biomejs · vladimir-ivanov · Sep 28, 2025 · Sep 29, 2025 · Sep 29, 2025 · Sep 29, 2025
diff --git a/.changeset/no_unused_private_class_members_amended.md b/.changeset/no_unused_private_class_members_amended.md
@@ -0,0 +1,47 @@
+---
+"@biomejs/biome": patch
+---
+
+Changed [`noUnusedPrivateClassMembers`](https://biomejs.dev/linter/rules/no-unused-private-class-members/) to align more fully with meaningful reads.
+
+This rule now distinguishes more carefully between writes and reads of private class members.
+
+- A *meaningful read* is any access that affects program behavior.
+- For example, `this.#x += 1` both reads and writes `#x`, so it counts as usage.
+- Pure writes without a read (e.g. `this.#x = 1` with no getter) are no longer treated as usage.
+
+This change ensures that private members are only considered “used” when they are actually read in a way that influences execution.
+
+***Invalid examples (previously valid)***
+
+```ts
+class UsedMember {
+  set #x(value) {
+    doSomething(value);
+  }
+
+  foo() {
+    // This assignment does not actually read #x, because there is no getter.
+    // Previously, this was considered a usage, but now it’s correctly flagged.
+    this.#x = 1;
+  }
+}
+```
+
+***Valid example (Previously invalid)***
+
+```js
+class Foo {
+  #usedOnlyInWriteStatement = 5;
+
+  method() {
+    // This counts as a meaningful read because we both read and write the value.
+    this.#usedOnlyInWriteStatement += 42;
+  }
+}
+```
+
+***Summary***
+•	Only accesses that read a value are considered meaningful for the purpose of this rule.
+•	Simple assignments to a setter without a corresponding getter no longer count as usage.
+•	Operations like +=, method calls returning a value, or reading the property for computation are considered meaningful reads.