[CI Broken] Dependency resolution failure in test (alldeps, 1.10)

[ChrisRackauckas-Claude]

CI Broken: Dependency Resolution Failure

Summary

The CI is currently broken on the master branch. The test (alldeps, 1.10) job is failing with an unsatisfiable dependency resolution error.

Which CI Job Failed

• Job: test (alldeps, 1.10)
• Status: ❌ Failed
• Duration: 51 seconds
• Failed CI Run: https://github.com/SciML/LabelledArrays.jl/actions/runs/20791387874/job/59714125646

Other CI Jobs Status

All other CI jobs passed:

• ✅ AllocCheck
• ✅ Documentation / Build and Deploy Documentation
• ✅ Spell Check with Typos
• ✅ Tests (1) / Tests
• ✅ Tests (lts) / Tests
• ✅ Tests (pre) / Tests
• ✅ runic

Error Details

The failure occurs during the dependency resolution phase after julia-downgrade-compat@v2 attempts to resolve minimal versions with --min=@alldeps mode.

Key Error Message:

ERROR: LoadError: Unsatisfiable requirements detected for package OrdinaryDiffEq [1dea7af3]:
 OrdinaryDiffEq [1dea7af3] log:
 ├─possible versions are: 4.0.0-6.105.0 or uninstalled
 ├─restricted to versions * by project [a0499a33], leaving only versions: 4.0.0-6.105.0
 ├─restricted by compatibility requirements with RecursiveArrayTools [731186ca] to versions: 6.62.0-6.99.0 or uninstalled, leaving only versions: 6.62.0-6.99.0
 │ └─RecursiveArrayTools [731186ca] log:
 │   ├─possible versions are: 0.16.0-3.42.1 or uninstalled
 │   ├─restricted to versions 3.1.0-3 by project [a0499a33], leaving only versions: 3.1.0-3.42.1
 │   └─restricted to versions 3.1.0 by an explicit requirement, leaving only versions: 3.1.0
 └─restricted by compatibility requirements with DataStructures [864edb3b] to versions: 4.0.0-5.42.3 or uninstalled — no versions left
   └─DataStructures [864edb3b] log:
     ├─possible versions are: 0.9.0-0.19.3 or uninstalled
     └─restricted to versions 0.17.20 by an explicit requirement, leaving only versions: 0.17.20

Root Cause Analysis

The issue is a dependency compatibility conflict in the "alldeps" (all dependencies at minimum versions) test configuration:

1. The downgrade-compat action is forcing RecursiveArrayTools to version 3.1.0 (minimum version)
2. The downgrade-compat action is also forcing DataStructures to version 0.17.20 (minimum version)
3. When trying to resolve OrdinaryDiffEq:
   • RecursiveArrayTools@3.1.0 requires OrdinaryDiffEq versions 6.62.0-6.99.0
   • DataStructures@0.17.20 restricts OrdinaryDiffEq to versions 4.0.0-5.42.3
   • These ranges don't overlap → unsatisfiable

This is a compat bounds issue where the minimum versions specified in Project.toml are incompatible with each other.

Suggested Fix

This likely requires updating the [compat] section in Project.toml to ensure the minimum version bounds are mutually compatible. Specifically:

1. Review the minimum version requirements for DataStructures, RecursiveArrayTools, and OrdinaryDiffEq in the [compat] section
2. Test that the minimum versions can actually be resolved together
3. Either:
   • Bump the minimum version of DataStructures to a version compatible with the current RecursiveArrayTools and OrdinaryDiffEq requirements, OR
   • Adjust the minimum versions of RecursiveArrayTools or OrdinaryDiffEq accordingly

The goal is to ensure that when all dependencies are downgraded to their minimum compat-specified versions (which is what the alldeps test does), they can still be resolved together.

Context

This issue was discovered during an automated CI health check (PR #185) that tests the master branch periodically to catch CI breakage proactively.

@ChrisRackauckas

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Detected: 2026-01-07 via automated CI health check