BUGFIX: template-no-yield-only — guard against native <template> as first HBS child#59
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BUGFIX: template-no-yield-only — guard against native <template> as first HBS child#59
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…first HBS child
In classic HBS, a native HTML `<template>` element can appear anywhere in
a template body — including as the first child. The current gjs-wrapper
detection descends into `body[0].children` whenever `body[0].tag === 'template'`,
so an HBS template like `<template>{{yield}}</template>{{#each items}}…{{/each}}`
is mistakenly treated as the GJS `<template>` module wrapper: the rule
walks the inner `<template>`'s children, sees only `{{yield}}`, and
flags it as yield-only — a false positive.
The GJS module wrapper is always `body.length === 1`. Add that guard so
we only descend in the actual GJS/GTS case. Matches the shape of the
sibling rule `template-no-bare-yield.js`.
Added an HBS-only regression test (the construct is invalid in GJS/GTS,
where a nested `<template>` is a parse error).
🏎️ Benchmark Comparison
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Summary
template-no-yield-only's gjs-wrapper detection descends intobody[0].childrenwheneverbody[0].tag === 'template', without checkingbody.length. In classic HBS, a native HTML<template>element can appear anywhere, and the rule mistakes it for the GJS module wrapper.<template>{{yield}}</template>{{#each items}}item{{/each}}. The rule walks the inner<template>'s children, sees only{{yield}}, and flags the whole template as yield-only — even though the real template has a{{#each}}block and is not yield-only.body.length === 1before descending, matching the shape of the sibling ruletemplate-no-bare-yield.js.Context
Closes drift with
template-no-bare-yield.js, which has this guard. Both rules are near-duplicates of the same upstreamember-template-lint/no-yield-only; the sibling kept pace, this one didn't.Independent of ember-cli#2736 (ember-cli/eslint-plugin-ember) and the CI fix there — that PR addresses the comment-node handling; this one addresses a separately latent wrapper-detection bug. They touch the same file but different regions.
Test plan
<template>{{yield}}</template>{{#each items}}item{{/each}}tovalidHbs; without the guard it false-positives, with it the template is correctly accepted.<template>(parse error); split intovalidHbsOnlyand fed to the hbs rule tester.pnpm exec vitest run tests/lib/rules/template-no-yield-only.js— 19/19 pass.