From 4ec3b26062b3e14e6769e410aefe5063d9ed185a Mon Sep 17 00:00:00 2001
From: sosukesuzuki <aosukeke@gmail.com>
Date: Thu, 17 Dec 2020 22:44:56 +0900
Subject: [PATCH 1/7] Parse await exp in non-async-function

---
 .../babel-parser/src/parser/expression.js     | 51 ++++++++++++-------
 packages/babel-parser/src/parser/util.js      |  6 +--
 2 files changed, 35 insertions(+), 22 deletions(-)

diff --git a/packages/babel-parser/src/parser/expression.js b/packages/babel-parser/src/parser/expression.js
index 3ed03e0e1a7b..54f6356e05aa 100644
--- a/packages/babel-parser/src/parser/expression.js
+++ b/packages/babel-parser/src/parser/expression.js
@@ -55,6 +55,7 @@ import {
   newExpressionScope,
 } from "../util/expression-scope.js";
 import { Errors } from "./error";
+import type State from "../tokenizer/state";
 
 export default class ExpressionParser extends LValParser {
   // Forward-declaration: defined in statement.js
@@ -492,8 +493,18 @@ export default class ExpressionParser extends LValParser {
   // Parse unary operators, both prefix and postfix.
   // https://tc39.es/ecma262/#prod-UnaryExpression
   parseMaybeUnary(refExpressionErrors: ?ExpressionErrors): N.Expression {
-    if (this.isContextual("await") && this.isAwaitAllowed()) {
-      return this.parseAwait();
+    if (this.isContextual("await")) {
+      if (this.isAwaitAllowed()) {
+        return this.parseAwait();
+      } else {
+        if (this.scope.inFunction) {
+          const lookahead = this.lookahead();
+          if (lookahead.type.startsExpr && !this.isAmbiguousAwait(lookahead)) {
+            this.raise(this.state.start, Errors.AwaitNotInAsyncContext);
+            return this.parseAwait();
+          }
+        }
+      }
     }
     const update = this.match(tt.incDec);
     const node = this.startNode();
@@ -2363,22 +2374,7 @@ export default class ExpressionParser extends LValParser {
     }
 
     if (!this.scope.inFunction && !this.options.allowAwaitOutsideFunction) {
-      if (
-        this.hasPrecedingLineBreak() ||
-        // All the following expressions are ambiguous:
-        //   await + 0, await - 0, await ( 0 ), await [ 0 ], await / 0 /u, await ``
-        this.match(tt.plusMin) ||
-        this.match(tt.parenL) ||
-        this.match(tt.bracketL) ||
-        this.match(tt.backQuote) ||
-        // Sometimes the tokenizer generates tt.slash for regexps, and this is
-        // handler by parseExprAtom
-        this.match(tt.regexp) ||
-        this.match(tt.slash) ||
-        // This code could be parsed both as a modulo operator or as an intrinsic:
-        //   await %x(0)
-        (this.hasPlugin("v8intrinsic") && this.match(tt.modulo))
-      ) {
+      if (this.isAmbiguousAwait()) {
         this.ambiguousScriptDifferentAst = true;
       } else {
         this.sawUnambiguousESM = true;
@@ -2392,6 +2388,25 @@ export default class ExpressionParser extends LValParser {
     return this.finishNode(node, "AwaitExpression");
   }
 
+  isAmbiguousAwait(state: State = this.state): boolean {
+    return (
+      this.hasPrecedingLineBreak(state) ||
+      // All the following expressions are ambiguous:
+      //   await + 0, await - 0, await ( 0 ), await [ 0 ], await / 0 /u, await ``
+      state.type === tt.plusMin ||
+      state.type === tt.parenL ||
+      state.type === tt.bracketL ||
+      state.type === tt.backQuote ||
+      // Sometimes the tokenizer generates tt.slash for regexps, and this is
+      // handler by parseExprAtom
+      state.type === tt.regexp ||
+      state.type === tt.slash ||
+      // This code could be parsed both as a modulo operator or as an intrinsic:
+      //   await %x(0)
+      (this.hasPlugin("v8intrinsic") && state.type === tt.modulo)
+    );
+  }
+
   // Parses yield expression inside generator.
 
   parseYield(): N.YieldExpression {
diff --git a/packages/babel-parser/src/parser/util.js b/packages/babel-parser/src/parser/util.js
index 9244cc983e51..2e3ac0e6b79d 100644
--- a/packages/babel-parser/src/parser/util.js
+++ b/packages/babel-parser/src/parser/util.js
@@ -90,10 +90,8 @@ export default class UtilParser extends Tokenizer {
     );
   }
 
-  hasPrecedingLineBreak(): boolean {
-    return lineBreak.test(
-      this.input.slice(this.state.lastTokEnd, this.state.start),
-    );
+  hasPrecedingLineBreak(state: State = this.state): boolean {
+    return lineBreak.test(this.input.slice(state.lastTokEnd, state.start));
   }
 
   // TODO

From 800d2f291165b604c0f5ffac7d2639d00b5d9de1 Mon Sep 17 00:00:00 2001
From: sosukesuzuki <aosukeke@gmail.com>
Date: Thu, 17 Dec 2020 22:45:34 +0900
Subject: [PATCH 2/7] Update tests

