Install static fields and private methods on the correct class

packages/babel-helpers/src/helpers.ts

@@ -2052,3 +2052,9 @@ if (!process.env.BABEL_8_BREAKING) {
     }
   `;
 }
+
+helpers.identity = helper("7.16.7")`
+  export default function _identity(x) {
+    return x;
+  }
+`;

packages/babel-plugin-proposal-decorators/src/transformer-2021-12.ts

@@ -1,5 +1,5 @@
 import type { NodePath } from "@babel/traverse";
-import { types as t } from "@babel/core";
+import { types as t, template } from "@babel/core";
 import syntaxDecorators from "@babel/plugin-syntax-decorators";
 import ReplaceSupers from "@babel/helper-replace-supers";
 import * as charCodes from "charcodes";
@@ -447,6 +447,19 @@ function isClassDecoratableElementPath(
   );
 }
 
+function staticBlockToIIFE(block: t.StaticBlock) {
+  return t.callExpression(
+    t.arrowFunctionExpression([], t.blockStatement(block.body)),
+    [],
+  );
+}
+
+function maybeSequenceExpression(exprs: t.Expression[]) {
+  if (exprs.length === 0) return t.unaryExpression("void", t.numericLiteral(0));
+  if (exprs.length === 1) return exprs[0];
+  return t.sequenceExpression(exprs);
+}
+
 function transformClass(
   path: NodePath<t.ClassExpression | t.ClassDeclaration>,
   state: any,
@@ -836,38 +849,6 @@ function transformClass(
     locals.push(staticInitLocal);
   }
 
-  const staticBlock = t.staticBlock(
-    [
-      t.expressionStatement(
-        t.assignmentExpression(
-          "=",
-          t.arrayPattern(locals),
-          t.callExpression(state.addHelper("applyDecs"), [
-            t.thisExpression(),
-            elementDecorations,
-            classDecorations,
-          ]),
-        ),
-      ),
-      requiresStaticInit &&
-        t.expressionStatement(
-          t.callExpression(t.cloneNode(staticInitLocal), [t.thisExpression()]),
-        ),
-    ].filter(v => v),
-  );
-
-  path.node.body.body.unshift(staticBlock as unknown as ClassElement);
-
-  if (classInitLocal) {
-    path.node.body.body.push(
-      t.staticBlock([
-        t.expressionStatement(
-          t.callExpression(t.cloneNode(classInitLocal), []),
-        ),
-      ]),
-    );
-  }
-
   if (decoratedPrivateMethods.size > 0) {
     path.traverse({
       PrivateName(path) {
@@ -902,6 +883,116 @@ function transformClass(
     });
   }
 
+  let classInitInjected = false;
+  const classInitCall =
+    classInitLocal && t.callExpression(t.cloneNode(classInitLocal), []);
+
+  const originalClass = path.node;
+
+  if (classDecorators) {
+    const statics = [];
+    let staticBlocks: t.StaticBlock[] = [];
+    path.get("body.body").forEach(element => {
+      // Static blocks cannot be compiled to "instance blocks", but we can inline
+      // them as IIFEs in the next property.
+      if (element.isStaticBlock()) {
+        staticBlocks.push(element.node);
+        element.remove();
+        return;
+      }
+
+      const isProperty =
+        element.isClassProperty() || element.isClassPrivateProperty();
+
+      if (
+        (isProperty || element.isClassPrivateMethod()) &&
+        element.node.static
+      ) {
+        if (isProperty && staticBlocks.length > 0) {
+          const allValues: t.Expression[] = staticBlocks.map(staticBlockToIIFE);
+          if (element.node.value) allValues.push(element.node.value);
+          element.node.value = maybeSequenceExpression(allValues);
+          staticBlocks = [];
+        }
+
+        element.node.static = false;
+        statics.push(element.node);
+        element.remove();
+      }
+    });
+
+    if (statics.length > 0 || staticBlocks.length > 0) {
+      const staticsClass = template.expression.ast`
+        class extends ${state.addHelper("identity")} {}
+      ` as t.ClassExpression;
+      staticsClass.body.body = [
+        t.staticBlock([t.toStatement(path.node, false)]),
+        ...statics,
+      ];
+
+      const constructorBody: t.Expression[] = [];
+
+      const newExpr = t.newExpression(staticsClass, []);
+
+      if (staticBlocks.length > 0) {
+        constructorBody.push(...staticBlocks.map(staticBlockToIIFE));
+      }
+      if (classInitCall) {
+        classInitInjected = true;
+        constructorBody.push(classInitCall);
+      }
+      if (constructorBody.length > 0) {
+        constructorBody.unshift(
+          t.callExpression(t.super(), [t.cloneNode(classLocal)]),
+        );
+
+        staticsClass.body.body.push(
+          t.classMethod(
+            "constructor",
+            t.identifier("constructor"),
+            [],
+            t.blockStatement([
+              t.expressionStatement(t.sequenceExpression(constructorBody)),
+            ]),
+          ),
+        );
+      } else {
+        newExpr.arguments.push(t.cloneNode(classLocal));
+      }
+
+      path.replaceWith(newExpr);
+    }
+  }
+  if (!classInitInjected && classInitCall) {
+    path.node.body.body.push(
+      t.staticBlock([t.expressionStatement(classInitCall)]),
+    );
+  }
+
+  originalClass.body.body.unshift(
+    t.staticBlock(
+      [
+        t.expressionStatement(
+          t.assignmentExpression(
+            "=",
+            t.arrayPattern(locals),
+            t.callExpression(state.addHelper("applyDecs"), [
+              t.thisExpression(),
+              elementDecorations,
+              classDecorations,
+            ]),
+          ),
+        ),
+        requiresStaticInit &&
+          t.expressionStatement(
+            t.callExpression(t.cloneNode(staticInitLocal), [
+              t.thisExpression(),
+            ]),
+          ),
+      ].filter(Boolean),
+    ),
+  );
+
   // Recrawl the scope to make sure new identifiers are properly synced
   path.scope.crawl();
 

