@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 
{
    
    hashBlock = block_hash;
    
    nIndex = posInBlock;
}
int CMerkleTx::GetDepthInMainChain(interfaces::Chain::Lock& locked_chain) const
{
    if (hashUnset())
        return 0;
    AssertLockHeld(cs_main);
    return locked_chain.getBlockDepth(hashBlock) * (nIndex == -1 ? -1 : 1);
}
int CMerkleTx::GetBlocksToMaturity(interfaces::Chain::Lock& locked_chain) const
{
    if (!IsCoinBase())
        return 0;
    int chain_depth = GetDepthInMainChain(locked_chain);
    assert(chain_depth >= 0); 
    return std::max(0, (COINBASE_MATURITY+1) - chain_depth);
}
bool CMerkleTx::IsImmatureCoinBase(interfaces::Chain::Lock& locked_chain) const
{
    
    return GetBlocksToMaturity(locked_chain) > 0;
}
bool CWalletTx::AcceptToMemoryPool(interfaces::Chain::Lock& locked_chain, const CAmount& nAbsurdFee, CValidationState& state)