Solving panics due to incorrect comparison function

[mdekstrand]

Checklist

• I added a descriptive title
• I searched open reports and couldn't find a duplicate

What happened?

Rust 1.81 introduce stricter checks for the correctness of Ord and PartialOrd implementations when sorting, panicing when it detects a non-total ordering instead of proceeding and allowing the sorted results to be incorrect. This causes Rattler's tests, and Pixi's solving, to fail when built with Rust 1.81.

Test error output

$ cargo +1.81.0 test
...
failures:

---- channel_priority_strict stdout ----
thread 'channel_priority_strict' panicked at library/core/src/slice/sort/shared/smallsort.rs:862:5:
user-provided comparison function does not correctly implement a total order

---- channel_specific_requirement stdout ----
thread 'channel_specific_requirement' panicked at library/core/src/slice/sort/shared/smallsort.rs:862:5:
user-provided comparison function does not correctly implement a total order

---- resolvo::test_solve_tensorboard stdout ----
thread 'resolvo::test_solve_tensorboard' panicked at library/core/src/slice/sort/shared/smallsort.rs:862:5:
user-provided comparison function does not correctly implement a total order

---- resolvo::test_solve_quetz stdout ----
thread 'resolvo::test_solve_quetz' panicked at library/core/src/slice/sort/shared/smallsort.rs:862:5:
user-provided comparison function does not correctly implement a total order

---- resolvo::test_solve_tensorflow stdout ----
thread 'resolvo::test_solve_tensorflow' panicked at library/core/src/slice/sort/shared/smallsort.rs:862:5:
user-provided comparison function does not correctly implement a total order

---- compare_solve_tensorboard stdout ----
libsolv_c took 2139ms
thread 'compare_solve_tensorboard' panicked at library/core/src/slice/sort/shared/smallsort.rs:862:5:
user-provided comparison function does not correctly implement a total order

---- compare_solve_tensorflow stdout ----
libsolv_c took 3183ms
thread 'compare_solve_tensorflow' panicked at library/core/src/slice/sort/shared/smallsort.rs:862:5:
user-provided comparison function does not correctly implement a total order

---- compare_solve_quetz stdout ----
libsolv_c took 4744ms
thread 'compare_solve_quetz' panicked at library/core/src/slice/sort/shared/smallsort.rs:862:5:
user-provided comparison function does not correctly implement a total order


failures:
    channel_priority_strict
    channel_specific_requirement
    compare_solve_quetz
    compare_solve_tensorboard
    compare_solve_tensorflow
    resolvo::test_solve_quetz
    resolvo::test_solve_tensorboard
    resolvo::test_solve_tensorflow

test result: FAILED. 53 passed; 8 failed; 0 ignored; 0 measured; 0 filtered out; finished in 9.15s

This is likely the cause of prefix-dev/pixi#2122.

Additional Context

I discovered this issue because Homebrew builds Pixi with latest Rust, and my Pixi dependency solves were panicing.

[tdejager]

Ah yes we should definitely fix this, let's see if we can implement a correct total ordering for the things that error out.

[tdejager]

I've a PR up that should fix this :)