Review checklist

This checklist is meant to assist creators of PRs (to let them know what reviewers will typically look for) and reviewers (to guide them in a structured review process). Items do not need to be checked explicitly for a PR to be eligible for merging.

Purpose and scope

• The PR has a single goal that is clear from the PR title and/or description.
• All code changes represent a single set of modifications that logically belong together.
• No more than 500 lines of code are changed or there is no obvious way to split the PR into multiple PRs.

Code quality

• The code can be understood easily.
• Newly introduced names for variables etc. are self-descriptive and consistent with existing naming conventions.
• There are no redundancies that can be removed by simple modularization/refactoring.
• There are no leftover debug statements or commented code sections.
• The code adheres to our conventions and style guide, and to the Julia guidelines.

Documentation

• New functions and types are documented with a docstring or top-level comment.
• Relevant publications are referenced in docstrings (see example for formatting).
• Inline comments are used to document longer or unusual code sections.
• Comments describe intent ("why?") and not just functionality ("what?").
• If the PR introduces a significant change or new feature, it is documented in NEWS.md with its PR number.

Testing

• The PR passes all tests.
• New or modified lines of code are covered by tests.
• New or modified tests run in less then 10 seconds.

Performance

• There are no type instabilities or memory allocations in performance-critical parts.
• If the PR intent is to improve performance, before/after time measurements are posted in the PR.

Verification

• The correctness of the code was verified using appropriate tests.
• If new equations/methods are added, a convergence test has been run and the results
  are posted in the PR.

Created with ❤️ by the Trixi.jl community.

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 96.39%. Comparing base (9c69e10) to head (ef2a9d0).
Report is 2 commits behind head on main.

@@           Coverage Diff           @@
##             main    #2188   +/-   ##
=======================================
  Coverage   96.39%   96.39%           
=======================================
  Files         483      483           
  Lines       38333    38333           
=======================================
  Hits        36948    36948           
  Misses       1385     1385           

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@ranocha do you remember why the argument was there in the first place? Did we plan on dispatching on it somehow?

We considered dispatching on it - maybe for entropy-stable mortars?

Well, since nobody is actively working on this (as far as I can tell) and it is easy to re-add if necessary, I'm ok with merging this once ready.

We considered dispatching on it - maybe for entropy-stable mortars?

But wouldn't those be dispatched based on the mortar type, i.e.,

function prolong2mortars!(cache, u,
                          mesh::TreeMesh{2}, equations,
                          mortar_l2::LobattoLegendreMortarEC, # instead of LobattoLegendreMortarL2
                          dg::DGSEM)

?

Yeah, that's true. Let's merge this PR when it's ready and CI passes.