fix(transformer): handle declare fields in class properties transformation

Fixes issue where declare fields were incorrectly transformed instead of being removed,
causing inheritance issues where child declare fields would interfere with parent
class property initialization.

- Add logic to remove declare fields when set_public_class_fields and remove_class_fields_without_initializer are both true
- Add comprehensive test cases covering declare fields in various scenarios
- Handle both instance and static declare fields
- Support declare fields with computed keys

Fixes #13733

Author: Dunqing

crates/oxc_transformer/src/es2022/class_properties/class.rs

@@ -261,7 +261,7 @@ impl<'a> ClassProperties<'a, '_> {
             #[expect(clippy::match_same_arms)]
             match element {
                 ClassElement::PropertyDefinition(prop) => {
-                    if !prop.r#static {
+                    if !prop.r#static && !prop.declare {
                         self.convert_instance_property(prop, &mut instance_inits, ctx);
                     }
                 }
@@ -766,6 +766,11 @@ impl<'a> ClassProperties<'a, '_> {
         class.body.body.retain_mut(|element| {
             match element {
                 ClassElement::PropertyDefinition(prop) => {
+                    if prop.declare {
+                        // Remove `declare` properties
+                        return false;
+                    }
+
                     if prop.r#static {
                         self.convert_static_property(prop, ctx);
                     } else if prop.computed {

crates/oxc_transformer/src/es2022/class_properties/mod.rs

@@ -404,7 +404,7 @@ impl<'a> Traverse<'a, TransformState<'a>> for ClassProperties<'a, '_> {
         prop: &mut PropertyDefinition<'a>,
         _ctx: &mut TraverseCtx<'a>,
     ) {
-        if prop.r#static {
+        if prop.r#static && !prop.declare {
             self.flag_entering_static_property_or_block();
         }
     }
@@ -414,7 +414,7 @@ impl<'a> Traverse<'a, TransformState<'a>> for ClassProperties<'a, '_> {
         prop: &mut PropertyDefinition<'a>,
         _ctx: &mut TraverseCtx<'a>,
     ) {
-        if prop.r#static {
+        if prop.r#static && !prop.declare {
             self.flag_exiting_static_property_or_block();
         }
     }

tasks/transform_conformance/snapshots/oxc.snap.md

@@ -1,6 +1,6 @@
 commit: 41d96516
 
-Passed: 186/313
+Passed: 187/315
 
 # All Passed:
 * babel-plugin-transform-class-static-block
@@ -39,7 +39,7 @@ after transform: SymbolId(4): ScopeId(1)
 rebuilt        : SymbolId(5): ScopeId(4)
 
 
-# babel-plugin-transform-class-properties (23/29)
+# babel-plugin-transform-class-properties (24/31)
 * private-field-resolve-to-method/input.js
 x Output mismatch
 
@@ -52,6 +52,11 @@ x Output mismatch
 * static-super-tagged-template/input.js
 x Output mismatch
 
+* typescript/declare-computed-keys/input.ts
+Symbol reference IDs mismatch for "KEY1":
+after transform: SymbolId(0): [ReferenceId(0), ReferenceId(2)]
+rebuilt        : SymbolId(1): []
+
 * typescript/optional-call/input.ts
 Symbol reference IDs mismatch for "X":
 after transform: SymbolId(0): [ReferenceId(0), ReferenceId(2), ReferenceId(6), ReferenceId(11), ReferenceId(16)]

tasks/transform_conformance/snapshots/oxc_exec.snap.md

@@ -2,7 +2,7 @@ commit: 41d96516
 
 node: v22.14.0
 
-Passed: 8 of 10 (80.00%)
+Passed: 9 of 11 (81.82%)
 
 Failures:
 

tasks/transform_conformance/tests/babel-plugin-transform-class-properties/test/fixtures/typescript/declare-computed-keys/input.ts

@@ -0,0 +1,17 @@
+// Test declare fields with computed keys
+const KEY1 = "dynamicKey1";
+const KEY2 = "dynamicKey2";
+
+class TestClass {
+  // declare field with computed key should be removed
+  declare [KEY1]: string;
+  
+  // regular field with computed key should be transformed
+  [KEY2]: number = 42;
+  
+  // static declare field with computed key should be removed
+  declare static [KEY1 + "Static"]: boolean;
+  
+  // regular static field with computed key should be transformed
+  static [KEY2 + "Static"]: string = "static";
+}

tasks/transform_conformance/tests/babel-plugin-transform-class-properties/test/fixtures/typescript/declare-computed-keys/output.js

@@ -0,0 +1,16 @@
+let _ref;
+// Test declare fields with computed keys
+const KEY1 = "dynamicKey1";
+const KEY2 = "dynamicKey2";
+_ref = KEY2 + "Static";
+
+class TestClass {
+  // regular field with computed key should be transformed
+  constructor() {
+    babelHelpers.defineProperty(this, KEY2, 42);
+  }
+  
+  // regular static field with computed key should be transformed
+}
+
+babelHelpers.defineProperty(TestClass, _ref, "static");

tasks/transform_conformance/tests/babel-plugin-transform-class-properties/test/fixtures/typescript/declare-fields/exec.ts

@@ -0,0 +1,21 @@
+// Test case for declare fields issue #13733
+class B {
+  public value: number = 3;
+  
+  constructor(value?: number) {
+    if (value !== undefined) {
+      this.value = value;
+    }
+  }
+}
+
+class C extends B {
+  declare public value: number;
+
+  log() {
+    return "C " + this.value
+  }
+}
+
+// This should log "C 6", not "C undefined"
+expect(new C(6).log()).toBe("C 6");

tasks/transform_conformance/tests/babel-plugin-transform-class-properties/test/fixtures/typescript/declare-fields/input.ts

@@ -0,0 +1,21 @@
+// Test case for declare fields issue #13733
+class B {
+	public value: number = 3;
+
+	constructor(value?: number) {
+		if (value !== undefined) {
+			this.value = value;
+		}
+	}
+}
+
+class C extends B {
+	public declare value: number;
+
+	log() {
+		return "C " + this.value;
+	}
+}
+
+// This should log "C 6", not "C undefined"
+expect(new C(6).log()).toBe("C 6");

tasks/transform_conformance/tests/babel-plugin-transform-class-properties/test/fixtures/typescript/declare-fields/output.js

@@ -0,0 +1,15 @@
+
+class B {
+  constructor(value) {
+    babelHelpers.defineProperty(this, "value", 3);
+    if (value !== undefined) {
+      this.value = value;
+    }
+  }
+}
+class C extends B {
+  log() {
+    return "C " + this.value;
+  }
+}
+expect(new C(6).log()).toBe("C 6");