feat(linter/prefer-template): implement autofix by Edweis · Pull Request #21502 · oxc-project/oxc

Edweis · 2026-04-16T11:19:29Z

Summary

Port the --fix implementation from ESLint's prefer-template rule
Convert string concatenation with non-string operands into template literals
Handle backtick/${ escaping, quote unescaping, comment preservation, and octal escape detection (skip fix when present)
Add 60+ fix test cases ported from ESLint

AI Disclosure: This PR was developed with AI assistance (Claude). All code has been reviewed and tested by the contributor.

Test plan

All existing prefer-template pass/fail tests still pass
60+ fix test cases covering: simple concatenation, nested expressions, parenthesized expressions, backtick escaping, ${ escaping, quote unescaping, comment preservation, octal escape no-fix, and multi-line strings
Snapshot updated
just ready full check

🤖 Generated with Claude Code

Edweis · 2026-04-16T11:22:46Z

Hello I am the contributor, to give more context the tests and implementation have been ported from eslint:

Port the `--fix` implementation from ESLint's `prefer-template` rule. Converts string concatenation with non-string operands into template literals, handling backtick/`${` escaping, quote unescaping, comment preservation, and octal escape detection (skip fix). Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

- Switch all backslash-containing test strings to raw strings for correct JS source representation - Add missing favorites.map arrow function test cases from ESLint - Fix octal escape test cases (\033, \08, \0) to match ESLint source - Update snapshot Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Restore all pass/fail test strings to match main exactly. Fix expectations computed for the original test strings. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

…ction helpers Reuse the existing `is_string_literal()` method from oxc_ast instead of manually matching on StringLiteral/TemplateLiteral variants. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

camc314 · 2026-04-16T13:05:19Z

also, is this ready for review? it's still marked as draft

Edweis · 2026-04-16T13:07:15Z

I am sending the final commit and then it will be ready for review. I'll ping you once ready.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Edweis · 2026-04-16T13:30:03Z

@camc314 ready for review 👍

codspeed-hq · 2026-04-16T13:49:05Z

Merging this PR will not alter performance

✅ 4 untouched benchmarks
⏩ 47 skipped benchmarks¹

_{Comparing Edweis:feat/prefer-template-fix (9e1fd61) with main (a5cab18)}

47 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

…21505) taken from #21502 to reduce the diff

camc314

Thank you!

# Oxlint ### 💥 BREAKING CHANGES - 24fb7eb allocator: [**BREAKING**] Rename `Box` and `Vec` methods (#21395) (overlookmotel) ### 🚀 Features - 38d8090 linter/jest: Implemented jest `version` settings in config file. (#21522) (Said Atrahouch) - 7dbbb99 linter/eslint: Implement suggestion for `no-case-declarations` rule (#21508) (Mikhail Baev) - 9b4d9f6 linter/prefer-template: Implement autofix (#21502) (François) - daa64ed linter/no-empty-pattern: Add `allowObjectPatternsAsParameters` option (#21474) (camc314) - cf2d281 linter/typescript: Implement explicit-member-accessibility (#21447) (Hunter Tunnicliff) - d48de6f linter/unicorn: Add help messages to 3 rule diagnostics (#21459) (Mukunda Rao Katta) - cffdc2e linter: Backfill rule version metadata (#21391) (Old Autumn) ### 🐛 Bug Fixes - 1e69b91 linter/no-useless-assignment: Improve diagnostic spans (#21581) (camc314) - f272594 linter/plugins: Align `RuleMeta.replacedBy` type with ESLint (#21544) (bab) - 4d57851 linter/eslint: Enhance `no-empty-function` rule to support async and generator functions in VariableDeclarator (#21542) (Mikhail Baev) - 00fc136 codegen: Preserve coverage comments before object properties (#21312) (bab) - a56b7b9 oxlint: Dont enable gitlab formatter by default (#21501) (camc314) - 9c9b6a2 linter/array-callback-return: Ignore non-exit CFG dead ends (#21497) (camc314) - 61088e0 linter/unicorn: Handle computed property access in `prefer-dom-node-remove` rule (#21470) (Mikhail Baev) - eab5934 linter: Report an error on unsupported `extends` values (#21406) (John Costa) - 3289ba0 linter/valid-expect-in-promise: Check a jest fn to be `test` instead of `describe` (#21422) (Said Atrahouch) - 4417fe3 linter/prefer-ending-with-an-expect: Ignore vi.mock factory callbacks (#21414) (Cédric Exbrayat) - a904883 linter/consistent-type-imports: Ignore vue/svelte/astro files (#21415) (bab) - 2498fe6 linter/no-unused-vars: Allow segments of dotted namespace declarations (#21416) (bab) - 44b5b35 linter: Preserve vitest-compatible jest rules when applying overrides (#21389) (Cameron) - 7bd8331 linter/prefer-ending-with-an-expect: Add missing `version` docs (#21390) (Said Atrahouch) - 43d8f0d linter/no-useless-assignment: Ignore writes read by closures (#21380) (camc314) ### 📚 Documentation - c1eeae3 linter: Add version to `rule.json` (#21547) (camchenry) - 0ec6ab2 linter: Improve the `vitest/no-importing-vitest-globals` rule documentation. (#21557) (connorshea) # Oxfmt ### 💥 BREAKING CHANGES - 24fb7eb allocator: [**BREAKING**] Rename `Box` and `Vec` methods (#21395) (overlookmotel) ### 🚀 Features - 5aa7fe1 oxfmt: Add `--disable-nested-config` CLI flag (#21514) (leaysgur) - b5cb8d1 oxfmt: Update prettier to 3.8.3 (#21451) (leaysgur) - 16713d5 oxfmt/cli: Support per-directory config (#21103) (leaysgur) - 952de06 oxfmt/lsp: Support per-directory config (#21081) (leaysgur) ### 🐛 Bug Fixes - a501a53 formatter: Handle comments after pipe in single-member union types (#21487) (John Costa) - 6f49fad oxfmt: Respect nested config.`ignorePatterns` (#21489) (leaysgur) - 7c98d52 oxfmt: Do not panic on finding invalid nested config (#21461) (leaysgur) - 41bb2d5 formatter: Preserve more `intrinsic` parens (#21449) (leaysgur) - f894750 formatter: Preserve parens around `intrinsic` in type alias annotation (#21410) (Dunqing) ### ⚡ Performance - df27b48 oxfmt: Skip ancestors check when no nested config found (#21517) (leaysgur) - 5e1522a oxfmt: Do not occupy the rayon thread solely for handover (#21408) (leaysgur) Co-authored-by: camc314 <18101008+camc314@users.noreply.github.com>

