fix(lint): lint/suspicous/noRedeclare should not report redeclarations for infer type in conditional types

[taga3s]

Summary

• Fixes 💅 lint/suspicious/noRedeclare wrongly reported on double type inferrence #7809

Currently, lint/suspicous/noRedeclare wrongly reports redeclarations for infer type in conditional types. So, I added checking if the declaration is infer type or not, and fixed not to report multiple usage of them.

This is my first contribution to this project. Please let me know if there's anything I should do.

Test Plan

I added a new test to valid-conditional-type.ts that demonstarates multiple infer declarations in conditional types.

Docs

[changeset-bot]

🦋 Changeset detected

Latest commit: 34ddf2f

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 13 packages

Name	Type
@biomejs/biome	Patch
@biomejs/cli-win32-x64	Patch
@biomejs/cli-win32-arm64	Patch
@biomejs/cli-darwin-x64	Patch
@biomejs/cli-darwin-arm64	Patch
@biomejs/cli-linux-x64	Patch
@biomejs/cli-linux-arm64	Patch
@biomejs/cli-linux-x64-musl	Patch
@biomejs/cli-linux-arm64-musl	Patch
@biomejs/wasm-web	Patch
@biomejs/wasm-bundler	Patch
@biomejs/wasm-nodejs	Patch
@biomejs/backend-jsonrpc	Patch

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[coderabbitai]

Walkthrough

This change adds a const helper is_infer_type() to AnyJsBindingDeclaration and updates the lint/suspicious/noRedeclare logic to treat two infer type declarations as non-redeclarations when both sides are infer types. A test case introducing TestMultipleInfer<T extends readonly string[]> was added to validate conditional-type scenarios. No public API signatures were otherwise altered.

Suggested reviewers

• ematipico
• dyc3
• arendjr

Pre-merge checks and finishing touches

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title accurately describes the main change: fixing the noRedeclare rule to not report redeclarations for infer types in conditional types.
Description check	✅ Passed	The description clearly explains the issue being fixed (issue #7809), the solution implemented, and mentions test coverage added.
Linked Issues check	✅ Passed	The PR fully addresses issue #7809 by adding an infer type check to prevent false positives when the same infer identifier appears multiple times in conditional types.
Out of Scope Changes check	✅ Passed	All changes are directly scoped to fixing the noRedeclare rule: the lint rule logic, a public helper method on AnyJsBindingDeclaration, a changeset, and a test case.

✨ Finishing touches

• 📝 Generate docstrings

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment

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📜 Recent review details

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between 158d8ee and 34ddf2f.

⛔ Files ignored due to path filters (1)

• crates/biome_js_analyze/tests/specs/suspicious/noRedeclare/valid-conditional-type.ts.snap is excluded by !**/*.snap and included by **

📒 Files selected for processing (4)

• .changeset/breezy-groups-hope.md (1 hunks)
• crates/biome_js_analyze/src/lint/suspicious/no_redeclare.rs (1 hunks)
• crates/biome_js_analyze/tests/specs/suspicious/noRedeclare/valid-conditional-type.ts (1 hunks)
• crates/biome_js_syntax/src/binding_ext.rs (1 hunks)

🚧 Files skipped from review as they are similar to previous changes (3)

• crates/biome_js_analyze/src/lint/suspicious/no_redeclare.rs
• crates/biome_js_syntax/src/binding_ext.rs
• .changeset/breezy-groups-hope.md

🧰 Additional context used

📓 Path-based instructions (1)

**/*.ts

📄 CodeRabbit inference engine (CONTRIBUTING.md)

For Node.js package development, build WebAssembly bindings and JSON-RPC bindings; run tests against compiled files after implementing features or bug fixes

Files:

• crates/biome_js_analyze/tests/specs/suspicious/noRedeclare/valid-conditional-type.ts

🧠 Learnings (3)

📓 Common learnings

Learnt from: CR
Repo: biomejs/biome PR: 0
File: crates/biome_js_type_info/CONTRIBUTING.md:0-0
Timestamp: 2025-11-24T18:05:42.356Z
Learning: Applies to crates/biome_js_type_info/**/js_module_info/collector.rs : Implement module-level (thin) inference to resolve `TypeReference::Qualifier` variants by looking up declarations in module scopes and handling import statements

📚 Learning: 2025-11-24T18:05:42.356Z

Learnt from: CR
Repo: biomejs/biome PR: 0
File: crates/biome_js_type_info/CONTRIBUTING.md:0-0
Timestamp: 2025-11-24T18:05:42.356Z
Learning: Applies to crates/biome_js_type_info/**/*.rs : Distinguish between `TypeData::Unknown` and `TypeData::UnknownKeyword` to measure inference effectiveness versus explicit user-provided unknown types

Applied to files:

• crates/biome_js_analyze/tests/specs/suspicious/noRedeclare/valid-conditional-type.ts

📚 Learning: 2025-11-24T18:05:42.356Z

Learnt from: CR
Repo: biomejs/biome PR: 0
File: crates/biome_js_type_info/CONTRIBUTING.md:0-0
Timestamp: 2025-11-24T18:05:42.356Z
Learning: Applies to crates/biome_js_type_info/**/js_module_info/collector.rs : Implement module-level (thin) inference to resolve `TypeReference::Qualifier` variants by looking up declarations in module scopes and handling import statements

Applied to files:

• crates/biome_js_analyze/tests/specs/suspicious/noRedeclare/valid-conditional-type.ts

🔇 Additional comments (1)

crates/biome_js_analyze/tests/specs/suspicious/noRedeclare/valid-conditional-type.ts (1)

5-9: Excellent test case for the issue!

This correctly demonstrates the scenario from #7809 where multiple infer Base declarations in a conditional type union should be valid. The test will verify that the lint rule no longer incorrectly flags this pattern as a redeclaration.

Welcome aboard, and nice first contribution! 🎉

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[codspeed-hq]

CodSpeed Performance Report

Merging #8417 will not alter performance

_{Comparing taga3s:fix-noredeclare-infer-type (34ddf2f) with main (c96dcf2)}

Summary

✅ 58 untouched
⏩ 95 skipped¹

Footnotes

1. 95 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. ↩