eslint-parser: ES2020 features (#11815)

* chore: update espree test on nullish coalescing

* feat: add optional chaining support

* fix: adapt to estree AST shape

* chore: update lockfile

* add estree optional-chaining test fixtures

* address review comments

* chore: simplify smoke test

* export * support

Co-authored-by: Brian Ng <bng412@gmail.com>

eslint/babel-eslint-parser/package.json

@@ -23,8 +23,8 @@
     "eslint": ">=6.0.0"
   },
   "dependencies": {
-    "eslint-scope": "5.0.0",
+    "eslint-scope": "5.1.0",
-    "eslint-visitor-keys": "^1.1.0",
+    "eslint-visitor-keys": "^1.3.0",
     "semver": "^6.3.0"
   },
   "devDependencies": {

eslint/babel-eslint-parser/src/convert/convertAST.js

@@ -1,4 +1,5 @@
 import { types as t, traverse } from "@babel/core";
+import VISITOR_KEYS from "../visitor-keys";
 
 function convertNodes(ast, code) {
   const astTransformVisitor = {
@@ -81,21 +82,28 @@ function convertNodes(ast, code) {
   };
   const state = { source: code };
 
-  // Monkey patch visitor keys in order to be able to traverse the estree nodes
+  const oldExportAllDeclarationKeys = t.VISITOR_KEYS.ExportAllDeclaration;
-  t.VISITOR_KEYS.Property = t.VISITOR_KEYS.ObjectProperty;
-  t.VISITOR_KEYS.MethodDefinition = [
-    "key",
-    "value",
-    "decorators",
-    "returnType",
-    "typeParameters",
-  ];
 
-  traverse(ast, astTransformVisitor, null, state);
+  try {
+    // Monkey patch visitor keys in order to be able to traverse the estree nodes
+    t.VISITOR_KEYS.ChainExpression = VISITOR_KEYS.ChainExpression;
+    t.VISITOR_KEYS.Property = VISITOR_KEYS.Property;
+    t.VISITOR_KEYS.MethodDefinition = VISITOR_KEYS.MethodDefinition;
 
-  // These can be safely deleted because they are not defined in the original visitor keys.
+    // Make sure we visit `exported` key to remove `identifierName` from loc node
-  delete t.VISITOR_KEYS.Property;
+    t.VISITOR_KEYS.ExportAllDeclaration = t.VISITOR_KEYS.ExportAllDeclaration.concat(
-  delete t.VISITOR_KEYS.MethodDefinition;
+      "exported",
+    );
+
+    traverse(ast, astTransformVisitor, null, state);
+  } finally {
+    // These can be safely deleted because they are not defined in the original visitor keys.
+    delete t.VISITOR_KEYS.ChainExpression;
+    delete t.VISITOR_KEYS.MethodDefinition;
+    delete t.VISITOR_KEYS.Property;
+
+    t.VISITOR_KEYS.ExportAllDeclaration = oldExportAllDeclarationKeys;
+  }
 }
 
 function convertProgramNode(ast) {

eslint/babel-eslint-parser/src/convert/convertTokens.js

@@ -115,7 +115,6 @@ function convertToken(token, source) {
     type === tt.incDec ||
     type === tt.colon ||
     type === tt.question ||
-    type === tt.questionDot ||
     type === tt.template ||
     type === tt.backQuote ||
     type === tt.dollarBraceL ||
@@ -173,6 +172,12 @@ function convertToken(token, source) {
   } else if (type === tt.bigint) {
     token.type = "Numeric";
     token.value = `${token.value}n`;
+  } else if (type === tt.questionDot) {
+    token.value = type.label;
+  }
+  if (typeof token.type !== "string") {
+    // Acorn does not have rightAssociative
+    delete token.type.rightAssociative;
   }
 
   return token;

eslint/babel-eslint-parser/src/visitor-keys.js

@@ -1,10 +1,13 @@
 import { types as t } from "@babel/core";
 import { KEYS as ESLINT_VISITOR_KEYS } from "eslint-visitor-keys";
 