---
 .../es2017/async-functions/9/options.json     |  3 -
 .../es2017/async-functions/9/output.json      | 54 +++++++++++
 .../options.json                              |  4 -
 .../output.json                               | 52 ++++++++++
 .../input.js                                  |  4 +
 .../output.json                               | 50 ++++++++++
 .../options.json                              |  3 -
 .../output.json                               | 48 ++++++++++
 .../options.json                              |  3 -
 .../output.json                               | 77 +++++++++++++++
 .../input.js                                  |  3 +
 .../output.json                               | 69 +++++++++++++
 .../invalid-await/options.json                |  7 +-
 .../invalid-await/output.json                 | 96 +++++++++++++++++++
 14 files changed, 455 insertions(+), 18 deletions(-)
 delete mode 100644 packages/babel-parser/test/fixtures/es2017/async-functions/9/options.json
 create mode 100644 packages/babel-parser/test/fixtures/es2017/async-functions/9/output.json
 delete mode 100644 packages/babel-parser/test/fixtures/es2017/async-functions/allow-await-outside-function-throw/options.json
 create mode 100644 packages/babel-parser/test/fixtures/es2017/async-functions/allow-await-outside-function-throw/output.json
 create mode 100644 packages/babel-parser/test/fixtures/es2017/async-functions/await-identifier-with-line-break-in-function/input.js
 create mode 100644 packages/babel-parser/test/fixtures/es2017/async-functions/await-identifier-with-line-break-in-function/output.json
 delete mode 100644 packages/babel-parser/test/fixtures/es2017/async-functions/await-inside-arrow-expression-disallowed/options.json
 create mode 100644 packages/babel-parser/test/fixtures/es2017/async-functions/await-inside-arrow-expression-disallowed/output.json
 delete mode 100644 packages/babel-parser/test/fixtures/es2017/async-functions/await-inside-parameters-of-nested-function/options.json
 create mode 100644 packages/babel-parser/test/fixtures/es2017/async-functions/await-inside-parameters-of-nested-function/output.json
 create mode 100644 packages/babel-parser/test/fixtures/es2017/async-functions/invalid-await-with-object-exp-in-function/input.js
 create mode 100644 packages/babel-parser/test/fixtures/es2017/async-functions/invalid-await-with-object-exp-in-function/output.json
 create mode 100644 packages/babel-parser/test/fixtures/experimental/class-static-block/invalid-await/output.json

