Add _unsetindex! methods for SubArrays and CartesianIndexes

base/abstractarray.jl

@@ -1472,7 +1472,10 @@ function _setindex!(::IndexCartesian, A::AbstractArray, v, I::Vararg{Int,M}) whe
     r
 end
 
-_unsetindex!(A::AbstractArray, i::Integer) = _unsetindex!(A, to_index(i))
+function _unsetindex!(A::AbstractArray, i::Integer...)
+    @_propagate_inbounds_meta
+    _unsetindex!(A, map(to_index, i)...)
+end
 
 """
     parent(A)

base/array.jl

@@ -219,7 +219,12 @@ function _unsetindex!(A::Array, i::Int)
     @inbounds _unsetindex!(GenericMemoryRef(A.ref, i))
     return A
 end
-
+function _unsetindex!(A::Array, i::Int...)
+    @inline
+    @boundscheck checkbounds(A, i...)
+    @inbounds _unsetindex!(A, _to_linear_index(A, i...))
+    return A
+end
 
 # TODO: deprecate this (aligned_sizeof and/or elsize and/or sizeof(Some{T}) are more correct)
 elsize(::Type{A}) where {T,A<:Array{T}} = aligned_sizeof(T)

base/multidimensional.jl

@@ -1610,6 +1610,12 @@ end
     end
 end
 
+# _unsetindex
+@propagate_inbounds function Base._unsetindex!(A::AbstractArray, i::CartesianIndex)
+    Base._unsetindex!(A, to_indices(A, (i,))...)
+    return A
+end
+
 ## permutedims
 
 ## Permute array dims ##

base/subarray.jl

@@ -410,6 +410,25 @@ function isassigned(V::FastSubArray{<:Any, 1}, i::Int)
     r
 end
 
+function _unsetindex!(V::FastSubArray, i::Int)
+    @inline
+    @boundscheck checkbounds(Bool, V, i)
+    @inbounds _unsetindex!(V.parent, _reindexlinear(V, i))
+    return V
+end
+function _unsetindex!(V::FastSubArray{<:Any,1}, i::Int)
+    @inline
+    @boundscheck checkbounds(Bool, V, i)
+    @inbounds _unsetindex!(V.parent, _reindexlinear(V, i))
+    return V
+end
+function _unsetindex!(V::SubArray{T,N}, i::Vararg{Int,N}) where {T,N}
+    @inline
+    @boundscheck checkbounds(Bool, V, i...)
+    @inbounds _unsetindex!(V.parent, reindex(V.indices, i)...)
+    return V
+end
+
 IndexStyle(::Type{<:FastSubArray}) = IndexLinear()
 IndexStyle(::Type{<:SubArray}) = IndexCartesian()
 

test/subarray.jl

@@ -1055,4 +1055,46 @@ end
         @test !isassigned(v, 1, 2) # inbounds but not assigned
         @test !isassigned(v, 3, 3) # out-of-bounds
     end
+
+    @testset "_unsetindex!" begin
+        function test_unsetindex(A, B)
+            copyto!(A, B)
+            for i in eachindex(A)
+                @test !isassigned(A, i)
+            end
+        end
+        @testset "dest IndexLinear, src IndexLinear" begin
+            for p in (fill(BigInt(2)), BigInt[1, 2], BigInt[1 2; 3 4])
+                A = view(copy(p), ntuple(_->:, ndims(p))...)
+                B = view(similar(A), ntuple(_->:, ndims(p))...)
+                test_unsetindex(A, B)
+                test_unsetindex(p, B)
+            end
+        end
+
+        @testset "dest IndexLinear, src IndexCartesian" begin
+            for p in (fill(BigInt(2)), BigInt[1, 2], BigInt[1 2; 3 4])
+                A = view(copy(p), ntuple(_->:, ndims(p))...)
+                B = view(similar(A), axes(A)...)
+                test_unsetindex(A, B)
+                test_unsetindex(p, B)
+            end
+        end
+
+        @testset "dest IndexCartesian, src IndexLinear" begin
+            for p in (fill(BigInt(2)), BigInt[1, 2], BigInt[1 2; 3 4])
+                A = view(p, axes(p)...)
+                B = similar(A)
+                test_unsetindex(A, B)
+            end
+        end
+
+        @testset "dest IndexCartesian, src IndexCartesian" begin
+            for p in (fill(BigInt(2)), BigInt[1, 2], BigInt[1 2; 3 4])
+                A = view(p, axes(p)...)
+                B = view(similar(A), axes(A)...)
+                test_unsetindex(A, B)
+            end
+        end
+    end
 end