Parenthesized expressions (#8025)

* Add parser createParenthesizedExpressions option  …

When set to `true` we create `ParenthesizedExpression` nodes instead of
setting `extra.parenthesized`.

* Also update babel-parser.d.ts

packages/babel-generator/test/fixtures/comments/create-parenthesized-expressions/input.js

@@ -0,0 +1,12 @@
+// One
+(1);
+
+/* Two */
+(2);
+
+(
+  // Three
+  3
+);
+
+(/* Four */ 4);

packages/babel-generator/test/fixtures/comments/create-parenthesized-expressions/options.json

@@ -0,0 +1,3 @@
+{
+  "parserOpts": {"createParenthesizedExpressions": true}
+}

packages/babel-generator/test/fixtures/comments/create-parenthesized-expressions/output.js

@@ -0,0 +1,10 @@
+// One
+(1);
+/* Two */
+
+(2);
+( // Three
+3);
+(
+/* Four */
+4);

packages/babel-generator/test/index.js

@@ -492,6 +492,7 @@ suites.forEach(function(testSuite) {
               strictMode: task.options.strictMode === false ? false : true,
               sourceType: "module",
               sourceMaps: !!task.sourceMap,
+              ...task.options.parserOpts,
             });
             const options = {
               sourceFileName: path.relative(__dirname, actual.loc),

packages/babel-parser/ast/spec.md

@@ -79,6 +79,7 @@ These are the core @babel/parser (babylon) AST node types.
   - [CallExpression](#callexpression)
   - [NewExpression](#newexpression)
   - [SequenceExpression](#sequenceexpression)
+  - [ParenthesizedExpression](#parenthesizedexpression)
   - [DoExpression](#doexpression)
 - [Template Literals](#template-literals)
   - [TemplateLiteral](#templateliteral)
@@ -945,6 +946,17 @@ interface SequenceExpression <: Expression {
 
 A sequence expression, i.e., a comma-separated sequence of expressions.
 