diff --git a/packages/babel-parser/test/fixtures/es2017/async-functions/9/options.json b/packages/babel-parser/test/fixtures/es2017/async-functions/9/options.json
deleted file mode 100644
index ff9c4d199005..000000000000
--- a/packages/babel-parser/test/fixtures/es2017/async-functions/9/options.json
+++ /dev/null
@@ -1,3 +0,0 @@
-{
-  "throws": "Unexpected token, expected \";\" (1:30)"
-}
diff --git a/packages/babel-parser/test/fixtures/es2017/async-functions/9/output.json b/packages/babel-parser/test/fixtures/es2017/async-functions/9/output.json
new file mode 100644
index 000000000000..0ee180e1b892
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/es2017/async-functions/9/output.json
@@ -0,0 +1,54 @@
+{
+  "type": "File",
+  "start":0,"end":40,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":40}},
+  "errors": [
+    "SyntaxError: 'await' is only allowed within async functions and at the top levels of modules (1:24)"
+  ],
+  "program": {
+    "type": "Program",
+    "start":0,"end":40,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":40}},
+    "sourceType": "script",
+    "interpreter": null,
+    "body": [
+      {
+        "type": "FunctionDeclaration",
+        "start":0,"end":40,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":40}},
+        "id": {
+          "type": "Identifier",
+          "start":9,"end":12,"loc":{"start":{"line":1,"column":9},"end":{"line":1,"column":12},"identifierName":"foo"},
+          "name": "foo"
+        },
+        "generator": false,
+        "async": false,
+        "params": [
+          {
+            "type": "Identifier",
+            "start":13,"end":20,"loc":{"start":{"line":1,"column":13},"end":{"line":1,"column":20},"identifierName":"promise"},
+            "name": "promise"
+          }
+        ],
+        "body": {
+          "type": "BlockStatement",
+          "start":22,"end":40,"loc":{"start":{"line":1,"column":22},"end":{"line":1,"column":40}},
+          "body": [
+            {
+              "type": "ExpressionStatement",
+              "start":24,"end":38,"loc":{"start":{"line":1,"column":24},"end":{"line":1,"column":38}},
+              "expression": {
+                "type": "AwaitExpression",
+                "start":24,"end":37,"loc":{"start":{"line":1,"column":24},"end":{"line":1,"column":37}},
+                "argument": {
+                  "type": "Identifier",
+                  "start":30,"end":37,"loc":{"start":{"line":1,"column":30},"end":{"line":1,"column":37},"identifierName":"promise"},
+                  "name": "promise"
+                }
+              }
+            }
+          ],
+          "directives": []
+        }
+      }
+    ],
+    "directives": []
+  }
+}
\ No newline at end of file
diff --git a/packages/babel-parser/test/fixtures/es2017/async-functions/allow-await-outside-function-throw/options.json b/packages/babel-parser/test/fixtures/es2017/async-functions/allow-await-outside-function-throw/options.json
deleted file mode 100644
index 3c9820fa55b8..000000000000
--- a/packages/babel-parser/test/fixtures/es2017/async-functions/allow-await-outside-function-throw/options.json
+++ /dev/null
@@ -1,4 +0,0 @@
-{
-  "allowAwaitOutsideFunction": true,
-  "throws": "Unexpected token, expected \";\" (2:15)"
-}
diff --git a/packages/babel-parser/test/fixtures/es2017/async-functions/allow-await-outside-function-throw/output.json b/packages/babel-parser/test/fixtures/es2017/async-functions/allow-await-outside-function-throw/output.json
new file mode 100644
index 000000000000..3f3e1cddf5b1
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/es2017/async-functions/allow-await-outside-function-throw/output.json
@@ -0,0 +1,52 @@
+{
+  "type": "File",
+  "start":0,"end":33,"loc":{"start":{"line":1,"column":0},"end":{"line":3,"column":1}},
+  "errors": [
+    "SyntaxError: 'await' is only allowed within async functions and at the top levels of modules (2:9)"
+  ],
+  "program": {
+    "type": "Program",
+    "start":0,"end":33,"loc":{"start":{"line":1,"column":0},"end":{"line":3,"column":1}},
+    "sourceType": "script",
+    "interpreter": null,
+    "body": [
+      {
+        "type": "FunctionDeclaration",
+        "start":0,"end":33,"loc":{"start":{"line":1,"column":0},"end":{"line":3,"column":1}},
+        "id": {
+          "type": "Identifier",
+          "start":9,"end":10,"loc":{"start":{"line":1,"column":9},"end":{"line":1,"column":10},"identifierName":"a"},
+          "name": "a"
+        },
+        "generator": false,
+        "async": false,
+        "params": [],
+        "body": {
+          "type": "BlockStatement",
+          "start":13,"end":33,"loc":{"start":{"line":1,"column":13},"end":{"line":3,"column":1}},
+          "body": [
+            {
+              "type": "ReturnStatement",
+              "start":17,"end":31,"loc":{"start":{"line":2,"column":2},"end":{"line":2,"column":16}},
+              "argument": {
+                "type": "AwaitExpression",
+                "start":24,"end":31,"loc":{"start":{"line":2,"column":9},"end":{"line":2,"column":16}},
+                "argument": {
+                  "type": "NumericLiteral",
+                  "start":30,"end":31,"loc":{"start":{"line":2,"column":15},"end":{"line":2,"column":16}},
+                  "extra": {
+                    "rawValue": 1,
+                    "raw": "1"
+                  },
+                  "value": 1
+                }
+              }
+            }
+          ],
+          "directives": []
+        }
+      }
+    ],
+    "directives": []
+  }
+}
\ No newline at end of file
diff --git a/packages/babel-parser/test/fixtures/es2017/async-functions/await-identifier-with-line-break-in-function/input.js b/packages/babel-parser/test/fixtures/es2017/async-functions/await-identifier-with-line-break-in-function/input.js
new file mode 100644
index 000000000000..87023699f3e1
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/es2017/async-functions/await-identifier-with-line-break-in-function/input.js