packages/babel-plugin-proposal-decorators/test/fixtures/2021-12-classes--to-es2015/initializers/output.js

@@ -1,33 +1,37 @@
-var _initClass, _initClass2;
+var _initClass, _temp2, _initClass2, _temp4;
 
 let _Foo;
 
-class Foo {}
+new (_temp2 = class extends babelHelpers.identity {
+  constructor() {
+    var _temp;
 
-(() => {
+    (_temp = super(_Foo), babelHelpers.defineProperty(this, "field", 123), _temp), _initClass();
+  }
+
+}, (() => {
+  class Foo {}
+
+  (() => {
     [_Foo, _initClass] = babelHelpers.applyDecs(Foo, [], [dec]);
-})();
+  })();
-
+})(), _temp2)();
-babelHelpers.defineProperty(Foo, "field", 123);
-
-(() => {
-  _initClass();
-})();
 
 let _Bar;
 
-class Bar extends _Foo {}
+new (_temp4 = class extends babelHelpers.identity {
+  constructor() {
+    var _temp3;
 
-(() => {
+    (_temp3 = super(_Bar), babelHelpers.defineProperty(this, "field", ((() => {
+      this.otherField = 456;
+    })(), 123)), _temp3), _initClass2();
+  }
+
+}, (() => {
+  class Bar extends _Foo {}
+
+  (() => {
     [_Bar, _initClass2] = babelHelpers.applyDecs(Bar, [], [dec]);
-})();
+  })();
-
+})(), _temp4)();
-(() => {
-  Bar.otherField = 456;
-})();
-
-babelHelpers.defineProperty(Bar, "field", 123);
-
-(() => {
-  _initClass2();
-})();

packages/babel-plugin-proposal-decorators/test/fixtures/2021-12-classes--to-es2015/replacement-static-installed-on-correct-class/exec.js

@@ -0,0 +1,33 @@
+let hasX, hasM, OriginalFoo;
+
+class Bar {}
+
+function dec(Foo) {
+  OriginalFoo = Foo;
+  return Bar;
+}
+
+@dec
+class Foo {
+  static #x;
+  static #m() {}
+
+  static x;
+  static m() {}
+
+  static {
+    hasX = o => #x in o;
+    hasM = o => #m in o;
+  }
+}
+
+expect(hasX(Bar)).toBe(true);
+expect(hasM(Bar)).toBe(true);
+expect(hasX(OriginalFoo)).toBe(false);
+expect(hasM(OriginalFoo)).toBe(false);
+
+expect(Bar.hasOwnProperty("x")).toBe(true);
+expect(OriginalFoo.hasOwnProperty("x")).toBe(false);
+
+expect(Bar.hasOwnProperty("m")).toBe(false);
+expect(OriginalFoo.hasOwnProperty("m")).toBe(true);

packages/babel-plugin-proposal-decorators/test/fixtures/2021-12-classes--to-es2015/replacement-static-installed-on-correct-class/input.js

@@ -0,0 +1,15 @@
+let hasX, hasM;
+
+@dec
+class Foo {
+  static #x;
+  static #m() {}
+
+  static x;
+  static m() {}
+
+  static {
+    hasX = o => #x in o;
+    hasM = o => #m in o;
+  }
+}

packages/babel-plugin-proposal-decorators/test/fixtures/2021-12-classes--to-es2015/replacement-static-installed-on-correct-class/output.js