+## ParenthesizedExpression
+
+```js
+interface ParenthesizedExpression <: Expression {
+    type "ParenthesizedExpression";
+    expression: Expression;
+}
+```
+
+An expression wrapped by parentheses.
+
 ## DoExpression
 
 ```js

packages/babel-parser/src/options.js

@@ -19,6 +19,7 @@ export type Options = {
   strictMode: ?boolean,
   ranges: boolean,
   tokens: boolean,
+  createParenthesizedExpressions: boolean,
 };
 
 export const defaultOptions: Options = {
@@ -55,6 +56,9 @@ export const defaultOptions: Options = {
   ranges: false,
   // Adds all parsed tokens to a `tokens` property on the `File` node
   tokens: false,
+  // Whether to create ParenthesizedExpression AST nodes (if false
+  // the parser sets extra.parenthesized on the expression nodes instead).
+  createParenthesizedExpressions: false,
 };
 
 // Interpret and default an options object

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

@@ -40,6 +40,12 @@ import {
   SCOPE_PROGRAM,
 } from "../util/scopeflags";
 
+const unwrapParenthesizedExpression = node => {
+  return node.type === "ParenthesizedExpression"
+    ? unwrapParenthesizedExpression(node.expression)
+    : node;
+};
+
 export default class ExpressionParser extends LValParser {
   // Forward-declaration: defined in statement.js
   +parseBlock: (
@@ -204,16 +210,22 @@ export default class ExpressionParser extends LValParser {
 
       this.checkLVal(left, undefined, undefined, "assignment expression");
 
+      const maybePattern = unwrapParenthesizedExpression(left);
+
       let patternErrorMsg;
-      if (left.type === "ObjectPattern") {
+      if (maybePattern.type === "ObjectPattern") {
         patternErrorMsg = "`({a}) = 0` use `({a} = 0)`";
-      } else if (left.type === "ArrayPattern") {
+      } else if (maybePattern.type === "ArrayPattern") {
         patternErrorMsg = "`([a]) = 0` use `([a] = 0)`";
       }
 
-      if (patternErrorMsg && left.extra && left.extra.parenthesized) {
+      if (
+        patternErrorMsg &&
+        ((left.extra && left.extra.parenthesized) ||
+          left.type === "ParenthesizedExpression")
+      ) {
         this.raise(
-          left.start,
+          maybePattern.start,
           `You're trying to assign to a parenthesized expression, eg. instead of ${patternErrorMsg}`,
         );
       }
@@ -326,7 +338,8 @@ export default class ExpressionParser extends LValParser {
         if (
           operator === "**" &&
           left.type === "UnaryExpression" &&
-          !(left.extra && left.extra.parenthesized)
+          (this.options.createParenthesizedExpressions ||
+            !(left.extra && left.extra.parenthesized))
         ) {
           this.raise(
             left.argument.start,
@@ -1161,13 +1174,6 @@ export default class ExpressionParser extends LValParser {
     return this.finishNode(node, type);
   }
 
-  parseParenExpression(): N.Expression {
-    this.expect(tt.parenL);
-    const val = this.parseExpression();
-    this.expect(tt.parenR);
-    return val;
-  }
-
   parseParenAndDistinguishExpression(canBeArrow: boolean): N.Expression {
     const startPos = this.state.start;
     const startLoc = this.state.startLoc;
@@ -1278,10 +1284,16 @@ export default class ExpressionParser extends LValParser {
       val = exprList[0];
     }
 
-    this.addExtra(val, "parenthesized", true);
+    if (!this.options.createParenthesizedExpressions) {
-    this.addExtra(val, "parenStart", startPos);
+      this.addExtra(val, "parenthesized", true);
+      this.addExtra(val, "parenStart", startPos);
+      return val;
+    }
 
-    return val;
+    const parenExpression = this.startNodeAt(startPos, startLoc);
+    parenExpression.expression = val;
+    this.finishNode(parenExpression, "ParenthesizedExpression");
+    return parenExpression;
   }
 
   shouldParseArrow(): boolean {

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

@@ -93,6 +93,14 @@ export default class LValParser extends NodeUtils {
           }
           break;
 
+        case "ParenthesizedExpression":
+          node.expression = this.toAssignable(
+            node.expression,
+            isBinding,
+            contextDescription,
+          );
+          break;
+
         case "MemberExpression":
           if (!isBinding) break;
 
@@ -413,6 +421,15 @@ export default class LValParser extends NodeUtils {
         );
         break;
 
+      case "ParenthesizedExpression":
+        this.checkLVal(
+          expr.expression,
+          bindingType,
+          checkClashes,
+          "parenthesized expression",
+        );
+        break;
+
       default: {
         const message =
           (bindingType === BIND_NONE

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

@@ -453,6 +453,13 @@ export default class StatementParser extends ExpressionParser {
     return this.finishNode(node, "DebuggerStatement");
   }
 
+  parseHeaderExpression(): N.Expression {
+    this.expect(tt.parenL);
+    const val = this.parseExpression();
+    this.expect(tt.parenR);
+    return val;
+  }
+
   parseDoStatement(node: N.DoWhileStatement): N.DoWhileStatement {
     this.next();
     this.state.labels.push(loopLabel);
@@ -469,7 +476,7 @@ export default class StatementParser extends ExpressionParser {
     this.state.labels.pop();
 
     this.expect(tt._while);
-    node.test = this.parseParenExpression();
+    node.test = this.parseHeaderExpression();
     this.eat(tt.semi);
     return this.finishNode(node, "DoWhileStatement");
