Do not allow member expressions to start async arrows (#10332)

* Do not allow member expressions to start async arrows

* Boolean -> boolean

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

@@ -578,21 +578,16 @@ export default class ExpressionParser extends LValParser {
     startLoc: Position,
     noCalls?: ?boolean,
   ): N.Expression {
-    const maybeAsyncArrow = this.atPossibleAsync(base);
-
     const state = {
       optionalChainMember: false,
+      maybeAsyncArrow: this.atPossibleAsync(base),
       stop: false,
     };
     do {
-      base = this.parseSubscript(
+      base = this.parseSubscript(base, startPos, startLoc, noCalls, state);
-        base,
+
-        startPos,
+      // After parsing a subscript, this isn't "async" for sure.
-        startLoc,
+      state.maybeAsyncArrow = false;
-        noCalls,
-        state,
-        maybeAsyncArrow,
-      );
     } while (!state.stop);
     return base;
   }
@@ -607,7 +602,6 @@ export default class ExpressionParser extends LValParser {
     startLoc: Position,
     noCalls: ?boolean,
     state: N.ParseSubscriptState,
-    maybeAsyncArrow: boolean,
   ): N.Expression {
     if (!noCalls && this.eat(tt.doubleColon)) {
       const node = this.startNodeAt(startPos, startLoc);
@@ -695,7 +689,7 @@ export default class ExpressionParser extends LValParser {
 
       node.arguments = this.parseCallExpressionArguments(
         tt.parenR,
-        maybeAsyncArrow,
+        state.maybeAsyncArrow,
         base.type === "Import",
         base.type !== "Super",
       );
@@ -705,7 +699,7 @@ export default class ExpressionParser extends LValParser {
         this.finishOptionalCallExpression(node);
       }
 
-      if (maybeAsyncArrow && this.shouldParseAsyncArrow()) {
+      if (state.maybeAsyncArrow && this.shouldParseAsyncArrow()) {
         state.stop = true;
 
         this.checkCommaAfterRestFromSpread();

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

@@ -2634,7 +2634,6 @@ export default (superClass: Class<Parser>): Class<Parser> =>
       startLoc: Position,
       noCalls: ?boolean,
       subscriptState: N.ParseSubscriptState,
-      maybeAsyncArrow: boolean,
     ): N.Expression {
       if (this.match(tt.questionDot) && this.isLookaheadRelational("<")) {
         this.expectPlugin("optionalChaining");
@@ -2687,7 +2686,6 @@ export default (superClass: Class<Parser>): Class<Parser> =>
         startLoc,
         noCalls,
         subscriptState,
-        maybeAsyncArrow,
       );
     }
 

packages/babel-parser/src/plugins/typescript/index.js

@@ -1568,7 +1568,6 @@ export default (superClass: Class<Parser>): Class<Parser> =>
       startLoc: Position,
       noCalls: ?boolean,
       state: N.ParseSubscriptState,
-      maybeAsyncArrow: boolean,
     ): N.Expression {
       if (!this.hasPrecedingLineBreak() && this.match(tt.bang)) {
         this.state.exprAllowed = false;
@@ -1631,14 +1630,7 @@ export default (superClass: Class<Parser>): Class<Parser> =>
         if (result) return result;
       }
 
-      return super.parseSubscript(
+      return super.parseSubscript(base, startPos, startLoc, noCalls, state);
-        base,
-        startPos,
-        startLoc,
-        noCalls,
-        state,
-        maybeAsyncArrow,
-      );
     }
 
     parseNewArguments(node: N.NewExpression): void {

packages/babel-parser/src/types.js

@@ -1447,5 +1447,6 @@ export type Placeholder<N: PlaceholderTypes> = NodeBase & {
 
 export type ParseSubscriptState = {
   optionalChainMember: boolean,
+  maybeAsyncArrow: boolean,
   stop: boolean,
 };

packages/babel-parser/test/fixtures/flow/regression/issue-10314/input.js

@@ -0,0 +1,3 @@
+// @flow
+
+true ? async.waterfall() : null;

