Forbid await/yield/arguments in class field inits

Summary: Manual port of D66266912 to SemanticResolver. Certain language features aren't allowed in class field initializers. 'arguments' is forbidden by the spec. Yield/await should be forbidden: tc39/ecma262#3333 Reviewed By: fbmal7 Differential Revision: D66711282 fbshipit-source-id: d0458700d42103917fcc5625884dd4eeb921e804
facebook · Dec 3, 2024 · 9b403d0 · 9b403d0
1 parent 2dd2314
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Showing 7 changed files with 191 additions and 4 deletions.
diff --git a/lib/Parser/JSParserImpl.cpp b/lib/Parser/JSParserImpl.cpp
@@ -4991,6 +4991,12 @@ Optional<ESTree::Node *> JSParserImpl::parseClassElement(
     if (checkAndEat(TokenKind::equal)) {
       // ClassElementName Initializer[opt]
       //                  ^
+      // NOTE: This is technically non-compliant, but having yield/await in the
+      // field initializer doesn't make sense.
+      // See https://github.com/tc39/ecma262/issues/3333
+      // Do [~Yield, +Await, ~Return] as suggested and error in resolution.
+      llvh::SaveAndRestore<bool> saveParamYield{paramYield_, false};
+      llvh::SaveAndRestore<bool> saveParamAwait{paramAwait_, true};
       auto optValue = parseAssignmentExpression();
       if (!optValue)
         return None;

diff --git a/lib/Sema/SemanticResolver.cpp b/lib/Sema/SemanticResolver.cpp
@@ -889,6 +889,11 @@ void SemanticResolver::visit(ESTree::ClassPropertyNode *node) {
     // method that performs the initializations.
     // Field initializers can always reference super.
     llvh::SaveAndRestore<bool> oldCanRefSuper{canReferenceSuper_, true};
+    llvh::SaveAndRestore<bool> oldForbidAwait{forbidAwaitExpression_, true};
+    // ES14.0 15.7.1
+    // It is a Syntax Error if Initializer is present and ContainsArguments of
+    // Initializer is true.
+    llvh::SaveAndRestore<bool> oldForbidArguments{forbidArguments_, true};
     FunctionContext funcCtx(
         *this, curClassContext_->getOrCreateFieldInitFunctionInfo());
     visitESTreeNode(*this, node->_value, node);
@@ -1018,10 +1023,8 @@ void SemanticResolver::visit(ESTree::YieldExpressionNode *node) {
 }
 
 void SemanticResolver::visit(ESTree::AwaitExpressionNode *awaitExpr) {
-  if (functionContext()->isGlobalScope() ||
-      (functionContext()->node && !ESTree::isAsync(functionContext()->node))) {
+  if (forbidAwaitExpression_)
     sm_.error(awaitExpr->getSourceRange(), "'await' not in an async function");
-  }
 
   if (functionContext()->isFormalParams) {
     // ES14.0 15.8.1
@@ -1331,6 +1334,16 @@ void SemanticResolver::visitFunctionLikeInFunctionContext(
   // in an incorrect scope!
   // visitESTreeNode(*this, getIdentifier(node), node);
 
+  // 'await' forbidden outside async functions.
+  llvh::SaveAndRestore<bool> oldForbidAwait{
+      forbidAwaitExpression_, !ESTree::isAsync(node)};
+  // Forbidden-ness of 'arguments' passes through arrow functions because they
+  // use the same 'arguments'.
+  llvh::SaveAndRestore<bool> oldForbidArguments{
+      forbidArguments_,
+      llvh::isa<ESTree::ArrowFunctionExpressionNode>(node) ? forbidArguments_
+                                                           : false};
+
   // Visit the parameters before we have hoisted the body declarations.
   // If there's a parameter named arguments, then the parameter init expressions
   // would refer to that declaration.
@@ -1461,8 +1474,11 @@ Decl *SemanticResolver::resolveIdentifier(
   Decl *decl = checkIdentifierResolved(identifier);
 
   // Is this the "arguments" object?
-  if (decl && decl->special == Decl::Special::Arguments)
+  if (decl && decl->special == Decl::Special::Arguments) {
+    if (forbidArguments_)
+      sm_.error(identifier->getSourceRange(), "invalid use of 'arguments'");
     curFunctionInfo()->usesArguments = true;
+  }
 
   if (LLVM_UNLIKELY(identifier->_name == kw_.identAwait) &&
       forbidAwaitAsIdentifier_) {

diff --git a/lib/Sema/SemanticResolver.h b/lib/Sema/SemanticResolver.h
@@ -92,6 +92,12 @@ class SemanticResolver
   /// SemanticResolver.
   bool forbidAwaitAsIdentifier_ = false;
 
+  /// True if we are forbidding await expressions.
+  bool forbidAwaitExpression_{false};
+
+  /// True if we are forbidding 'arguments' identifier.
+  bool forbidArguments_{false};
+
  public:
   /// This constant enables the more expensive path in RecursiveVisitorDispatch,
   /// enabling us to mutate NodeList.

