Optimize build: Reduce compiler memory usage by introducing TypeList (Part 2) (backport #953)

[mergify]

🎉 New feature

Needs #916

Summary

This commit introduces a lightweight TypeList to replace std::tuple for intermediate template metaprogramming operations (filtering, flattening, and deduping feature lists).

By using TypeList and C++17 fold expressions instead of recursive std::tuple instantiations, we drastically reduce compiler memory consumption (Max RSS) and build times. The public API retains std::tuple for backward compatibility, but internal operations are fully modernized.

Using GNU time, I measured a 33% peak RSS memory reduction on macOS and 68.9% reduction on Linux 🎉 (inside a VM with no swap).

Test it

Compare against main by building the code while measuring memory consumption

/usr/bin/time -v make gz-physics-dartsim-plugin

Results from Linux test

Before this change:

        Command being timed: "ninja -j1 gz-physics-dartsim-plugin"
        User time (seconds): 71.59
        System time (seconds): 7.72
        Percent of CPU this job got: 75%
        Elapsed (wall clock) time (h:mm:ss or m:ss): 1:45.64
        Average shared text size (kbytes): 0
        Average unshared data size (kbytes): 0
        Average stack size (kbytes): 0
        Average total size (kbytes): 0
        Maximum resident set size (kbytes): 5472448
 

After this PR:

        Command being timed: "ninja -j1 gz-physics-dartsim-plugin"
        User time (seconds): 56.75
        System time (seconds): 6.98
        Percent of CPU this job got: 71%
        Elapsed (wall clock) time (h:mm:ss or m:ss): 1:29.49
        Average shared text size (kbytes): 0
        Average unshared data size (kbytes): 0
        Average stack size (kbytes): 0
        Average total size (kbytes): 0
        Maximum resident set size (kbytes): 1701576
 

Checklist

• Signed all commits for DCO
• Added a screen capture or video to the PR description that demonstrates the feature
• Added tests
• Added example and/or tutorial
• Updated documentation (as needed)
• Updated migration guide (as needed)
• Consider updating Python bindings (if the library has them)
• codecheck passed (See contributing)
• All tests passed (See test coverage)
• Updated Bazel files (if adding new files). Created an issue otherwise.
• While waiting for a review on your PR, please help review another open pull request to support the maintainers
• Was GenAI used to generate this PR? If so, make sure to add "Generated-by" to your commits. (See this policy for more info.)

Generated-By: Gemini 3.0 Pro

Note to maintainers: Remember to use Squash-Merge and edit the commit message to match the pull request summary while retaining Signed-off-by and Generated-by messages.

Backports: If this is a backport, please use Rebase and Merge instead.

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This is an automatic backport of pull request #917 done by Mergify.

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This is an automatic backport of pull request #953 done by Mergify.

[mergify]

Cherry-pick of cc44170 has failed:

On branch mergify/bp/gz-physics7/pr-953
Your branch is up to date with 'origin/gz-physics7'.

You are currently cherry-picking commit cc44170.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Changes to be committed:
	modified:   include/gz/physics/FeatureList.hh
	modified:   include/gz/physics/FindFeatures.hh
	modified:   include/gz/physics/RequestEngine.hh
	modified:   include/gz/physics/TemplateHelpers.hh
	modified:   include/gz/physics/detail/Entity.hh
	modified:   include/gz/physics/detail/FeatureList.hh
	modified:   include/gz/physics/detail/InspectFeatures.hh
	modified:   include/gz/physics/detail/Register.hh
	modified:   src/FeatureList_TEST.cc
	renamed:    src/FilterTuple_TEST.cc -> src/FilterTypeList_TEST.cc

Unmerged paths:
  (use "git add/rm <file>..." as appropriate to mark resolution)
	deleted by us:   include/gz/physics/detail/RegisterStatic.hh

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally

[azeey]

Can I get a review on this since I fixed conflicts?