   }
@@ -567,7 +574,7 @@ export default class StatementParser extends ExpressionParser {
 
   parseIfStatement(node: N.IfStatement): N.IfStatement {
     this.next();
-    node.test = this.parseParenExpression();
+    node.test = this.parseHeaderExpression();
     node.consequent = this.parseStatement("if");
     node.alternate = this.eat(tt._else) ? this.parseStatement("if") : null;
     return this.finishNode(node, "IfStatement");
@@ -596,7 +603,7 @@ export default class StatementParser extends ExpressionParser {
 
   parseSwitchStatement(node: N.SwitchStatement): N.SwitchStatement {
     this.next();
-    node.discriminant = this.parseParenExpression();
+    node.discriminant = this.parseHeaderExpression();
     const cases = (node.cases = []);
     this.expect(tt.braceL);
     this.state.labels.push(switchLabel);
@@ -715,7 +722,7 @@ export default class StatementParser extends ExpressionParser {
 
   parseWhileStatement(node: N.WhileStatement): N.WhileStatement {
     this.next();
-    node.test = this.parseParenExpression();
+    node.test = this.parseHeaderExpression();
     this.state.labels.push(loopLabel);
 
     node.body =
@@ -737,7 +744,7 @@ export default class StatementParser extends ExpressionParser {
       this.raise(this.state.start, "'with' in strict mode");
     }
     this.next();
-    node.object = this.parseParenExpression();
+    node.object = this.parseHeaderExpression();
 
     node.body =
       // For the smartPipelines plugin:

packages/babel-parser/src/types.js

@@ -574,6 +574,11 @@ export type SequenceExpression = NodeBase & {
   expressions: $ReadOnlyArray<Expression>,
 };
 
+export type ParenthesizedExpression = NodeBase & {
+  type: "ParenthesizedExpression",
+  expression: Expression,
+};
+
 // Pipelines
 
 export type PipelineBody = NodeBase & {

packages/babel-parser/test/fixtures/comments/basic/create-parenthesized-expressions/input.js

@@ -0,0 +1,12 @@
+// One
+(1);
+
+/* Two */
+(2);
+
+(
+  // Three
+  3
+);
+
+(/* Four */ 4);

packages/babel-parser/test/fixtures/comments/basic/create-parenthesized-expressions/options.json

@@ -0,0 +1,3 @@
+{
+  "createParenthesizedExpressions": true
+}

packages/babel-parser/test/fixtures/comments/basic/create-parenthesized-expressions/output.json

@@ -0,0 +1,391 @@
+{
+  "type": "File",
+  "start": 0,
+  "end": 65,
+  "loc": {
+    "start": {
+      "line": 1,
+      "column": 0
+    },
+    "end": {
+      "line": 12,
+      "column": 15
+    }
+  },
+  "program": {
+    "type": "Program",
+    "start": 0,
+    "end": 65,
+    "loc": {
+      "start": {
+        "line": 1,
+        "column": 0
+      },
+      "end": {
+        "line": 12,
+        "column": 15
+      }
+    },
+    "sourceType": "script",
+    "interpreter": null,
+    "body": [
+      {
+        "type": "ExpressionStatement",
+        "start": 7,
+        "end": 11,
+        "loc": {
+          "start": {
+            "line": 2,
+            "column": 0
+          },
+          "end": {
+            "line": 2,
+            "column": 4
+          }
+        },
+        "expression": {
+          "type": "ParenthesizedExpression",
+          "start": 7,
+          "end": 10,
+          "loc": {
+            "start": {
+              "line": 2,
+              "column": 0
+            },
+            "end": {
+              "line": 2,
+              "column": 3
+            }
+          },
+          "expression": {
+            "type": "NumericLiteral",
+            "start": 8,
+            "end": 9,
+            "loc": {
+              "start": {
+                "line": 2,
+                "column": 1
+              },
+              "end": {
+                "line": 2,
+                "column": 2
+              }
+            },
+            "extra": {
+              "rawValue": 1,
+              "raw": "1"
+            },
+            "value": 1
+          }
+        },
+        "leadingComments": [
+          {
+            "type": "CommentLine",
+            "value": " One",
+            "start": 0,
+            "end": 6,
+            "loc": {
+              "start": {
+                "line": 1,
+                "column": 0
+              },
+              "end": {
+                "line": 1,
+                "column": 6
+              }
+            }
+          }
+        ],
+        "trailingComments": [
+          {
+            "type": "CommentBlock",
+            "value": " Two ",
+            "start": 13,
+            "end": 22,
+            "loc": {
+              "start": {
+                "line": 4,
+                "column": 0
+              },
+              "end": {
+                "line": 4,
+                "column": 9
+              }
+            }
+          }
+        ]
+      },
+      {
+        "type": "ExpressionStatement",
+        "start": 23,
+        "end": 27,
+        "loc": {
+          "start": {
+            "line": 5,
+            "column": 0
+          },
+          "end": {
+            "line": 5,
+            "column": 4
+          }
+        },
+        "expression": {
+          "type": "ParenthesizedExpression",
+          "start": 23,
+          "end": 26,
+          "loc": {
+            "start": {
+              "line": 5,
+              "column": 0
+            },
+            "end": {
+              "line": 5,
+              "column": 3
+            }
+          },
+          "expression": {
+            "type": "NumericLiteral",
+            "start": 24,
