views should preserve static axes information (#295)

* views should preserve static axes information

Author: chriselrod

Project.toml

@@ -1,6 +1,6 @@
 name = "ArrayInterface"
 uuid = "4fba245c-0d91-5ea0-9b3e-6abc04ee57a9"
-version = "6.0.10"
+version = "6.0.11"
 
 [deps]
 ArrayInterfaceCore = "30b0a656-2188-435a-8636-2ec0e6a096e2"

src/axes.jl

@@ -103,7 +103,7 @@ axes(A::ReshapedArray) = Base.axes(A)
 axes(A::PermutedDimsArray) = permute(axes(parent(A)), to_parent_dims(A))
 axes(A::MatAdjTrans) = permute(axes(parent(A)), to_parent_dims(A))
 axes(A::VecAdjTrans) = (SOneTo{1}(), axes(parent(A), 1))
-axes(A::SubArray) = map(Base.axes1, permute(A.indices, to_parent_dims(A)))
+axes(A::SubArray{<:Any,N}) where {N} = map(Base.Fix1(axes, A), Static.nstatic(Val(N)))
 
 @inline axes(A, dim) = _axes(A, to_dims(A, dim))
 @inline function _axes(A, dim::Int)
@@ -120,19 +120,24 @@ end
         return getfield(axes(A), Int(dim))
     end
 end
-
+@inline function _inbound_axes(A::SubArray, dim)
+    pd = to_parent_dims(A, to_dims(A, dim))
+    ax = getindex(A.indices, pd)
+    ax isa Base.Slice || return axes(ax, 1)
+    axes(parent(A))[pd]
+end
 @inline function axes(A::SubArray, dim::CanonicalInt)
     if dim > ndims(A)
         return OneTo(1)
     else
-        return axes(getindex(A.indices, to_parent_dims(A, to_dims(A, dim))), 1)
+        return _inbound_axes(A, dim)
     end
 end
 @inline function axes(A::SubArray, ::StaticInt{dim}) where {dim}
     if dim > ndims(A)
         return SOneTo{1}()
     else
-        return axes(getindex(A.indices, to_parent_dims(A, to_dims(A, dim))), 1)
+        return _inbound_axes(A, StaticInt(dim))
     end
 end
 

test/axes.jl

@@ -71,7 +71,7 @@ end
 @testset "SubArray Adjoint Axis" begin
   N = 4; d = rand(N);
 
-  @test @inferred(ArrayInterface.axes_types(typeof(view(d',:,1:2)))) === Tuple{ArrayInterface.OptionallyStaticUnitRange{StaticInt{1}, StaticInt{1}}, Base.OneTo{Int64}}
+  @test @inferred(ArrayInterface.axes_types(typeof(view(d',:,1:2)))) === Tuple{ArrayInterface.OptionallyStaticUnitRange{StaticInt{1}, StaticInt{1}}, Base.OneTo{Int64}} === typeof(@inferred(ArrayInterface.axes(view(d',:,1:2)))) === typeof((ArrayInterface.axes(view(d',:,1:2),1),ArrayInterface.axes(view(d',:,1:2),2)))
 
 end
 if isdefined(Base, :ReshapedReinterpretArray)