Cannot use ObjectiveC on Julia 1.12-nightly

[eschnett]

Using ObjectiveC (which is required by Metal) leads to this error:

 $ julia +1.12-nightly
               _
   _       _ _(_)_     |  Documentation: https://docs.julialang.org
  (_)     | (_) (_)    |
   _ _   _| |_  __ _   |  Type "?" for help, "]?" for Pkg help.
  | | | | | | |/ _` |  |
  | | |_| | | | (_| |  |  Version 1.12.0-DEV.1976 (2025-02-04)
 _/ |\__'_|_|_|\__'_|  |  Commit 0c1e800dbdc (8 days old master)
|__/                   |

(@v1.12) pkg> add ObjectiveC
   Resolving package versions...
    Updating `~/.julia/environments/v1.12/Project.toml`
  [e86c9b32] + ObjectiveC v3.4.0
    Updating `~/.julia/environments/v1.12/Manifest.toml`
  [fa961155] + CEnum v0.5.0
  [e86c9b32] + ObjectiveC v3.4.0
  [21216c6a] + Preferences v1.4.3
  [ade2ca70] + Dates v1.11.0
  [8f399da3] + Libdl v1.11.0
  [de0858da] + Printf v1.11.0
  [fa267f1f] + TOML v1.0.3
  [4ec0a83e] + Unicode v1.11.0
  ✗ ObjectiveC
Precompiling packages finished.
  0 dependencies successfully precompiled in 2 seconds. 6 already precompiled.
  1 dependency errored.
  For a report of the errors see `julia> err`. To retry use `pkg> precompile`

julia> err
PkgPrecompileError: The following 1 direct dependency failed to precompile:

ObjectiveC

Failed to precompile ObjectiveC [e86c9b32-1129-44ac-8ea0-90d5bb39ded9] to "/Users/eschnett/.julia/compiled/v1.12/ObjectiveC/jl_7BI05u".
ERROR: LoadError: MethodError: no method matching is_unavailable(::OncePerProcess{VersionNumber, ObjectiveC.var"#17#18"}, ::ObjectiveC.PlatformAvailability{:macos})
The function `is_unavailable` exists, but no method is defined for this combination of argument types.

Closest candidates are:
  is_unavailable(::Function, ::ObjectiveC.PlatformAvailability)
   @ ObjectiveC ~/.julia/packages/ObjectiveC/FimnA/src/availability.jl:32
  is_unavailable(::ObjectiveC.PlatformAvailability{:darwin})
   @ ObjectiveC ~/.julia/packages/ObjectiveC/FimnA/src/availability.jl:75
  is_unavailable(::ObjectiveC.PlatformAvailability{:macos})
   @ ObjectiveC ~/.julia/packages/ObjectiveC/FimnA/src/availability.jl:75
  ...

Stacktrace:
  [1] is_unavailable(avail::ObjectiveC.PlatformAvailability{:macos})
    @ ObjectiveC ~/.julia/packages/ObjectiveC/FimnA/src/availability.jl:75
  [2] top-level scope
    @ none:1
  [3] eval(m::Module, e::Any)
    @ Core ./boot.jl:486
  [4] var"@static"(__source__::LineNumberNode, __module__::Module, ex::Any)
    @ Base ./osutils.jl:29
  [5] include(mapexpr::Function, mod::Module, _path::String)
    @ Base ./Base.jl:308
  [6] top-level scope
    @ ~/.julia/packages/ObjectiveC/FimnA/src/ObjectiveC.jl:41
  [7] include(mod::Module, _path::String)
    @ Base ./Base.jl:307
  [8] include_package_for_output(pkg::Base.PkgId, input::String, depot_path::Vector{String}, dl_load_path::Vector{String}, load_path::Vector{String}, concrete_deps::Vector{Pair{Base.PkgId, UInt128}}, source::Nothing)
    @ Base ./loading.jl:3004
  [9] top-level scope
    @ stdin:6
 [10] eval(m::Module, e::Any)
    @ Core ./boot.jl:486
 [11] include_string(mapexpr::typeof(identity), mod::Module, code::String, filename::String)
    @ Base ./loading.jl:2855
 [12] include_string
    @ ./loading.jl:2865 [inlined]
 [13] exec_options(opts::Base.JLOptions)
    @ Base ./client.jl:327
 [14] _start()
    @ Base ./client.jl:557
in expression starting at /Users/eschnett/.julia/packages/ObjectiveC/FimnA/src/syntax.jl:355
in expression starting at /Users/eschnett/.julia/packages/ObjectiveC/FimnA/src/foundation.jl:1
in expression starting at /Users/eschnett/.julia/packages/ObjectiveC/FimnA/src/ObjectiveC.jl:1
in expression starting at stdin:

[eschnett]

ObjectiveC @3.3.0 is working for me.

[maleadt]

cc @christiangnrd

[christiangnrd]

This is fixed by JuliaLang/julia#57289 and should be resolved if you update to the latest nightly.

@maleadt Maybe I should remove the ::Function type parameter? Jameson did mention it being an anti-pattern in Julia.

[eschnett]

I can't use nightly because GPUCompiler overloads MethodError, and that isn't supported there... but that's a different issue.

[christiangnrd]

This should be fixed soonish, but if you want to fix it quickly, devving ObjectiveC and removing the ::Function type parameter here and here. However, if you're trying to run Metal, you won't be able to use custom kernels since we don't yet support LLVM 18.

[maleadt]

Maybe I should remove the ::Function type parameter?

Yeah, that's probably best. I guess it's kind of a anti-pattern because every type can be callable without being a subtype of Function (I rather use Base.Callable when needed for disambiguation purposes).

[christiangnrd]

#57