fix(compiler-vapor): handle template children in Transition by jackma9604 · Pull Request #14606 · vuejs/core

jackma9604 · 2026-03-19T10:28:18Z

Problem Description

The program will report an error if there is a template tag inside Transition

Vue Version

3.6.0-beta.8

Link to minimal reproduction

Any additional comments

I don't know if it was intentional. but this is normal in VDOM mode.
I tried to fix it, If it's incorrect, please close this PR

Summary by CodeRabbit

Bug Fixes
- Improved transition component handling with conditional templates and v-for directives; refined warning detection logic to provide more accurate feedback when using <transition> with template structures.
Tests
- Added comprehensive test coverage for transition warning behavior with various template configurations, ensuring warnings are correctly emitted or omitted based on child element structures.

coderabbitai · 2026-03-19T10:28:26Z

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pkg-pr-new · 2026-03-19T10:29:02Z

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commit: 041b2bf

github-actions · 2026-03-19T10:29:13Z

Size Report

Bundles

File	Size	Gzip	Brotli
compiler-dom.global.prod.js	86.4 kB	30.2 kB	26.6 kB
runtime-dom.global.prod.js	111 kB	41.9 kB	37.5 kB
vue.global.prod.js	170 kB	61.7 kB	55 kB

Usages

Name	Size	Gzip	Brotli
createApp (CAPI only)	50.6 kB	19.8 kB	18 kB
createApp	59.6 kB	23.1 kB	21 kB
createApp + vaporInteropPlugin	85 kB	31.4 kB	28.4 kB
createVaporApp	28.7 kB	11.1 kB	10.2 kB
createSSRApp	63.9 kB	24.8 kB	22.5 kB
createVaporSSRApp	31.9 kB	12.3 kB	11.3 kB
defineCustomElement	66.2 kB	25.1 kB	22.8 kB
defineVaporCustomElement	39.3 kB	14.5 kB	13.3 kB
overall	74.5 kB	28.4 kB	25.8 kB

edison1105 · 2026-03-20T09:51:03Z

Thank you for your contribution, but it introduced some regressions, which I have fixed. See f99df63

coderabbitai

🧹 Nitpick comments (1)

packages/compiler-vapor/src/transforms/transformTransition.ts (1)

56-57: Consider simplifying the redundant condition.

The condition (!isTemplateNode(c) || (isTemplateNode(c) && !hasMultipleChildren(c))) is logically equivalent to !isTemplateNode(c) || !hasMultipleChildren(c) since if the first operand is false, isTemplateNode(c) is necessarily true.

♻️ Suggested simplification

        c.type === NodeTypes.ELEMENT &&
-        (!isTemplateNode(c) ||
-          (isTemplateNode(c) && !hasMultipleChildren(c))) &&
+        (!isTemplateNode(c) || !hasMultipleChildren(c)) &&
        // not has v-for

🤖 Prompt for AI Agents

Verify each finding against the current code and only fix it if needed.

In `@packages/compiler-vapor/src/transforms/transformTransition.ts` around lines
56 - 57, The boolean expression in the condition is redundant: replace the
current check `(!isTemplateNode(c) || (isTemplateNode(c) &&
!hasMultipleChildren(c)))` with the simplified equivalent `!isTemplateNode(c) ||
!hasMultipleChildren(c)` to remove the unnecessary repeated call to
isTemplateNode; update the expression wherever it appears (e.g., in the
conditional that references isTemplateNode and hasMultipleChildren for node
variable c) to improve readability and performance.

🤖 Prompt for all review comments with AI agents

Verify each finding against the current code and only fix it if needed.

Nitpick comments:
In `@packages/compiler-vapor/src/transforms/transformTransition.ts`:
- Around line 56-57: The boolean expression in the condition is redundant:
replace the current check `(!isTemplateNode(c) || (isTemplateNode(c) &&
!hasMultipleChildren(c)))` with the simplified equivalent `!isTemplateNode(c) ||
!hasMultipleChildren(c)` to remove the unnecessary repeated call to
isTemplateNode; update the expression wherever it appears (e.g., in the
conditional that references isTemplateNode and hasMultipleChildren for node
variable c) to improve readability and performance.

ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

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Run ID: c077ce9c-4987-40b9-8532-79df5c7bf114

📥 Commits

Reviewing files that changed from the base of the PR and between c245dae and f99df63.

📒 Files selected for processing (2)

packages/compiler-vapor/__tests__/transforms/TransformTransition.spec.ts
packages/compiler-vapor/src/transforms/transformTransition.ts

fix(compiler-vapor): Transition accepts template tags

0a1c469

chore: update test

686e8b3

edison1105 added the scope: vapor related to vapor mode label Mar 20, 2026

fix(compiler-vapor): handle template children in Transition

f99df63

edison1105 changed the title ~~fix(compiler-vapor): Transition accepts template tags~~ fix(compiler-vapor): handle template children in Transition Mar 20, 2026

coderabbitai bot reviewed Mar 20, 2026

View reviewed changes

chore: tweaks

041b2bf

edison1105 merged commit 5fb8b33 into vuejs:minor Mar 20, 2026
14 of 15 checks passed

jackma9604 deleted the fix/transitionTransition branch March 20, 2026 10:02

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fix(compiler-vapor): handle template children in Transition#14606

fix(compiler-vapor): handle template children in Transition#14606
edison1105 merged 4 commits intovuejs:minorfrom
jackma9604:fix/transitionTransition

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Problem Description

Vue Version

Link to minimal reproduction

Any additional comments

Summary by CodeRabbit

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