Depwarn when mix ReverseDiff with ForwardDiff

[YingboMa]

I have the following code

using ReverseDiff

m,g = 1, 9.8
t = 1
p = [5.,6]
q = [1.,2]

L(t,q,q̇) = m/2 * dot(q̇,q̇) - m*g*q[2]

function Legendre_transformation(F, w)
    wv = a->ForwardDiff.gradient(F, a)
    z = zeros(w)
    M = ForwardDiff.jacobian(wv, z)
    b = wv(z)
    v = M\(w-b)
    w'v - F(v)
end

function Lagrangian2Hamiltonian(Lagrangian, t, q, p)
    L = q̇ -> Lagrangian(t, q, q̇)
    Legendre_transformation(L, p)
end

H = (q, p)->Lagrangian2Hamiltonian(L, t, q, p)

ṗ(p, q) = ReverseDiff.gradient(a->-H(a, p), q)
ṗ(p, q)

that will produce the following depwarn

WARNING: `invoke(f, (types...), ...)` is deprecated, use `invoke(f, Tuple{types...}, ...)` instead                                                             
Stacktrace:                            
 [1] depwarn(::String, ::Symbol) at ./deprecated.jl:70                                                                                                         
 [2] -(::ForwardDiff.Dual{2,ForwardDiff.Dual{2,Float64}}, ::ReverseDiff.TrackedReal{Float64,Float64,Void}) at /home/arch/.julia/v0.6/ReverseDiff/src/derivative
s/scalars.jl:20
...