StaticArray types with cartesian index style

I was trying to create a new static array type (an unsafe strided statically-sized view - or USS View for short). Because of the strided this type must have a cartesian index style. Most of the generated functions in StaticArrays generate code with linear indexing. Unfortunately, splitting a linear index to a cartesian one is fairly slow.

Ideally one could generate code using linear indexing for linear-indexable types and cartesian indexing for cartesian-indexable types. I tried to write a patch like this, but it turns out that generated (that is, generator) functions run in an older world and can't see new methods to Base.IndexStyle. Ouch.

So if there's interest in supporting external subtypes of StaticArray with different index styles, I believe this has to be encoded on the type level as a new parameter, i.e.

abstract type StaticArray{S, T, N, I<:IndexStyle} <: AbstractArray{T, N} end
Base.IndexStyle(::Type{StaticArray{S,T,N,I}}) where {S,T,N,I} = I()
struct SArray{S, T, N, L} <: StaticArray{S, T, N, IndexLinear} # .... etc

Is there interest in doing this?

Start by reading the StaticArray and SArray type definitions and the existing generated functions that use linear indexing. Check how Base.IndexStyle is currently handled, then determine whether a type-level index-style parameter can support external cartesian-indexable subtypes without the slow linear-to-cartesian conversion; the issue does not name tests or files.