Pkg reorders Project.toml with extensions in Julia 1.6

[gdalle]

I have a package with extensions. When I update or resolve the environment, it seems that different things happen depending on the Julia version.

• In Julia 1.6, Pkg reorders the sections of the Project.toml file like so

  deps
  compat
  extensions
  extras
  targets
  weakdeps

• In Julia 1.7 through 1.9, Pkg reorders the sections of the Project.toml file like so:

  deps
  weakdeps
  extensions
  compat
  extras
  targets

This causes issues for automated quality checking with Aqua.jl (JuliaTesting/Aqua.jl#105). Is there a rationale behind this behavior?

[KristofferC]

Is there a rationale behind this behavior?

1.6 doesn't know about extensions.

[gdalle]

Of course, but the reordering itself causes CI failures when packages

1. use extensions for 1.9 and above
2. are still compatible with 1.6 and below
3. run tests with Aqua in CI

which is an increasingly common combination

Example: https://github.com/gdalle/ImplicitDifferentiation.jl/actions/runs/5001651819

[KristofferC]

You asked about the rationale for the behavior. And that is because 1.6 does not know about extensions?

[gdalle]

Ok that's fair :) Follow-ups then:

• Why does it change starting at 1.7?
• Is it an issue that can be solved at the Pkg level or that should be tackled only in Aqua?

[KristofferC]

In order for it to be fixed in Julia there needs to be a new 1.6 release, it seems easier if possible to add a workaround in Aqua.

Why it is different on 1.7 I don't know.

[gdalle]

Ok cool, thanks for the answers! I'll try to fix it in Aqua, and at least the topic is out there in case someone else wonders

[jishnub]

In general, is it expected that resolve may alter a Project.toml file, or is this a bug? My impression was that a Project.toml is entirely specified by the developer, and from the perspective of an end user who may resolve or instantiate the package, this is read-only.

[KristofferC]

I think it is fixed so that it is only written to if the content changed. But that might be after 1.6.