The function `parse_args` throws when it is invoked in a spawned task and julia has been started with multiple threads

[charnik]

The behaviour of the title happens on the latest commit to master (3becf32), which corresponds to the version 1.2.0.

Here is a working example that can be used for a reproduction.

Starting julia with a single thread:

$ pwd
~/julia/ArgParse.jl

$ julia --project=. -t 1
               _
   _       _ _(_)_     |  Documentation: https://docs.julialang.org
  (_)     | (_) (_)    |
   _ _   _| |_  __ _   |  Type "?" for help, "]?" for Pkg help.
  | | | | | | |/ _` |  |
  | | |_| | | | (_| |  |  Version 1.10.2 (2024-03-01)
 _/ |\__'_|_|_|\__'_|  |  Official https://julialang.org/ release
|__/                   |

julia> using ArgParse

julia> s = ArgParseSettings();

julia> add_arg_table!(s, ["--foo"], Dict(:arg_type=>Int64));

julia> ArgParse.parse_args(["--foo", "42"], s);

julia> fetch(Threads.@spawn ArgParse.parse_args(["--foo", "42"], s))
Dict{String, Any} with 1 entry:
  "foo" => 42

Starting julia with two threads:

$ julia --project=. -t 2
               _
   _       _ _(_)_     |  Documentation: https://docs.julialang.org
  (_)     | (_) (_)    |
   _ _   _| |_  __ _   |  Type "?" for help, "]?" for Pkg help.
  | | | | | | |/ _` |  |
  | | |_| | | | (_| |  |  Version 1.10.2 (2024-03-01)
 _/ |\__'_|_|_|\__'_|  |  Official https://julialang.org/ release
|__/                   |

julia> using ArgParse

julia> s = ArgParseSettings();

julia> add_arg_table!(s, ["--foo"], Dict(:arg_type=>Int64));

julia> ArgParse.parse_args(["--foo", "42"], s);

julia> fetch(Threads.@spawn ArgParse.parse_args(["--foo", "42"], s))
ERROR: TaskFailedException
Stacktrace:
 [1] wait
   @ ./task.jl:352 [inlined]
 [2] fetch(t::Task)
   @ Base ./task.jl:372
 [3] top-level scope
   @ threadingconstructs.jl:447

    nested task error: ArgParseError("too many arguments")
    Stacktrace:
     [1] argparse_error(x::Any)
       @ ArgParse ~/julia/ArgParse.jl/src/parsing.jl:9
     [2] parse_arg!(state::ArgParse.ParserState, settings::ArgParseSettings)
       @ ArgParse ~/julia/ArgParse.jl/src/parsing.jl:919
     [3] parse_args_unhandled(args_list::Vector, settings::ArgParseSettings, truncated_shopts::Bool)
       @ ArgParse ~/julia/ArgParse.jl/src/parsing.jl:633
     [4] parse_args_unhandled(args_list::Vector, settings::ArgParseSettings)
       @ ArgParse ~/julia/ArgParse.jl/src/parsing.jl:596
     [5] parse_args(args_list::Vector, settings::ArgParseSettings; as_symbols::Bool)
       @ ArgParse ~/julia/ArgParse.jl/src/parsing.jl:470
     [6] parse_args(args_list::Vector, settings::ArgParseSettings)
       @ ArgParse ~/julia/ArgParse.jl/src/parsing.jl:466
     [7] (::var"#1#2")()
       @ Main ./REPL[5]:1

The issue persists if instead of add_arg_table! the macro @add_arg_table! is used.