SOneTo subtypes AbstractOneTo (#1302)

On a recent nightly (v"1.13.0-DEV.347"), `Base` has added
`AbstractOneTo` (JuliaLang/julia#56902), and in
this PR we change `SOneTo` to subtype `AbstractOneTo` when this is
available. This makes combinations of `SOneTo`, `Base.OneTo` and
`Integer`s dispatch to `Base` methods, and we don't need to disambiguate
these in this package.

Fixes #1248. After
this, `StaticArrays` only needs to define `similar` methods for `Tuple`s
of `SOneTo` as indices.

---------

Co-authored-by: Neven Sajko <4944410+nsajko@users.noreply.github.com>
Co-authored-by: Mateusz Baran <mateuszbaran89@gmail.com>

Author: 3 people

src/SOneTo.jl

@@ -1,10 +1,12 @@
+const SOneToSupertype = isdefined(Base, :AbstractOneTo) ?  Base.AbstractOneTo : AbstractUnitRange
+
 """
     SOneTo(n)
 
 Return a statically-sized `AbstractUnitRange` starting at `1`, functioning as the `axes` of
 a `StaticArray`.
 """
-struct SOneTo{n} <: AbstractUnitRange{Int}
+struct SOneTo{n} <: SOneToSupertype{Int}
 end
 
 SOneTo(n::Int) = SOneTo{n}()

src/abstractarray.jl

@@ -142,8 +142,13 @@ const HeterogeneousBaseShape = Union{Integer, Base.OneTo}
 const HeterogeneousShape = Union{HeterogeneousBaseShape, SOneTo}
 const HeterogeneousShapeTuple = Tuple{Vararg{HeterogeneousShape}}
 
-similar(A::AbstractArray, ::Type{T}, shape::HeterogeneousShapeTuple) where {T} = similar(A, T, homogenize_shape(shape))
-similar(::Type{A}, shape::HeterogeneousShapeTuple) where {A<:AbstractArray} = similar(A, homogenize_shape(shape))
+@static if isdefined(Base, :AbstractOneTo)
+    similar(A::AbstractArray, ::Type{T}, shape::Tuple{SOneTo, Vararg{SOneTo}}) where {T} = similar(A, T, homogenize_shape(shape))
+    similar(::Type{A}, shape::Tuple{SOneTo, Vararg{SOneTo}}) where {A<:AbstractArray} = similar(A, homogenize_shape(shape))
+else
+    similar(A::AbstractArray, ::Type{T}, shape::HeterogeneousShapeTuple) where {T} = similar(A, T, homogenize_shape(shape))
+    similar(::Type{A}, shape::HeterogeneousShapeTuple) where {A<:AbstractArray} = similar(A, homogenize_shape(shape))
+end
 # Use an Array for StaticArrays if we don't have a statically-known size
 similar(::Type{A}, shape::Tuple{Int, Vararg{Int}}) where {A<:StaticArray} = Array{eltype(A)}(undef, shape)