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feat(biome_js_analyze): Improve no_unused_private_class_members to handle dynamic access class members based on their ts type
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‎.changeset/no_unused_private_class_members_amended.md‎

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---
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"@biomejs/biome": patch
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---
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Changed [`noUnusedPrivateClassMembers`](https://biomejs.dev/linter/rules/no-unused-private-class-members/) to align more fully with meaningful reads.
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This rule now distinguishes more carefully between writes and reads of private class members.
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- A *meaningful read* is any access that affects program behavior.
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- For example, `this.#x += 1` both reads and writes `#x`, so it counts as usage.
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- Pure writes without a read (e.g. `this.#x = 1` with no getter) are no longer treated as usage.
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This change ensures that private members are only considered “used” when they are actually read in a way that influences execution.
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***Invalid examples (previously valid)***
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```ts
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class UsedMember {
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set #x(value) {
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doSomething(value);
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}
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foo() {
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// This assignment does not actually read #x, because there is no getter.
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// Previously, this was considered a usage, but now it’s correctly flagged.
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this.#x = 1;
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}
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}
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```
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***Valid example (Previously invalid)***
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```js
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class Foo {
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#usedOnlyInWriteStatement = 5;
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method() {
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// This counts as a meaningful read because we both read and write the value.
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this.#usedOnlyInWriteStatement += 42;
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}
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}
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```
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***Summary***
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• Only accesses that read a value are considered meaningful for the purpose of this rule.
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• Simple assignments to a setter without a corresponding getter no longer count as usage.
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• Operations like +=, method calls returning a value, or reading the property for computation are considered meaningful reads.

‎.changeset/no_unused_private_class_members_dynamic_usages.md‎

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"@biomejs/biome": patch
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**Improved detection of used private class members**
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The analysis for private class members has been improved: now the tool only considers a private member “used” if it is actually referenced in the code.
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- Previously, some private members might have been reported as used even if they weren’t actually accessed.
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- With this change, only members that are truly read or called in the code are counted as used.
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- Members that are never accessed will now be correctly reported as unused.
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This makes reports about unused private members more accurate and helps you clean up truly unused code.
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***Example (previously valid)***
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```ts
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type YesNo = "yes" | "no";
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export class SampleYesNo {
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private yes: () => void;
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private no: () => void;
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private dontKnow: () => void; // <- will now report as unused
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on(action: YesNo): void {
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this[action]();
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}
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}
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```

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