fix(noInvalidUseBeforeDeclaration): handle class, enum, import-equals #8113

Conaclos · 2025-11-15T11:46:31Z

Summary

This PR adds the handling of classes, enums, and TS's import-equals to the noInvalidUseBeforeDeclaration rule.

For example, The following code is now reported as invalid:

new C();
class C {}

Note that the following code is not reported because it is valid:

function f() {
  new C();
}
let c: C;
class C {}

new C2();
declare class C2 {}

Test Plan

I added several tests to cover the new cases.

Docs

I added a changeset.
I also updated the rule's description.

changeset-bot · 2025-11-15T11:46:35Z

🦋 Changeset detected

Latest commit: b43edcc

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 · 2025-11-15T11:53:16Z

Walkthrough

This PR extends the noInvalidUseBeforeDeclaration lint to add Class and Enum as distinct DeclarationKind variants, updates end-of-declaration and control-flow-root logic to special-case classes/enums, refines ambient/declare handling and import-equals recognition, maps diagnostics for the new kinds to "class" and "enum", derives Eq/PartialEq where needed, and updates tests to cover JavaScript and TypeScript class, enum and import‑equals usage-before-declaration scenarios.

Possibly related PRs

fix(noInvalidUseBeforeDeclaration): don't report use before ambient var declaration #8104 — Modifies the same no_invalid_use_before_declaration rule, including DeclarationKind and ambient-declaration handling; strong code-level overlap.

Suggested reviewers

dyc3
ematipico

Pre-merge checks and finishing touches

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	You can run `@coderabbitai generate docstrings` to improve docstring coverage.

✅ Passed checks (2 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title directly and concisely captures the main change: extending noInvalidUseBeforeDeclaration to handle classes, enums, and import-equals.
Description check	✅ Passed	The description is well-related to the changeset, providing clear examples and explaining the new functionality, test coverage, and documentation updates.

✨ Finishing touches

📝 Generate docstrings

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Create PR with unit tests
Post copyable unit tests in a comment
Commit unit tests in branch conaclos/noInvalidUseBeforeDeclaration-class-enum

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codspeed-hq · 2025-11-15T11:57:59Z

CodSpeed Performance Report

Merging #8113 will not alter performance

_{Comparing conaclos/noInvalidUseBeforeDeclaration-class-enum (b43edcc) with main (041196b)}

Summary

✅ 58 untouched
⏩ 95 skipped¹

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. ↩

coderabbitai

Actionable comments posted: 1

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crates/biome_js_analyze/tests/specs/correctness/noInvalidUseBeforeDeclaration/valid.js (1 hunks)

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🔇 Additional comments (1)

crates/biome_js_analyze/tests/specs/correctness/noInvalidUseBeforeDeclaration/valid.js (1)

16-18: Good test case for self-referencing static fields.

This correctly validates that static field initialisers can reference their own class, as they execute after the class is fully declared.

crates/biome_js_analyze/tests/specs/correctness/noInvalidUseBeforeDeclaration/valid.js

Conaclos · 2025-11-15T12:43:21Z

crates/biome_js_analyze/src/lint/correctness/no_invalid_use_before_declaration.rs

-            let declaration_end = declaration.range().end();
-            let declaration_control_flow_root =
-                if let AnyJsBindingDeclaration::JsVariableDeclarator(declarator) = declaration
-                    .parent_binding_pattern_declaration()
-                    .unwrap_or(declaration)
-                {
-                    declarator
-                        .syntax()
-                        .ancestors()
-                        .skip(1)
-                        .find(|ancestor| AnyJsControlFlowRoot::can_cast(ancestor.kind()))
-                } else {
-                    None
-                };


I don't know why we did this. No test seems to cover this. Previously we handled only variables and enum members. It seems that we wished to exclude enum members from same-scope checking.

coderabbitai

Actionable comments posted: 0

🧹 Nitpick comments (1)

crates/biome_js_analyze/src/lint/correctness/no_invalid_use_before_declaration.rs (1)
119-128: Consider clarifying the comment about class and enum handling.

The logic is correct—using id.range().end() for classes and enums allows self-references within the declaration body whilst flagging earlier uses. The comment could be more explicit about this distinction.

