Simple hello world example fails with JuliaC using --experimental --trim

[cmhamel]

I've been playing around with JuliaC and thought I would give a simple MPI.jl example a go. This is a simple adaptation of this Hello, World! example

using MPI

function @main(ARGS)
    MPI.Init()
    comm = MPI.COMM_WORLD
    print(Core.stdout, "Hello world, I am rank $(MPI.Comm_rank(comm)) of $(MPI.Comm_size(comm))\n")
    return 0
end

Without --experimental --trim=safe everything works as expected with a binary size of around 300MB.

However, with --experimental --trim=safe we get the following errors

Compiling...Verifier error #1: unresolved call from statement (Base.memoryrefget(Base.memoryrefnew(Base.getfield(MPI.mpi_init_hooks, :ref)::MemoryRef{Any}, 1, false::Bool)::MemoryRef{Any}, :not_atomic, false::Bool)::Any)()::Any
Stacktrace:
 [1] run_init_hooks()
   @ MPI ~/.julia/packages/MPI/hNJm0/src/environment.jl:66
 [2] Init(; threadlevel::Symbol, finalize_atexit::Bool, errors_return::Bool)
   @ MPI ~/.julia/packages/MPI/hNJm0/src/environment.jl:155
 [3] Init()
   @ MPI ~/.julia/packages/MPI/hNJm0/src/environment.jl:114 [inlined]
 [4] main(ARGS::Vector{String})
   @ Main ~/Cthonios/ParaTaxi/examples/src/HelloWorld.jl:4
 [5] _main(argc::Int32, argv::Ptr{Ptr{Int8}})
   @ Main ~/.julia/packages/JuliaC/EFQEY/src/scripts/juliac-buildscript.jl:77

Verifier error #2: unresolved call from statement (f::typeof(MPI.call))(φ ()::Any)::Any
Stacktrace:
 [1] foreach(f::typeof(MPI.call), itr::Vector{Any})
   @ Base abstractarray.jl:3188
 [2] run_load_time_hooks()
   @ MPI ~/.julia/packages/MPI/hNJm0/src/MPI.jl:74
 [3] __init__()
   @ MPI ~/.julia/packages/MPI/hNJm0/src/MPI.jl:174

Verifier error #3: unresolved call from statement (%new()::MPI.var"#copy#copy##0"{MPI.OpWrapper{typeof(xor), Any}, Ptr{Nothing}, Ptr{Nothing}, Int32})(MPI.to_type(%new()::MPI.Datatype)::Any)::Any
Stacktrace:
 [1] (::MPI.OpWrapper{typeof(xor), Any})(_a::Ptr{Nothing}, _b::Ptr{Nothing}, _len::Ptr{Int32}, t::Ptr{Int32})
   @ MPI ~/.julia/packages/MPI/hNJm0/src/operators.jl:98

Verifier error #4: unresolved call from statement (%new()::MPI.var"#copy#copy##0"{MPI.OpWrapper{typeof(|), Any}, Ptr{Nothing}, Ptr{Nothing}, Int32})(MPI.to_type(%new()::MPI.Datatype)::Any)::Any
Stacktrace:
 [1] (::MPI.OpWrapper{typeof(|), Any})(_a::Ptr{Nothing}, _b::Ptr{Nothing}, _len::Ptr{Int32}, t::Ptr{Int32})
   @ MPI ~/.julia/packages/MPI/hNJm0/src/operators.jl:98

Verifier error #5: unresolved call from statement (%new()::MPI.var"#copy#copy##0"{MPI.OpWrapper{typeof(&), Any}, Ptr{Nothing}, Ptr{Nothing}, Int32})(MPI.to_type(%new()::MPI.Datatype)::Any)::Any
Stacktrace:
 [1] (::MPI.OpWrapper{typeof(&), Any})(_a::Ptr{Nothing}, _b::Ptr{Nothing}, _len::Ptr{Int32}, t::Ptr{Int32})
   @ MPI ~/.julia/packages/MPI/hNJm0/src/operators.jl:98