@@ -0,0 +1,4 @@
+function foo() {
+  await
+  foo;
+}
diff --git a/packages/babel-parser/test/fixtures/es2017/async-functions/await-identifier-with-line-break-in-function/output.json b/packages/babel-parser/test/fixtures/es2017/async-functions/await-identifier-with-line-break-in-function/output.json
new file mode 100644
index 000000000000..cbacec0cbd8a
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/es2017/async-functions/await-identifier-with-line-break-in-function/output.json
@@ -0,0 +1,50 @@
+{
+  "type": "File",
+  "start":0,"end":33,"loc":{"start":{"line":1,"column":0},"end":{"line":4,"column":1}},
+  "program": {
+    "type": "Program",
+    "start":0,"end":33,"loc":{"start":{"line":1,"column":0},"end":{"line":4,"column":1}},
+    "sourceType": "script",
+    "interpreter": null,
+    "body": [
+      {
+        "type": "FunctionDeclaration",
+        "start":0,"end":33,"loc":{"start":{"line":1,"column":0},"end":{"line":4,"column":1}},
+        "id": {
+          "type": "Identifier",
+          "start":9,"end":12,"loc":{"start":{"line":1,"column":9},"end":{"line":1,"column":12},"identifierName":"foo"},
+          "name": "foo"
+        },
+        "generator": false,
+        "async": false,
+        "params": [],
+        "body": {
+          "type": "BlockStatement",
+          "start":15,"end":33,"loc":{"start":{"line":1,"column":15},"end":{"line":4,"column":1}},
+          "body": [
+            {
+              "type": "ExpressionStatement",
+              "start":19,"end":24,"loc":{"start":{"line":2,"column":2},"end":{"line":2,"column":7}},
+              "expression": {
+                "type": "Identifier",
+                "start":19,"end":24,"loc":{"start":{"line":2,"column":2},"end":{"line":2,"column":7},"identifierName":"await"},
+                "name": "await"
+              }
+            },
+            {
+              "type": "ExpressionStatement",
+              "start":27,"end":31,"loc":{"start":{"line":3,"column":2},"end":{"line":3,"column":6}},
+              "expression": {
+                "type": "Identifier",
+                "start":27,"end":30,"loc":{"start":{"line":3,"column":2},"end":{"line":3,"column":5},"identifierName":"foo"},
+                "name": "foo"
+              }
+            }
+          ],
+          "directives": []
+        }
+      }
+    ],
+    "directives": []
+  }
+}
\ No newline at end of file
diff --git a/packages/babel-parser/test/fixtures/es2017/async-functions/await-inside-arrow-expression-disallowed/options.json b/packages/babel-parser/test/fixtures/es2017/async-functions/await-inside-arrow-expression-disallowed/options.json
deleted file mode 100644
index 6079f56395bd..000000000000
--- a/packages/babel-parser/test/fixtures/es2017/async-functions/await-inside-arrow-expression-disallowed/options.json
+++ /dev/null
@@ -1,3 +0,0 @@
-{
-  "throws": "Unexpected token, expected \";\" (1:14)"
-}
diff --git a/packages/babel-parser/test/fixtures/es2017/async-functions/await-inside-arrow-expression-disallowed/output.json b/packages/babel-parser/test/fixtures/es2017/async-functions/await-inside-arrow-expression-disallowed/output.json
new file mode 100644
index 000000000000..b12eebc08943
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/es2017/async-functions/await-inside-arrow-expression-disallowed/output.json
@@ -0,0 +1,48 @@
+{
+  "type": "File",
+  "start":0,"end":17,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":17}},
+  "errors": [
+    "SyntaxError: 'await' is only allowed within async functions and at the top levels of modules (1:8)"
+  ],
+  "program": {
+    "type": "Program",
+    "start":0,"end":17,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":17}},
+    "sourceType": "script",
+    "interpreter": null,
+    "body": [
+      {
+        "type": "ExpressionStatement",
+        "start":0,"end":17,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":17}},
+        "expression": {
+          "type": "ArrowFunctionExpression",
+          "start":0,"end":17,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":17}},
+          "id": null,
+          "generator": false,
+          "async": false,
+          "params": [],
+          "body": {
+            "type": "BlockStatement",
+            "start":6,"end":17,"loc":{"start":{"line":1,"column":6},"end":{"line":1,"column":17}},
+            "body": [
+              {
+                "type": "ExpressionStatement",
+                "start":8,"end":15,"loc":{"start":{"line":1,"column":8},"end":{"line":1,"column":15}},
+                "expression": {
+                  "type": "AwaitExpression",
+                  "start":8,"end":15,"loc":{"start":{"line":1,"column":8},"end":{"line":1,"column":15}},
+                  "argument": {
+                    "type": "Identifier",
+                    "start":14,"end":15,"loc":{"start":{"line":1,"column":14},"end":{"line":1,"column":15},"identifierName":"x"},
+                    "name": "x"
+                  }
+                }
+              }
+            ],
+            "directives": []
+          }
+        }
+      }
+    ],
+    "directives": []
+  }
+}
\ No newline at end of file
diff --git a/packages/babel-parser/test/fixtures/es2017/async-functions/await-inside-parameters-of-nested-function/options.json b/packages/babel-parser/test/fixtures/es2017/async-functions/await-inside-parameters-of-nested-function/options.json
deleted file mode 100644
index b260169ecd70..000000000000
--- a/packages/babel-parser/test/fixtures/es2017/async-functions/await-inside-parameters-of-nested-function/options.json
+++ /dev/null
@@ -1,3 +0,0 @@
-{
-  "throws": "Unexpected token, expected \",\" (2:25)"
-}
diff --git a/packages/babel-parser/test/fixtures/es2017/async-functions/await-inside-parameters-of-nested-function/output.json b/packages/babel-parser/test/fixtures/es2017/async-functions/await-inside-parameters-of-nested-function/output.json
new file mode 100644
index 000000000000..c7d4e8fb8241