+            "end": 25,
+            "loc": {
+              "start": {
+                "line": 5,
+                "column": 1
+              },
+              "end": {
+                "line": 5,
+                "column": 2
+              }
+            },
+            "extra": {
+              "rawValue": 2,
+              "raw": "2"
+            },
+            "value": 2
+          }
+        },
+        "leadingComments": [
+          {
+            "type": "CommentBlock",
+            "value": " Two ",
+            "start": 13,
+            "end": 22,
+            "loc": {
+              "start": {
+                "line": 4,
+                "column": 0
+              },
+              "end": {
+                "line": 4,
+                "column": 9
+              }
+            }
+          }
+        ]
+      },
+      {
+        "type": "ExpressionStatement",
+        "start": 29,
+        "end": 48,
+        "loc": {
+          "start": {
+            "line": 7,
+            "column": 0
+          },
+          "end": {
+            "line": 10,
+            "column": 2
+          }
+        },
+        "expression": {
+          "type": "ParenthesizedExpression",
+          "start": 29,
+          "end": 47,
+          "loc": {
+            "start": {
+              "line": 7,
+              "column": 0
+            },
+            "end": {
+              "line": 10,
+              "column": 1
+            }
+          },
+          "expression": {
+            "type": "NumericLiteral",
+            "start": 44,
+            "end": 45,
+            "loc": {
+              "start": {
+                "line": 9,
+                "column": 2
+              },
+              "end": {
+                "line": 9,
+                "column": 3
+              }
+            },
+            "extra": {
+              "rawValue": 3,
+              "raw": "3"
+            },
+            "value": 3,
+            "leadingComments": [
+              {
+                "type": "CommentLine",
+                "value": " Three",
+                "start": 33,
+                "end": 41,
+                "loc": {
+                  "start": {
+                    "line": 8,
+                    "column": 2
+                  },
+                  "end": {
+                    "line": 8,
+                    "column": 10
+                  }
+                }
+              }
+            ]
+          }
+        }
+      },
+      {
+        "type": "ExpressionStatement",
+        "start": 50,
+        "end": 65,
+        "loc": {
+          "start": {
+            "line": 12,
+            "column": 0
+          },
+          "end": {
+            "line": 12,
+            "column": 15
+          }
+        },
+        "expression": {
+          "type": "ParenthesizedExpression",
+          "start": 50,
+          "end": 64,
+          "loc": {
+            "start": {
+              "line": 12,
+              "column": 0
+            },
+            "end": {
+              "line": 12,
+              "column": 14
+            }
+          },
+          "expression": {
+            "type": "NumericLiteral",
+            "start": 62,
+            "end": 63,
+            "loc": {
+              "start": {
+                "line": 12,
+                "column": 12
+              },
+              "end": {
+                "line": 12,
+                "column": 13
+              }
+            },
+            "extra": {
+              "rawValue": 4,
+              "raw": "4"
+            },
+            "value": 4,
+            "leadingComments": [
+              {
+                "type": "CommentBlock",
+                "value": " Four ",
+                "start": 51,
+                "end": 61,
+                "loc": {
+                  "start": {
+                    "line": 12,
+                    "column": 1
+                  },
+                  "end": {
+                    "line": 12,
+                    "column": 11
+                  }
+                }
+              }
+            ]
+          }
+        }
+      }
+    ],
+    "directives": []
+  },
+  "comments": [
+    {
+      "type": "CommentLine",
+      "value": " One",
+      "start": 0,
+      "end": 6,
+      "loc": {
+        "start": {
+          "line": 1,
+          "column": 0
+        },
+        "end": {
+          "line": 1,
+          "column": 6
+        }
+      }
+    },
+    {
+      "type": "CommentBlock",
+      "value": " Two ",
+      "start": 13,
+      "end": 22,
+      "loc": {
+        "start": {
+          "line": 4,
+          "column": 0
+        },
+        "end": {
+          "line": 4,
+          "column": 9
+        }
+      }
+    },
+    {
+      "type": "CommentLine",
+      "value": " Three",
+      "start": 33,
+      "end": 41,
+      "loc": {
+        "start": {
+          "line": 8,
+          "column": 2
+        },
+        "end": {
+          "line": 8,
+          "column": 10
+        }
+      }
+    },
+    {
+      "type": "CommentBlock",
+      "value": " Four ",
+      "start": 51,
+      "end": 61,
+      "loc": {
+        "start": {
+          "line": 12,
+          "column": 1
+        },
+        "end": {
+          "line": 12,
+          "column": 11
+        }
+      }
+    }
+  ]
+}

packages/babel-parser/test/fixtures/core/uncategorised/556/input.js

@@ -0,0 +1 @@
+({x}) = {x: 1};

packages/babel-parser/test/fixtures/core/uncategorised/556/options.json