-const { VISITOR_KEYS: BABEL_VISITOR_KEYS } = t;
+/*eslint no-unused-vars: ["error", { "ignoreRestSiblings": true }]*/
+const { ExportAllDeclaration, ...BABEL_VISITOR_KEYS } = t.VISITOR_KEYS;
 
 export default Object.assign(
   {
+    ChainExpression: ESLINT_VISITOR_KEYS.ChainExpression,
+    ExportAllDeclaration: ESLINT_VISITOR_KEYS.ExportAllDeclaration,
     Literal: ESLINT_VISITOR_KEYS.Literal,
     MethodDefinition: ["decorators"].concat(
       ESLINT_VISITOR_KEYS.MethodDefinition,

eslint/babel-eslint-parser/test/index.js

@@ -253,6 +253,10 @@ describe("Babel and Espree", () => {
     parseAndAssertSame('import "foo";');
   });
 
+  it("import meta", () => {
+    parseAndAssertSame("const url = import.meta.url");
+  });
+
   it("export default class declaration", () => {
     parseAndAssertSame("export default class Foo {}");
   });
@@ -273,15 +277,8 @@ describe("Babel and Espree", () => {
     parseAndAssertSame('export * from "foo";');
   });
 
-  // Espree doesn't support `export * as ns` yet
   it("export * as ns", () => {
-    const code = 'export * as Foo from "foo";';
+    parseAndAssertSame('export * as Foo from "foo";');
-    const babylonAST = parseForESLint(code, {
-      eslintVisitorKeys: true,
-      eslintScopeManager: true,
-      babelOptions: BABEL_OPTIONS,
-    }).ast;
-    expect(babylonAST.tokens[1].type).toEqual("Punctuator");
   });
 
   it("export named", () => {
@@ -292,26 +289,12 @@ describe("Babel and Espree", () => {
     parseAndAssertSame("var foo = 1;export { foo as bar };");
   });
 
-  // Espree doesn't support the optional chaining operator yet
+  it("optional chaining operator", () => {
-  it("optional chaining operator (token)", () => {
+    parseAndAssertSame("foo?.bar?.().qux()");
-    const code = "foo?.bar";
-    const babylonAST = parseForESLint(code, {
-      eslintVisitorKeys: true,
-      eslintScopeManager: true,
-      babelOptions: BABEL_OPTIONS,
-    }).ast;
-    expect(babylonAST.tokens[1].type).toEqual("Punctuator");
   });
 
-  // Espree doesn't support the nullish coalescing operator yet
+  it("nullish coalescing operator", () => {
-  it("nullish coalescing operator (token)", () => {
+    parseAndAssertSame("foo ?? bar");
-    const code = "foo ?? bar";
-    const babylonAST = parseForESLint(code, {
-      eslintVisitorKeys: true,
-      eslintScopeManager: true,
-      babelOptions: BABEL_OPTIONS,
-    }).ast;
-    expect(babylonAST.tokens[1].type).toEqual("Punctuator");
   });
 
   // Espree doesn't support the pipeline operator yet

eslint/babel-eslint-plugin/src/rules/no-unused-expressions.js

@@ -53,7 +53,8 @@ function isOptionalCallExpression(node) {
   return (
     !!node &&
     node.type === "ExpressionStatement" &&
-    node.expression.type === "OptionalCallExpression"
+    node.expression.type === "ChainExpression" &&
+    node.expression.expression.type === "CallExpression"
   );
 }
 

packages/babel-parser/src/plugins/estree.js

@@ -388,8 +388,6 @@ export default (superClass: Class<Parser>): Class<Parser> =>
         delete node.arguments;
         // $FlowIgnore - callee isn't optional in the type definition
         delete node.callee;
-      } else if (node.type === "CallExpression") {
-        (node: N.Node).optional = false;
       }
 
       return node;
@@ -431,10 +429,38 @@ export default (superClass: Class<Parser>): Class<Parser> =>
       return node;
     }
 
-    parseSubscript(...args) {
+    parseSubscript(
-      const node = super.parseSubscript(...args);
+      base: N.Expression,
+      startPos: number,
+      startLoc: Position,
+      noCalls: ?boolean,
+      state: N.ParseSubscriptState,
+    ) {
+      const node = super.parseSubscript(
+        base,
+        startPos,
+        startLoc,
+        noCalls,
+        state,
+      );
 