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/es2017/async-functions/await-inside-parameters-of-nested-function/output.json
@@ -0,0 +1,77 @@
+{
+  "type": "File",
+  "start":0,"end":55,"loc":{"start":{"line":1,"column":0},"end":{"line":3,"column":1}},
+  "errors": [
+    "SyntaxError: 'await' is only allowed within async functions and at the top levels of modules (2:19)",
+    "SyntaxError: await is not allowed in async function parameters (2:19)"
+  ],
+  "program": {
+    "type": "Program",
+    "start":0,"end":55,"loc":{"start":{"line":1,"column":0},"end":{"line":3,"column":1}},
+    "sourceType": "script",
+    "interpreter": null,
+    "body": [
+      {
+        "type": "FunctionDeclaration",
+        "start":0,"end":55,"loc":{"start":{"line":1,"column":0},"end":{"line":3,"column":1}},
+        "id": {
+          "type": "Identifier",
+          "start":15,"end":18,"loc":{"start":{"line":1,"column":15},"end":{"line":1,"column":18},"identifierName":"foo"},
+          "name": "foo"
+        },
+        "generator": false,
+        "async": true,
+        "params": [],
+        "body": {
+          "type": "BlockStatement",
+          "start":21,"end":55,"loc":{"start":{"line":1,"column":21},"end":{"line":3,"column":1}},
+          "body": [
+            {
+              "type": "FunctionDeclaration",
+              "start":25,"end":53,"loc":{"start":{"line":2,"column":2},"end":{"line":2,"column":30}},
+              "id": {
+                "type": "Identifier",
+                "start":34,"end":37,"loc":{"start":{"line":2,"column":11},"end":{"line":2,"column":14},"identifierName":"bar"},
+                "name": "bar"
+              },
+              "generator": false,
+              "async": false,
+              "params": [
+                {
+                  "type": "AssignmentPattern",
+                  "start":38,"end":49,"loc":{"start":{"line":2,"column":15},"end":{"line":2,"column":26}},
+                  "left": {
+                    "type": "Identifier",
+                    "start":38,"end":39,"loc":{"start":{"line":2,"column":15},"end":{"line":2,"column":16},"identifierName":"x"},
+                    "name": "x"
+                  },
+                  "right": {
+                    "type": "AwaitExpression",
+                    "start":42,"end":49,"loc":{"start":{"line":2,"column":19},"end":{"line":2,"column":26}},
+                    "argument": {
+                      "type": "NumericLiteral",
+                      "start":48,"end":49,"loc":{"start":{"line":2,"column":25},"end":{"line":2,"column":26}},
+                      "extra": {
+                        "rawValue": 2,
+                        "raw": "2"
+                      },
+                      "value": 2
+                    }
+                  }
+                }
+              ],
+              "body": {
+                "type": "BlockStatement",
+                "start":51,"end":53,"loc":{"start":{"line":2,"column":28},"end":{"line":2,"column":30}},
+                "body": [],
+                "directives": []
+              }
+            }
+          ],
+          "directives": []
+        }
+      }
+    ],
+    "directives": []
+  }
+}
\ No newline at end of file
diff --git a/packages/babel-parser/test/fixtures/es2017/async-functions/invalid-await-with-object-exp-in-function/input.js b/packages/babel-parser/test/fixtures/es2017/async-functions/invalid-await-with-object-exp-in-function/input.js
new file mode 100644
index 000000000000..8b9c602112ed
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/es2017/async-functions/invalid-await-with-object-exp-in-function/input.js
@@ -0,0 +1,3 @@
+function foo() {
+  await { foo };
+}
diff --git a/packages/babel-parser/test/fixtures/es2017/async-functions/invalid-await-with-object-exp-in-function/output.json b/packages/babel-parser/test/fixtures/es2017/async-functions/invalid-await-with-object-exp-in-function/output.json
new file mode 100644
index 000000000000..d64bc787b0ab
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/es2017/async-functions/invalid-await-with-object-exp-in-function/output.json
@@ -0,0 +1,69 @@
+{
+  "type": "File",
+  "start":0,"end":35,"loc":{"start":{"line":1,"column":0},"end":{"line":3,"column":1}},
+  "errors": [
+    "SyntaxError: 'await' is only allowed within async functions and at the top levels of modules (2:2)"
+  ],
+  "program": {
+    "type": "Program",
+    "start":0,"end":35,"loc":{"start":{"line":1,"column":0},"end":{"line":3,"column":1}},
+    "sourceType": "script",
+    "interpreter": null,
+    "body": [
+      {
+        "type": "FunctionDeclaration",
+        "start":0,"end":35,"loc":{"start":{"line":1,"column":0},"end":{"line":3,"column":1}},
+        "id": {
+          "type": "Identifier",
+          "start":9,"end":12,"loc":{"start":{"line":1,"column":9},"end":{"line":1,"column":12},"identifierName":"foo"},
+          "name": "foo"
+        },
+        "generator": false,
+        "async": false,
+        "params": [],
+        "body": {
+          "type": "BlockStatement",
+          "start":15,"end":35,"loc":{"start":{"line":1,"column":15},"end":{"line":3,"column":1}},
+          "body": [
+            {
+              "type": "ExpressionStatement",
+              "start":19,"end":33,"loc":{"start":{"line":2,"column":2},"end":{"line":2,"column":16}},
+              "expression": {
+                "type": "AwaitExpression",
+                "start":19,"end":32,"loc":{"start":{"line":2,"column":2},"end":{"line":2,"column":15}},
+                "argument": {
+                  "type": "ObjectExpression",
+                  "start":25,"end":32,"loc":{"start":{"line":2,"column":8},"end":{"line":2,"column":15}},
+                  "properties": [
+                    {
+                      "type": "ObjectProperty",
+                      "start":27,"end":30,"loc":{"start":{"line":2,"column":10},"end":{"line":2,"column":13}},
+                      "extra": {
+                        "shorthand": true
