fix(compiler-dom): improve HTML nesting validation to allow any child element within template tag

[edison1105]

close #13318

Summary by CodeRabbit

• Bug Fixes

  • Improved HTML nesting validation to allow any child element within a tag.

  • Tests

    • Added comprehensive tests to verify correct behavior of HTML and SVG element nesting validation, including new scenarios for , tables, forms, and SVG elements.

[coderabbitai]

Walkthrough

The changes update the HTML nesting validation logic to allow any child within a <template> element, and extend the test suite with new cases to verify this behavior and comprehensively test the isValidHTMLNesting function across various HTML and SVG tag combinations.

Changes

File(s)	Change Summary
packages/compiler-dom/src/htmlNesting.ts	Modified isValidHTMLNesting to always return true when the parent is 'template'.
packages/compiler-dom/tests/transforms/validateHtmlNesting.spec.ts packages/compiler-dom/tests/transforms/htmlNesting.spec.ts	Added and expanded test cases for <template> nesting and for isValidHTMLNesting with various HTML/SVG tag pairs.

Sequence Diagram(s)

sequenceDiagram
    participant Validator as isValidHTMLNesting
    participant Caller as ValidationCaller

    Caller->>Validator: validate(parent, child)
    alt parent is 'template'
        Validator-->>Caller: return true
    else
        Validator->>Validator: check standard HTML nesting rules
        Validator-->>Caller: return true/false
    end

Loading

Assessment against linked issues

Objective	Addressed	Explanation
Remove incorrect warning for <tr> as a child of <template> (#13318)	✅
Ensure <template> allows any child element without restriction (#13318)	✅

Poem

🐇
In a warren of tags, the template stands tall,
Now welcomes all children, both big and small.
No warnings for <tr>, no fuss, no fight—
The validator’s logic now gets it right!
With tests all expanded, the rules are precise,
This patch makes HTML nesting quite nice.

---

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📥 Commits

Reviewing files that changed from the base of the PR and between c489a3e and 8842891.

📒 Files selected for processing (2)

• packages/compiler-dom/__tests__/transforms/validateHtmlNesting.spec.ts (2 hunks)
• packages/compiler-dom/src/htmlNesting.ts (1 hunks)

🧰 Additional context used

🧬 Code Graph Analysis (1)

packages/compiler-dom/__tests__/transforms/validateHtmlNesting.spec.ts (1)

packages/compiler-dom/src/htmlNesting.ts (1)

• isValidHTMLNesting (13-44)

⏰ Context from checks skipped due to timeout of 90000ms (3)

• GitHub Check: Redirect rules
• GitHub Check: Header rules
• GitHub Check: Pages changed

🔇 Additional comments (4)

packages/compiler-dom/src/htmlNesting.ts (1)

14-17: Good addition to handle template tag correctly.

This change properly addresses issue #13318 by adding a special case for <template> elements. Since the HTML <template> element is designed to hold inert content that shouldn't be rendered immediately, standard HTML nesting rules don't apply to its children. The early return ensures any child element within a template tag is considered valid.

This matches the HTML specification's behavior and prevents false validation warnings during compilation.

packages/compiler-dom/__tests__/transforms/validateHtmlNesting.spec.ts (3)

2-2: Good addition to import the function being tested.

The import of isValidHTMLNesting is necessary for the new test suite that directly tests this function.

---

22-29: Good test for the template tag fix.

This test correctly verifies the fix for issue #13318 by confirming that no validation warning is emitted when a <tr> element is placed inside a <template> tag. This is a good targeted test case that directly corresponds to the code change in htmlNesting.ts.

---

32-201: Excellent comprehensive test suite for HTML nesting validation.

This thorough test suite covers a wide range of HTML element combinations and ensures the isValidHTMLNesting function behaves correctly for both valid and invalid nesting scenarios. The tests are well-organized by element type and clearly separate valid from invalid cases.

The test coverage includes:

• Basic elements (form, p, a, button)
• Table-related elements (table, td, tbody, tr)
• List elements (li)
• Headings (h1-h6)
• SVG elements
• Definition list elements (dl, dt, dd)

This comprehensive approach helps prevent regressions and validates the overall HTML nesting validation logic beyond just the template tag fix.

✨ Finishing Touches

• 📝 Generate Docstrings

---

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[github-actions]

Size Report

Bundles

File	Size	Gzip	Brotli
runtime-dom.global.prod.js	101 kB	38.3 kB	34.5 kB
vue.global.prod.js	159 kB	58.5 kB	52 kB

Usages

Name	Size	Gzip	Brotli
createApp (CAPI only)	46.6 kB	18.2 kB	16.7 kB
createApp	54.5 kB	21.2 kB	19.4 kB
createSSRApp	58.8 kB	23 kB	20.9 kB
defineCustomElement	59.5 kB	22.8 kB	20.8 kB
overall	68.6 kB	26.4 kB	24.1 kB

[pkg-pr-new]

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commit: 8842891

[LittleSound]

Maybe we can add some unit tests