Add rule: ember/template-no-deprecated by wagenet · Pull Request #2448 · ember-cli/eslint-plugin-ember

wagenet · 2026-02-26T01:24:40Z

Summary

Adds ember/template-no-deprecated, a new type-aware rule that flags deprecated Glimmer components, helpers, and modifiers used in <template> blocks
Enabled in recommended-gts config; no-op without parserServices.program (i.e. in plain .gjs files)
Also fixes tests/rule-setup.js to filter subdirectories when comparing test filenames to rule names

How it works

The rule bridges the gap between Glimmer's synthetic AST nodes and TypeScript's type system:

Walk GlimmerElementNode / GlimmerPathExpression → find ESLint scope reference
Resolve to the import binding definition (def.type === 'ImportBinding')
Map def.node → TypeScript AST node via esTreeNodeToTSNodeMap
Walk the alias chain (checker.getImmediateAliasedSymbol) to reach the exported symbol
Check symbol.getJsDocTags(checker) for a @deprecated tag

Covered syntax

Template syntax	AST node
`<DeprecatedComponent />`	`GlimmerElementNode`
`{{deprecatedHelper}}`	`GlimmerPathExpression`
`{{#deprecatedBlock}}`	`GlimmerPathExpression` (block path)
`<div {{deprecatedModifier}}>`	`GlimmerPathExpression`

<MyComp @deprecatedArg={{x}}> is not covered — @arg nodes are not scope-registered by ember-eslint-parser. Options and constraints are documented in docs/arg-deprecation-future-work.md.

Test plan

pnpm test passes (137/137 test files, 3696/3696 tests)
Typed test block exercises deprecated component (element), deprecated helper (mustache), deprecated component (block) — all reported correctly
Non-typed test block confirms rule is a no-op without parserServices.program

🤖 Generated with Claude Code

@deprecated

Flags deprecated Glimmer components, helpers, and modifiers used in <template> by walking from the template reference → ESLint scope variable → import binding → TypeScript symbol → JSDoc @deprecated tag. Requires TypeScript (parserServices.program); no-op in plain .gjs files. Enabled in recommended-gts config. Covers: - <DeprecatedComponent /> (GlimmerElementNode) - {{deprecatedHelper}} (GlimmerPathExpression) - {{#deprecatedBlock}} (GlimmerPathExpression block path) - <div {{deprecatedModifier}}> (GlimmerPathExpression modifier) @arg deprecation is not yet implemented; see docs/arg-deprecation-future-work.md. Also fixes tests/rule-setup.js to filter out subdirectories when checking that test file names match rule names. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

NullVoxPopuli · 2026-02-26T01:55:17Z

Enabled in recommended-gts config;

Rules that add new rules are not allowed to also add to the recommended set.

Changing the recommended set is a breaking change, and we're currently queuing up > 100 new rules for the next release, which should not be a breaking change release.

NullVoxPopuli

please undo the config changes

void-mAlex · 2026-02-26T11:46:24Z

docs/rules/template-no-deprecated.md

+
+## Rule Details
+
+The rule resolves template references through ESLint's scope analysis: a `<Component>` or `{{helper}}` reference is traced back to its import declaration, then the TypeScript type checker inspects the exported symbol's JSDoc tags for `@deprecated`.


this worries me as not all coomponents/helpers modifiers will be imported
gjs format allows for multiple components in a single file as well as in scope helpers modifiers or declared on the class itself

The scope tracking should handle that

- Remove `require('ts-api-utils')` and `require('typescript')` (not declared deps); inline TS_ALIAS_FLAG constant and displayPartsToString logic - Remove `recommendedGts: true` and `requiresTypeChecking` from meta (breaking change, per review; fixes meta-property-ordering lint error) - Fix `eqeqeq`: use `!== undefined` instead of `!= null` - Fix `no-param-reassign`: use `current` variable instead of reassigning `symbol` param - Add `output: null` to invalid test cases (consistent-output lint rule) - Regenerate config files and docs (rule no longer in recommended configs) Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

NullVoxPopuli · 2026-02-26T16:50:24Z

lib/recommended-rules.js

PR needs cleanup

NullVoxPopuli · 2026-02-26T16:50:33Z

tests/__snapshots__/recommended.js.snap

why's this here?

docs/arg-deprecation-future-work.md

tests/lib/rules/template-no-deprecated.js

tests/rule-setup.js

- Remove template-no-deprecated from recommended config snapshot - Revert unrelated semicolon change in recommended-rules.js - Delete docs/arg-deprecation-future-work.md (not part of this PR) - Replace box-drawing characters in test comments with plain ASCII - Revert rule-setup.js filter change (no .ts files in tests/lib/rules/) Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