+                      },
+                      "method": false,
+                      "key": {
+                        "type": "Identifier",
+                        "start":27,"end":30,"loc":{"start":{"line":2,"column":10},"end":{"line":2,"column":13},"identifierName":"foo"},
+                        "name": "foo"
+                      },
+                      "computed": false,
+                      "shorthand": true,
+                      "value": {
+                        "type": "Identifier",
+                        "start":27,"end":30,"loc":{"start":{"line":2,"column":10},"end":{"line":2,"column":13},"identifierName":"foo"},
+                        "name": "foo"
+                      }
+                    }
+                  ]
+                }
+              }
+            }
+          ],
+          "directives": []
+        }
+      }
+    ],
+    "directives": []
+  }
+}
\ No newline at end of file
diff --git a/packages/babel-parser/test/fixtures/experimental/class-static-block/invalid-await/options.json b/packages/babel-parser/test/fixtures/experimental/class-static-block/invalid-await/options.json
index ed5be518c9cc..70adcb5e62d3 100644
--- a/packages/babel-parser/test/fixtures/experimental/class-static-block/invalid-await/options.json
+++ b/packages/babel-parser/test/fixtures/experimental/class-static-block/invalid-await/options.json
@@ -1,6 +1,3 @@
 {
-  "plugins": [
-    "classStaticBlock"
-  ],
-  "throws": "Unexpected token, expected \";\" (5:12)"
-}
\ No newline at end of file
+  "plugins": ["classStaticBlock"]
+}
diff --git a/packages/babel-parser/test/fixtures/experimental/class-static-block/invalid-await/output.json b/packages/babel-parser/test/fixtures/experimental/class-static-block/invalid-await/output.json
new file mode 100644
index 000000000000..3d29d5376d60
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/experimental/class-static-block/invalid-await/output.json
@@ -0,0 +1,96 @@
+{
+  "type": "File",
+  "start":0,"end":95,"loc":{"start":{"line":1,"column":0},"end":{"line":8,"column":1}},
+  "errors": [
+    "SyntaxError: 'await' is only allowed within async functions and at the top levels of modules (5:6)"
+  ],
+  "program": {
+    "type": "Program",
+    "start":0,"end":95,"loc":{"start":{"line":1,"column":0},"end":{"line":8,"column":1}},
+    "sourceType": "script",
+    "interpreter": null,
+    "body": [
+      {
+        "type": "FunctionDeclaration",
+        "start":0,"end":95,"loc":{"start":{"line":1,"column":0},"end":{"line":8,"column":1}},
+        "id": {
+          "type": "Identifier",
+          "start":15,"end":18,"loc":{"start":{"line":1,"column":15},"end":{"line":1,"column":18},"identifierName":"foo"},
+          "name": "foo"
+        },
+        "generator": false,
+        "async": true,
+        "params": [],
+        "body": {
+          "type": "BlockStatement",
+          "start":21,"end":95,"loc":{"start":{"line":1,"column":21},"end":{"line":8,"column":1}},
+          "body": [
+            {
+              "type": "ClassDeclaration",
+              "start":25,"end":93,"loc":{"start":{"line":2,"column":2},"end":{"line":7,"column":3}},
+              "id": {
+                "type": "Identifier",
+                "start":31,"end":32,"loc":{"start":{"line":2,"column":8},"end":{"line":2,"column":9},"identifierName":"C"},
+                "name": "C"
+              },
+              "superClass": null,
+              "body": {
+                "type": "ClassBody",
+                "start":33,"end":93,"loc":{"start":{"line":2,"column":10},"end":{"line":7,"column":3}},
+                "body": [
+                  {
+                    "type": "ClassMethod",
+                    "start":39,"end":54,"loc":{"start":{"line":3,"column":4},"end":{"line":3,"column":19}},
+                    "static": true,
+                    "key": {
+                      "type": "Identifier",
+                      "start":46,"end":49,"loc":{"start":{"line":3,"column":11},"end":{"line":3,"column":14},"identifierName":"foo"},
+                      "name": "foo"
+                    },
+                    "computed": false,
+                    "kind": "method",
+                    "id": null,
+                    "generator": false,
+                    "async": false,
+                    "params": [],
+                    "body": {
+                      "type": "BlockStatement",
+                      "start":52,"end":54,"loc":{"start":{"line":3,"column":17},"end":{"line":3,"column":19}},
+                      "body": [],
+                      "directives": []
+                    }
+                  },
+                  {
+                    "type": "StaticBlock",
+                    "start":59,"end":89,"loc":{"start":{"line":4,"column":4},"end":{"line":6,"column":5}},
+                    "body": [
+                      {
+                        "type": "ExpressionStatement",
+                        "start":74,"end":83,"loc":{"start":{"line":5,"column":6},"end":{"line":5,"column":15}},
+                        "expression": {
+                          "type": "AwaitExpression",
+                          "start":74,"end":82,"loc":{"start":{"line":5,"column":6},"end":{"line":5,"column":14}},
+                          "argument": {
+                            "type": "NumericLiteral",
+                            "start":80,"end":82,"loc":{"start":{"line":5,"column":12},"end":{"line":5,"column":14}},
+                            "extra": {
+                              "rawValue": 42,
+                              "raw": "42"
+                            },
+                            "value": 42
+                          }
+                        }
+                      }
+                    ]
+                  }
+                ]
+              }
+            }
+          ],
+          "directives": []
+        }
+      }
+    ],
+    "directives": []
+  }
+}
\ No newline at end of file

