hcat(A, B) is SArray, but [ A ;; B] is not

[dev10110]

Hi,

consider this MWE:

using LinearAlgebra, StaticArrays

A = @SMatrix randn(3, 4)
B = @SMatrix randn(3, 2)

as expected,

hcat(A, B)  #returns 3×6 SMatrix{3, 6, Float64, 18}

but

[ A ;; B]  # returns 3×6 Matrix{Float64}

If we compare this to vcat,

A = @SMatrix randn(3, 4)
B = @SMatrix randn(2, 4)
vcat(A, B) # returns 5×4 SMatrix{5, 4, Float64, 20} (as expected)
[ A ; B] # returns 5×4 SMatrix{5, 4, Float64, 20} (as expected)

So somehow, the array concatenation works for vcat but not for hcat.

Is this expected behavior?