Multiplication of ScalMat and FillArray is ambiguous

[Wu-Chenyang]

The following code runs into errors.

julia> using PDMats, Distributions, LinearAlgebra
julia> ScalMat(3, 1) * MvNormal(I(3))
ERROR: MethodError: *(::ScalMat{Int64}, ::Falses{1, Tuple{Base.OneTo{Int64}}}) is ambiguous.

Candidates:
  *(a::ScalMat, x::AbstractVector)
    @ PDMats ~/.julia/packages/PDMats/cAM9h/src/scalmat.jl:43
  *(a::AbstractMatrix{T}, b::FillArrays.AbstractZeros{T, 1} where T) where T
    @ FillArrays ~/.julia/packages/FillArrays/lVl4c/src/fillalgebra.jl:103

Possible fix, define
  *(::ScalMat{T}, ::FillArrays.AbstractZeros{T, 1} where T) where T<:Real

This is due to the compatibility issue of ScalMat and FillArrays and can be fixed by, e.g., replacing the Falses(3) mean vector with zeros(3) or the ScalMat(3, 1) with I(3). Maybe I should submit this issue to FillArrays or PDMats?

[devmotion]

Yes, to me this seems to be an issue of FillArrays + PDMats. Note that FillArrays already has an extension for PDMats, so IMO the missing method should be defined there.

[Wu-Chenyang]

Thanks for your helpful response! I'll close this issue and submit it to FillArrays.