Incomplete promotion rules for sparse matrices about sparsearrays.jl

[jebej]

Is this ok:

promote_rule(::Type{SparseMatrixCSC{T1,S1}},::Type{SparseMatrixCSC{T2,S2}}) where {T1,T2,S1,S2} = SparseMatrixCSC{promote_type(T1,T2),promote_type(S1,S2)}

[fredrikekre]

JuliaLang/julia#22757

[jebej]

Does JuliaLang/julia#22757 fix this problem?

[jebej]

I have been using the following locally:

promote_rule{T1,T2,S1,S2}(::Type{SparseMatrixCSC{T1,S1}},::Type{SparseMatrixCSC{T2,S2}}) = SparseMatrixCSC{promote_type(T1,T2),promote_type(S1,S2)}
promote_rule{T1,S1,T2,S2<:AbstractMatrix{T2}}(::Type{SparseMatrixCSC{T1,S1}},::Type{S2}) = Matrix{promote_type(T1,T2)}
promote_rule{T1,S1,T2,S2<:AbstractMatrix{T2}}(::Type{S2},::Type{SparseMatrixCSC{T1,S1}}) = Matrix{promote_type(T1,T2)}

should I make a PR?

[ViralBShah]

Revisiting old sparse issues. This does need the PR.