@deprecated

The .ts fixture files and usage.gts placeholder are required because: 1. The tsconfig glob must match a physically-existing file for TypeScript to include it in the project. 2. The rule only checks ImportBinding definitions, so TypeScript must resolve the imports and read @deprecated from the source files. Added a comment in the test explaining why these files are needed and why other rules can use virtual filenames without real files. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Remove leading newlines and indentation from template literal test cases so character positions in error messages are not offset by invisible whitespace. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

NullVoxPopuli · 2026-02-26T19:49:32Z

lib/rules/template-no-deprecated.js

@@ -0,0 +1,127 @@
+'use strict';
+
+// ts.SymbolFlags.Alias = 2097152 (1 << 21) — stable across all TypeScript versions


is this actually stable across all TS versions? do we have that guarantee?

❯ "ts.SymbolFlags.Alias = 2097152 (1 << 21) — stable across all TypeScript versions" is this guaranteed?

⏺ No. TypeScript's compiler API has no stability guarantee — SymbolFlags is a const enum and values can shift if flags are inserted. The comment overstates it.

In practice, Alias = 1 << 21 has been unchanged since TypeScript was open-sourced (~2014) and is very unlikely to move because it would silently break every @typescript-eslint/* rule that bit-tests it. But "unlikely to change" ≠ "guaranteed".

The defensible fix is to read the value from the TypeScript module the user has installed rather than hardcoding it:

// Get ts from the program's internal reference to avoid adding a direct dependency
const ts = services.program.getCompilerOptions().configFilePath
? require('typescript')
: undefined;
const TS_ALIAS_FLAG = ts?.SymbolFlags?.Alias ?? 2_097_152;

But that's awkward. The cleaner options are:

Add typescript as a peer dependency (already required for typed linting) and require('typescript') directly — this is what @typescript-eslint rules do.

Keep the hardcoded value but fix the comment to say "stable in practice since TypeScript 1.x, not formally guaranteed" — honest and low-risk.

let's keep the hard-coded value, but add this context into the file, as it's important historical context, and may one day requires us require the user's typescript

tests/lib/rules/template-no-deprecated.js

tests/lib/rules-preprocessor/template-no-deprecated/usage.gts

NullVoxPopuli

seems a lot closer -- ci red tho

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

NullVoxPopuli · 2026-02-26T20:45:06Z

lints!

Explains why it's hardcoded, its stability history, and what to do if it ever changes in a future TypeScript release. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

NullVoxPopuli · 2026-02-26T21:28:02Z

lints!

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

docs/rules/template-no-deprecated.md

Remove implementation detail from Rule Details; drop broken "see future work" reference since that doc was removed. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

docs/rules/template-no-deprecated.md

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

docs/rules/template-no-deprecated.md

Detects deprecated component arguments in Glimmer templates via a new GlimmerAttrNode visitor. Navigates the TypeScript type chain from the component's import symbol through getBaseTypes/getTypeArguments to the Args object, then checks getJsDocTags on the specific arg's symbol. Components without typed Args are silently skipped. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

tests/lib/rules/template-no-deprecated.js

NullVoxPopuli · 2026-02-27T01:54:41Z

tests/lib/rules/template-no-deprecated.js

+      output: null,
+      errors: [{ messageId: 'deprecatedWithReason', type: 'GlimmerElementNodePart' }],
+    },
+    // Deprecated helper in mustache position


should also test the sub-expression syntax.

e.g.: {{fn (deprecatedFn 1 2)}}

docs/rules/template-no-deprecated.md

Co-authored-by: wagenet <9835+wagenet@users.noreply.github.com>

…xpression test Co-authored-by: wagenet <9835+wagenet@users.noreply.github.com>

Co-authored-by: wagenet <9835+wagenet@users.noreply.github.com>

Fix review comments on ember/template-no-deprecated

docs/rules/template-no-deprecated.md

NullVoxPopuli · 2026-02-27T20:13:13Z

tests/lib/rules/template-no-deprecated.js

+      filename: path.join(FIXTURES_DIR, 'usage.gts'),
+      code: "import { deprecatedHelper } from './deprecated-helper';\n<template>{{fn (deprecatedHelper)}}</template>",
+      output: null,
+      errors: [{ messageId: 'deprecated', type: 'VarHead' }],


verified VarHead type https://stackblitz.com/edit/stackblitz-starters-uows6skj?description=Starter%20project%20for%20Node.js,%20a%20JavaScript%20runtime%20built%20on%20Chrome%27s%20V8%20JavaScript%20engine&file=index.js&title=node.new%20Starter

NullVoxPopuli requested changes Feb 26, 2026

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void-mAlex reviewed Feb 26, 2026

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