[decorators] Set method names at compile time instead of at runtime (#9244)

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

@@ -1,5 +1,6 @@
 import { types as t, template } from "@babel/core";
 import ReplaceSupers from "@babel/helper-replace-supers";
+import nameFunction from "@babel/helper-function-name";
 
 export function hasOwnDecorators(node) {
   return !!(node.decorators && node.decorators.length);
@@ -14,11 +15,13 @@ function prop(key, value) {
   return t.objectProperty(t.identifier(key), value);
 }
 
-function value(body, params = [], async, generator) {
+function method(key, body) {
-  const method = t.objectMethod("method", t.identifier("value"), params, body);
+  return t.objectMethod(
-  method.async = !!async;
+    "method",
-  method.generator = !!generator;
+    t.identifier(key),
-  return method;
+    [],
+    t.blockStatement(body),
+  );
 }
 
 function takeDecorators(node) {
@@ -74,13 +77,20 @@ function extractElementDescriptor(/* this: File, */ classRef, superRef, path) {
     prop("decorators", takeDecorators(node)),
     prop("static", node.static && t.booleanLiteral(true)),
     prop("key", getKey(node)),
-    isMethod
-      ? value(node.body, node.params, node.async, node.generator)
-      : node.value
-      ? value(template.ast`{ return ${node.value} }`)
-      : prop("value", scope.buildUndefinedNode()),
   ].filter(Boolean);
 
+  if (isMethod) {
+    const id = node.computed ? null : node.key;
+    t.toExpression(node);
+    properties.push(prop("value", nameFunction({ node, id, scope }) || node));
+  } else if (node.value) {
+    properties.push(
+      method("value", template.statements.ast`return ${node.value}`),
+    );
+  } else {
+    properties.push(prop("value", scope.buildUndefinedNode()));
+  }
+
   path.remove();
 
   return t.objectExpression(properties);

packages/babel-helpers/src/helpers.js

@@ -1653,10 +1653,6 @@ helpers.decorate = helper("7.1.5")`
         configurable: true,
         enumerable: false,
       };
-      Object.defineProperty(def.value, "name", {
-        value: typeof key === "symbol" ? "" : key,
-        configurable: true,
-      });
     } else if (def.kind === "get") {
       descriptor = { get: def.value, configurable: true, enumerable: false };
     } else if (def.kind === "set") {

packages/babel-plugin-proposal-decorators/test/fixtures/duplicated-keys/computed-keys-same-ast/output.js

@@ -13,19 +13,15 @@ let Foo = babelHelpers.decorate([_ => desc = _], function (_initialize) {
     d: [{
       kind: "method",
       key: getKey(),
-
+      value: function () {
-      value() {
         return 1;
       }
-
     }, {
       kind: "method",
       key: getKey(),
-
+      value: function () {
-      value() {
         return 2;
       }
-
     }]
   };
 });

packages/babel-plugin-proposal-decorators/test/fixtures/duplicated-keys/computed-keys-same-value/output.js

@@ -13,19 +13,15 @@ let Foo = babelHelpers.decorate([_ => desc = _], function (_initialize) {
     d: [{
       kind: "method",
       key: getKeyI(),
-
+      value: function () {
-      value() {
         return 1;
       }
-
     }, {
       kind: "method",
       key: getKeyJ(),
-
+      value: function () {
-      value() {
         return 2;
       }
-
     }]
   };
 });

packages/babel-plugin-proposal-decorators/test/fixtures/misc/method-name-not-shadow/exec.js

@@ -0,0 +1,13 @@
+function decorator() {}
+
+var method = 1;
+
+@decorator
+class Foo {
+  method() {
+    return method;
+  }
+}
+
+expect(new Foo().method()).toBe(1);
+expect(Foo.prototype.method.name).toBe("method");

packages/babel-plugin-proposal-decorators/test/fixtures/misc/method-name-not-shadow/input.js

@@ -0,0 +1,8 @@
+var method = 1;
+
+@decorator
+class Foo {
+  method() {
+    return method;
+  }
+}

packages/babel-plugin-proposal-decorators/test/fixtures/misc/method-name-not-shadow/output.js

@@ -0,0 +1,22 @@
+var _method = 1;
+let Foo = babelHelpers.decorate([decorator], function (_initialize) {
+  "use strict";
+
+  class Foo {
+    constructor() {
+      _initialize(this);
+    }
+
+  }
+
+  return {
+    F: Foo,
+    d: [{
+      kind: "method",
+      key: "method",
+      value: function method() {
+        return _method;
+      }
+    }]
+  };
+});

packages/babel-plugin-proposal-decorators/test/fixtures/transformation/arguments/output.js

@@ -14,9 +14,7 @@ let A = babelHelpers.decorate([dec(a, b, ...c)], function (_initialize) {
       kind: "method",
       decorators: [dec(a, b, ...c)],
       key: "method",
-
+      value: function method() {}
-      value() {}
-
     }]
   };
 });

packages/babel-plugin-proposal-decorators/test/fixtures/transformation/async-generator-method/output.js

@@ -13,21 +13,15 @@ let Foo = babelHelpers.decorate([decorator], function (_initialize) {
     d: [{
       kind: "method",
       key: "f1",
-
+      value: async function f1() {}
-      async value() {}
-
     }, {
       kind: "method",
       key: "f2",
-
+      value: function* f2() {}
-      *value() {}
-
     }, {
       kind: "method",
       key: "f3",
-
+      value: async function* f3() {}
-      async *value() {}
-
     }]
   };
 });

packages/babel-plugin-proposal-decorators/test/fixtures/transformation/strict-directive/output.js

@@ -14,9 +14,7 @@
       d: [{
         kind: "method",
         key: "method",
-
+        value: function method() {}
-        value() {}
-
       }]
     };
   });
@@ -38,9 +36,7 @@
       d: [{
         kind: "method",
         key: "method",
-
+        value: function method() {}
-        value() {}
-
       }]
     };
   });