-      if (node.type === "MemberExpression") {
+      if (state.optionalChainMember) {
+        // https://github.com/estree/estree/blob/master/es2020.md#chainexpression
+        if (
+          node.type === "OptionalMemberExpression" ||
+          node.type === "OptionalCallExpression"
+        ) {
+          node.type = node.type.substring(8); // strip Optional prefix
+        }
+        if (state.stop) {
+          const chain = this.startNodeAtNode(node);
+          chain.expression = node;
+          return this.finishNode(chain, "ChainExpression");
+        }
+      } else if (
+        node.type === "MemberExpression" ||
+        node.type === "CallExpression"
+      ) {
         node.optional = false;
       }
 

packages/babel-parser/test/fixtures/estree/optional-chaining/optional-call-call/input.js

@@ -0,0 +1 @@
+(foo?.())()

packages/babel-parser/test/fixtures/estree/optional-chaining/optional-call-call/output.json

@@ -0,0 +1,41 @@
+{
+  "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": "CallExpression",
+          "start":0,"end":11,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":11}},
+          "callee": {
+            "type": "ChainExpression",
+            "start":1,"end":8,"loc":{"start":{"line":1,"column":1},"end":{"line":1,"column":8}},
+            "expression": {
+              "type": "CallExpression",
+              "start":1,"end":8,"loc":{"start":{"line":1,"column":1},"end":{"line":1,"column":8}},
+              "callee": {
+                "type": "Identifier",
+                "start":1,"end":4,"loc":{"start":{"line":1,"column":1},"end":{"line":1,"column":4},"identifierName":"foo"},
+                "name": "foo"
+              },
+              "optional": true,
+              "arguments": []
+            },
+            "extra": {
+              "parenthesized": true,
+              "parenStart": 0
+            }
+          },
+          "arguments": [],
+          "optional": false
+        }
+      }
+    ]
+  }
+}

packages/babel-parser/test/fixtures/estree/optional-chaining/optional-call-chained-call/input.js

@@ -0,0 +1 @@
+foo?.()()

packages/babel-parser/test/fixtures/estree/optional-chaining/optional-call-chained-call/output.json

@@ -0,0 +1,37 @@
+{
+  "type": "File",
+  "start":0,"end":9,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":9}},
+  "program": {
+    "type": "Program",
+    "start":0,"end":9,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":9}},
+    "sourceType": "script",
+    "interpreter": null,
+    "body": [
+      {
+        "type": "ExpressionStatement",
+        "start":0,"end":9,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":9}},
+        "expression": {
+          "type": "ChainExpression",
+          "start":0,"end":9,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":9}},
+          "expression": {
+            "type": "CallExpression",
+            "start":0,"end":9,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":9}},
+            "callee": {
+              "type": "CallExpression",
+              "start":0,"end":7,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":7}},
+              "callee": {
+                "type": "Identifier",
+                "start":0,"end":3,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":3},"identifierName":"foo"},
+                "name": "foo"
+              },
+              "optional": true,
+              "arguments": []
+            },
+            "optional": false,
+            "arguments": []
+          }
+        }
+      }
+    ]
+  }
+}

packages/babel-parser/test/fixtures/estree/optional-chaining/optional-call-chained-member/input.js

@@ -0,0 +1 @@
+foo?.().bar

packages/babel-parser/test/fixtures/estree/optional-chaining/optional-call-chained-member/output.json

@@ -0,0 +1,42 @@
+{
+  "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": "ChainExpression",
+          "start":0,"end":11,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":11}},
+          "expression": {
+            "type": "MemberExpression",
+            "start":0,"end":11,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":11}},
+            "object": {
+              "type": "CallExpression",
+              "start":0,"end":7,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":7}},
+              "callee": {
+                "type": "Identifier",
+                "start":0,"end":3,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":3},"identifierName":"foo"},
+                "name": "foo"
+              },
+              "optional": true,
+              "arguments": []
+            },
+            "property": {
+              "type": "Identifier",
+              "start":8,"end":11,"loc":{"start":{"line":1,"column":8},"end":{"line":1,"column":11},"identifierName":"bar"},
+              "name": "bar"
+            },
+            "computed": false,
+            "optional": false
+          }
+        }
+      }
+    ]
+  }
+}

packages/babel-parser/test/fixtures/estree/optional-chaining/optional-call-member/input.js

