fix: Decorators when super() exists & protoInit not needed (#16385)

packages/babel-helper-create-class-features-plugin/src/decorators.ts

@@ -475,26 +475,28 @@ function optimizeSuperCallAndExpressions(
   expressions: t.Expression[],
   protoInitLocal: t.Identifier,
 ) {
-  // Merge `super(), protoInit(this)` into `protoInit(super())`
-  if (
-    expressions.length >= 2 &&
-    isProtoInitCallExpression(expressions[1], protoInitLocal)
-  ) {
-    const mergedSuperCall = t.callExpression(t.cloneNode(protoInitLocal), [
-      expressions[0],
-    ]);
-    expressions.splice(0, 2, mergedSuperCall);
-  }
-  // Merge `protoInit(super()), this` into `protoInit(super())`
-  if (
-    expressions.length >= 2 &&
-    t.isThisExpression(expressions[expressions.length - 1]) &&
-    isProtoInitCallExpression(
-      expressions[expressions.length - 2],
-      protoInitLocal,
-    )
-  ) {
-    expressions.splice(expressions.length - 1, 1);
+  if (protoInitLocal) {
+    if (
+      expressions.length >= 2 &&
+      isProtoInitCallExpression(expressions[1], protoInitLocal)
+    ) {
+      // Merge `super(), protoInit(this)` into `protoInit(super())`
+      const mergedSuperCall = t.callExpression(t.cloneNode(protoInitLocal), [
+        expressions[0],
+      ]);
+      expressions.splice(0, 2, mergedSuperCall);
+    }
+    // Merge `protoInit(super()), this` into `protoInit(super())`
+    if (
+      expressions.length >= 2 &&
+      t.isThisExpression(expressions[expressions.length - 1]) &&
+      isProtoInitCallExpression(
+        expressions[expressions.length - 2],
+        protoInitLocal,
+      )
+    ) {
+      expressions.splice(expressions.length - 1, 1);
+    }
   }
   return maybeSequenceExpression(expressions);
 }

packages/babel-plugin-proposal-decorators/test/fixtures/2023-11-misc--to-es2015/initField-existing-derived-constructor/exec.js

@@ -0,0 +1,175 @@
+{
+  let self, a, initCalled;
+
+  function deco(_, context) {
+    context.addInitializer(() => {
+      initCalled = true;
+    });
+  }
+
+  class B {
+    constructor(s) {
+      a = s;
+    }
+  }
+
+  class A extends B {
+    constructor() {
+      let a = 2;
+      self = super(a);
+    }
+
+    @deco
+    accessor foo = 42;
+  }
+
+  let instance = new A();
+  expect(self).toBe(instance);
+  expect(a).toBe(2);
+  expect(initCalled).toBe(true);
+}
+
+{
+  const dec = ({ get, set }) => {
+    return {
+      get() {
+        return get.call(this) + 100;
+      },
+
+      set(v) {
+        set.call(this, v);
+      },
+    }
+  };
+
+  class B {
+    constructor(v) {
+      this.a = v;
+    }
+    method() {
+      return this.a;
+    }
+  }
+
+  {
+    ("super() nested within another constructor should not be transformed");
+    let log = [];
+    class A extends B {
+      constructor() {
+        log.push(super(3).method());
+        new (class Dummy extends B {
+          constructor() {
+            log.push(super(4).method());
+          }
+        })();
+      }
+
+      @dec
+      accessor foo = 42;
+    }
+
+    const a = new A();
+
+    expect(log + "").toBe("3,4");
+    expect(a.foo).toBe(142);
+  }
+
+  {
+    ("super() not in decorated derived constructor should not be transformed: computed key");
+    let log = [];
+    new (class Dummy extends B {
+      constructor() {
+        let key;
+        class A extends B {
+          constructor() {
+            log.push(super(6).method());
+          }
+
+          @dec
+          accessor foo = 42;
+
+          [((key = super(5).method()), log.push(key), key)];
+        }
+
+        const a = new A();
+
+        expect(a.foo).toBe(142);
+      }
+    })();
+
+    expect(log + "").toBe("5,6");
+  }
+
+  {
+    ("super() in decorator expression within decorated derived constructor should be transformed: decorator expression");
+    let log = [];
+    const noop = () => (fn) => fn;
+    new (class extends B {
+      constructor() {
+        class A extends B {
+          constructor() {
+            log.push(super(8).method());
+          }
+
+          @dec
+          accessor foo = 42;
+
+          @noop(log.push(super(7).method())) noop() {}
+        }
+
+        const a = new A();
+        expect(a.foo).toBe(142);
+      }
+    })();
+
+    expect(log + "").toBe("7,8");
+  }
+
+  {
+    ("super() within decorated derived constructor should be transformed: computed key");
+    let log = [];
+    class A extends B {
+      constructor() {
+        let key;
+        new (class Dummy extends B {
+          constructor() {
+            log.push(super(10).method());
+          }
+          [((key = super(9).method()), log.push(key), key)];
+        })();
+      }
+
+      @dec
+      accessor foo = 42;
+    }
+
+    const a = new A();
+
+    expect(log + "").toBe("9,10");
+    expect(a.foo).toBe(142);
+  }
+
+  {
+    ("super() within decorated derived constructor should be transformed: decorator expression");
+    let log = [];
+    const noop = () => (fn) => fn;
+    class A extends B {
+      constructor() {
+        new (class Dummy extends B {
+          constructor() {
+            log.push(super(12).method());
+          }
+          @noop(log.push(super(11).method())) noop() {}
+        })();
+      }
+
+      @dec
+      accessor foo = 42;
+    }
+
+    const a = new A();
+
+    expect(log + "").toBe("11,12");
+    expect(a.foo).toBe(142);
+  }
+}