packages/babel-parser/test/fixtures/flow/regression/issue-10314/output.json

@@ -0,0 +1,198 @@
+{
+  "type": "File",
+  "start": 0,
+  "end": 42,
+  "loc": {
+    "start": {
+      "line": 1,
+      "column": 0
+    },
+    "end": {
+      "line": 3,
+      "column": 32
+    }
+  },
+  "program": {
+    "type": "Program",
+    "start": 0,
+    "end": 42,
+    "loc": {
+      "start": {
+        "line": 1,
+        "column": 0
+      },
+      "end": {
+        "line": 3,
+        "column": 32
+      }
+    },
+    "sourceType": "module",
+    "interpreter": null,
+    "body": [
+      {
+        "type": "ExpressionStatement",
+        "start": 10,
+        "end": 42,
+        "loc": {
+          "start": {
+            "line": 3,
+            "column": 0
+          },
+          "end": {
+            "line": 3,
+            "column": 32
+          }
+        },
+        "expression": {
+          "type": "ConditionalExpression",
+          "start": 10,
+          "end": 41,
+          "loc": {
+            "start": {
+              "line": 3,
+              "column": 0
+            },
+            "end": {
+              "line": 3,
+              "column": 31
+            }
+          },
+          "test": {
+            "type": "BooleanLiteral",
+            "start": 10,
+            "end": 14,
+            "loc": {
+              "start": {
+                "line": 3,
+                "column": 0
+              },
+              "end": {
+                "line": 3,
+                "column": 4
+              }
+            },
+            "value": true
+          },
+          "consequent": {
+            "type": "CallExpression",
+            "start": 17,
+            "end": 34,
+            "loc": {
+              "start": {
+                "line": 3,
+                "column": 7
+              },
+              "end": {
+                "line": 3,
+                "column": 24
+              }
+            },
+            "callee": {
+              "type": "MemberExpression",
+              "start": 17,
+              "end": 32,
+              "loc": {
+                "start": {
+                  "line": 3,
+                  "column": 7
+                },
+                "end": {
+                  "line": 3,
+                  "column": 22
+                }
+              },
+              "object": {
+                "type": "Identifier",
+                "start": 17,
+                "end": 22,
+                "loc": {
+                  "start": {
+                    "line": 3,
+                    "column": 7
+                  },
+                  "end": {
+                    "line": 3,
+                    "column": 12
+                  },
+                  "identifierName": "async"
+                },
+                "name": "async"
+              },
+              "property": {
+                "type": "Identifier",
+                "start": 23,
+                "end": 32,
+                "loc": {
+                  "start": {
+                    "line": 3,
+                    "column": 13
+                  },
+                  "end": {
+                    "line": 3,
+                    "column": 22
+                  },
+                  "identifierName": "waterfall"
+                },
+                "name": "waterfall"
+              },
+              "computed": false
+            },
+            "arguments": []
+          },
+          "alternate": {
+            "type": "NullLiteral",
+            "start": 37,
+            "end": 41,
+            "loc": {
+              "start": {
+                "line": 3,
+                "column": 27
+              },
+              "end": {
+                "line": 3,
+                "column": 31
+              }
+            }
+          }
+        },
+        "leadingComments": [
+          {
+            "type": "CommentLine",
+            "value": " @flow",
+            "start": 0,
+            "end": 8,
+            "loc": {
+              "start": {
+                "line": 1,
+                "column": 0
+              },
+              "end": {
+                "line": 1,
+                "column": 8
+              }
+            }
+          }
+        ]
+      }
+    ],
+    "directives": []
+  },
+  "comments": [
+    {
+      "type": "CommentLine",
+      "value": " @flow",
+      "start": 0,
+      "end": 8,
+      "loc": {
+        "start": {
+          "line": 1,
+          "column": 0
+        },
+        "end": {
+          "line": 1,
+          "column": 8
+        }
+      }
+    }
+  ]
+}