github-actions Bot added A-linter Area - Linter C-enhancement Category - New feature or request labels Apr 16, 2026

Edweis and others added 3 commits April 16, 2026 13:24

style: apply rustfmt formatting

430da8c

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

docs: add comment explaining noop fix for octal escapes

0c90d77

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Edweis force-pushed the feat/prefer-template-fix branch from 00fcc49 to 0c90d77 Compare April 16, 2026 11:41

camc314 reviewed Apr 16, 2026

View reviewed changes

Comment thread crates/oxc_linter/src/rules/eslint/prefer_template.rs Outdated

camc314 reviewed Apr 16, 2026

View reviewed changes

Comment thread crates/oxc_linter/src/rules/eslint/prefer_template.rs Outdated

Edweis and others added 3 commits April 16, 2026 14:24

fix: restore original tests, only add fix vec

bfadbe1

Restore all pass/fail test strings to match main exactly. Fix expectations computed for the original test strings. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

chore: remove stale comment

2fd446d

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Edweis commented Apr 16, 2026

View reviewed changes

Comment thread crates/oxc_linter/src/rules/eslint/prefer_template.rs

Edweis and others added 3 commits April 16, 2026 15:12

chore: update stacktrace snapshot for Node.js v24.15.0

1add0df

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

fix: address clippy collapsible_if and disallowed_methods lints

6852481

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

fix: address clippy needless_raw_string_hashes and explicit_auto_deref

face53d

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

github-actions Bot added the A-codegen Area - Code Generation label Apr 16, 2026

Edweis marked this pull request as ready for review April 16, 2026 13:30

Merge branch 'main' into feat/prefer-template-fix

daca521

Edweis commented Apr 16, 2026

View reviewed changes

Comment thread crates/oxc_codegen/tests/integration/snapshots/stacktrace_is_correct.snap Outdated

fix snapshot

eabb2f8

Edweis force-pushed the feat/prefer-template-fix branch from ebf67cf to eabb2f8 Compare April 16, 2026 13:54

camc314 removed the A-codegen Area - Code Generation label Apr 16, 2026

camc314 mentioned this pull request Apr 16, 2026

refactor(linter/prefer-template): simplify string expression checks #21505

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u

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graphite-app Bot pushed a commit that referenced this pull request Apr 16, 2026

refactor(linter/prefer-template): simplify string expression checks (#…

a5cab18

…21505) taken from #21502 to reduce the diff

camc314 added 2 commits April 16, 2026 17:07

clippy

f2495c0

Merge branch 'main' into feat/prefer-template-fix

9e1fd61

camc314 approved these changes Apr 16, 2026

View reviewed changes

camc314 self-assigned this Apr 16, 2026

camc314 merged commit 9b4d9f6 into oxc-project:main Apr 16, 2026
26 checks passed

Edweis deleted the feat/prefer-template-fix branch April 16, 2026 16:28

This was referenced Apr 17, 2026

fix(isolated_declarations): drop required type check for private parameter properties on private constructors #21515

Merged

fix(isolated_declarations): collect types from private accessors for paired inference #21516

Merged

This was referenced Apr 20, 2026

release(apps): oxlint v1.61.0 && oxfmt v0.46.0 #21573

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release(apps): oxlint v1.61.0 && oxfmt v0.46.0 #21583

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feat(linter/prefer-template): implement autofix#21502

feat(linter/prefer-template): implement autofix#21502
camc314 merged 15 commits intooxc-project:mainfrom
Edweis:feat/prefer-template-fix

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Merging this PR will not alter performance

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Edweis commented Apr 16, 2026 •

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