Merge pull request #420 from jlchan/jc/fix_similar_VoA

fix `Base.similar` for `VectorOfArray` of `AbstractArray{<:StaticArray}`

Author: ChrisRackauckas

src/vector_of_array.jl

@@ -704,6 +704,12 @@ function Base.similar(vec::VectorOfArray{
     return VectorOfArray(similar.(Base.parent(vec)))
 end
 
+function Base.similar(vec::VectorOfArray{
+        T, N, AT}) where {T, N, AT <: AbstractArray{<:StaticArraysCore.StaticVecOrMat{T}}}
+    # this avoids behavior such as similar(SVector) returning an MVector
+    return VectorOfArray(similar(Base.parent(vec)))
+end
+
 @inline function Base.similar(VA::VectorOfArray, ::Type{T} = eltype(VA)) where {T}
     VectorOfArray(similar.(VA.u, T))
 end

test/copy_static_array_test.jl

@@ -120,4 +120,14 @@ x = StructArray{SVector{2, Float64}}((randn(2), randn(2)))
 vx = VectorOfArray(x)
 vx2 = copy(vx) .+ 1
 ans = vx .+ vx2
-@test ans.u isa StructArray
+@test ans.u isa StructArray
+
+# check that Base.similar(VectorOfArray{<:StaticArray}) returns the 
+# same type as the original VectorOfArray
+x_staticvector = [SVector(0.0, 0.0) for _ in 1:2]
+x_structarray = StructArray{SVector{2, Float64}}((randn(2), randn(2)))
+x_mutablefv = [MutableFV(1.0, 2.0)]
+x_immutablefv = [ImmutableFV(1.0, 2.0)]
+for vec in [x_staticvector, x_structarray, x_mutablefv, x_immutablefv]
+    @test typeof(similar(VectorOfArray(vec))) === typeof(VectorOfArray(vec))
+end