Stream: helpdesk (published)

Topic: StaticArrays.jl fails with ForwardDiff.jl

view this post on Zulip JΓΊlio Hoffimann (Apr 06 2026 at 11:01):

We are getting a strange error message with a custom static vector of Dual:

DimensionMismatch: No precise constructor for Vec{2, Quantity{T, 𝐋, Unitful.FreeUnits{(m,), 𝐋, nothing}} where T} found. Length of input was 2.
  Stacktrace:
    [1] _no_precise_size(SA::Type, x::Tuple{Quantity{ForwardDiff.Dual{ForwardDiff.Tag{Meshes.var"#f#376"{Box{𝔼{2}, Cartesian2D{NoDatum, Quantity{Float64, 𝐋, Unitful.FreeUnits{(m,), 𝐋, nothing}}}}, Tuple{Float64, Float64}, Int64, Int64}, Float64}, Float64, 1}, 𝐋, Unitful.FreeUnits{(m,), 𝐋, nothing}}, Quantity{Float64, 𝐋, Unitful.FreeUnits{(m,), 𝐋, nothing}}})
      @ StaticArrays ~/.julia/packages/StaticArrays/0cEwi/src/convert.jl:169
    [2] construct_type(::Type{Vec{2, Quantity{T, 𝐋, Unitful.FreeUnits{(m,), 𝐋, nothing}} where T}}, x::StaticArrays.Args{Tuple{Tuple{Tuple{Quantity{ForwardDiff.Dual{ForwardDiff.Tag{Meshes.var"#f#376"{Box{𝔼{2}, Cartesian2D{NoDatum, Quantity{Float64, 𝐋, Unitful.FreeUnits{(m,), 𝐋, nothing}}}}, Tuple{Float64, Float64}, Int64, Int64}, Float64}, Float64, 1}, 𝐋, Unitful.FreeUnits{(m,), 𝐋, nothing}}, Quantity{Float64, 𝐋, Unitful.FreeUnits{(m,), 𝐋, nothing}}}}}})
      @ StaticArrays ~/.julia/packages/StaticArrays/0cEwi/src/convert.jl:89
    [3] StaticArray (repeats 2 times)
      @ ~/.julia/packages/StaticArrays/0cEwi/src/convert.jl:173 [inlined]
    [4] _broadcast
      @ ~/.julia/packages/StaticArrays/0cEwi/src/broadcast.jl:120 [inlined]
    [5] copy
      @ ~/.julia/packages/StaticArrays/0cEwi/src/broadcast.jl:60 [inlined]
    [6] materialize
      @ ./broadcast.jl:894 [inlined]
    [7] (::Box{𝔼{2}, Cartesian2D{NoDatum, Quantity{Float64, 𝐋, Unitful.FreeUnits{(m,), 𝐋, nothing}}}})(::ForwardDiff.Dual{ForwardDiff.Tag{Meshes.var"#f#376"{Box{𝔼{2}, Cartesian2D{NoDatum, Quantity{Float64, 𝐋, Unitful.FreeUnits{(m,), 𝐋, nothing}}}}, Tuple{Float64, Float64}, Int64, Int64}, Float64}, Float64, 1}, ::Float64)
      @ Meshes ~/.julia/dev/Meshes/src/geometries/primitives/box.jl:63

If you pull the PR at https://github.com/JuliaGeometry/Meshes.jl/pull/1347, you can reproduce the error with the following code:

using Meshes

integral(p -> 1, Box((0, 0), (1, 1)))

It works fine if we run the example with 1D boxes (i.e., coordinate vectors of length 1):

integraintegral(p -> 1, Box((0,), (1,)))

So I am assuming the issue must be related to our custom Vec definition:

https://github.com/JuliaGeometry/Meshes.jl/blob/master/src/vectors.jl

Do we need to add a method for StaticArrays.construct_type?

Appreciate any help.

Last updated: Apr 21 2026 at 06:18 UTC