fix(compiler-core): preserve whitespace around interpolations (fix #7542)

[fengnovo]

Summary

Preserve condensed boundary whitespace when an interpolation is the first or last child of a non-root element.

This makes interpolated content consistent with static text in inline markup. For example:

<span>Foo</span>
<span>
  {{ bar }}
</span>

now renders with the source whitespace between Foo and the interpolated value instead of collapsing the output to FooBar.

Root cause

condenseWhitespace() unconditionally removed all-whitespace text nodes at the start and end of every child list. That also removed whitespace adjacent to an interpolation, even though equivalent static text preserves a condensed space.

The parser now distinguishes root-level whitespace from element boundary whitespace. In the default condense mode, it keeps a single boundary space next to an interpolation inside an element. Root-level behavior and whitespace: 'preserve' behavior remain unchanged.

Tests

• Added parser coverage for leading and trailing whitespace around interpolations.
• Added guards for root-level whitespace and whitespace: 'preserve'.
• Updated compiler and runtime expectations affected by the corrected output.
• ./node_modules/.bin/vitest --project 'unit*' run
  • 182 test files passed, 1 skipped
  • 3629 tests passed, 6 skipped
• ./node_modules/.bin/tsc --incremental --noEmit

Fixes #7542

[coderabbitai]

Important

Review skipped

Draft detected.

Please check the settings in the CodeRabbit UI or the .coderabbit.yaml file in this repository. To trigger a single review, invoke the @coderabbitai review command.

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro Plus

Run ID: 9d916d7f-7792-4b3d-a3fd-76b97321338d

You can disable this status message by setting the reviews.review_status to false in the CodeRabbit configuration file.

Use the checkbox below for a quick retry:

• 🔍 Trigger review

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands.}