allocate_result type-unstable for ProductArray

[sethaxen]

allocate_result is type-unstable for ProductArray. This appears to be due to type-instability of ManifoldsBase.allocate_result_type for this type. This drastically slows down our allocating functions on product manifolds. Here's an example:

using Manifolds, Test
M = Euclidean(2) × Euclidean(3)
parray(x) = Manifolds.ProductArray(Manifolds.ShapeSpecification(Manifolds.StaticReshaper(), M.manifolds...), x)
p = parray(randn(5))

julia> @inferred Manifolds.allocate_result(M, Manifolds.log, p, p)
ERROR: return type Manifolds.ProductArray{Manifolds.ShapeSpecification{(1:2, 3:5), Tuple{Tuple{2}, Tuple{3}}, Tuple{Manifolds.StaticReshaper, Manifolds.StaticReshaper}}, Float64, 1, Vector{Float64}, Tuple{Manifolds.SizedAbstractArray{Tuple{2}, Float64, 1, 1, SubArray{Float64, 1, Vector{Float64}, Tuple{UnitRange{Int64}}, true}}, Manifolds.SizedAbstractArray{Tuple{3}, Float64, 1, 1, SubArray{Float64, 1, Vector{Float64}, Tuple{UnitRange{Int64}}, true}}}, Tuple{Manifolds.StaticReshaper, Manifolds.StaticReshaper}} does not match inferred return type Manifolds.ProductArray{Manifolds.ShapeSpecification{(1:2, 3:5), Tuple{Tuple{2}, Tuple{3}}, Tuple{Manifolds.StaticReshaper, Manifolds.StaticReshaper}}, T, 1, _B, _C, Tuple{Manifolds.StaticReshaper, Manifolds.StaticReshaper}} where _C<:Tuple where _B<:AbstractVector{T} where T
Stacktrace:
[1] error(s::String)
    @ Base ./error.jl:33
[2] top-level scope
    @ REPL[17]:1

[mateuszbaran]

Thanks, I'll check that.