`@static_unpack` does not seem to work as advertised

[mchitre]

Describe the bug 🐞

The example for @static_unpack in v0.15 release notes (see NEWS.md) fails.

Expected behavior

Straight from the NEWS.md:

julia> x = ComponentArray(a=5, b=[4, 1], c = [1 2; 3 4], d=(e=2, f=[6, 30.0]));

julia> @static_unpack a, b, c, d = x;

julia> a
5.0

julia> b
2-element SVector{2, Float64} with indices SOneTo(2):
 4.0
 1.0

julia> c
2×2 SMatrix{2, 2, Float64, 4} with indices SOneTo(2)×SOneTo(2):
 1.0  2.0
 3.0  4.0

julia> d
ComponentVector{Float64,SubArray...}(e = 2.0, f = [6.0, 30.0])

Minimal Reproducible Example 👇

This is what I get:

julia> x = ComponentArray(a=5, b=[4, 1], c = [1 2; 3 4], d=(e=2, f=[6, 30.0]));

julia> @static_unpack a, b, c, d = x;
ERROR: MethodError: no method matching (StaticArraysCore.SVector{2})(::SubArray{Float64, 1, Vector{Float64}, Tuple{UnitRange{Int64}}, true})
The type `StaticArraysCore.SVector{2}` exists, but no method is defined for this combination of argument types when trying to construct it.
Stacktrace:
 [1] _maybe_SArray(x::SubArray{Float64, 1, Vector{Float64}, Tuple{UnitRange{Int64}}, true}, ::Val{2}, ::FlatAxis)
   @ ComponentArrays ~/.julia/packages/ComponentArrays/7tm5j/src/compat/static_arrays.jl:5
 [2] macro expansion
   @ ./abstractarray.jl:0 [inlined]
 [3] static_getproperty(ca::ComponentVector{Float64, Vector{Float64}, Tuple{Axis{…}}}, ::Val{:b})
   @ ComponentArrays ~/.julia/packages/ComponentArrays/7tm5j/src/compat/static_arrays.jl:9
 [4] top-level scope
   @ REPL[50]:1
Some type information was truncated. Use `show(err)` to see complete types.

Environment (please complete the following information):

• Output of using Pkg; Pkg.status()

Status `/private/var/folders/hx/kbmkkbqd0rxbwlgymb6hfkmh0000gn/T/jl_4YHy5n/Project.toml`
  [b0b7db55] ComponentArrays v0.15.19
  [a0c0ee7d] DifferentiationInterface v0.6.27
  [f6369f11] ForwardDiff v0.10.38

• Output of using Pkg; Pkg.status(; mode = PKGMODE_MANIFEST)

