Broadcast of concreterarray requires scalar indexing

[wsmoses]

julia> x = Reactant.to_rarray(ones(10))
2025-03-13 22:42:56.375804: I external/xla/xla/service/service.cc:152] XLA service 0xc4a4510 initialized for platform CUDA (this does not guarantee that XLA will be used). Devices:
2025-03-13 22:42:56.375897: I external/xla/xla/service/service.cc:160]   StreamExecutor device (0): NVIDIA GeForce RTX 3090, Compute Capability 8.6
WARNING: All log messages before absl::InitializeLog() is called are written to STDERR
I0000 00:00:1741920176.377112   56835 se_gpu_pjrt_client.cc:951] Using BFC allocator.
I0000 00:00:1741920176.377291   56835 gpu_helpers.cc:136] XLA backend allocating 18988744704 bytes on device 0 for BFCAllocator.
I0000 00:00:1741920176.377471   56835 gpu_helpers.cc:177] XLA backend will use up to 6329581568 bytes on device 0 for CollectiveBFCAllocator.
I0000 00:00:1741920176.396166   56835 cuda_dnn.cc:529] Loaded cuDNN version 90400
10-element ConcretePJRTArray{Float64,1}:
 1.0
 1.0
 1.0
 1.0
 1.0
 1.0
 1.0
 1.0
 1.0
 1.0

julia> y = Reactant.to_rarray(ones(10))
10-element ConcretePJRTArray{Float64,1}:
 1.0
 1.0
 1.0
 1.0
 1.0
 1.0
 1.0
 1.0
 1.0
 1.0

julia> x .= y ./ 2
ERROR: Scalar indexing is disallowed.
Invocation of getindex(::ConcretePJRTArray, ::Vararg{Int, N}) resulted in scalar indexing of a GPU array.
This is typically caused by calling an iterating implementation of a method.
Such implementations *do not* execute on the GPU, but very slowly on the CPU,
and therefore should be avoided.

If you want to allow scalar iteration, use `allowscalar` or `@allowscalar`
to enable scalar iteration globally or for the operations in question.
Stacktrace:
  [1] error(s::String)
    @ Base ./error.jl:35
  [2] errorscalar(op::String)
    @ GPUArraysCore ~/.julia/packages/GPUArraysCore/aNaXo/src/GPUArraysCore.jl:151
  [3] _assertscalar(op::String, behavior::GPUArraysCore.ScalarIndexing)
    @ GPUArraysCore ~/.julia/packages/GPUArraysCore/aNaXo/src/GPUArraysCore.jl:124
  [4] assertscalar(op::String)
    @ GPUArraysCore ~/.julia/packages/GPUArraysCore/aNaXo/src/GPUArraysCore.jl:112
  [5] getindex(a::ConcretePJRTArray{Float64, 1, 1, Reactant.Sharding.ShardInfo{Reactant.Sharding.NoSharding, Nothing}}, args::Int64)
    @ Reactant ~/git/Reactant.jl/src/ConcreteRArray.jl:245
  [6] _broadcast_getindex
    @ ./broadcast.jl:675 [inlined]
  [7] _getindex
    @ ./broadcast.jl:705 [inlined]
  [8] _broadcast_getindex
    @ ./broadcast.jl:681 [inlined]
  [9] getindex
    @ ./broadcast.jl:636 [inlined]
 [10] macro expansion
    @ ./broadcast.jl:1004 [inlined]
 [11] macro expansion
    @ ./simdloop.jl:77 [inlined]
 [12] copyto!
    @ ./broadcast.jl:1003 [inlined]
 [13] copyto!
    @ ./broadcast.jl:956 [inlined]
 [14] materialize!
    @ ./broadcast.jl:914 [inlined]
 [15] materialize!(dest::ConcretePJRTArray{Float64, 1, 1, Reactant.Sharding.ShardInfo{…}}, bc::Base.Broadcast.Broadcasted{Base.Broadcast.ArrayStyle{…}, Nothing, typeof(/), Tuple{…}})
    @ Base.Broadcast ./broadcast.jl:911
 [16] top-level scope
    @ REPL[5]:1
Some type information was truncated. Use `show(err)` to see complete types.