@@ -0,0 +1 @@
+(foo?.()).bar

packages/babel-parser/test/fixtures/estree/optional-chaining/optional-call-member/output.json

@@ -0,0 +1,46 @@
+{
+  "type": "File",
+  "start":0,"end":13,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":13}},
+  "program": {
+    "type": "Program",
+    "start":0,"end":13,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":13}},
+    "sourceType": "script",
+    "interpreter": null,
+    "body": [
+      {
+        "type": "ExpressionStatement",
+        "start":0,"end":13,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":13}},
+        "expression": {
+          "type": "MemberExpression",
+          "start":0,"end":13,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":13}},
+          "object": {
+            "type": "ChainExpression",
+            "start":1,"end":8,"loc":{"start":{"line":1,"column":1},"end":{"line":1,"column":8}},
+            "expression": {
+              "type": "CallExpression",
+              "start":1,"end":8,"loc":{"start":{"line":1,"column":1},"end":{"line":1,"column":8}},
+              "callee": {
+                "type": "Identifier",
+                "start":1,"end":4,"loc":{"start":{"line":1,"column":1},"end":{"line":1,"column":4},"identifierName":"foo"},
+                "name": "foo"
+              },
+              "optional": true,
+              "arguments": []
+            },
+            "extra": {
+              "parenthesized": true,
+              "parenStart": 0
+            }
+          },
+          "property": {
+            "type": "Identifier",
+            "start":10,"end":13,"loc":{"start":{"line":1,"column":10},"end":{"line":1,"column":13},"identifierName":"bar"},
+            "name": "bar"
+          },
+          "computed": false,
+          "optional": false
+        }
+      }
+    ]
+  }
+}

packages/babel-parser/test/fixtures/estree/optional-chaining/optional-call-optional-call/input.js

@@ -0,0 +1 @@
+foo?.()?.()

packages/babel-parser/test/fixtures/estree/optional-chaining/optional-call-optional-call/output.json

@@ -0,0 +1,37 @@
+{
+  "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": "ChainExpression",
+          "start":0,"end":11,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":11}},
+          "expression": {
+            "type": "CallExpression",
+            "start":0,"end":11,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":11}},
+            "callee": {
+              "type": "CallExpression",
+              "start":0,"end":7,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":7}},
+              "callee": {
+                "type": "Identifier",
+                "start":0,"end":3,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":3},"identifierName":"foo"},
+                "name": "foo"
+              },
+              "optional": true,
+              "arguments": []
+            },
+            "optional": true,
+            "arguments": []
+          }
+        }
+      }
+    ]
+  }
+}

packages/babel-parser/test/fixtures/estree/optional-chaining/optional-call-optional-member/input.js

@@ -0,0 +1 @@
+foo?.()?.bar

packages/babel-parser/test/fixtures/estree/optional-chaining/optional-call-optional-member/output.json

@@ -0,0 +1,42 @@
+{
+  "type": "File",
+  "start":0,"end":12,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":12}},
+  "program": {
+    "type": "Program",
+    "start":0,"end":12,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":12}},
+    "sourceType": "script",
+    "interpreter": null,
+    "body": [
+      {
+        "type": "ExpressionStatement",
+        "start":0,"end":12,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":12}},
+        "expression": {
+          "type": "ChainExpression",
+          "start":0,"end":12,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":12}},
+          "expression": {
+            "type": "MemberExpression",
+            "start":0,"end":12,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":12}},
+            "object": {
+              "type": "CallExpression",
+              "start":0,"end":7,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":7}},
+              "callee": {
+                "type": "Identifier",
+                "start":0,"end":3,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":3},"identifierName":"foo"},
+                "name": "foo"
+              },
+              "optional": true,
+              "arguments": []
+            },
+            "property": {
+              "type": "Identifier",
+              "start":9,"end":12,"loc":{"start":{"line":1,"column":9},"end":{"line":1,"column":12},"identifierName":"bar"},
+              "name": "bar"
+            },
+            "computed": false,
+            "optional": true
+          }
+        }
+      }
+    ]
+  }
+}

packages/babel-parser/test/fixtures/estree/optional-chaining/optional-call/input.js

