A bare literal in a template is not a dropped statement

[alextakitani]

Probed on main (26365fa).

The view walker's catch-all files a lower_residue line ("template statement dropped (unknown stmt)") so dropped template statements are visible. Every <% unless %> trips it with a false positive, and without a location:

<% unless @articles.empty? %>
  <p>listed</p>
<% end %>

unless reaches the walker as if cond then nil else … end. The then arm is a synthesized nil literal (synthetic span), so the catch-all reports it as a dropped statement with no file or line. The rendered output is already correct; only the ledger is wrong. In a real app (a Rails time tracker) these were the only "template statement dropped" lines left, and with no span there was nothing to follow.

A literal in statement position renders nothing and runs no side effect, so there is nothing to drop. It now lowers to the same io << "" without a ledger line (noop_io_append, split out of todo_io_append). Genuine drops still report, pinned by the existing an_unlowerable_statement_files_residue.

Tests (tests/view_walker_residue.rs): an_unless_block_files_no_residue_and_keeps_its_body and a_literal_statement_files_no_residue; both fail on main.

Ran: view_walker_residue (5), emit_and_run (107), lowered_ruby_emit (108), real_blog (6).

Summary by CodeRabbit

• Bug Fixes
  • Literal statements and unless block bodies no longer produce unexpected residue in generated output.

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📥 Commits

Reviewing files that changed from the base of the PR and between 26365fa and 179addd.

📒 Files selected for processing (3)

• src/lower/view_to_library/mod.rs
• src/lower/view_to_library/walker.rs
• tests/view_walker_residue.rs

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📝 Walkthrough

Walkthrough

Bare literal statements now lower to no-op appends instead of unknown-statement TODO appends. Regression tests check that unless bodies remain in output and that literal nil statements produce no residue.

Changes

Literal statement lowering

Layer / File(s)	Summary
No-op append handling src/lower/view_to_library/mod.rs, src/lower/view_to_library/walker.rs, tests/view_walker_residue.rs	todo_io_append returns a no-op append after its diagnostic call. The walker uses a no-op append for bare literal statements. Tests check unless output and confirm that unless and nil statements produce no residue.

Priority: ⬇️ Low

Estimated code review effort: 2 (Simple) | ~10 minutes

Change: Bug fix

Suggested reviewers: rubys

Merge Risk: ⚪ Minimal · up to 179ad

The change addresses false residue reports for bare literals while retaining diagnostics for unsupported statements. No material merge-blocking risk is evident.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly describes the main change: treating bare literals in templates as statements rather than reporting them as dropped.
Docstring Coverage	✅ Passed	Docstring coverage is 83.33% which is sufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 6 functions across 3 files.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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