"Unsatisfiable Requirement" edge case error when juliacall is upgraded but Julia registries are not

[brian-dellabetta]

Hi there,
we have come across an edge case when upgrading PythonCall/juliacall, and I am curious if anyone knows of a workaround or clean solution.

Initial Condition:

• User has juliacall==0.9.14 installed in their Python env
• User has [email protected] installed in the Julia project that juliacall links to.
• User has not updated their julia registry to know that a new version of [email protected] available.

Steps to reproduce:

• User does pip install juliacall==0.9.15
• User runs from juliacall import Main as jl
  This will result in the following error:

ERROR: Unsatisfiable requirements detected for package PythonCall [6099a3de]:
 PythonCall [6099a3de] log:
 ├─possible versions are: 0.1.0-0.9.14 or uninstalled
 ├─restricted to versions * by <redacted>, leaving only versions: 0.1.0-0.9.14
 │ └─<redacted> log:
 │   ├─possible versions are: 0.1.0 or uninstalled
 │   └─<redacted> is fixed to version 0.1.0
 └─restricted to versions 0.9.15 by an explicit requirement — no versions left
Stacktrace:
  [1] check_constraints(graph::Pkg.Resolve.Graph)
    @ Pkg.Resolve ~/.julia/environments/pyjuliapkg/pyjuliapkg/install/share/julia/stdlib/v1.9/Pkg/src/Resolve/graphtype.jl:998
  [2] Pkg.Resolve.Graph(compat::Dict{Base.UUID, Dict{VersionNumber, Dict{Base.UUID, Pkg.Versions.VersionSpec}}}, compat_weak::Dict{Base.UUID, Dict{VersionNumber, Set{Base.UUID}}}, uuid_to_name::Dict{Base.UUID, String}, reqs::Dict{Base.UUID, Pkg.Versions.VersionSpec}, fixed::Dict{Base.UUID, Pkg.Resolve.Fixed}, verbose::Bool, julia_version::VersionNumber)
    @ Pkg.Resolve ~/.julia/environments/pyjuliapkg/pyjuliapkg/install/share/julia/stdlib/v1.9/Pkg/src/Resolve/graphtype.jl:345
  [3] deps_graph(env::Pkg.Types.EnvCache, registries::Vector{Pkg.Registry.RegistryInstance}, uuid_to_name::Dict{Base.UUID, String}, reqs::Dict{Base.UUID, Pkg.Versions.VersionSpec}, fixed::Dict{Base.UUID, Pkg.Resolve.Fixed}, julia_version::VersionNumber, installed_only::Bool)
    @ Pkg.Operations ~/.julia/environments/pyjuliapkg/pyjuliapkg/install/share/julia/stdlib/v1.9/Pkg/src/Operations.jl:587
  [4] resolve_versions!(env::Pkg.Types.EnvCache, registries::Vector{Pkg.Registry.RegistryInstance}, pkgs::Vector{Pkg.Types.PackageSpec}, julia_version::VersionNumber, installed_only::Bool)
    @ Pkg.Operations ~/.julia/environments/pyjuliapkg/pyjuliapkg/install/share/julia/stdlib/v1.9/Pkg/src/Operations.jl:407
  [5] targeted_resolve(env::Pkg.Types.EnvCache, registries::Vector{Pkg.Registry.RegistryInstance}, pkgs::Vector{Pkg.Types.PackageSpec}, preserve::Pkg.Types.PreserveLevel, julia_version::VersionNumber)
    @ Pkg.Operations ~/.julia/environments/pyjuliapkg/pyjuliapkg/install/share/julia/stdlib/v1.9/Pkg/src/Operations.jl:1357
  [6] tiered_resolve(env::Pkg.Types.EnvCache, registries::Vector{Pkg.Registry.RegistryInstance}, pkgs::Vector{Pkg.Types.PackageSpec}, julia_version::VersionNumber, try_all_installed::Bool)
    @ Pkg.Operations ~/.julia/environments/pyjuliapkg/pyjuliapkg/install/share/julia/stdlib/v1.9/Pkg/src/Operations.jl:1346
  [7] _resolve(io::Base.TTY, env::Pkg.Types.EnvCache, registries::Vector{Pkg.Registry.RegistryInstance}, pkgs::Vector{Pkg.Types.PackageSpec}, preserve::Pkg.Types.PreserveLevel, julia_version::VersionNumber)
    @ Pkg.Operations ~/.julia/environments/pyjuliapkg/pyjuliapkg/install/share/julia/stdlib/v1.9/Pkg/src/Operations.jl:1367
  [8] develop(ctx::Pkg.Types.Context, pkgs::Vector{Pkg.Types.PackageSpec}, new_git::Set{Base.UUID}; preserve::Pkg.Types.PreserveLevel, platform::Base.BinaryPlatforms.Platform)
    @ Pkg.Operations ~/.julia/environments/pyjuliapkg/pyjuliapkg/install/share/julia/stdlib/v1.9/Pkg/src/Operations.jl:1407
  [9] develop
    @ ~/.julia/environments/pyjuliapkg/pyjuliapkg/install/share/julia/stdlib/v1.9/Pkg/src/Operations.jl:1399 [inlined]
 [10] develop(ctx::Pkg.Types.Context, pkgs::Vector{Pkg.Types.PackageSpec}; shared::Bool, preserve::Pkg.Types.PreserveLevel, platform::Base.BinaryPlatforms.Platform, kwargs::Base.Pairs{Symbol, Base.TTY, Tuple{Symbol}, NamedTuple{(:io,), Tuple{Base.TTY}}})
    @ Pkg.API ~/.julia/environments/pyjuliapkg/pyjuliapkg/install/share/julia/stdlib/v1.9/Pkg/src/API.jl:222
 [11] develop(pkgs::Vector{Pkg.Types.PackageSpec}; io::Base.TTY, kwargs::Base.Pairs{Symbol, Union{}, Tuple{}, NamedTuple{(), Tuple{}}})
    @ Pkg.API ~/.julia/environments/pyjuliapkg/pyjuliapkg/install/share/julia/stdlib/v1.9/Pkg/src/API.jl:156
 [12] develop(pkgs::Vector{Pkg.Types.PackageSpec})
    @ Pkg.API ~/.julia/environments/pyjuliapkg/pyjuliapkg/install/share/julia/stdlib/v1.9/Pkg/src/API.jl:145
 [13] top-level scope
    @ none:1

All I need to do is run jl.seval("import Pkg; Pkg.registry.update()") but I can't get access to jl, I hit the error above first. Any suggestions on how to programmatically resolve this, ideally in Python? Hoping there's a way without having to edit juliacall source code to allow for an init/startup script. If that is the case, I can create an issue and take a shot at a PR. It may be as simple as adding another env var option that injects Pkg.registry.update() in the init script somewhere around this line.

Thanks!