@@ -0,0 +1 @@
+foo?.()

packages/babel-parser/test/fixtures/estree/optional-chaining/optional-call/output.json

@@ -0,0 +1,31 @@
+{
+  "type": "File",
+  "start":0,"end":7,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":7}},
+  "program": {
+    "type": "Program",
+    "start":0,"end":7,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":7}},
+    "sourceType": "script",
+    "interpreter": null,
+    "body": [
+      {
+        "type": "ExpressionStatement",
+        "start":0,"end":7,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":7}},
+        "expression": {
+          "type": "ChainExpression",
+          "start":0,"end":7,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":7}},
+          "expression": {
+            "type": "CallExpression",
+            "start":0,"end":7,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":7}},
+            "callee": {
+              "type": "Identifier",
+              "start":0,"end":3,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":3},"identifierName":"foo"},
+              "name": "foo"
+            },
+            "optional": true,
+            "arguments": []
+          }
+        }
+      }
+    ]
+  }
+}

packages/babel-parser/test/fixtures/estree/optional-chaining/optional-member-call/input.js

@@ -0,0 +1 @@
+(foo?.bar)()

packages/babel-parser/test/fixtures/estree/optional-chaining/optional-member-call/output.json

@@ -0,0 +1,46 @@
+{
+  "type": "File",
+  "start":0,"end":12,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":12}},
+  "program": {
+    "type": "Program",
+    "start":0,"end":12,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":12}},
+    "sourceType": "script",
+    "interpreter": null,
+    "body": [
+      {
+        "type": "ExpressionStatement",
+        "start":0,"end":12,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":12}},
+        "expression": {
+          "type": "CallExpression",
+          "start":0,"end":12,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":12}},
+          "callee": {
+            "type": "ChainExpression",
+            "start":1,"end":9,"loc":{"start":{"line":1,"column":1},"end":{"line":1,"column":9}},
+            "expression": {
+              "type": "MemberExpression",
+              "start":1,"end":9,"loc":{"start":{"line":1,"column":1},"end":{"line":1,"column":9}},
+              "object": {
+                "type": "Identifier",
+                "start":1,"end":4,"loc":{"start":{"line":1,"column":1},"end":{"line":1,"column":4},"identifierName":"foo"},
+                "name": "foo"
+              },
+              "property": {
+                "type": "Identifier",
+                "start":6,"end":9,"loc":{"start":{"line":1,"column":6},"end":{"line":1,"column":9},"identifierName":"bar"},
+                "name": "bar"
+              },
+              "computed": false,
+              "optional": true
+            },
+            "extra": {
+              "parenthesized": true,
+              "parenStart": 0
+            }
+          },
+          "arguments": [],
+          "optional": false
+        }
+      }
+    ]
+  }
+}

packages/babel-parser/test/fixtures/estree/optional-chaining/optional-member-chained-call/input.js

@@ -0,0 +1 @@
+foo?.bar()

packages/babel-parser/test/fixtures/estree/optional-chaining/optional-member-chained-call/output.json

@@ -0,0 +1,42 @@
+{
+  "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": "ChainExpression",
+          "start":0,"end":10,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":10}},
+          "expression": {
+            "type": "CallExpression",
+            "start":0,"end":10,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":10}},
+            "callee": {
+              "type": "MemberExpression",
+              "start":0,"end":8,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":8}},
+              "object": {
+                "type": "Identifier",
+                "start":0,"end":3,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":3},"identifierName":"foo"},
+                "name": "foo"
+              },
+              "property": {
+                "type": "Identifier",
+                "start":5,"end":8,"loc":{"start":{"line":1,"column":5},"end":{"line":1,"column":8},"identifierName":"bar"},
+                "name": "bar"
+              },
+              "computed": false,
+              "optional": true
+            },
+            "optional": false,
+            "arguments": []
+          }
+        }
+      }
+    ]
+  }
+}

packages/babel-parser/test/fixtures/estree/optional-chaining/optional-member-chained-member/input.js

@@ -0,0 +1 @@
+foo?.bar.qux

packages/babel-parser/test/fixtures/estree/optional-chaining/optional-member-chained-member/output.json

