Compatibility with DynamicQuantities.jl – use `oneunit(::T)` instead of `oneunit(::Type{T})` about differentialequations.jl HOT 3 OPEN

using DynamicQuantities, OrdinaryDiffEq, RecursiveArrayTools

function RecursiveArrayTools.recursive_unitless_bottom_eltype(a::Type{
                                                                      <:DynamicQuantities.Quantity{T}
                                                                      }) where T
    T
end

function RecursiveArrayTools.recursive_unitless_eltype(a::Type{<:DynamicQuantities.Quantity{T}}) where T
    T
end

DiffEqBase.value(x::DynamicQuantities.Quantity) = x.value
@inline function DiffEqBase.UNITLESS_ABS2(x::AbstractArray)
    mapreduce(DiffEqBase.UNITLESS_ABS2, DiffEqBase.abs2_and_sum, x, init = zero(real(first(DiffEqBase.value(x)))))
end
@inline function DiffEqBase.UNITLESS_ABS2(x::DynamicQuantities.Quantity)
    abs(DiffEqBase.value(x))
end

function DiffEqBase.abs2_and_sum(x::DynamicQuantities.Quantity, y::Float64)
    reduce(Base.add_sum, DiffEqBase.value(x), init = zero(real(DiffEqBase.value(x)))) +
    reduce(Base.add_sum, y, init = zero(real(DiffEqBase.value(eltype(y)))))
end

DiffEqBase.recursive_length(u::Array) = length(u)
Base.sign(x::DynamicQuantities.Quantity) = Base.sign(DiffEqBase.value(x))

function DiffEqBase.prob2dtmin(prob; use_end_time = true)
    DiffEqBase.prob2dtmin(prob.tspan, oneunit(first(prob.tspan)), use_end_time)
end

DiffEqBase.NAN_CHECK(x::DynamicQuantities.Quantity) = isnan(x)
Base.zero(x::Array{T}) where {T<:DynamicQuantities.Quantity} = zero.(x)

@inline function DiffEqBase.calculate_residuals(ũ, u₀, u₁, α, ρ, internalnorm, t)
    @. DiffEqBase.calculate_residuals(ũ, u₀, u₁, α, ρ, internalnorm, t)
end

f(u, p, t) = u / t;
problem = ODEProblem(f, [1.0u"km/s"], (0.0u"s", 1.0u"s"));
sol = solve(problem, Tsit5(), dt = 0.1u"s")

julia> typeof(one(0.0u"s"))
Quantity{Float64, Dimensions{DynamicQuantities.FixedRational{Int32, 25200}}}

julia> sol = solve(problem, Tsit5(), dt = 0.1u"s")
ERROR: Cannot create a dimensionful 1 for a `UnionAbstractQuantity` type without knowing the dimensions. Please use `oneunit(::UnionAbstractQuantity)` instead.
Stacktrace:
 [1] error(s::String)
   @ Base ./error.jl:35
 [2] oneunit(::Type{Quantity{Float64, Dimensions{DynamicQuantities.FixedRational{Int32, 25200}}}})
   @ DynamicQuantities ~/Documents/DynamicQuantities.jl/src/utils.jl:191
 [3] __init(prob::ODEProblem{…}, alg::Tsit5{…}, timeseries_init::Tuple{}, ts_init::Tuple{}, ks_init::Tuple{}, recompile::Type{…}; saveat::Tuple{}, tstops::Tuple{}, d_discontinuities::Tuple{}, save_idxs::Nothing, save_everystep::Bool, save_on::Bool, save_start::Bool, save_end::Nothing, callback::Nothing, dense::Bool, calck::Bool, dt::Quantity{…}, dtmin::Nothing, dtmax::Quantity{…}, force_dtmin::Bool, adaptive::Bool, gamma::Rational{…}, abstol::Nothing, reltol::Nothing, qmin::Rational{…}, qmax::Int64, qsteady_min::Int64, qsteady_max::Int64, beta1::Nothing, beta2::Nothing, qoldinit::Rational{…}, controller::Nothing, fullnormalize::Bool, failfactor::Int64, maxiters::Int64, internalnorm::typeof(DiffEqBase.ODE_DEFAULT_NORM), internalopnorm::typeof(LinearAlgebra.opnorm), isoutofdomain::typeof(DiffEqBase.ODE_DEFAULT_ISOUTOFDOMAIN), unstable_check::typeof(DiffEqBase.ODE_DEFAULT_UNSTABLE_CHECK), verbose::Bool, timeseries_errors::Bool, dense_errors::Bool, advance_to_tstop::Bool, stop_at_next_tstop::Bool, initialize_save::Bool, progress::Bool, progress_steps::Int64, progress_name::String, progress_message::typeof(DiffEqBase.ODE_DEFAULT_PROG_MESSAGE), progress_id::Symbol, userdata::Nothing, allow_extrapolation::Bool, initialize_integrator::Bool, alias_u0::Bool, alias_du0::Bool, initializealg::OrdinaryDiffEq.DefaultInit, kwargs::@Kwargs{})
   @ OrdinaryDiffEq ~/.julia/packages/OrdinaryDiffEq/qxpST/src/solve.jl:220
 [4] __solve(::ODEProblem{…}, ::Tsit5{…}; kwargs::@Kwargs{…})
   @ OrdinaryDiffEq ~/.julia/packages/OrdinaryDiffEq/qxpST/src/solve.jl:5
 [5] solve_call(_prob::ODEProblem{…}, args::Tsit5{…}; merge_callbacks::Bool, kwargshandle::Nothing, kwargs::@Kwargs{…})
   @ DiffEqBase ~/.julia/packages/DiffEqBase/NYLhl/src/solve.jl:557
 [6] solve_up(prob::ODEProblem{…}, sensealg::Nothing, u0::Vector{…}, p::SciMLBase.NullParameters, args::Tsit5{…}; kwargs::@Kwargs{…})
   @ DiffEqBase ~/.julia/packages/DiffEqBase/NYLhl/src/solve.jl:1006
 [7] solve(prob::ODEProblem{…}, args::Tsit5{…}; sensealg::Nothing, u0::Nothing, p::Nothing, wrap::Val{…}, kwargs::@Kwargs{…})
   @ DiffEqBase ~/.julia/packages/DiffEqBase/NYLhl/src/solve.jl:929
 [8] top-level scope
   @ REPL[21]:1
Some type information was truncated. Use `show(err)` to see complete types.