@@ -0,0 +1,4 @@
+{
+  "createParenthesizedExpressions": true,
+  "throws": "You're trying to assign to a parenthesized expression, eg. instead of `({a}) = 0` use `({a} = 0)` (1:1)"
+}

packages/babel-parser/test/fixtures/core/uncategorised/557/input.js

@@ -0,0 +1 @@
+("hello");

packages/babel-parser/test/fixtures/core/uncategorised/557/options.json

@@ -0,0 +1,3 @@
+{
+  "createParenthesizedExpressions": true
+}

packages/babel-parser/test/fixtures/core/uncategorised/557/output.json

@@ -0,0 +1,85 @@
+{
+  "type": "File",
+  "start": 0,
+  "end": 10,
+  "loc": {
+    "start": {
+      "line": 1,
+      "column": 0
+    },
+    "end": {
+      "line": 1,
+      "column": 10
+    }
+  },
+  "program": {
+    "type": "Program",
+    "start": 0,
+    "end": 10,
+    "loc": {
+      "start": {
+        "line": 1,
+        "column": 0
+      },
+      "end": {
+        "line": 1,
+        "column": 10
+      }
+    },
+    "sourceType": "script",
+    "interpreter": null,
+    "body": [
+      {
+        "type": "ExpressionStatement",
+        "start": 0,
+        "end": 10,
+        "loc": {
+          "start": {
+            "line": 1,
+            "column": 0
+          },
+          "end": {
+            "line": 1,
+            "column": 10
+          }
+        },
+        "expression": {
+          "type": "ParenthesizedExpression",
+          "start": 0,
+          "end": 9,
+          "loc": {
+            "start": {
+              "line": 1,
+              "column": 0
+            },
+            "end": {
+              "line": 1,
+              "column": 9
+            }
+          },
+          "expression": {
+            "type": "StringLiteral",
+            "start": 1,
+            "end": 8,
+            "loc": {
+              "start": {
+                "line": 1,
+                "column": 1
+              },
+              "end": {
+                "line": 1,
+                "column": 8
+              }
+            },
+            "extra": {
+              "rawValue": "hello",
+              "raw": "\"hello\""
+            },
+            "value": "hello"
+          }
+        }
+      }
+    ],
+    "directives": []
+  }
+}

packages/babel-parser/test/fixtures/core/uncategorised/558/input.js

@@ -0,0 +1 @@
+([a]) = []

packages/babel-parser/test/fixtures/core/uncategorised/558/options.json

@@ -0,0 +1,4 @@
+{
+  "createParenthesizedExpressions": true,
+  "throws": "You're trying to assign to a parenthesized expression, eg. instead of `([a]) = 0` use `([a] = 0)` (1:1)"
+}

packages/babel-parser/test/fixtures/es2015/arrow-functions/create-parenthesized-expressions/input.js

@@ -0,0 +1 @@
+(foo) => {}

packages/babel-parser/test/fixtures/es2015/arrow-functions/create-parenthesized-expressions/options.json

@@ -0,0 +1,3 @@
+{
+  "createParenthesizedExpressions": true
+}

packages/babel-parser/test/fixtures/es2015/arrow-functions/create-parenthesized-expressions/output.json

@@ -0,0 +1,104 @@
+{
+  "type": "File",
+  "start": 0,
+  "end": 11,
+  "loc": {
+    "start": {
+      "line": 1,
+      "column": 0
+    },
+    "end": {
+      "line": 1,
+      "column": 11
+    }
+  },
+  "program": {
+    "type": "Program",
+    "start": 0,
+    "end": 11,
+    "loc": {
+      "start": {
+        "line": 1,
+        "column": 0
+      },
+      "end": {
+        "line": 1,
+        "column": 11
+      }
+    },
+    "sourceType": "script",
+    "interpreter": null,
+    "body": [
+      {
+        "type": "ExpressionStatement",
+        "start": 0,
+        "end": 11,
+        "loc": {
+          "start": {
+            "line": 1,
+            "column": 0
+          },
+          "end": {
+            "line": 1,
+            "column": 11
+          }
+        },
+        "expression": {
+          "type": "ArrowFunctionExpression",
+          "start": 0,
+          "end": 11,
+          "loc": {
+            "start": {
+              "line": 1,
+              "column": 0
+            },
+            "end": {
+              "line": 1,
+              "column": 11
+            }
+          },
+          "id": null,
+          "generator": false,
+          "async": false,
+          "params": [
+            {
+              "type": "Identifier",
+              "start": 1,
+              "end": 4,
+              "loc": {
+                "start": {
+                  "line": 1,
+                  "column": 1
+                },
+                "end": {
+                  "line": 1,
+                  "column": 4
+                },
+                "identifierName": "foo"
+              },
+              "name": "foo"
+            }
+          ],
+          "body": {
+            "type": "BlockStatement",
+            "start": 9,
+            "end": 11,
+            "loc": {
+              "start": {
+                "line": 1,
+                "column": 9
+              },
+              "end": {
+                "line": 1,
+                "column": 11
+              }
+            },
+            "body": [],
+            "directives": []
+          }
+        }
+      }
+    ],
+    "directives": []
+  }
+}

packages/babel-parser/test/fixtures/es2015/uncategorised/394/input.js

@@ -0,0 +1,4 @@
+var a;
+(a) = {};
+(a.b) = {};
+(a['c']) = {};

packages/babel-parser/test/fixtures/es2015/uncategorised/394/options.json

@@ -0,0 +1,3 @@
+{
+  "createParenthesizedExpressions": true
+}

packages/babel-parser/test/fixtures/es2015/uncategorised/394/output.json

@@ -0,0 +1,392 @@