@@ -0,0 +1,47 @@
+{
+  "type": "File",
+  "start":0,"end":12,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":12}},
+  "program": {
+    "type": "Program",
+    "start":0,"end":12,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":12}},
+    "sourceType": "script",
+    "interpreter": null,
+    "body": [
+      {
+        "type": "ExpressionStatement",
+        "start":0,"end":12,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":12}},
+        "expression": {
+          "type": "ChainExpression",
+          "start":0,"end":12,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":12}},
+          "expression": {
+            "type": "MemberExpression",
+            "start":0,"end":12,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":12}},
+            "object": {
+              "type": "MemberExpression",
+              "start":0,"end":8,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":8}},
+              "object": {
+                "type": "Identifier",
+                "start":0,"end":3,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":3},"identifierName":"foo"},
+                "name": "foo"
+              },
+              "property": {
+                "type": "Identifier",
+                "start":5,"end":8,"loc":{"start":{"line":1,"column":5},"end":{"line":1,"column":8},"identifierName":"bar"},
+                "name": "bar"
+              },
+              "computed": false,
+              "optional": true
+            },
+            "property": {
+              "type": "Identifier",
+              "start":9,"end":12,"loc":{"start":{"line":1,"column":9},"end":{"line":1,"column":12},"identifierName":"qux"},
+              "name": "qux"
+            },
+            "computed": false,
+            "optional": false
+          }
+        }
+      }
+    ]
+  }
+}

packages/babel-parser/test/fixtures/estree/optional-chaining/optional-member-member/input.js

@@ -0,0 +1 @@
+(foo?.bar).qux

packages/babel-parser/test/fixtures/estree/optional-chaining/optional-member-member/output.json

@@ -0,0 +1,51 @@
+{
+  "type": "File",
+  "start":0,"end":14,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":14}},
+  "program": {
+    "type": "Program",
+    "start":0,"end":14,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":14}},
+    "sourceType": "script",
+    "interpreter": null,
+    "body": [
+      {
+        "type": "ExpressionStatement",
+        "start":0,"end":14,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":14}},
+        "expression": {
+          "type": "MemberExpression",
+          "start":0,"end":14,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":14}},
+          "object": {
+            "type": "ChainExpression",
+            "start":1,"end":9,"loc":{"start":{"line":1,"column":1},"end":{"line":1,"column":9}},
+            "expression": {
+              "type": "MemberExpression",
+              "start":1,"end":9,"loc":{"start":{"line":1,"column":1},"end":{"line":1,"column":9}},
+              "object": {
+                "type": "Identifier",
+                "start":1,"end":4,"loc":{"start":{"line":1,"column":1},"end":{"line":1,"column":4},"identifierName":"foo"},
+                "name": "foo"
+              },
+              "property": {
+                "type": "Identifier",
+                "start":6,"end":9,"loc":{"start":{"line":1,"column":6},"end":{"line":1,"column":9},"identifierName":"bar"},
+                "name": "bar"
+              },
+              "computed": false,
+              "optional": true
+            },
+            "extra": {
+              "parenthesized": true,
+              "parenStart": 0
+            }
+          },
+          "property": {
+            "type": "Identifier",
+            "start":11,"end":14,"loc":{"start":{"line":1,"column":11},"end":{"line":1,"column":14},"identifierName":"qux"},
+            "name": "qux"
+          },
+          "computed": false,
+          "optional": false
+        }
+      }
+    ]
+  }
+}

packages/babel-parser/test/fixtures/estree/optional-chaining/optional-member-optional-call/input.js

@@ -0,0 +1 @@
+foo?.bar?.()

packages/babel-parser/test/fixtures/estree/optional-chaining/optional-member-optional-call/output.json