@@ -0,0 +1,32 @@
+var _initClass, _x, _m, _temp2;
+
+let hasX, hasM;
+
+let _Foo;
+
+new (_temp2 = (_x = /*#__PURE__*/new WeakMap(), _m = /*#__PURE__*/new WeakSet(), class extends babelHelpers.identity {
+  constructor() {
+    var _temp;
+
+    (_temp = super(_Foo), babelHelpers.classPrivateMethodInitSpec(this, _m), babelHelpers.classPrivateFieldInitSpec(this, _x, {
+      writable: true,
+      value: void 0
+    }), babelHelpers.defineProperty(this, "x", void 0), _temp), (() => {
+      hasX = o => _x.has(o);
+
+      hasM = o => _m.has(o);
+    })(), _initClass();
+  }
+
+}), (() => {
+  class Foo {
+    static m() {}
+
+  }
+
+  (() => {
+    [_Foo, _initClass] = babelHelpers.applyDecs(Foo, [], [dec]);
+  })();
+})(), _temp2)();
+
+function _m2() {}

packages/babel-plugin-proposal-decorators/test/fixtures/2021-12-classes--to-es2015/replacement-static-this/exec.js

@@ -0,0 +1,19 @@
+
+class Bar {}
+
+let _this, _this2, _this3;
+
+@(() => Bar)
+class Foo {
+  static {
+    _this = this;
+  }
+  static field = (_this2 = this);
+  static {
+    _this3 = this;
+  }
+}
+
+expect(_this).toBe(Bar);
+expect(_this2).toBe(Bar);
+expect(_this3).toBe(Bar);

packages/babel-plugin-proposal-decorators/test/fixtures/2021-12-classes--to-es2015/replacement-static-this/input.js

@@ -0,0 +1,10 @@
+@dec
+class Foo {
+  static {
+    this
+  }
+  static field = this;
+  static {
+    this
+  }
+}

packages/babel-plugin-proposal-decorators/test/fixtures/2021-12-classes--to-es2015/replacement-static-this/output.js

@@ -0,0 +1,22 @@
+var _initClass, _temp2;
+
+let _Foo;
+
+new (_temp2 = class extends babelHelpers.identity {
+  constructor() {
+    var _temp;
+
+    (_temp = super(_Foo), babelHelpers.defineProperty(this, "field", ((() => {
+      this;
+    })(), this)), _temp), (() => {
+      this;
+    })(), _initClass();
+  }
+
+}, (() => {
+  class Foo {}
+
+  (() => {
+    [_Foo, _initClass] = babelHelpers.applyDecs(Foo, [], [dec]);
+  })();
+})(), _temp2)();

packages/babel-plugin-proposal-decorators/test/fixtures/2021-12-classes--to-es2015/replacement/output.js

@@ -1,17 +1,19 @@
-var _initClass;
+var _initClass, _temp2;
 
 let _Foo;
 
-class Foo {}
+new (_temp2 = class extends babelHelpers.identity {
+  constructor() {
+    var _temp;
 
-(() => {
+    (_temp = super(_Foo), babelHelpers.defineProperty(this, "foo", new _Foo()), _temp), _initClass();
+  }
+
+}, (() => {
+  class Foo {}
+
+  (() => {
     [_Foo, _initClass] = babelHelpers.applyDecs(Foo, [], [dec]);
-})();
+  })();
-
+})(), _temp2)();
-babelHelpers.defineProperty(Foo, "foo", new _Foo());
-
-(() => {
-  _initClass();
-})();
-
 const foo = new _Foo();

packages/babel-plugin-proposal-decorators/test/fixtures/2021-12-classes/initializers/output.js

@@ -2,29 +2,40 @@ var _initClass, _initClass2;
 
 let _Foo;
 
-class Foo {
+new class extends babelHelpers.identity {
+  static {
+    class Foo {
       static {
         [_Foo, _initClass] = babelHelpers.applyDecs(this, [], [dec]);
       }
-  static field = 123;
+    }
-  static {
-    _initClass();
 
   }
-}
+  field = 123;
+
+  constructor() {
+    super(_Foo), _initClass();
+  }
+
+}();
 
 let _Bar;
 
-class Bar extends _Foo {
+new class extends babelHelpers.identity {
+  static {
+    class Bar extends _Foo {
       static {
         [_Bar, _initClass2] = babelHelpers.applyDecs(this, [], [dec]);
       }
-  static {
-    this.otherField = 456;
     }
-  static field = 123;
-  static {
-    _initClass2();
 
   }
-}
+  field = ((() => {
+    this.otherField = 456;
+  })(), 123);
+
+  constructor() {
+    super(_Bar), _initClass2();
+  }
+
+}();

packages/babel-plugin-proposal-decorators/test/fixtures/2021-12-classes/replacement-static-installed-on-correct-class/input.js

