Don't duplicate the base class when using constantSuper

packages/babel-helper-create-class-features-plugin/src/fields.js

@@ -672,7 +672,7 @@ const thisContextVisitor = traverse.visitors.merge([
 function replaceThisContext(
   path,
   ref,
-  superRef,
+  getSuperRef,
   file,
   isStaticBlock,
   constantSuper,
@@ -682,9 +682,9 @@ function replaceThisContext(
   const replacer = new ReplaceSupers({
     methodPath: path,
     constantSuper,
-    superRef,
     file,
     refToPreserve: ref,
+    getSuperRef,
     getObjectRef() {
       state.needsClassRef = true;
       return isStaticBlock || path.node.static
@@ -710,11 +710,20 @@ export function buildFieldsInitNodes(
   constantSuper,
 ) {
   let needsClassRef = false;
+  let injectSuperRef;
   const staticNodes = [];
   const instanceNodes = [];
   // These nodes are pure and can be moved to the closest statement position
   const pureStaticNodes = [];
 
+  const getSuperRef = t.isIdentifier(superRef)
+    ? () => superRef
+    : () => {
+        injectSuperRef ??=
+          props[0].scope.generateUidIdentifierBasedOnNode(superRef);
+        return injectSuperRef;
+      };
+
   for (const prop of props) {
     ts.assertFieldTransformed(prop);
 
@@ -730,7 +739,7 @@ export function buildFieldsInitNodes(
       const replaced = replaceThisContext(
         prop,
         ref,
-        superRef,
+        getSuperRef,
         state,
         isStaticBlock,
         constantSuper,
@@ -865,6 +874,14 @@ export function buildFieldsInitNodes(
         prop.remove();
       }
 
+      if (injectSuperRef) {
+        path.scope.push({ id: t.cloneNode(injectSuperRef) });
+        path.set(
+          "superClass",
+          t.assignmentExpression("=", injectSuperRef, path.node.superClass),
+        );
+      }
+
       if (!needsClassRef) return path;
 
       if (path.isClassExpression()) {

packages/babel-helper-replace-supers/src/index.ts

@@ -206,22 +206,20 @@ const looseHandlers = {
   },
 
   get(superMember) {
-    const { isStatic, superRef } = this;
+    const { isStatic, getSuperRef } = this;
     const { computed } = superMember.node;
     const prop = this.prop(superMember);
 
     let object;
     if (isStatic) {
-      object = superRef
-        ? t.cloneNode(superRef)
-        : t.memberExpression(
-            t.identifier("Function"),
-            t.identifier("prototype"),
-          );
+      object =
+        getSuperRef() ??
+        t.memberExpression(t.identifier("Function"), t.identifier("prototype"));
     } else {
-      object = superRef
-        ? t.memberExpression(t.cloneNode(superRef), t.identifier("prototype"))
-        : t.memberExpression(t.identifier("Object"), t.identifier("prototype"));
+      object = t.memberExpression(
+        getSuperRef() ?? t.identifier("Object"),
+        t.identifier("prototype"),
+      );
     }
 
     return t.memberExpression(object, prop, computed);
@@ -264,15 +262,15 @@ type ReplaceSupersOptionsBase = {
   refToPreserve?: t.Identifier;
 };
 
-type ReplaceSupersOptions =
-  | ({
-      objectRef?: undefined;
-      getObjectRef: () => t.Node;
-    } & ReplaceSupersOptionsBase)
-  | ({
-      objectRef: t.Node;
-      getObjectRef?: () => t.Node;
-    } & ReplaceSupersOptionsBase);
+type ReplaceSupersOptions = ReplaceSupersOptionsBase &
+  (
+    | { objectRef?: undefined; getObjectRef: () => t.Node }
+    | { objectRef: t.Node; getObjectRef?: undefined }
+  ) &
+  (
+    | { superRef?: undefined; getSuperRef: () => t.Node }
+    | { superRef: t.Node; getSuperRef?: undefined }
+  );
 