diff --git a/test/Parser/arguments-field-error.js b/test/Parser/arguments-field-error.js
@@ -0,0 +1,20 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+// RUN: (! %hermesc -dump-transformed-ast %s 2>&1 ) | %FileCheckOrRegen --match-full-lines %s
+
+function* foo() {
+  class C {
+    x = () => arguments;
+  }
+}
+
+// Auto-generated content below. Please do not modify manually.
+
+// CHECK:{{.*}}arguments-field-error.js:12:15: error: invalid use of 'arguments'
+// CHECK-NEXT:    x = () => arguments;
+// CHECK-NEXT:              ^~~~~~~~~
diff --git a/test/Parser/await-field-error.js b/test/Parser/await-field-error.js
@@ -0,0 +1,26 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+// RUN: (! %hermesc -dump-transformed-ast %s 2>&1 ) | %FileCheck --match-full-lines %s
+
+async function foo() {
+  class C {
+    x = await 1;
+  }
+
+  class D {
+    x = class { [await 1] = 1; };
+  }
+}
+
+
+// CHECK:{{.*}}await-field-error.js:12:9: error: 'await' not in an async function
+// CHECK-NEXT:    x = await 1;
+// CHECK-NEXT:        ^~~~~~~
+// CHECK-NEXT:{{.*}}await-field-error.js:16:18: error: 'await' not in an async function
+// CHECK-NEXT:    x = class { [await 1] = 1; };
+// CHECK-NEXT:                 ^~~~~~~
diff --git a/test/Parser/class-props-yield-await.js b/test/Parser/class-props-yield-await.js
@@ -0,0 +1,93 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+// RUN: %hermesc -dump-ast -pretty-json %s | %FileCheck %s --match-full-lines
+
+// CHECK-LABEL: {
+// CHECK-NEXT:   "type": "Program",
+// CHECK-NEXT:   "body": [
+// CHECK-NEXT:     {
+
+async function* foo() {
+// CHECK-NEXT:       "type": "FunctionDeclaration",
+// CHECK-NEXT:       "id": {
+// CHECK-NEXT:         "type": "Identifier",
+// CHECK-NEXT:         "name": "foo"
+// CHECK-NEXT:       },
+// CHECK-NEXT:       "params": [],
+// CHECK-NEXT:       "body": {
+// CHECK-NEXT:         "type": "BlockStatement",
+// CHECK-NEXT:         "body": [
+
+  class C {
+// CHECK-NEXT:           {
+// CHECK-NEXT:             "type": "ClassDeclaration",
+// CHECK-NEXT:             "id": {
+// CHECK-NEXT:               "type": "Identifier",
+// CHECK-NEXT:               "name": "C"
+// CHECK-NEXT:             },
+// CHECK-NEXT:             "superClass": null,
+// CHECK-NEXT:             "body": {
+// CHECK-NEXT:               "type": "ClassBody",
+// CHECK-NEXT:               "body": [
+
+    [yield 1] = 1;
+// CHECK-NEXT:                 {
+// CHECK-NEXT:                   "type": "ClassProperty",
+// CHECK-NEXT:                   "key": {
+// CHECK-NEXT:                     "type": "YieldExpression",
+// CHECK-NEXT:                     "argument": {
+// CHECK-NEXT:                       "type": "NumericLiteral",
+// CHECK-NEXT:                       "value": 1,
+// CHECK-NEXT:                       "raw": "1"
+// CHECK-NEXT:                     },
+// CHECK-NEXT:                     "delegate": false
+// CHECK-NEXT:                   },
+// CHECK-NEXT:                   "value": {
+// CHECK-NEXT:                     "type": "NumericLiteral",
+// CHECK-NEXT:                     "value": 1,
+// CHECK-NEXT:                     "raw": "1"
+// CHECK-NEXT:                   },
+// CHECK-NEXT:                   "computed": true,
+// CHECK-NEXT:                   "static": false,
+// CHECK-NEXT:                   "declare": false
+// CHECK-NEXT:                 },
+
+    [await 1] = 1;
+// CHECK-NEXT:                 {
+// CHECK-NEXT:                   "type": "ClassProperty",
+// CHECK-NEXT:                   "key": {
+// CHECK-NEXT:                     "type": "AwaitExpression",
+// CHECK-NEXT:                     "argument": {
+// CHECK-NEXT:                       "type": "NumericLiteral",
+// CHECK-NEXT:                       "value": 1,
+// CHECK-NEXT:                       "raw": "1"
+// CHECK-NEXT:                     }
+// CHECK-NEXT:                   },
+// CHECK-NEXT:                   "value": {
+// CHECK-NEXT:                     "type": "NumericLiteral",
+// CHECK-NEXT:                     "value": 1,
+// CHECK-NEXT:                     "raw": "1"
+// CHECK-NEXT:                   },
+// CHECK-NEXT:                   "computed": true,
+// CHECK-NEXT:                   "static": false,
+// CHECK-NEXT:                   "declare": false
+// CHECK-NEXT:                 }
+
+  }
+// CHECK-NEXT:               ]
+// CHECK-NEXT:             }
+// CHECK-NEXT:           }
+// CHECK-NEXT:         ]
+
+}
+// CHECK-NEXT:       },
+// CHECK-NEXT:       "generator": true,
+// CHECK-NEXT:       "async": true
+// CHECK-NEXT:     }
+// CHECK-NEXT:   ]
+// CHECK-NEXT: }
diff --git a/test/Parser/yield-field-error.js b/test/Parser/yield-field-error.js
@@ -0,0 +1,20 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+// RUN: (! %hermesc -dump-ast %s 2>&1 ) | %FileCheckOrRegen --match-full-lines %s
+
+function* foo() {
+  class C {
+    x = yield;
+  }
+}
+
+// Auto-generated content below. Please do not modify manually.
+
+// CHECK:{{.*}}yield-field-error.js:12:9: error: invalid expression
+// CHECK-NEXT:    x = yield;
+// CHECK-NEXT:        ^