From 9a9a5ee112af81c704362a4591b98eaba57b1f3b Mon Sep 17 00:00:00 2001
From: sosukesuzuki <aosukeke@gmail.com>
Date: Tue, 22 Dec 2020 16:12:11 +0900
Subject: [PATCH 3/7] Avoid to lookahead

---
 .../babel-parser/src/parser/expression.js     | 59 ++++++++++---------
 packages/babel-parser/src/parser/util.js      |  6 +-
 2 files changed, 36 insertions(+), 29 deletions(-)

diff --git a/packages/babel-parser/src/parser/expression.js b/packages/babel-parser/src/parser/expression.js
index 54f6356e05aa..f7d01c4e9e38 100644
--- a/packages/babel-parser/src/parser/expression.js
+++ b/packages/babel-parser/src/parser/expression.js
@@ -55,7 +55,6 @@ import {
   newExpressionScope,
 } from "../util/expression-scope.js";
 import { Errors } from "./error";
-import type State from "../tokenizer/state";
 
 export default class ExpressionParser extends LValParser {
   // Forward-declaration: defined in statement.js
@@ -493,19 +492,15 @@ export default class ExpressionParser extends LValParser {
   // Parse unary operators, both prefix and postfix.
   // https://tc39.es/ecma262/#prod-UnaryExpression
   parseMaybeUnary(refExpressionErrors: ?ExpressionErrors): N.Expression {
-    if (this.isContextual("await")) {
-      if (this.isAwaitAllowed()) {
-        return this.parseAwait();
-      } else {
-        if (this.scope.inFunction) {
-          const lookahead = this.lookahead();
-          if (lookahead.type.startsExpr && !this.isAmbiguousAwait(lookahead)) {
-            this.raise(this.state.start, Errors.AwaitNotInAsyncContext);
-            return this.parseAwait();
-          }
-        }
-      }
+    const startPos = this.state.start;
+    const startLoc = this.state.startLoc;
+    const isAwait = this.isContextual("await");
+
+    if (isAwait && this.isAwaitAllowed()) {
+      this.next();
+      return this.parseAwait(startPos, startLoc);
     }
+
     const update = this.match(tt.incDec);
     const node = this.startNode();
     if (this.state.type.prefix) {
@@ -537,7 +532,19 @@ export default class ExpressionParser extends LValParser {
       }
     }
 
-    return this.parseUpdate(node, update, refExpressionErrors);
+    const expr = this.parseUpdate(node, update, refExpressionErrors);
+
+    if (
+      isAwait &&
+      this.scope.inFunction &&
+      this.state.type.startsExpr &&
+      !this.isAmbiguousAwait()
+    ) {
+      this.raise(startPos, Errors.AwaitNotInAsyncContext);
+      return this.parseAwait(startPos, startLoc);
+    }
+
+    return expr;
   }
 
   // https://tc39.es/ecma262/#prod-UpdateExpression
@@ -2359,10 +2366,8 @@ export default class ExpressionParser extends LValParser {
 
   // Parses await expression inside async function.
 
-  parseAwait(): N.AwaitExpression {
-    const node = this.startNode();
-
-    this.next();
+  parseAwait(startPos: number, startLoc: Position): N.AwaitExpression {
+    const node = this.startNodeAt(startPos, startLoc);
 
     this.expressionScope.recordParameterInitializerError(
       node.start,
@@ -2388,22 +2393,22 @@ export default class ExpressionParser extends LValParser {
     return this.finishNode(node, "AwaitExpression");
   }
 
-  isAmbiguousAwait(state: State = this.state): boolean {
+  isAmbiguousAwait(): boolean {
     return (
-      this.hasPrecedingLineBreak(state) ||
+      this.hasPrecedingLineBreak() ||
       // All the following expressions are ambiguous:
       //   await + 0, await - 0, await ( 0 ), await [ 0 ], await / 0 /u, await ``
-      state.type === tt.plusMin ||
-      state.type === tt.parenL ||
-      state.type === tt.bracketL ||
-      state.type === tt.backQuote ||
+      this.match(tt.plusMin) ||
+      this.match(tt.parenL) ||
+      this.match(tt.bracketL) ||
+      this.match(tt.backQuote) ||
       // Sometimes the tokenizer generates tt.slash for regexps, and this is
       // handler by parseExprAtom
-      state.type === tt.regexp ||
-      state.type === tt.slash ||
+      this.match(tt.regexp) ||
+      this.match(tt.slash) ||
       // This code could be parsed both as a modulo operator or as an intrinsic:
       //   await %x(0)
-      (this.hasPlugin("v8intrinsic") && state.type === tt.modulo)
+      (this.hasPlugin("v8intrinsic") && this.match(tt.modulo))
     );
   }
 
diff --git a/packages/babel-parser/src/parser/util.js b/packages/babel-parser/src/parser/util.js
index 2e3ac0e6b79d..9244cc983e51 100644
--- a/packages/babel-parser/src/parser/util.js
+++ b/packages/babel-parser/src/parser/util.js
@@ -90,8 +90,10 @@ export default class UtilParser extends Tokenizer {
     );
   }
 
-  hasPrecedingLineBreak(state: State = this.state): boolean {
-    return lineBreak.test(this.input.slice(state.lastTokEnd, state.start));
+  hasPrecedingLineBreak(): boolean {
+    return lineBreak.test(
+      this.input.slice(this.state.lastTokEnd, this.state.start),
+    );
   }
 
   // TODO

From 6536b9886ed57ca2c75edbb309fa66a692fdd5e8 Mon Sep 17 00:00:00 2001
From: sosukesuzuki <aosukeke@gmail.com>
Date: Wed, 23 Dec 2020 23:01:48 +0900
Subject: [PATCH 4/7] Support TLA error in script

