Bug: `recursivefill!` fails on `VectorOfArray` with mixed immutable and mutable StaticArrays

[pankaj-bind]

Description

The recursivefill! function fails with a setindex! error when used on a VectorOfArray that contains a mix of immutable and mutable StaticArray types (e.g., SVector and MVector).

The function attempts to fill all subarrays in-place. This works for mutable types like MVector, but it fails for immutable types like SVector, which cannot be modified after creation.

This appears to be a bug in the Base.fill! implementation for AbstractVectorOfArray in src/vector_of_array.jl, which does not check for immutability before attempting to modify the arrays.

@ChrisRackauckas

[JoshuaLampert]

I ran into a similar issue when calling recursivefill! on a VectorOfArray{Float64, 2, Vector{VectorOfArray{Float64, 1, Vector{Float64}}}}. An MWE is:

julia> u = VectorOfArray([VectorOfArray([1.0])])
VectorOfArray{Float64,2}:
1-element Vector{VectorOfArray{Float64, 1, Vector{Float64}}}:
 VectorOfArray{Float64, 1, Vector{Float64}}([1.0])

julia> recursivefill!(u, false)
ERROR: MethodError: Cannot `convert` an object of type Bool to an object of type VectorOfArray{Float64, 1, Vector{Float64}}
The function `convert` exists, but no method is defined for this combination of argument types.

Closest candidates are:
  (::Type{VectorOfArray{T, N, A}} where {T, N, A})(::Any)
   @ RecursiveArrayTools ~/.julia/packages/RecursiveArrayTools/MMSrL/src/vector_of_array.jl:40
  convert(::Type{T}, ::T) where T
   @ Base Base.jl:126

Stacktrace:
 [1] setindex!(A::Vector{VectorOfArray{Float64, 1, Vector{Float64}}}, x::Bool, i::Int64)
   @ Base ./array.jl:987
 [2] setindex!
   @ ~/.julia/packages/RecursiveArrayTools/MMSrL/src/vector_of_array.jl:523 [inlined]
 [3] fill!
   @ ~/.julia/packages/RecursiveArrayTools/MMSrL/src/vector_of_array.jl:831 [inlined]
 [4] recursivefill!(b::VectorOfArray{Float64, 2, Vector{VectorOfArray{Float64, 1, Vector{Float64}}}}, a::Bool)
   @ RecursiveArrayTools ~/.julia/packages/RecursiveArrayTools/MMSrL/src/utils.jl:141
 [5] top-level scope
   @ REPL[101]:1