Elide total unused Lua tuple components

[Frotty]

Summary

• let Lua tuple lowering discard recursively total scalar operator expressions when their component is unused
• retain evaluation for calls, member/array accesses, integer division, modulo, and other expressions which can have effects or fail
• document that the existing post-lowering garbage pass already removes unread tuple return slots and their pure producers

Generated Lua

For pair(left + 1, right + 2).x, the generated function now computes and returns only left + 1. It emits neither right + 2 nor a __wurst_tuple_discard_* helper.

Verification

• regression demonstrated red before the implementation and green afterward
• ./gradlew.bat test --tests "tests.wurstscript.tests.LuaBackendAuditTests" --tests "tests.wurstscript.tests.TupleTests"
• ./gradlew.bat test
• git diff --check

All checks pass locally. The full suite completed successfully in 4m27s.

[chatgpt-codex-connector]

Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-09-03T08:36:55.227611Z	16983b0	PR opened

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