Update decorators to the latest spec

- Update `initialize` -> `init`
- Update decorator application ordering:
  1. Static method decorators
  2. Proto method decorators
  3. Static field decorators
  4. Proto field decorators
- Throw errors when `addInitializer` or metadata methods are called
  outside of decoration

packages/babel-helpers/src/helpers/applyDecs.js

@@ -18,9 +18,20 @@
   CLASS = 10; // only used in assertValidReturnValue
 */
 
-function createMetadataMethodsForProperty(metadataMap, kind, property) {
+function createMetadataMethodsForProperty(
+  metadataMap,
+  kind,
+  property,
+  decorationState
+) {
   return {
     getMetadata: function (key) {
+      if (decorationState.finished) {
+        throw new Error(
+          "attempted to call getMetadata after decoration was finished"
+        );
+      }
+
       if (typeof key !== "symbol") {
         throw new TypeError("Metadata keys must be symbols, received: " + key);
       }
@@ -44,6 +55,12 @@ function createMetadataMethodsForProperty(metadataMap, kind, property) {
       }
     },
     setMetadata: function (key, value) {
+      if (decorationState.finished) {
+        throw new Error(
+          "attempted to call setMetadata after decoration was finished"
+        );
+      }
+
       if (typeof key !== "symbol") {
         throw new TypeError("Metadata keys must be symbols, received: " + key);
       }
@@ -120,8 +137,14 @@ function convertMetadataMapToFinal(obj, metadataMap) {
   obj[Symbol.metadata || Symbol.for("Symbol.metadata")] = metadataMap;
 }
 
-function createAddInitializerMethod(initializers) {
+function createAddInitializerMethod(initializers, decorationState) {
   return function addInitializer(initializer) {
+    if (decorationState.finished) {
+      throw new Error(
+        "attempted to call addInitializer after decoration was finished"
+      );
+    }
+
     assertCallable(initializer, "An initializer");
     initializers.push(initializer);
   };
@@ -134,7 +157,8 @@ function memberDecCtx(
   initializers,
   kind,
   isStatic,
-  isPrivate
+  isPrivate,
+  decorationState
 ) {
   var kindStr;
 
@@ -163,7 +187,10 @@ function memberDecCtx(
   };
 
   if (kind !== 0 /* FIELD */) {
-    ctx.addInitializer = createAddInitializerMethod(initializers);
+    ctx.addInitializer = createAddInitializerMethod(
+      initializers,
+      decorationState
+    );
   }
 
   var metadataKind, metadataName;
@@ -204,7 +231,12 @@ function memberDecCtx(
 
   return Object.assign(
     ctx,
-    createMetadataMethodsForProperty(metadataMap, metadataKind, metadataName)
+    createMetadataMethodsForProperty(
+      metadataMap,
+      metadataKind,
+      metadataName,
+      decorationState
+    )
   );
 }
 
@@ -220,7 +252,7 @@ function assertValidReturnValue(kind, value) {
   if (kind === 1 /* ACCESSOR */) {
     if (type !== "object" || value === null) {
       throw new TypeError(
-        "accessor decorators must return an object with get, set, or initializer properties or void 0"
+        "accessor decorators must return an object with get, set, or init properties or void 0"
       );
     }
     if (value.get !== undefined) {
@@ -229,8 +261,8 @@ function assertValidReturnValue(kind, value) {
     if (value.set !== undefined) {
       assertCallable(value.set, "accessor.set");
     }
-    if (value.initialize !== undefined) {
-      assertCallable(value.initialize, "accessor.initialize");
+    if (value.init !== undefined) {
+      assertCallable(value.init, "accessor.init");
     }
   } else if (type !== "function") {
     var hint;
@@ -296,28 +328,32 @@ function applyMemberDec(
     value = desc.set;
   }
 
-  var ctx = memberDecCtx(
-    name,
-    desc,
-    metadataMap,
-    initializers,
-    kind,
-    isStatic,
-    isPrivate
-  );
-
-  var newValue, get, set;
+  var newValue, get, set, decorationState, ctx;
 
   if (typeof decs === "function") {
+    decorationState = { finished: false };
+    ctx = memberDecCtx(
+      name,
+      desc,
+      metadataMap,
+      initializers,
+      kind,
+      isStatic,
+      isPrivate,
+      decorationState
+    );
+
     newValue = decs(value, ctx);
 
