fix: component array of empty namedtuple

upstreamed from Lux.jl. See LuxDL/Lux.jl#1359

Author: avik-pal

Project.toml

@@ -1,7 +1,7 @@
 name = "ComponentArrays"
 uuid = "b0b7db55-cfe3-40fc-9ded-d10e2dbeff66"
 authors = ["Jonnie Diegelman <[email protected]>"]
-version = "0.15.27"
+version = "0.15.28"
 
 [deps]
 Adapt = "79e6a3ab-5dfb-504d-930d-738a2a938a0e"

src/componentarray.jl

@@ -59,6 +59,13 @@ function ComponentArray(data, ax::AbstractAxis...)
     return LazyArray(ComponentArray(x, axs...) for x in part_data)
 end
 
+# This code-path is hit for empty NamedTuples. We force a Float32 eltype here if
+# length(data) == 0
+function ComponentArray(data::Vector{Any}, axes::Tuple{FlatAxis})
+    length(data) == 0 && return ComponentArray(Float32[], axes)
+    return ComponentArray{Any,1,typeof(data),typeof(axes)}(data, axes)
+end
+
 function Adapt.adapt_structure(to, x::ComponentArray)
     data = Adapt.adapt(to, getdata(x))
     return ComponentArray(data, getaxes(x))

test/runtests.jl

@@ -936,6 +936,10 @@ end
     @test_throws ArgumentError axpby!(2, x, 3, y)
 end
 
+@testset "Empty NamedTuple" begin
+    @test ComponentArray(NamedTuple()) isa ComponentVector{Float32}
+end
+
 @testset "Functors" begin
     for carray in (ca, ca_Float32, ca_MVector, ca_SVector, ca_composed, ca2, caa)
         θ, re = Functors.functor(carray)