+{
+  "type": "File",
+  "start": 0,
+  "end": 43,
+  "loc": {
+    "start": {
+      "line": 1,
+      "column": 0
+    },
+    "end": {
+      "line": 4,
+      "column": 14
+    }
+  },
+  "program": {
+    "type": "Program",
+    "start": 0,
+    "end": 43,
+    "loc": {
+      "start": {
+        "line": 1,
+        "column": 0
+      },
+      "end": {
+        "line": 4,
+        "column": 14
+      }
+    },
+    "sourceType": "script",
+    "interpreter": null,
+    "body": [
+      {
+        "type": "VariableDeclaration",
+        "start": 0,
+        "end": 6,
+        "loc": {
+          "start": {
+            "line": 1,
+            "column": 0
+          },
+          "end": {
+            "line": 1,
+            "column": 6
+          }
+        },
+        "declarations": [
+          {
+            "type": "VariableDeclarator",
+            "start": 4,
+            "end": 5,
+            "loc": {
+              "start": {
+                "line": 1,
+                "column": 4
+              },
+              "end": {
+                "line": 1,
+                "column": 5
+              }
+            },
+            "id": {
+              "type": "Identifier",
+              "start": 4,
+              "end": 5,
+              "loc": {
+                "start": {
+                  "line": 1,
+                  "column": 4
+                },
+                "end": {
+                  "line": 1,
+                  "column": 5
+                },
+                "identifierName": "a"
+              },
+              "name": "a"
+            },
+            "init": null
+          }
+        ],
+        "kind": "var"
+      },
+      {
+        "type": "ExpressionStatement",
+        "start": 7,
+        "end": 16,
+        "loc": {
+          "start": {
+            "line": 2,
+            "column": 0
+          },
+          "end": {
+            "line": 2,
+            "column": 9
+          }
+        },
+        "expression": {
+          "type": "AssignmentExpression",
+          "start": 7,
+          "end": 15,
+          "loc": {
+            "start": {
+              "line": 2,
+              "column": 0
+            },
+            "end": {
+              "line": 2,
+              "column": 8
+            }
+          },
+          "operator": "=",
+          "left": {
+            "type": "ParenthesizedExpression",
+            "start": 7,
+            "end": 10,
+            "loc": {
+              "start": {
+                "line": 2,
+                "column": 0
+              },
+              "end": {
+                "line": 2,
+                "column": 3
+              }
+            },
+            "expression": {
+              "type": "Identifier",
+              "start": 8,
+              "end": 9,
+              "loc": {
+                "start": {
+                  "line": 2,
+                  "column": 1
+                },
+                "end": {
+                  "line": 2,
+                  "column": 2
+                },
+                "identifierName": "a"
+              },
+              "name": "a"
+            }
+          },
+          "right": {
+            "type": "ObjectExpression",
+            "start": 13,
+            "end": 15,
+            "loc": {
+              "start": {
+                "line": 2,
+                "column": 6
+              },
+              "end": {
+                "line": 2,
+                "column": 8
+              }
+            },
+            "properties": []
+          }
+        }
+      },
+      {
+        "type": "ExpressionStatement",
+        "start": 17,
+        "end": 28,
+        "loc": {
+          "start": {
+            "line": 3,
+            "column": 0
+          },
+          "end": {
+            "line": 3,
+            "column": 11
+          }
+        },
+        "expression": {
+          "type": "AssignmentExpression",
+          "start": 17,
+          "end": 27,
+          "loc": {
+            "start": {
+              "line": 3,
+              "column": 0
+            },
+            "end": {
+              "line": 3,
+              "column": 10
+            }
+          },
+          "operator": "=",
+          "left": {
+            "type": "ParenthesizedExpression",
+            "start": 17,
+            "end": 22,
+            "loc": {
+              "start": {
+                "line": 3,
+                "column": 0
+              },
+              "end": {
+                "line": 3,
+                "column": 5
+              }
+            },
+            "expression": {
+              "type": "MemberExpression",
+              "start": 18,
+              "end": 21,
+              "loc": {
+                "start": {
+                  "line": 3,
+                  "column": 1
+                },
+                "end": {
+                  "line": 3,
+                  "column": 4
+                }
+              },
+              "object": {
+                "type": "Identifier",
+                "start": 18,
+                "end": 19,
+                "loc": {
+                  "start": {
+                    "line": 3,
+                    "column": 1
+                  },
+                  "end": {
+                    "line": 3,
+                    "column": 2
+                  },
+                  "identifierName": "a"
+                },
+                "name": "a"
+              },
+              "property": {