+    decorationState.finished = true;
+
     if (newValue !== void 0) {
       assertValidReturnValue(kind, newValue);
 
       if (kind === 0 /* FIELD */) {
         initializer = newValue;
       } else if (kind === 1 /* ACCESSOR */) {
-        initializer = newValue.initialize;
+        initializer = newValue.init;
 
         get = newValue.get || value.get;
         set = newValue.set || value.set;
@@ -330,17 +366,30 @@ function applyMemberDec(
   } else {
     for (var i = decs.length - 1; i >= 0; i--) {
       var dec = decs[i];
+      decorationState = { finished: false };
+      ctx = memberDecCtx(
+        name,
+        desc,
+        metadataMap,
+        initializers,
+        kind,
+        isStatic,
+        isPrivate,
+        decorationState
+      );
 
       newValue = dec(value, ctx);
 
+      decorationState.finished = true;
+
       if (newValue !== void 0) {
         assertValidReturnValue(kind, newValue);
         var newInit;
 
         if (kind === 0 /* FIELD */) {
           newInit = newValue;
         } else if (kind === 1 /* ACCESSOR */) {
-          newInit = newValue.initialize;
+          newInit = newValue.init;
 
           get = newValue.get || value.get;
           set = newValue.set || value.set;
@@ -537,23 +586,35 @@ function applyClassDecs(ret, targetClass, metadataMap, classDecs) {
   if (classDecs.length > 0) {
     var initializers = [];
     var newClass = targetClass;
-
     var name = targetClass.name;
-    var ctx = Object.assign(
-      {
-        kind: "class",
-        name: name,
-        addInitializer: createAddInitializerMethod(initializers),
-      },
-      createMetadataMethodsForProperty(metadataMap, 0 /* CONSTRUCTOR */, name)
-    );
 
     for (var i = classDecs.length - 1; i >= 0; i--) {
+      var decorationState = { finished: false };
+
+      var ctx = Object.assign(
+        {
+          kind: "class",
+          name: name,
+          addInitializer: createAddInitializerMethod(
+            initializers,
+            decorationState
+          ),
+        },
+        createMetadataMethodsForProperty(
+          metadataMap,
+          0 /* CONSTRUCTOR */,
+          name,
+          decorationState
+        )
+      );
+
       var nextNewClass = classDecs[i](newClass, ctx);
       if (nextNewClass !== undefined) {
         assertValidReturnValue(10 /* CLASS */, nextNewClass);
         newClass = nextNewClass;
       }
+
+      decorationState.finished = true;
     }
 
     ret.push(newClass);

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

@@ -311,11 +311,28 @@ function isDecoratorInfo(
   return "decorators" in info;
 }
 
+function filteredOrderedDecoratorInfo(
+  info: (DecoratorInfo | ComputedPropInfo)[],
+): DecoratorInfo[] {
+  const filtered = info.filter(isDecoratorInfo);
+
+  return [
+    ...filtered.filter(
+      el => el.isStatic && el.kind >= ACCESSOR && el.kind <= SETTER,
+    ),
+    ...filtered.filter(
+      el => !el.isStatic && el.kind >= ACCESSOR && el.kind <= SETTER,
+    ),
+    ...filtered.filter(el => el.isStatic && el.kind === FIELD),
+    ...filtered.filter(el => !el.isStatic && el.kind === FIELD),
+  ];
+}
+
 function generateDecorationExprs(
   info: (DecoratorInfo | ComputedPropInfo)[],
 ): t.ArrayExpression {
   return t.arrayExpression(
-    info.filter(isDecoratorInfo).map(el => {
+    filteredOrderedDecoratorInfo(info).map(el => {
       const decs =
         el.decorators.length > 1
           ? t.arrayExpression(el.decorators)
@@ -341,19 +358,19 @@ function generateDecorationExprs(
 function extractElementLocalAssignments(
   decorationInfo: (DecoratorInfo | ComputedPropInfo)[],
 ) {
-  const locals: t.Identifier[] = [];
+  const localIds: t.Identifier[] = [];
 
-  for (const el of decorationInfo) {
-    if ("locals" in el && el.locals) {
-      if (Array.isArray(el.locals)) {
-        locals.push(...el.locals);
-      } else {
-        locals.push(el.locals);
-      }
+  for (const el of filteredOrderedDecoratorInfo(decorationInfo)) {
+    const { locals } = el;
+
+    if (Array.isArray(locals)) {
+      localIds.push(...locals);
+    } else if (locals !== undefined) {
+      localIds.push(locals);
     }
   }
 
-  return locals;
+  return localIds;
 }
 
 function addCallAccessorsFor(

packages/babel-plugin-proposal-decorators/test/fixtures/2021-12-accessors--to-es2015/private/exec.js

