@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 
{
    AssertLockHeld(cs_wallet); 
    
    int nIn = 0;
    for (auto& input : tx.vin) {
        std::map<uint256, CWalletTx>::const_iterator mi = mapWallet.find(input.prevout.hash);
        if(mi == mapWallet.end() || input.prevout.n >= mi->second.tx->vout.size()) {
            return false;
        }
        const CScript& scriptPubKey = mi->second.tx->vout[input.prevout.n].scriptPubKey;
        const CAmount& amount = mi->second.tx->vout[input.prevout.n].nValue;
        SignatureData sigdata;
        if (!ProduceSignature(*this, MutableTransactionSignatureCreator(&tx, nIn, amount, SIGHASH_ALL), scriptPubKey, sigdata)) {
            return false;
        }
        UpdateInput(input, sigdata);
        nIn++;
    }
    return true;
}
bool CWallet::FundTransaction(CMutableTransaction& tx, CAmount& nFeeRet, int& nChangePosInOut, std::string& strFailReason, bool lockUnspents, const std::set<int>& setSubtractFeeFromOutputs, CCoinControl coinControl)