Odd behavior with mul!() and @view

General Usage
2

Method 1 lowers to getindex i.e. makes another slice. Method 2 lowers to setindex!

julia> Meta.@lower mul!(out2[:,1], A, b)
:($(Expr(:thunk, CodeInfo(
    @ none within `top-level scope`
1 ─ %1 = Base.getindex(out2, :, 1)
│   %2 = A
│   %3 = mul!(%1, %2, b)
└──      return %3
))))

julia> Meta.@lower out2[:,1] = A*b
:($(Expr(:thunk, CodeInfo(
    @ none within `top-level scope`
1 ─ %1 = A * b
│        Base.setindex!(out2, %1, :, 1)
└──      return %1
))))

what is the motivation for using mul! specifically rather than * ? also I think if you use another view this will work as intended

# equivalently, mul!(view(out2, :, 1), A, b)
julia> @views mul!(out2[:,1], A, b)
10-element view(::Matrix{Float64}, :, 3) with eltype Float64:
 10.0
 10.0
 10.0
 10.0
 10.0
 10.0
 10.0
 10.0
 10.0
 10.0