feat: support changes for lockfile v7

[baszalmstra]

Goes alongside prefix-dev/pixi#4824

[Hofer-Julian]

The remaining problem is that out-of-tree git dependencies cannot be solved if there are multiple platforms with different variants each.

You have this e.g. when running tests/integration_python/test_specified_build_source/test_git.py::test_git_path_lock_consistent_across_platforms. pixi-build-cmake only injects the variant cxx_compiler=vs2019 on Windows. When you then try to solve you get the following error message:

Error:   × failed to write lock-file to disk
  ╰─▶ Failed to disambiguate source packages at location '.'. Multiple source packages exist but cannot be distinguished without variant information. This typically occurs when converting from lock file format V6 to V7.
      Conflicting packages:
        - simple-app
        - simple-app [variants: cxx_compiler=vs2019]

, code: 1

[baszalmstra]

This should have been fixed by your previous PR to the backends, which we may not have released yet. That ensures that the target_platform variant is added.

[Hofer-Julian]

This should have been fixed by your previous PR to the backends, which we may not have released yet. That ensures that the target_platform variant is added.

This shouldn't affect the testsuite as long as they are merged. Or is the PR not merged yet?

[Hofer-Julian]

Ah, I read too quickly. You mean my PR that ensures that all variants are returned.

I will double check if that doesn't work with out-of-source git dependencies for some reason

[baszalmstra]

It is, so maybe that is somehow broken?

Using your PR the target_platform should be added to the variants which disambiguates this.

[Hofer-Julian]

It is, so maybe that is somehow broken?

Yeah, I think so.
I just tried with "normal" builds and there it works:

- conda: .
  name: simple-app
  depends:
  - vc >=14.2,<15
  - vc14_runtime >=14.29.30139
  - ucrt >=10.0.20348.0
  input:
    hash: 8d1d52341921800e7ab8a779709ab7deec64a6281480dfda121b9e6aaea71c4d
    globs: []
  variants:
    cxx_compiler: vs2019
    target_platform: win-64
- conda: .
  name: simple-app
  depends:
  - libstdcxx >=15
  - libgcc >=15
  input:
    hash: 8d1d52341921800e7ab8a779709ab7deec64a6281480dfda121b9e6aaea71c4d
    globs: []
  variants:
    target_platform: linux-64

It seems like there's a problem specifically with out-of-tree (git) builds