qt5.6 compatibility due to calling the lambda version of `addAction` that was added in Qt5.6.

We currently [support](https://github.com/bitcoin/bitcoin/blob/master/doc/dependencies.md) QT >=5.2, but hardly anyone tests with that. If we make one of the Travis machines use it, we should have a better change of catching this.

See also discussion about minimum QT version in #13478 
{
    bool fUpdated = false;
    {
        LOCK(cs_wallet); 
        std::map<CTxDestination, CAddressBookData>::iterator mi = mapAddressBook.find(address);
        fUpdated = mi != mapAddressBook.end();
        mapAddressBook[address].name = strName;
        if (!strPurpose.empty()) 
            mapAddressBook[address].purpose = strPurpose;
    }
    NotifyAddressBookChanged(this, address, strName, ::IsMine(*this, address) != ISMINE_NO,
                             strPurpose, (fUpdated ? CT_UPDATED : CT_NEW) );
    if (!strPurpose.empty() && !WalletBatch(*database).WritePurpose(EncodeDestination(address), strPurpose))
        return false;
    return WalletBatch(*database).WriteName(EncodeDestination(address), strName);
}
bool CWallet::DelAddressBook(const CTxDestination& address)