@@ -0,0 +1,42 @@
+{
+  "type": "File",
+  "start":0,"end":12,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":12}},
+  "program": {
+    "type": "Program",
+    "start":0,"end":12,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":12}},
+    "sourceType": "script",
+    "interpreter": null,
+    "body": [
+      {
+        "type": "ExpressionStatement",
+        "start":0,"end":12,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":12}},
+        "expression": {
+          "type": "ChainExpression",
+          "start":0,"end":12,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":12}},
+          "expression": {
+            "type": "CallExpression",
+            "start":0,"end":12,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":12}},
+            "callee": {
+              "type": "MemberExpression",
+              "start":0,"end":8,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":8}},
+              "object": {
+                "type": "Identifier",
+                "start":0,"end":3,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":3},"identifierName":"foo"},
+                "name": "foo"
+              },
+              "property": {
+                "type": "Identifier",
+                "start":5,"end":8,"loc":{"start":{"line":1,"column":5},"end":{"line":1,"column":8},"identifierName":"bar"},
+                "name": "bar"
+              },
+              "computed": false,
+              "optional": true
+            },
+            "optional": true,
+            "arguments": []
+          }
+        }
+      }
+    ]
+  }
+}

packages/babel-parser/test/fixtures/estree/optional-chaining/optional-member-optional-member/input.js

@@ -0,0 +1 @@
+foo?.bar?.qux

packages/babel-parser/test/fixtures/estree/optional-chaining/optional-member-optional-member/output.json

@@ -0,0 +1,47 @@
+{
+  "type": "File",
+  "start":0,"end":13,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":13}},
+  "program": {
+    "type": "Program",
+    "start":0,"end":13,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":13}},
+    "sourceType": "script",
+    "interpreter": null,
+    "body": [
+      {
+        "type": "ExpressionStatement",
+        "start":0,"end":13,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":13}},
+        "expression": {
+          "type": "ChainExpression",
+          "start":0,"end":13,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":13}},
+          "expression": {
+            "type": "MemberExpression",
+            "start":0,"end":13,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":13}},
+            "object": {
+              "type": "MemberExpression",
+              "start":0,"end":8,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":8}},
+              "object": {
+                "type": "Identifier",
+                "start":0,"end":3,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":3},"identifierName":"foo"},
+                "name": "foo"
+              },
+              "property": {
+                "type": "Identifier",
+                "start":5,"end":8,"loc":{"start":{"line":1,"column":5},"end":{"line":1,"column":8},"identifierName":"bar"},
+                "name": "bar"
+              },
+              "computed": false,
+              "optional": true
+            },
+            "property": {
+              "type": "Identifier",
+              "start":10,"end":13,"loc":{"start":{"line":1,"column":10},"end":{"line":1,"column":13},"identifierName":"qux"},
+              "name": "qux"
+            },
+            "computed": false,
+            "optional": true
+          }
+        }
+      }
+    ]
+  }
+}

packages/babel-parser/test/fixtures/estree/optional-chaining/optional-member/input.js

@@ -0,0 +1 @@
+foo?.bar

packages/babel-parser/test/fixtures/estree/optional-chaining/optional-member/output.json

@@ -0,0 +1,36 @@
+{
+  "type": "File",
+  "start":0,"end":8,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":8}},
+  "program": {
+    "type": "Program",
+    "start":0,"end":8,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":8}},
+    "sourceType": "script",
+    "interpreter": null,
+    "body": [
+      {
+        "type": "ExpressionStatement",
+        "start":0,"end":8,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":8}},
+        "expression": {
+          "type": "ChainExpression",
+          "start":0,"end":8,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":8}},
+          "expression": {
+            "type": "MemberExpression",
+            "start":0,"end":8,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":8}},
+            "object": {
+              "type": "Identifier",
+              "start":0,"end":3,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":3},"identifierName":"foo"},
+              "name": "foo"
+            },
+            "property": {
+              "type": "Identifier",
+              "start":5,"end":8,"loc":{"start":{"line":1,"column":5},"end":{"line":1,"column":8},"identifierName":"bar"},
+              "name": "bar"
+            },
+            "computed": false,
+            "optional": true
+          }
+        }
+      }
+    ]
+  }
+}

yarn.lock

@@ -2120,12 +2120,7 @@ acorn@^6.0.1:
   resolved "https://registry.yarnpkg.com/acorn/-/acorn-6.4.1.tgz#531e58ba3f51b9dacb9a6646ca4debf5b14ca474"
   integrity sha512-ZVA9k326Nwrj3Cj9jlh3wGFutC2ZornPNARZwsNYqQYgN0EsV2d53w5RN/co65Ohn4sUAUtb1rSUAOD6XN9idA==
 