+                "type": "Identifier",
+                "start": 20,
+                "end": 21,
+                "loc": {
+                  "start": {
+                    "line": 3,
+                    "column": 3
+                  },
+                  "end": {
+                    "line": 3,
+                    "column": 4
+                  },
+                  "identifierName": "b"
+                },
+                "name": "b"
+              },
+              "computed": false
+            }
+          },
+          "right": {
+            "type": "ObjectExpression",
+            "start": 25,
+            "end": 27,
+            "loc": {
+              "start": {
+                "line": 3,
+                "column": 8
+              },
+              "end": {
+                "line": 3,
+                "column": 10
+              }
+            },
+            "properties": []
+          }
+        }
+      },
+      {
+        "type": "ExpressionStatement",
+        "start": 29,
+        "end": 43,
+        "loc": {
+          "start": {
+            "line": 4,
+            "column": 0
+          },
+          "end": {
+            "line": 4,
+            "column": 14
+          }
+        },
+        "expression": {
+          "type": "AssignmentExpression",
+          "start": 29,
+          "end": 42,
+          "loc": {
+            "start": {
+              "line": 4,
+              "column": 0
+            },
+            "end": {
+              "line": 4,
+              "column": 13
+            }
+          },
+          "operator": "=",
+          "left": {
+            "type": "ParenthesizedExpression",
+            "start": 29,
+            "end": 37,
+            "loc": {
+              "start": {
+                "line": 4,
+                "column": 0
+              },
+              "end": {
+                "line": 4,
+                "column": 8
+              }
+            },
+            "expression": {
+              "type": "MemberExpression",
+              "start": 30,
+              "end": 36,
+              "loc": {
+                "start": {
+                  "line": 4,
+                  "column": 1
+                },
+                "end": {
+                  "line": 4,
+                  "column": 7
+                }
+              },
+              "object": {
+                "type": "Identifier",
+                "start": 30,
+                "end": 31,
+                "loc": {
+                  "start": {
+                    "line": 4,
+                    "column": 1
+                  },
+                  "end": {
+                    "line": 4,
+                    "column": 2
+                  },
+                  "identifierName": "a"
+                },
+                "name": "a"
+              },
+              "property": {
+                "type": "StringLiteral",
+                "start": 32,
+                "end": 35,
+                "loc": {
+                  "start": {
+                    "line": 4,
+                    "column": 3
+                  },
+                  "end": {
+                    "line": 4,
+                    "column": 6
+                  }
+                },
+                "extra": {
+                  "rawValue": "c",
+                  "raw": "'c'"
+                },
+                "value": "c"
+              },
+              "computed": true
+            }
+          },
+          "right": {
+            "type": "ObjectExpression",
+            "start": 40,
+            "end": 42,
+            "loc": {
+              "start": {
+                "line": 4,
+                "column": 11
+              },
+              "end": {
+                "line": 4,
+                "column": 13
+              }
+            },
+            "properties": []
+          }
+        }
+      }
+    ],
+    "directives": []
+  }
+}

packages/babel-parser/test/fixtures/es2015/uncategorised/395/input.js

@@ -0,0 +1 @@
+([a.a]) => 42

packages/babel-parser/test/fixtures/es2015/uncategorised/395/options.json

@@ -0,0 +1,4 @@
+{
+  "createParenthesizedExpressions": true,
+  "throws": "Invalid left-hand side in arrow function parameters (1:2)"
+}

packages/babel-parser/test/fixtures/es2016/exponentiation-operator/15/input.js

@@ -0,0 +1 @@
+-(5) ** 6;

packages/babel-parser/test/fixtures/es2016/exponentiation-operator/15/options.json

@@ -0,0 +1,4 @@
+{
+  "createParenthesizedExpressions": true,
+  "throws": "Illegal expression. Wrap left hand side or entire exponentiation in parentheses. (1:1)"
+}

packages/babel-parser/test/fixtures/es2016/exponentiation-operator/16/input.js

@@ -0,0 +1 @@
+(-5 ** 6);

packages/babel-parser/test/fixtures/es2016/exponentiation-operator/16/options.json

@@ -0,0 +1,4 @@
+{
+  "createParenthesizedExpressions": true,
+  "throws": "Illegal expression. Wrap left hand side or entire exponentiation in parentheses. (1:2)"
+}

packages/babel-parser/typings/babel-parser.d.ts

@@ -78,6 +78,14 @@ export interface ParserOptions {
      * Adds all parsed tokens to a tokens property on the File node.
      */
     tokens?: boolean;
+
+    /**
+     * By default, the parser adds information about parentheses by setting
+     * `extra.parenthesized` to `true` as needed.
+     * When this option is `true` the parser creates `ParenthesizedExpression`
+     * AST nodes instead of using the `extra` property.
+     */
+    createParenthesizedExpressions?: boolean;
