# This just add debug info to Base.isbits(t::DataType) 
function Base.isbits(t::DataType)
    if !isa(t,DataType)
        @show typeof(t)
        error("Shouldn't dispatch to here!")
    end
    !t.mutable & t.pointerfree & isleaftype(t)
end
## # this fixes it:
## function Base.isbits(t::TypeConstructor)
##     false
## end

g() = Integer # needs to return a Type
gg(::Int) = nothing
tmm = first(methods(gg))
sig = Tuple{tmm.sig.parameters[2:end]...}
#    sig = (tmm.sig[2:end]...) # 0.3 version works
fret_typ = Base.return_types(g, sig)
println("$fret_typ")  # without this line no error is thrown later
@show methods(getindex) # error thrown here