Status `/private/var/folders/hx/kbmkkbqd0rxbwlgymb6hfkmh0000gn/T/jl_4YHy5n/Manifest.toml`
  [47edcb42] ADTypes v1.11.0
  [79e6a3ab] Adapt v4.1.1
  [4fba245c] ArrayInterface v7.17.1
  [d360d2e6] ChainRulesCore v1.25.0
  [bbf7d656] CommonSubexpressions v0.3.1
  [f70d9fcc] CommonWorldInvalidations v1.0.0
  [34da2185] Compat v4.16.0
  [b0b7db55] ComponentArrays v0.15.19
  [187b0558] ConstructionBase v1.5.8
  [163ba53b] DiffResults v1.1.0
  [b552c78f] DiffRules v1.15.1
  [a0c0ee7d] DifferentiationInterface v0.6.27
  [ffbed154] DocStringExtensions v0.9.3
  [f6369f11] ForwardDiff v0.10.38
  [d9f16b24] Functors v0.5.2
  [615f187c] IfElse v0.1.1
  [92d709cd] IrrationalConstants v0.2.2
  [692b3bcd] JLLWrappers v1.6.1
  [2ab3a3ac] LogExpFunctions v0.3.28
  [1914dd2f] MacroTools v0.5.13
  [77ba4419] NaNMath v1.0.2
  [aea7be01] PrecompileTools v1.2.1
  [21216c6a] Preferences v1.4.3
  [ae029012] Requires v1.3.0
  [276daf66] SpecialFunctions v2.4.0
  [aedffcd0] Static v1.1.1
  [0d7ed370] StaticArrayInterface v1.8.0
  [1e83bf80] StaticArraysCore v1.4.3
  [efe28fd5] OpenSpecFun_jll v0.5.5+0
  [0dad84c5] ArgTools v1.1.2
  [56f22d72] Artifacts v1.11.0
  [2a0f44e3] Base64 v1.11.0
  [ade2ca70] Dates v1.11.0
  [f43a241f] Downloads v1.6.0
  [7b1f6079] FileWatching v1.11.0
  [b27032c2] LibCURL v0.6.4
  [76f85450] LibGit2 v1.11.0
  [8f399da3] Libdl v1.11.0
  [37e2e46d] LinearAlgebra v1.11.0
  [56ddb016] Logging v1.11.0
  [d6f4376e] Markdown v1.11.0
  [ca575930] NetworkOptions v1.2.0
  [44cfe95a] Pkg v1.11.0
  [de0858da] Printf v1.11.0
  [9a3f8284] Random v1.11.0
  [ea8e919c] SHA v0.7.0
  [fa267f1f] TOML v1.0.3
  [a4e569a6] Tar v1.10.0
  [cf7118a7] UUIDs v1.11.0
  [4ec0a83e] Unicode v1.11.0
  [e66e0078] CompilerSupportLibraries_jll v1.1.1+0
  [deac9b47] LibCURL_jll v8.6.0+0
  [e37daf67] LibGit2_jll v1.7.2+0
  [29816b5a] LibSSH2_jll v1.11.0+1
  [c8ffd9c3] MbedTLS_jll v2.28.6+0
  [14a3606d] MozillaCACerts_jll v2023.12.12
  [4536629a] OpenBLAS_jll v0.3.27+1
  [05823500] OpenLibm_jll v0.8.1+2
  [83775a58] Zlib_jll v1.2.13+1
  [8e850b90] libblastrampoline_jll v5.11.0+0
  [8e850ede] nghttp2_jll v1.59.0+0
  [3f19e933] p7zip_jll v17.4.0+2

• Output of versioninfo()

Julia Version 1.11.2
Commit 5e9a32e7af2 (2024-12-01 20:02 UTC)
Build Info:
  Official https://julialang.org/ release
Platform Info:
  OS: macOS (arm64-apple-darwin24.0.0)
  CPU: 10 × Apple M1 Pro
  WORD_SIZE: 64
  LLVM: libLLVM-16.0.6 (ORCJIT, apple-m1)
Threads: 1 default, 0 interactive, 1 GC (on 8 virtual cores)

[xlxs4]

Hi @mchitre, does the issue persist if you also do using StaticArrays before the @static_unpack call? i.e.,

julia> using ComponentArrays, StaticArrays

julia> x = ComponentVector(a=5, b=[4, 1], c = [1 2; 3 4], d=(e=2, f=[6, 30.0]));

julia> @static_unpack a, b, c, d = x;

julia> a
5.0

[mchitre]

Just tested. using StaticArrays indeed fixes the problem.

It is, however, not clear from the NEWS.md that importing StaticArrays explicitly is needed.

[xlxs4]

The docs in https://docs.sciml.ai/ComponentArrays/stable/static_unpack/ could be updated to be more explicit. For the specific example, ComponentArrays uses the StaticArraysCore package for the SArray definition. However, StaticArraysCore doesn't provide a constructor of that form, and that's what the error is about. The example does work if you bring StaticArrays over, since it defines additional constructors (for this specific example, you'd be looking at https://github.com/JuliaArrays/StaticArrays.jl/blob/15a2672708870702831eab815edc6d191f5d489c/src/SArray.jl#L198)