Allow empty indexing of zero-dimensional MArrays

src/Scalar.jl

@@ -14,7 +14,6 @@ const Scalar{T} = SArray{Tuple{},T,0,1}
 end
 @inline convert(::Type{SA}, sa::SA) where {SA <: Scalar} = sa
 
-getindex(v::Scalar) = v.data[1]
 @propagate_inbounds function getindex(v::Scalar, i::Int)
     @boundscheck if i != 1
         error("Attempt to index Scalar at index $i")

src/indexing.jl

@@ -14,6 +14,13 @@ setindex!(a::StaticArray, value, i::Int) = error("setindex!(::$(typeof(a)), valu
 end
 
 @generated function _getindex_scalar(::Size{S}, a::StaticArray, inds::Int...) where S
+    if length(inds) == 0
+        return quote
+            @_propagate_inbounds_meta
+            a[1]
+        end
+    end
+
     stride = 1
     ind_expr = :()
     for i ∈ 1:length(inds)
@@ -36,6 +43,13 @@ end
 end
 
 @generated function _setindex!_scalar(::Size{S}, a::StaticArray, value, inds::Int...) where S
+    if length(inds) == 0
+        return quote
+            @_propagate_inbounds_meta
+            a[1] = value
+        end
+    end
+
     stride = 1
     ind_expr = :()
     for i ∈ 1:length(inds)

test/MArray.jl

@@ -157,4 +157,11 @@
         @test @inferred(promote_type(MMatrix{2,3,Float32,6}, MMatrix{2,3,Complex{Float64},6})) === MMatrix{2,3,Complex{Float64},6}
         @test @inferred(promote_type(MArray{Tuple{2, 2, 2, 2},Float32, 4, 16}, MArray{Tuple{2, 2, 2, 2}, Complex{Float64}, 4, 16})) === MArray{Tuple{2, 2, 2, 2}, Complex{Float64}, 4, 16}
     end
+
+    @testset "zero-dimensional" begin
+        v = MArray{Tuple{}, Int, 0, 1}(1)
+        @test v[] == 1
+        v[] = 2
+        @test v[] == 2
+    end
 end