Verifier error #6: unresolved call from statement (%new()::MPI.var"#copy#copy##0"{MPI.OpWrapper{typeof(*), Any}, Ptr{Nothing}, Ptr{Nothing}, Int32})(MPI.to_type(%new()::MPI.Datatype)::Any)::Any
Stacktrace:
 [1] (::MPI.OpWrapper{typeof(*), Any})(_a::Ptr{Nothing}, _b::Ptr{Nothing}, _len::Ptr{Int32}, t::Ptr{Int32})
   @ MPI ~/.julia/packages/MPI/hNJm0/src/operators.jl:98

Verifier error #7: unresolved call from statement (%new()::MPI.var"#copy#copy##0"{MPI.OpWrapper{typeof(+), Any}, Ptr{Nothing}, Ptr{Nothing}, Int32})(MPI.to_type(%new()::MPI.Datatype)::Any)::Any
Stacktrace:
 [1] (::MPI.OpWrapper{typeof(+), Any})(_a::Ptr{Nothing}, _b::Ptr{Nothing}, _len::Ptr{Int32}, t::Ptr{Int32})
   @ MPI ~/.julia/packages/MPI/hNJm0/src/operators.jl:98

Verifier error #8: unresolved call from statement (%new()::MPI.var"#copy#copy##0"{MPI.OpWrapper{typeof(max), Any}, Ptr{Nothing}, Ptr{Nothing}, Int32})(MPI.to_type(%new()::MPI.Datatype)::Any)::Any
Stacktrace:
 [1] (::MPI.OpWrapper{typeof(max), Any})(_a::Ptr{Nothing}, _b::Ptr{Nothing}, _len::Ptr{Int32}, t::Ptr{Int32})
   @ MPI ~/.julia/packages/MPI/hNJm0/src/operators.jl:98

Verifier error #9: unresolved call from statement (%new()::MPI.var"#copy#copy##0"{MPI.OpWrapper{typeof(min), Any}, Ptr{Nothing}, Ptr{Nothing}, Int32})(MPI.to_type(%new()::MPI.Datatype)::Any)::Any
Stacktrace:
 [1] (::MPI.OpWrapper{typeof(min), Any})(_a::Ptr{Nothing}, _b::Ptr{Nothing}, _len::Ptr{Int32}, t::Ptr{Int32})
   @ MPI ~/.julia/packages/MPI/hNJm0/src/operators.jl:98

Verifier error #10: unresolved call from statement (Base.memoryrefget(Base.memoryrefnew(Base.getfield(MPI.mpi_init_hooks, :ref)::MemoryRef{Any}, 1, false::Bool)::MemoryRef{Any}, :not_atomic, false::Bool)::Any)()::Any
Stacktrace:
 [1] run_init_hooks()
   @ MPI ~/.julia/packages/MPI/hNJm0/src/environment.jl:66
 [2] Init(; threadlevel::Symbol, finalize_atexit::Bool, errors_return::Bool)
   @ MPI ~/.julia/packages/MPI/hNJm0/src/environment.jl:155
 [3] Init()
   @ MPI ~/.julia/packages/MPI/hNJm0/src/environment.jl:114 [inlined]
 [4] main(ARGS::Vector{String})
   @ Main ~/Cthonios/ParaTaxi/examples/src/HelloWorld.jl:4
◐ Compiling..._main(argc::Int32, argv::Ptr{Ptr{Int8}})
   @ Main ~/.julia/packages/JuliaC/EFQEY/src/scripts/juliac-buildscript.jl:77

Trim verify finished with 10 errors, 0 warnings.
✓ Compiling...
ERROR: LoadError: Failed to compile src/HelloWorld.jl
Stacktrace:
 [1] error(s::String)
   @ Base ./error.jl:44
 [2] compile_products(recipe::ImageRecipe)
   @ JuliaC ~/.julia/packages/JuliaC/EFQEY/src/compiling.jl:142
 [3] top-level scope
   @ ~/Cthonios/ParaTaxi/examples/build.jl:24
 [4] include(mod::Module, _path::String)
   @ Base ./Base.jl:306
 [5] exec_options(opts::Base.JLOptions)
   @ Base ./client.jl:317
 [6] _start()
   @ Base ./client.jl:550

From what I can gather through looking through the src code, it looks like there's an array of functions at the module level that are run during MPI.Init() that leads to these unresolved calls.

I'm happy to help put effort into fixing this currently niche use case, but thought I would open an issue first to see if the maintainers have any qualms before putting effort in.

It would be great to bring small binaries with MPI to the community!