Recover from shorthand assign exprs (#13968)

* refactor: avoid duplicate property access

* refactor: tweak parseMember

* polish: recover from shorthand assign in exprs

packages/babel-parser/src/parser/error-message.js

@@ -78,6 +78,7 @@ export const ErrorMessages = makeErrorTemplates(
     ImportCallSpreadArgument: "`...` is not allowed in `import()`.",
     InvalidBigIntLiteral: "Invalid BigIntLiteral.",
     InvalidCodePoint: "Code point out of bounds.",
+    InvalidCoverInitializedName: "Invalid shorthand property initializer.",
     InvalidDecimal: "Invalid decimal.",
     InvalidDigit: "Expected number in radix %0.",
     InvalidEscapeSequence: "Bad character escape sequence.",

packages/babel-parser/src/parser/expression.js

@@ -770,24 +770,17 @@ export default class ExpressionParser extends LValParser {
     const node = this.startNodeAt(startPos, startLoc);
     node.object = base;
     node.computed = computed;
-    const privateName =
-      !computed && this.match(tt.privateName) && this.state.value;
-    const property = computed
-      ? this.parseExpression()
-      : privateName
-      ? this.parsePrivateName()
-      : this.parseIdentifier(true);
-
-    if (privateName !== false) {
-      if (node.object.type === "Super") {
+    if (computed) {
+      node.property = this.parseExpression();
+      this.expect(tt.bracketR);
+    } else if (this.match(tt.privateName)) {
+      if (base.type === "Super") {
         this.raise(startPos, Errors.SuperPrivateField);
       }
-      this.classScope.usePrivateName(privateName, property.start);
-    }
-    node.property = property;
-
-    if (computed) {
-      this.expect(tt.bracketR);
+      this.classScope.usePrivateName(this.state.value, this.state.start);
+      node.property = this.parsePrivateName();
+    } else {
+      node.property = this.parseIdentifier(true);
     }
 
     if (state.optionalChainMember) {
@@ -2137,7 +2130,7 @@ export default class ExpressionParser extends LValParser {
     if (!prop.computed && prop.key.type === "Identifier") {
       // PropertyDefinition:
       //   IdentifierReference
-      //   CoveredInitializedName
+      //   CoverInitializedName
       // Note: `{ eval } = {}` will be checked in `checkLVal` later.
       this.checkReservedWord(prop.key.name, prop.key.start, true, false);
 
@@ -2147,9 +2140,14 @@ export default class ExpressionParser extends LValParser {
           startLoc,
           cloneIdentifier(prop.key),
         );
-      } else if (this.match(tt.eq) && refExpressionErrors) {
-        if (refExpressionErrors.shorthandAssign === -1) {
-          refExpressionErrors.shorthandAssign = this.state.start;
+      } else if (this.match(tt.eq)) {
+        const shorthandAssign = this.state.start;
+        if (refExpressionErrors != null) {
+          if (refExpressionErrors.shorthandAssign === -1) {
+            refExpressionErrors.shorthandAssign = shorthandAssign;
+          }
+        } else {
+          this.raise(shorthandAssign, Errors.InvalidCoverInitializedName);
         }
         prop.value = this.parseMaybeDefault(
           startPos,

packages/babel-parser/src/parser/util.js

@@ -270,7 +270,7 @@ export default class UtilParser extends Tokenizer {
       return hasErrors;
     } else if (hasErrors) {
       if (shorthandAssign >= 0) {
-        this.unexpected(shorthandAssign);
+        this.raise(shorthandAssign, Errors.InvalidCoverInitializedName);
       }
       if (doubleProto >= 0) {
         this.raise(doubleProto, Errors.DuplicateProto);

packages/babel-parser/src/util/class-scope.js

@@ -61,11 +61,12 @@ export default class ClassScopeHandler {
     elementType: ClassElementTypes,
     pos: number,
   ) {
-    const classScope = this.current();
-    let redefined = classScope.privateNames.has(name);
+    const { privateNames, loneAccessors, undefinedPrivateNames } =
+      this.current();
+    let redefined = privateNames.has(name);
 
     if (elementType & CLASS_ELEMENT_KIND_ACCESSOR) {
-      const accessor = redefined && classScope.loneAccessors.get(name);
+      const accessor = redefined && loneAccessors.get(name);
       if (accessor) {
         const oldStatic = accessor & CLASS_ELEMENT_FLAG_STATIC;
         const newStatic = elementType & CLASS_ELEMENT_FLAG_STATIC;
@@ -78,9 +79,9 @@ export default class ClassScopeHandler {
         // they have the same placement (static or not).
         redefined = oldKind === newKind || oldStatic !== newStatic;
 
-        if (!redefined) classScope.loneAccessors.delete(name);
+        if (!redefined) loneAccessors.delete(name);
       } else if (!redefined) {
-        classScope.loneAccessors.set(name, elementType);
+        loneAccessors.set(name, elementType);
       }
     }
 
@@ -88,8 +89,8 @@ export default class ClassScopeHandler {
       this.raise(pos, Errors.PrivateNameRedeclaration, name);
     }
 
-    classScope.privateNames.add(name);
-    classScope.undefinedPrivateNames.delete(name);
+    privateNames.add(name);
+    undefinedPrivateNames.delete(name);
   }
 
   usePrivateName(name: string, pos: number) {