From d2c75c2d380ba8ab6bb15eeb926e48330d05b2ef Mon Sep 17 00:00:00 2001
From: Retsam <Retsam@users.noreply.github.com>
Date: Tue, 9 Oct 2018 17:25:31 -0400
Subject: [PATCH] fix: corrects handling of newline after async with paren-less
 arrow function (#8830)

If async is followed by a newline, then a paren-less arrow function should be parsed as two expressions
---
 .../babel-parser/src/parser/expression.js     |   7 +-
 .../async-functions/newline-arrow/input.js    |   2 +
 .../async-functions/newline-arrow/output.json | 136 ++++++++++++++++++
 3 files changed, 144 insertions(+), 1 deletion(-)
 create mode 100644 packages/babel-parser/test/fixtures/es2017/async-functions/newline-arrow/input.js
 create mode 100644 packages/babel-parser/test/fixtures/es2017/async-functions/newline-arrow/output.json

diff --git a/packages/babel-parser/src/parser/expression.js b/packages/babel-parser/src/parser/expression.js
index e1ea1aa55d..dae74bf3d6 100644
--- a/packages/babel-parser/src/parser/expression.js
+++ b/packages/babel-parser/src/parser/expression.js
@@ -794,7 +794,12 @@ export default class ExpressionParser extends LValParser {
         ) {
           this.next();
           return this.parseFunction(node, false, false, true);
-        } else if (canBeArrow && id.name === "async" && this.match(tt.name)) {
+        } else if (
+          canBeArrow &&
+          !this.canInsertSemicolon() &&
+          id.name === "async" &&
+          this.match(tt.name)
+        ) {
           const oldYield = this.state.yieldInPossibleArrowParameters;
           this.state.yieldInPossibleArrowParameters = null;
           const params = [this.parseIdentifier()];
diff --git a/packages/babel-parser/test/fixtures/es2017/async-functions/newline-arrow/input.js b/packages/babel-parser/test/fixtures/es2017/async-functions/newline-arrow/input.js
new file mode 100644
index 0000000000..200a144766
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/es2017/async-functions/newline-arrow/input.js
@@ -0,0 +1,2 @@
+async
+x => x
diff --git a/packages/babel-parser/test/fixtures/es2017/async-functions/newline-arrow/output.json b/packages/babel-parser/test/fixtures/es2017/async-functions/newline-arrow/output.json
new file mode 100644
index 0000000000..4c44c11863
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/es2017/async-functions/newline-arrow/output.json
@@ -0,0 +1,136 @@
+{
+  "type": "File",
+  "start": 0,
+  "end": 12,
+  "loc": {
+    "start": {
+      "line": 1,
+      "column": 0
+    },
+    "end": {
+      "line": 2,
+      "column": 6
+    }
+  },
+  "program": {
+    "type": "Program",
+    "start": 0,
+    "end": 12,
+    "loc": {
+      "start": {
+        "line": 1,
+        "column": 0
+      },
+      "end": {
+        "line": 2,
+        "column": 6
+      }
+    },
+    "sourceType": "script",
+    "interpreter": null,
+    "body": [
+      {
+        "type": "ExpressionStatement",
+        "start": 0,
+        "end": 5,
+        "loc": {
+          "start": {
+            "line": 1,
+            "column": 0
+          },
+          "end": {
+            "line": 1,
+            "column": 5
+          }
+        },
+        "expression": {
+          "type": "Identifier",
+          "start": 0,
+          "end": 5,
+          "loc": {
+            "start": {
+              "line": 1,
+              "column": 0
+            },
+            "end": {
+              "line": 1,
+              "column": 5
+            },
+            "identifierName": "async"
+          },
+          "name": "async"
+        }
+      },
+      {
+        "type": "ExpressionStatement",
+        "start": 6,
+        "end": 12,
+        "loc": {
+          "start": {
+            "line": 2,
+            "column": 0
+          },
+          "end": {
+            "line": 2,
+            "column": 6
+          }
+        },
+        "expression": {
+          "type": "ArrowFunctionExpression",
+          "start": 6,
+          "end": 12,
+          "loc": {
+            "start": {
+              "line": 2,
+              "column": 0
+            },
+            "end": {
+              "line": 2,
+              "column": 6
+            }
+          },
+          "id": null,
+          "generator": false,
+          "async": false,
+          "params": [
+            {
+              "type": "Identifier",
+              "start": 6,
+              "end": 7,
+              "loc": {
+                "start": {
+                  "line": 2,
+                  "column": 0
+                },
+                "end": {
+                  "line": 2,
+                  "column": 1
+                },
+                "identifierName": "x"
+              },
+              "name": "x"
+            }
+          ],
+          "body": {
+            "type": "Identifier",
+            "start": 11,
+            "end": 12,
+            "loc": {
+              "start": {
+                "line": 2,
+                "column": 5
+              },
+              "end": {
+                "line": 2,
+                "column": 6
+              },
+              "identifierName": "x"
+            },
+            "name": "x"
+          }
+        }
+      }
+    ],
+    "directives": []
+  }
+}
\ No newline at end of file