Exception when getting the index on the CPU backend

[JamesWrigley]

When running this slightly minified code from the quickstart guide:

import KernelAbstractions as KA

KA.@kernel function mul2_kernel(A)
    I = KA.@index(Global, Linear)
end
    
dev = KA.CPU()
A = ones(1024, 1024)
ev = mul2_kernel(dev, 64)(A, ndrange=size(A))
KA.synchronize(dev)
all(A .== 2.0)

I get this exception (only on the CPU backend, the CUDA backend works):

TaskFailedException

    nested task error: MethodError: no method matching __index_Global_Linear(::KernelAbstractions.CompilerMetadata{KernelAbstractions.NDIteration.DynamicSize, KernelAbstractions.NDIteration.NoDynamicCheck, CartesianIndex{2}, CartesianIndices{2, Tuple{Base.OneTo{Int64}, Base.OneTo{Int64}}}, KernelAbstractions.NDIteration.NDRange{2, KernelAbstractions.NDIteration.DynamicSize, KernelAbstractions.NDIteration.StaticSize{(64, 1)}, CartesianIndices{2, Tuple{Base.OneTo{Int64}, Base.OneTo{Int64}}}, Nothing}})
    The function `__index_Global_Linear` exists, but no method is defined for this combination of argument types.
    
    Closest candidates are:
      __index_Global_Linear(::Any, ::CartesianIndex)
       @ KernelAbstractions ~/.julia/packages/KernelAbstractions/491pi/src/cpu.jl:163
    
    Stacktrace:
     [1] macro expansion
       @ ./In[85]:3 [inlined]
     [2] cpu_mul2_kernel
       @ ~/.julia/packages/KernelAbstractions/491pi/src/macros.jl:291 [inlined]
     [3] (::var"#cpu_mul2_kernel#9")(__ctx__::KernelAbstractions.CompilerMetadata{KernelAbstractions.NDIteration.DynamicSize, KernelAbstractions.NDIteration.NoDynamicCheck, CartesianIndex{2}, CartesianIndices{2, Tuple{Base.OneTo{Int64}, Base.OneTo{Int64}}}, KernelAbstractions.NDIteration.NDRange{2, KernelAbstractions.NDIteration.DynamicSize, KernelAbstractions.NDIteration.StaticSize{(64, 1)}, CartesianIndices{2, Tuple{Base.OneTo{Int64}, Base.OneTo{Int64}}}, Nothing}}, A::Matrix{Float64})
       @ Main ./none:0
     [4] __thread_run(tid::Int64, len::Int64, rem::Int64, obj::KernelAbstractions.Kernel{CPU, KernelAbstractions.NDIteration.StaticSize{(64,)}, KernelAbstractions.NDIteration.DynamicSize, var"#cpu_mul2_kernel#9"}, ndrange::Tuple{Int64, Int64}, iterspace::KernelAbstractions.NDIteration.NDRange{2, KernelAbstractions.NDIteration.DynamicSize, KernelAbstractions.NDIteration.StaticSize{(64, 1)}, CartesianIndices{2, Tuple{Base.OneTo{Int64}, Base.OneTo{Int64}}}, Nothing}, args::Tuple{Matrix{Float64}}, dynamic::KernelAbstractions.NDIteration.NoDynamicCheck)
       @ KernelAbstractions ~/.julia/packages/KernelAbstractions/491pi/src/cpu.jl:144
     [5] (::KernelAbstractions.var"#20#23"{KernelAbstractions.Kernel{CPU, KernelAbstractions.NDIteration.StaticSize{(64,)}, KernelAbstractions.NDIteration.DynamicSize, var"#cpu_mul2_kernel#9"}, Tuple{Int64, Int64}, KernelAbstractions.NDIteration.NDRange{2, KernelAbstractions.NDIteration.DynamicSize, KernelAbstractions.NDIteration.StaticSize{(64, 1)}, CartesianIndices{2, Tuple{Base.OneTo{Int64}, Base.OneTo{Int64}}}, Nothing}, Tuple{Matrix{Float64}}, KernelAbstractions.NDIteration.NoDynamicCheck, Int64})()
       @ KernelAbstractions ~/.julia/packages/KernelAbstractions/491pi/src/cpu.jl:119

...and 39 more exceptions.


Stacktrace:
 [1] sync_end(c::Channel{Any})
   @ Base ./task.jl:466
 [2] macro expansion
   @ ./task.jl:499 [inlined]
 [3] __run(obj::KernelAbstractions.Kernel{CPU, KernelAbstractions.NDIteration.StaticSize{(64,)}, KernelAbstractions.NDIteration.DynamicSize, var"#cpu_mul2_kernel#9"}, ndrange::Tuple{Int64, Int64}, iterspace::KernelAbstractions.NDIteration.NDRange{2, KernelAbstractions.NDIteration.DynamicSize, KernelAbstractions.NDIteration.StaticSize{(64, 1)}, CartesianIndices{2, Tuple{Base.OneTo{Int64}, Base.OneTo{Int64}}}, Nothing}, args::Tuple{Matrix{Float64}}, dynamic::KernelAbstractions.NDIteration.NoDynamicCheck, static_threads::Bool)
   @ KernelAbstractions ~/.julia/packages/KernelAbstractions/491pi/src/cpu.jl:118
 [4] (::KernelAbstractions.Kernel{CPU, KernelAbstractions.NDIteration.StaticSize{(64,)}, KernelAbstractions.NDIteration.DynamicSize, var"#cpu_mul2_kernel#9"})(args::Matrix{Float64}; ndrange::Tuple{Int64, Int64}, workgroupsize::Nothing)
   @ KernelAbstractions ~/.julia/packages/KernelAbstractions/491pi/src/cpu.jl:46
 [5] top-level scope
   @ In[85]:9

These are the versions I'm running it with:

% julia --project
               _
   _       _ _(_)_     |  Documentation: https://docs.julialang.org
  (_)     | (_) (_)    |
   _ _   _| |_  __ _   |  Type "?" for help, "]?" for Pkg help.
  | | | | | | |/ _` |  |
  | | |_| | | | (_| |  |  Version 1.11.1 (2024-10-16)
 _/ |\__'_|_|_|\__'_|  |  Official https://julialang.org/ release
|__/                   |

(james) pkg> st
Status `Project.toml`
  [824d6782] Bonito v3.2.2
  [052768ef] CUDA v5.5.2
  [f68482b8] Cthulhu v2.15.2
  [8bb1440f] DelimitedFiles v1.9.1
  [7a1cc6ca] FFTW v1.8.0
  [63c18a36] KernelAbstractions v0.9.28
  [2fda8390] LsqFit v0.15.0
  [67456a42] OhMyThreads v0.7.0
  [6099a3de] PythonCall v0.9.23
  [276b4fcb] WGLMakie v0.10.14