@@ -0,0 +1,15 @@
+let hasX, hasM;
+
+@dec
+class Foo {
+  static #x;
+  static #m() {}
+
+  static x;
+  static m() {}
+
+  static {
+    hasX = o => #x in o;
+    hasM = o => #m in o;
+  }
+}

packages/babel-plugin-proposal-decorators/test/fixtures/2021-12-classes/replacement-static-installed-on-correct-class/output.js

@@ -0,0 +1,33 @@
+var _initClass;
+
+let hasX, hasM;
+
+let _Foo;
+
+new class extends babelHelpers.identity {
+  static {
+    class Foo {
+      static {
+        [_Foo, _initClass] = babelHelpers.applyDecs(this, [], [dec]);
+      }
+
+      static m() {}
+
+    }
+
+  }
+  #x;
+
+  #m() {}
+
+  x;
+
+  constructor() {
+    super(_Foo), (() => {
+      hasX = o => #x in o;
+
+      hasM = o => #m in o;
+    })(), _initClass();
+  }
+
+}();

packages/babel-plugin-proposal-decorators/test/fixtures/2021-12-classes/replacement-static-this/input.js

@@ -0,0 +1,10 @@
+@dec
+class Foo {
+  static {
+    this
+  }
+  static field = this;
+  static {
+    this
+  }
+}

packages/babel-plugin-proposal-decorators/test/fixtures/2021-12-classes/replacement-static-this/output.js

@@ -0,0 +1,24 @@
+var _initClass;
+
+let _Foo;
+
+new class extends babelHelpers.identity {
+  static {
+    class Foo {
+      static {
+        [_Foo, _initClass] = babelHelpers.applyDecs(this, [], [dec]);
+      }
+    }
+
+  }
+  field = ((() => {
+    this;
+  })(), this);
+
+  constructor() {
+    super(_Foo), (() => {
+      this;
+    })(), _initClass();
+  }
+
+}();

packages/babel-plugin-proposal-decorators/test/fixtures/2021-12-classes/replacement/output.js

@@ -2,15 +2,20 @@ var _initClass;
 
 let _Foo;
 
-class Foo {
+new class extends babelHelpers.identity {
+  static {
+    class Foo {
       static {
         [_Foo, _initClass] = babelHelpers.applyDecs(this, [], [dec]);
       }
-  static foo = new _Foo();
+    }
-  static {
-    _initClass();
 
   }
-}
+  foo = new _Foo();
 
+  constructor() {
+    super(_Foo), _initClass();
+  }
+
+}();
 const foo = new _Foo();

packages/babel-runtime-corejs2/package.json

@@ -846,6 +846,15 @@
       "./helpers/classPrivateMethodSet.js"
     ],
     "./helpers/esm/classPrivateMethodSet": "./helpers/esm/classPrivateMethodSet.js",
+    "./helpers/identity": [
+      {
+        "node": "./helpers/identity.js",
+        "import": "./helpers/esm/identity.js",
+        "default": "./helpers/identity.js"
+      },
+      "./helpers/identity.js"
+    ],
+    "./helpers/esm/identity": "./helpers/esm/identity.js",
     "./package": "./package.json",
     "./package.json": "./package.json",
     "./regenerator": "./regenerator/index.js",

packages/babel-runtime-corejs3/package.json

@@ -845,6 +845,15 @@
       "./helpers/classPrivateMethodSet.js"
     ],
     "./helpers/esm/classPrivateMethodSet": "./helpers/esm/classPrivateMethodSet.js",
+    "./helpers/identity": [
+      {
+        "node": "./helpers/identity.js",
+        "import": "./helpers/esm/identity.js",
+        "default": "./helpers/identity.js"
+      },
+      "./helpers/identity.js"
+    ],
+    "./helpers/esm/identity": "./helpers/esm/identity.js",
     "./package": "./package.json",
     "./package.json": "./package.json",
     "./regenerator": "./regenerator/index.js",

packages/babel-runtime/package.json

@@ -845,6 +845,15 @@
       "./helpers/classPrivateMethodSet.js"
     ],
     "./helpers/esm/classPrivateMethodSet": "./helpers/esm/classPrivateMethodSet.js",
+    "./helpers/identity": [
+      {
+        "node": "./helpers/identity.js",
+        "import": "./helpers/esm/identity.js",
+        "default": "./helpers/identity.js"
+      },
+      "./helpers/identity.js"
+    ],
+    "./helpers/esm/identity": "./helpers/esm/identity.js",
     "./package": "./package.json",
     "./package.json": "./package.json",
     "./regenerator": "./regenerator/index.js",