Make op(Array, Scalar) use broadcast

[andreasnoack]

These are broadcast operations and could therefore just use the broadcast functionality. @martinholters I had to tighten a single type test that you added but I believe that this can just be considered an improvement.

[stevengj]

The original thinking was that, for example, we shouldn't widen Array{Float32} even when multiplying it by a Float64. But in cases where this matters, one probably wants to use the (new) in-place operations anyway, so this seems like a reasonable change to me.

Needs a NEWS item under breaking changes, though.

[martinholters]

I had to tighten a single type test that you added but I believe that this can just be considered an improvement.

I had the same change in the branch mentioned in #19669, so 👍.

[kshyatt]

Can we merge this?

[andreasnoack]

Still needs an updated NEWS.md. Will do that now.

[andreasnoack]

Done.

[tkelman]

@nanosoldier runbenchmarks(ALL, vs = ":master")

[KristofferC]

So code like f(x::Vector) = x[1] < 0.5 ? x[1] * x : 0.1 * x will now be type unstable for Vector{Float32}?

[andreasnoack]

Yes. Unless we change the behavior of broadcast promotion. I don't really think it makes sense to have different promotion behavior between these and broadcast. The main point here is to make the two similar but I also think it makes more sense to follow the scalar-scalar promotion rules. The function is type unstable in the same way f(x::Number) = x < 0.5 ? x*x : 0.1*x is type unstable for Float32.

[nanosoldier]

Your benchmark job has completed - possible performance regressions were detected. A full report can be found here. cc @jrevels

[andreasnoack]

Couldn't reproduce the regression locally so I assume it is noise.