fix: rework broadcasting copyto!

Author: AayushSabharwal

src/vector_of_array.jl

@@ -658,40 +658,49 @@ Broadcast.broadcastable(x::AbstractVectorOfArray) = x
     end)
 end
 
-@inline function Base.copyto!(dest::AbstractVectorOfArray,
-    bc::Broadcast.Broadcasted{<:VectorOfArrayStyle})
-    bc = Broadcast.flatten(bc)
-    N = narrays(bc)
-    @inbounds for i in 1:N
-        if dest[:, i] isa AbstractArray && ArrayInterface.ismutable(dest[:, i])
-            copyto!(dest[:, i], unpack_voa(bc, i))
-        else
-            unpacked = unpack_voa(bc, i)
-            dest[:, i] = unpacked.f(unpacked.args...)
-        end
-    end
-    dest
-end
-
-@inline function Base.copyto!(dest::AbstractVectorOfArray,
-    bc::Broadcast.Broadcasted{<:Broadcast.DefaultArrayStyle})
-    bc = Broadcast.flatten(bc)
-    @inbounds for i in 1:length(dest.u)
-        if dest[:, i] isa AbstractArray && ArrayInterface.ismutable(dest[:, i])
-            copyto!(dest[:, i], unpack_voa(bc, i))
-        else
-            unpacked = unpack_voa(bc, i)
-            value = unpacked.f(unpacked.args...)
-            dest[:, i] = if value isa Number && dest[:, i] isa AbstractArray
-                fill(value, StaticArraysCore.similar_type(dest[:, i]))
+for (type, N_expr) in [
+        (Broadcast.Broadcasted{<:VectorOfArrayStyle}, :(narrays(bc))),
+        (Broadcast.Broadcasted{<:Broadcast.DefaultArrayStyle}, :(length(dest.u)))
+    ]
+    @eval @inline function Base.copyto!(dest::AbstractVectorOfArray,
+        bc::$type)
+        bc = Broadcast.flatten(bc)
+        N = $N_expr
+        @inbounds for i in 1:N
+            if dest[:, i] isa AbstractArray
+                if ArrayInterface.ismutable(dest[:, i])
+                    copyto!(dest[:, i], unpack_voa(bc, i))
+                else
+                    unpacked = unpack_voa(bc, i)
+                    arr_type = StaticArraysCore.similar_type(dest[:, i])
+                    dest[:, i] = if length(unpacked) == 1
+                        fill(copy(unpacked), arr_type)
+                    else
+                        arr_type(unpacked[j] for j in eachindex(unpacked))
+                    end
+                end
             else
-                value
+                dest[:, i] = copy(unpack_voa(bc, i))
             end
         end
+        dest
     end
-    dest
 end
 
+# @inline function Base.copyto!(dest::AbstractVectorOfArray,
+#     bc::Broadcast.Broadcasted{<:Broadcast.DefaultArrayStyle})
+#     bc = Broadcast.flatten(bc)
+#     @inbounds for i in 1:length(dest.u)
+#         if dest[:, i] isa AbstractArray && ArrayInterface.ismutable(dest[:, i])
+#             copyto!(dest[:, i], unpack_voa(bc, i))
+#         else
+#             unpacked = unpack_voa(bc, i)
+#             dest[:, i] = StaticArraysCore.similar_type(dest[:, i])(unpacked[j] for j in eachindex(unpacked))
+#         end
+#     end
+#     dest
+# end
+
 ## broadcasting utils
 
 """