 }
 
 export type ParserPlugin =

packages/babel-traverse/src/path/inference/inferers.js

@@ -102,6 +102,10 @@ export function SequenceExpression() {
     .getTypeAnnotation();
 }
 
+export function ParenthesizedExpression() {
+  return this.get("expression").getTypeAnnotation();
+}
+
 export function AssignmentExpression() {
   return this.get("right").getTypeAnnotation();
 }

packages/babel-types/src/asserts/generated/index.js

@@ -162,6 +162,12 @@ export function assertSequenceExpression(
 ): void {
   assert("SequenceExpression", node, opts);
 }
+export function assertParenthesizedExpression(
+  node: Object,
+  opts?: Object = {},
+): void {
+  assert("ParenthesizedExpression", node, opts);
+}
 export function assertSwitchCase(node: Object, opts?: Object = {}): void {
   assert("SwitchCase", node, opts);
 }
@@ -654,12 +660,6 @@ export function assertJSXClosingFragment(
 export function assertNoop(node: Object, opts?: Object = {}): void {
   assert("Noop", node, opts);
 }
-export function assertParenthesizedExpression(
-  node: Object,
-  opts?: Object = {},
-): void {
-  assert("ParenthesizedExpression", node, opts);
-}
 export function assertArgumentPlaceholder(
   node: Object,
   opts?: Object = {},

packages/babel-types/src/builders/generated/index.js

@@ -161,6 +161,10 @@ export function SequenceExpression(...args: Array<any>): Object {
   return builder("SequenceExpression", ...args);
 }
 export { SequenceExpression as sequenceExpression };
+export function ParenthesizedExpression(...args: Array<any>): Object {
+  return builder("ParenthesizedExpression", ...args);
+}
+export { ParenthesizedExpression as parenthesizedExpression };
 export function SwitchCase(...args: Array<any>): Object {
   return builder("SwitchCase", ...args);
 }
@@ -592,10 +596,6 @@ export function Noop(...args: Array<any>): Object {
   return builder("Noop", ...args);
 }
 export { Noop as noop };
-export function ParenthesizedExpression(...args: Array<any>): Object {
-  return builder("ParenthesizedExpression", ...args);
-}
-export { ParenthesizedExpression as parenthesizedExpression };
 export function ArgumentPlaceholder(...args: Array<any>): Object {
   return builder("ArgumentPlaceholder", ...args);
 }

packages/babel-types/src/definitions/core.js

@@ -736,6 +736,16 @@ defineType("SequenceExpression", {
   aliases: ["Expression"],
 });
 
+defineType("ParenthesizedExpression", {
+  visitor: ["expression"],
+  aliases: ["Expression", "ExpressionWrapper"],
+  fields: {
+    expression: {
+      validate: assertNodeType("Expression"),
+    },
+  },
+});
+
 defineType("SwitchCase", {
   visitor: ["test", "consequent"],
   fields: {

packages/babel-types/src/definitions/misc.js

@@ -1,16 +1,6 @@
 // @flow
-import defineType, { assertNodeType } from "./utils";
+import defineType from "./utils";
 
 defineType("Noop", {
   visitor: [],
 });
-
-defineType("ParenthesizedExpression", {
-  visitor: ["expression"],
-  aliases: ["Expression", "ExpressionWrapper"],
-  fields: {
-    expression: {
-      validate: assertNodeType("Expression"),
-    },
-  },
-});

packages/babel-types/src/validators/generated/index.js

@@ -551,6 +551,23 @@ export function isSequenceExpression(node: ?Object, opts?: Object): boolean {
 
   return false;
 }
+export function isParenthesizedExpression(
+  node: ?Object,
+  opts?: Object,
+): boolean {
+  if (!node) return false;
+
+  const nodeType = node.type;
+  if (nodeType === "ParenthesizedExpression") {
+    if (typeof opts === "undefined") {
+      return true;
+    } else {
+      return shallowEqual(node, opts);
+    }
+  }
+
+  return false;
+}
 export function isSwitchCase(node: ?Object, opts?: Object): boolean {
   if (!node) return false;
 
@@ -2076,23 +2093,6 @@ export function isNoop(node: ?Object, opts?: Object): boolean {
 
   return false;
 }
-export function isParenthesizedExpression(
-  node: ?Object,
-  opts?: Object,
-): boolean {
-  if (!node) return false;
-
-  const nodeType = node.type;
-  if (nodeType === "ParenthesizedExpression") {
-    if (typeof opts === "undefined") {
-      return true;
-    } else {
-      return shallowEqual(node, opts);
-    }
-  }
-
-  return false;
-}
 export function isArgumentPlaceholder(node: ?Object, opts?: Object): boolean {
   if (!node) return false;
 
@@ -3256,6 +3256,7 @@ export function isExpression(node: ?Object, opts?: Object): boolean {
     "NewExpression" === nodeType ||
     "ObjectExpression" === nodeType ||
     "SequenceExpression" === nodeType ||
+    "ParenthesizedExpression" === nodeType ||
     "ThisExpression" === nodeType ||
     "UnaryExpression" === nodeType ||
     "UpdateExpression" === nodeType ||
@@ -3269,7 +3270,6 @@ export function isExpression(node: ?Object, opts?: Object): boolean {
     "TypeCastExpression" === nodeType ||
     "JSXElement" === nodeType ||
     "JSXFragment" === nodeType ||
-    "ParenthesizedExpression" === nodeType ||
     "AwaitExpression" === nodeType ||
     "BindExpression" === nodeType ||
     "OptionalMemberExpression" === nodeType ||
@@ -3559,8 +3559,8 @@ export function isExpressionWrapper(node: ?Object, opts?: Object): boolean {
   if (
     nodeType === "ExpressionWrapper" ||
     "ExpressionStatement" === nodeType ||
-    "TypeCastExpression" === nodeType ||
+    "ParenthesizedExpression" === nodeType ||
-    "ParenthesizedExpression" === nodeType
+    "TypeCastExpression" === nodeType
   ) {
     if (typeof opts === "undefined") {
       return true;