add CartesianIndex() for Ref getindex and setindex! (#32653)

* add CartesianIndex() for Ref getindex and setindex!

* fix typo

* add NEWS.md entry

* move definitions later in the load sequence

Author: mbauman

NEWS.md

@@ -32,6 +32,7 @@ New library functions
   to search for that character in a string passed as the second argument ([#31664]).
 * New `findall(pattern, string)` method where `pattern` is a string or regex ([#31834]).
 * `istaskfailed` is now documented and exported, like its siblings `istaskdone` and `istaskstarted` ([#32300]).
+* `RefArray` and `RefValue` objects now accept index `CartesianIndex()` in  `getindex` and `setindex!` ([#32653])
 
 Standard library changes
 ------------------------

base/multidimensional.jl

@@ -1743,3 +1743,6 @@ function _sortslices(A::AbstractArray, d::Val{dims}; kws...) where dims
         B
     end
 end
+
+getindex(b::Ref, ::CartesianIndex{0}) = getindex(b)
+setindex!(b::Ref, x, ::CartesianIndex{0}) = setindex!(b, x)

test/abstractarray.jl

@@ -987,3 +987,11 @@ end
     @test_throws DimensionMismatch promote_shape(Dims((2, 2)), Dims((2,)))
     @test_throws DimensionMismatch promote_shape(Dims((2, 3, 1)), Dims((2,2)))
 end
+
+@testset "getindex and setindex! for Ref" begin
+    for x in [Ref(1), Ref([1,2,3], 1)]
+        @test getindex(x) == getindex(x, CartesianIndex()) == 1
+        x[CartesianIndex()] = 10
+        @test getindex(x) == getindex(x, CartesianIndex()) == 10
+    end
+end