 export default class ReplaceSupers {
   constructor(opts: ReplaceSupersOptions) {
@@ -286,7 +284,6 @@ export default class ReplaceSupers {
     this.isPrivateMethod = path.isPrivate() && path.isMethod();
 
     this.file = opts.file;
-    this.superRef = opts.superRef;
     this.constantSuper = process.env.BABEL_8_BREAKING
       ? opts.constantSuper
       : // Fallback to isLoose for backward compatibility
@@ -301,12 +298,16 @@ export default class ReplaceSupers {
   declare isStatic: boolean;
   declare methodPath: NodePath;
   declare opts: ReplaceSupersOptions;
-  declare superRef: any;
 
   getObjectRef() {
     return t.cloneNode(this.opts.objectRef || this.opts.getObjectRef());
   }
 
+  getSuperRef() {
+    if (this.opts.superRef) return t.cloneNode(this.opts.superRef);
+    if (this.opts.getSuperRef) return t.cloneNode(this.opts.getSuperRef());
+  }
+
   replace() {
     // https://github.com/babel/babel/issues/11994
     if (this.opts.refToPreserve) {
@@ -324,7 +325,7 @@ export default class ReplaceSupers {
       isStatic: this.isStatic,
       isPrivateMethod: this.isPrivateMethod,
       getObjectRef: this.getObjectRef.bind(this),
-      superRef: this.superRef,
+      getSuperRef: this.getSuperRef.bind(this),
       ...handler,
     });
   }

packages/babel-plugin-proposal-class-properties/test/fixtures/assumption-constantSuper/complex-super-class/input.js

@@ -0,0 +1,3 @@
+class A extends class B {} {
+  static x = super.x;
+}

packages/babel-plugin-proposal-class-properties/test/fixtures/assumption-constantSuper/complex-super-class/output.js

@@ -0,0 +1,5 @@
+var _B;
+
+class A extends (_B = class B {}) {}
+
+babelHelpers.defineProperty(A, "x", _B.x);

packages/babel-plugin-proposal-class-properties/test/fixtures/assumption-constantSuper/instance-field/input.js

@@ -0,0 +1,3 @@
+class A extends B {
+  foo = super.bar;
+}

packages/babel-plugin-proposal-class-properties/test/fixtures/assumption-constantSuper/instance-field/output.js

@@ -0,0 +1,7 @@
+class A extends B {
+  constructor(...args) {
+    super(...args);
+    babelHelpers.defineProperty(this, "foo", super.bar);
+  }
+
+}

packages/babel-plugin-proposal-class-properties/test/fixtures/assumption-constantSuper/options.json

@@ -0,0 +1,6 @@
+{
+  "assumptions": {
+    "constantSuper": true
+  },
+  "plugins": ["proposal-class-properties"]
+}

packages/babel-plugin-proposal-class-properties/test/fixtures/assumption-constantSuper/static-field/input.js

@@ -0,0 +1,3 @@
+class A extends B {
+  static foo = super.bar;
+}

packages/babel-plugin-proposal-class-properties/test/fixtures/assumption-constantSuper/static-field/output.js

@@ -0,0 +1,3 @@
+class A extends B {}
+
+babelHelpers.defineProperty(A, "foo", B.bar);

packages/babel-plugin-proposal-class-static-block/test/fixtures/integration-loose/super-static-block/output.js

@@ -1,17 +1,13 @@
-var _class, _temp;
+var _ref, _class, _temp;
 
-class Foo extends (_temp = _class = class {}, (() => {
+class Foo extends (_ref = (_temp = _class = class _ref {}, (() => {
   _class.bar = 42;
-})(), _temp) {}
+})(), _temp)) {}
 
 Foo.bar = 21;
 
 (() => {
-  var _class2, _temp2;
-
-  Foo.foo = (_temp2 = _class2 = class {}, (() => {
-    _class2.bar = 42;
-  })(), _temp2).bar;
+  Foo.foo = _ref.bar;
 })();
 
 expect(Foo.foo).toBe(42);