-acorn@^7.0.0, acorn@^7.1.0:
+acorn@^7.0.0, acorn@^7.1.0, acorn@^7.1.1:
-  version "7.1.1"
-  resolved "https://registry.yarnpkg.com/acorn/-/acorn-7.1.1.tgz#e35668de0b402f359de515c5482a1ab9f89a69bf"
-  integrity sha512-add7dgA5ppRPxCFJoAGfMDi7PIBXq1RtGo7BhbLaxwrXPOmw8gq48Y9ozT01hUKy9byMjlR20EJhu5zlkErEkg==
-
-acorn@^7.1.1:
   version "7.3.1"
   resolved "https://registry.yarnpkg.com/acorn/-/acorn-7.3.1.tgz#85010754db53c3fbaf3b9ea3e083aa5c5d147ffd"
   integrity sha512-tLc0wSnatxAQHVHUapaHdz72pi9KUyHjq5KyHjGg9Y8Ifdc79pTh2XvI6I1/chZbnM7QtNKzh66ooDogPZSleA==
@@ -4365,7 +4360,7 @@ eslint-plugin-prettier@^3.1.2:
   dependencies:
     prettier-linter-helpers "^1.0.0"
 
-eslint-scope@5.0.0, eslint-scope@^5.0.0:
+eslint-scope@5.0.0:
   version "5.0.0"
   resolved "https://registry.yarnpkg.com/eslint-scope/-/eslint-scope-5.0.0.tgz#e87c8887c73e8d1ec84f1ca591645c358bfc8fb9"
   integrity sha512-oYrhJW7S0bxAFDvWqzvMPRm6pcgcnWc4QnofCAqRTRfQC0JcwenzGglTtsLyIuuWFfkqDG9vz67cnttSd53djw==
@@ -4373,6 +4368,14 @@ eslint-scope@5.0.0, eslint-scope@^5.0.0:
     esrecurse "^4.1.0"
     estraverse "^4.1.1"
 
+eslint-scope@5.1.0, eslint-scope@^5.0.0:
+  version "5.1.0"
+  resolved "https://registry.yarnpkg.com/eslint-scope/-/eslint-scope-5.1.0.tgz#d0f971dfe59c69e0cada684b23d49dbf82600ce5"
+  integrity sha512-iiGRvtxWqgtx5m8EyQUJihBloE4EnYeGE/bz1wSPwJE6tZuJUtHlhqDM4Xj2ukE8Dyy1+HCZ4hE0fzIVMzb58w==
+  dependencies:
+    esrecurse "^4.1.0"
+    estraverse "^4.1.1"
+
 eslint-utils@^1.4.3:
   version "1.4.3"
   resolved "https://registry.yarnpkg.com/eslint-utils/-/eslint-utils-1.4.3.tgz#74fec7c54d0776b6f67e0251040b5806564e981f"
@@ -4380,10 +4383,10 @@ eslint-utils@^1.4.3:
   dependencies:
     eslint-visitor-keys "^1.1.0"
 
-eslint-visitor-keys@^1.1.0:
+eslint-visitor-keys@^1.1.0, eslint-visitor-keys@^1.3.0:
-  version "1.1.0"
+  version "1.3.0"
-  resolved "https://registry.yarnpkg.com/eslint-visitor-keys/-/eslint-visitor-keys-1.1.0.tgz#e2a82cea84ff246ad6fb57f9bde5b46621459ec2"
+  resolved "https://registry.yarnpkg.com/eslint-visitor-keys/-/eslint-visitor-keys-1.3.0.tgz#30ebd1ef7c2fdff01c3a4f151044af25fab0523e"
-  integrity sha512-8y9YjtM1JBJU/A9Kc+SbaOV4y29sSWckBwMHa+FGtVj5gN/sbnKDf6xJUl+8g7FAij9LVaP8C24DUiH/f/2Z9A==
+  integrity sha512-6J72N8UNa462wa/KFODt/PJ3IU60SDpC3QXC1Hjc1BXXpfL2C9R5+AU7jhe0F6GREqVMh4Juu+NY7xn+6dipUQ==
 
 eslint@^6.8.0:
   version "6.8.0"