For example:
-// A class can be instantiated by its properties.
-// Enum members can be qualified by the enum name.
+// For classes and enums, use the identifier position as the declaration end.
+// This allows self-references within the class/enum body (e.g., `new C()` in a method)
+// whilst still flagging usage before the identifier (e.g., `new C(); class C {}`).

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crates/biome_js_analyze/src/lint/correctness/no_invalid_use_before_declaration.rs (8 hunks)
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crates/biome_js_analyze/tests/specs/correctness/noInvalidUseBeforeDeclaration/valid.ts (2 hunks)

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crates/biome_js_analyze/tests/specs/correctness/noInvalidUseBeforeDeclaration/valid.ts

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crates/biome_js_analyze/tests/specs/correctness/noInvalidUseBeforeDeclaration/valid.js (1)

crates/biome_js_analyze/tests/specs/correctness/noInvalidUseBeforeDeclaration/invalid.js (1)

instance (20-20)

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🔇 Additional comments (6)

crates/biome_js_analyze/tests/specs/correctness/noInvalidUseBeforeDeclaration/valid.js (1)

13-18: LGTM! Past duplicate function issue resolved and test cases are spot-on.

The function has been properly renamed from f() to useClassInFunction(), resolving the previous duplicate declaration concern. Both test cases correctly validate the rule's intended behaviour:

Using Class inside an uncalled function before its declaration is valid (the class will exist when the function eventually executes)

Self-referencing Class in its own static field is valid (static initialisers run after the constructor is defined)

crates/biome_js_analyze/src/lint/correctness/no_invalid_use_before_declaration.rs (5)

14-73: Documentation clearly explains the extended rule coverage.

The updated description and examples effectively communicate that the rule now handles classes and enums alongside variables and parameters.

192-193: Diagnostic text mapping is correct.

The new variants are properly mapped to their user-facing names.

219-226: Enum extension and derives look good.

The Eq and PartialEq derives are necessary for the pattern matching at line 119, and the new Class and Enum variants properly extend the declaration kinds.

257-271: Ambient class and enum handling is correct.

Properly excludes declare class and declare enum from use-before-declaration checks, as these ambient declarations can be used before their declarations appear in the source.

240-240: The implementation is correct—no changes needed.

TypeScript's import x = require("mod") emits a runtime const x = require() assignment, not a hoisted ES module binding. It therefore behaves like any const declaration and should be subject to use-before-declaration checks. The existing test confirms this: x; import x = require("file"); is correctly flagged as invalid. Both forms of import = (require and namespace) are appropriately classified as Variable.

…biomejs#8113) Co-authored-by: autofix-ci[bot] <114827586+autofix-ci[bot]@users.noreply.github.com>

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Conaclos force-pushed the conaclos/noInvalidUseBeforeDeclaration-class-enum branch from 622c837 to 1ecb148 Compare November 15, 2025 12:32

fix(noInvalidUseBeforeDeclaration): handle class, enum, import-equals

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Conaclos force-pushed the conaclos/noInvalidUseBeforeDeclaration-class-enum branch from 1ecb148 to ec559b9 Compare November 15, 2025 12:40

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Conaclos commented Nov 15, 2025

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[autofix.ci] apply automated fixes

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Conaclos force-pushed the conaclos/noInvalidUseBeforeDeclaration-class-enum branch 3 times, most recently from f2779e5 to b43edcc Compare November 15, 2025 12:55

Conaclos requested review from a team November 15, 2025 12:56

fix: take review into account

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dyc3 approved these changes Nov 15, 2025

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Conaclos merged commit fb8e3e7 into main Nov 15, 2025
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Conaclos deleted the conaclos/noInvalidUseBeforeDeclaration-class-enum branch November 15, 2025 15:51

github-actions bot mentioned this pull request Nov 15, 2025

ci: release #8076

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coderabbitai bot mentioned this pull request Nov 18, 2025

fix(noInvalidUseBeforeDeclaration): ignore valid use before declarations #8157

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ematipico pushed a commit to hamirmahal/biome that referenced this pull request Nov 19, 2025

fix(noInvalidUseBeforeDeclaration): handle class, enum, import-equals (…

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Conaclos commented Nov 15, 2025

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