@@ -12,7 +12,7 @@ function dec({ get, set }, context) {
       set.call(this, v + 1);
     },
 
-    initialize(v) {
+    init(v) {
       return v ? v : 1;
     }
   }

packages/babel-plugin-proposal-decorators/test/fixtures/2021-12-accessors--to-es2015/public/exec.js

@@ -12,7 +12,7 @@ function dec({ get, set }, context) {
       set.call(this, v + 1);
     },
 
-    initialize(v) {
+    init(v) {
       return v ? v : 1;
     }
   }

packages/babel-plugin-proposal-decorators/test/fixtures/2021-12-accessors--to-es2015/static-private/exec.js

@@ -12,7 +12,7 @@ function dec({ get, set }, context) {
       set.call(this, v + 1);
     },
 
-    initialize(v) {
+    init(v) {
       return v ? v : 1;
     }
   }

packages/babel-plugin-proposal-decorators/test/fixtures/2021-12-accessors--to-es2015/static-public/exec.js

@@ -12,7 +12,7 @@ function dec({ get, set }, context) {
       set.call(this, v + 1);
     },
 
-    initialize(v) {
+    init(v) {
       return v ? v : 1;
     }
   }

packages/babel-plugin-proposal-decorators/test/fixtures/2021-12-duplicated-keys--to-es2015/method-and-field/exec.js

@@ -17,7 +17,7 @@ class Foo {
 expect(elements).toHaveLength(2);
 
 expect(elements[0].context.name).toBe("a");
-expect(elements[0].val).toBe(undefined);
+expect(elements[0].val()).toBe(1);
 
 expect(elements[1].context.name).toBe("a");
-expect(elements[1].val()).toBe(1);
+expect(elements[1].val).toBe(undefined);

packages/babel-plugin-proposal-decorators/test/fixtures/2021-12-duplicated-keys--to-es2015/method-and-field/output.js

@@ -13,4 +13,4 @@ class Foo {
 
 }
 
-[_init_a, _initProto] = babelHelpers.applyDecs(Foo, [[dec, 0, "a"], [dec, 2, "a"]], []);
+[_init_a, _initProto] = babelHelpers.applyDecs(Foo, [[dec, 2, "a"], [dec, 0, "a"]], []);

packages/babel-plugin-proposal-decorators/test/fixtures/2021-12-duplicated-keys/method-and-field/output.js

@@ -4,7 +4,7 @@ const dec = () => {};
 
 class Foo {
   static {
-    [_init_a, _initProto] = babelHelpers.applyDecs(this, [[dec, 0, "a"], [dec, 2, "a"]], []);
+    [_init_a, _initProto] = babelHelpers.applyDecs(this, [[dec, 2, "a"], [dec, 0, "a"]], []);
   }
   a = (_initProto(this), _init_a(this, 123));
 

packages/babel-plugin-proposal-decorators/test/fixtures/2021-12-misc--to-es2015/leaked-context-addInitializer/exec.js

@@ -0,0 +1,14 @@
+let addInitializer;
+
+function decMethod(_, context) {
+  ({ addInitializer } = context);
+  addInitializer(() => null);
+}
+
+class C {
+  @decMethod m() {}
+}
+
+expect(() => {
+  addInitializer(() => null);
+}).toThrow('attempted to call addInitializer after decoration was finished')

packages/babel-plugin-proposal-decorators/test/fixtures/2021-12-misc--to-es2015/leaked-context-get-metadata/exec.js

@@ -0,0 +1,15 @@
+let getMetadata;
+let metadataSymbol = Symbol();
+
+function decMethod(_, context) {
+  ({ getMetadata } = context);
+  getMetadata(metadataSymbol);
+}
+
+class C {
+  @decMethod m() {}
+}
+
+expect(() => {
+  getMetadata(metadataSymbol);
+}).toThrow('attempted to call getMetadata after decoration was finished')

packages/babel-plugin-proposal-decorators/test/fixtures/2021-12-misc--to-es2015/leaked-context-set-metadata/exec.js

@@ -0,0 +1,15 @@
+let setMetadata;
+let metadataSymbol = Symbol();
+
+function decMethod(_, context) {
+  ({ setMetadata } = context);
+  setMetadata(metadataSymbol, 'value');
+}
+
+class C {
+  @decMethod m() {}
+}
+
+expect(() => {
+  setMetadata(metadataSymbol, 'value');
+}).toThrow('attempted to call setMetadata after decoration was finished')