---
 .../babel-parser/src/parser/expression.js     | 10 ++++--
 .../top-level-script/options.json             |  3 +-
 .../top-level-script/output.json              | 33 +++++++++++++++++++
 3 files changed, 41 insertions(+), 5 deletions(-)
 create mode 100644 packages/babel-parser/test/fixtures/experimental/top-level-await/top-level-script/output.json

diff --git a/packages/babel-parser/src/parser/expression.js b/packages/babel-parser/src/parser/expression.js
index f7d01c4e9e38..38496a423b13 100644
--- a/packages/babel-parser/src/parser/expression.js
+++ b/packages/babel-parser/src/parser/expression.js
@@ -534,11 +534,15 @@ export default class ExpressionParser extends LValParser {
 
     const expr = this.parseUpdate(node, update, refExpressionErrors);
 
+    const startsExpr = this.hasPlugin("v8intrinsic")
+      ? this.state.type.startsExpr
+      : this.state.type.startsExpr && !this.match(tt.modulo);
     if (
       isAwait &&
-      this.scope.inFunction &&
-      this.state.type.startsExpr &&
-      !this.isAmbiguousAwait()
+      startsExpr &&
+      !this.isAmbiguousAwait() &&
+      (this.scope.inFunction ||
+        (this.hasPlugin("topLevelAwait") && !this.inModule))
     ) {
       this.raise(startPos, Errors.AwaitNotInAsyncContext);
       return this.parseAwait(startPos, startLoc);
diff --git a/packages/babel-parser/test/fixtures/experimental/top-level-await/top-level-script/options.json b/packages/babel-parser/test/fixtures/experimental/top-level-await/top-level-script/options.json
index c9dc6113fea3..fc666b8d2c59 100644
--- a/packages/babel-parser/test/fixtures/experimental/top-level-await/top-level-script/options.json
+++ b/packages/babel-parser/test/fixtures/experimental/top-level-await/top-level-script/options.json
@@ -1,5 +1,4 @@
 {
   "plugins": ["topLevelAwait"],
-  "sourceType": "script",
-  "throws": "Unexpected token, expected \";\" (1:6)"
+  "sourceType": "script"
 }
diff --git a/packages/babel-parser/test/fixtures/experimental/top-level-await/top-level-script/output.json b/packages/babel-parser/test/fixtures/experimental/top-level-await/top-level-script/output.json
new file mode 100644
index 000000000000..1b4283b27129
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/experimental/top-level-await/top-level-script/output.json
@@ -0,0 +1,33 @@
+{
+  "type": "File",
+  "start":0,"end":8,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":8}},
+  "errors": [
+    "SyntaxError: 'await' is only allowed within async functions and at the top levels of modules (1:0)"
+  ],
+  "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": "AwaitExpression",
+          "start":0,"end":7,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":7}},
+          "argument": {
+            "type": "NumericLiteral",
+            "start":6,"end":7,"loc":{"start":{"line":1,"column":6},"end":{"line":1,"column":7}},
+            "extra": {
+              "rawValue": 0,
+              "raw": "0"
+            },
+            "value": 0
+          }
+        }
+      }
+    ],
+    "directives": []
+  }
+}
\ No newline at end of file

From 9082ef680152e851e50b0f85bf02c941fd194ced Mon Sep 17 00:00:00 2001
From: sosukesuzuki <aosukeke@gmail.com>
Date: Sun, 10 Jan 2021 13:26:11 +0900
Subject: [PATCH 5/7] Address reviwed points

---
 packages/babel-parser/src/parser/expression.js             | 7 ++++++-
 .../test/fixtures/es2017/async-functions/9/output.json     | 2 +-
 .../allow-await-outside-function-throw/output.json         | 2 +-
 .../await-inside-arrow-expression-disallowed/output.json   | 2 +-
 .../await-inside-parameters-of-nested-function/output.json | 2 +-
 .../invalid-await-with-object-exp-in-function/output.json  | 2 +-
 .../class-static-block/invalid-await/output.json           | 2 +-
 7 files changed, 12 insertions(+), 7 deletions(-)

diff --git a/packages/babel-parser/src/parser/expression.js b/packages/babel-parser/src/parser/expression.js
index 38496a423b13..49e4cc181640 100644
--- a/packages/babel-parser/src/parser/expression.js
+++ b/packages/babel-parser/src/parser/expression.js
@@ -544,7 +544,12 @@ export default class ExpressionParser extends LValParser {
       (this.scope.inFunction ||
         (this.hasPlugin("topLevelAwait") && !this.inModule))
     ) {
-      this.raise(startPos, Errors.AwaitNotInAsyncContext);
+      this.raise(
+        startPos,
+        this.hasPlugin("topLevelAwait")
+          ? Errors.AwaitNotInAsyncContext
+          : Errors.AwaitNotInAsyncFunction,
+      );
       return this.parseAwait(startPos, startLoc);
     }
 
diff --git a/packages/babel-parser/test/fixtures/es2017/async-functions/9/output.json b/packages/babel-parser/test/fixtures/es2017/async-functions/9/output.json
index 0ee180e1b892..27d691134ed7 100644
--- a/packages/babel-parser/test/fixtures/es2017/async-functions/9/output.json
+++ b/packages/babel-parser/test/fixtures/es2017/async-functions/9/output.json
@@ -2,7 +2,7 @@
   "type": "File",
   "start":0,"end":40,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":40}},
   "errors": [
-    "SyntaxError: 'await' is only allowed within async functions and at the top levels of modules (1:24)"
+    "SyntaxError: 'await' is only allowed within async functions (1:24)"
   ],
   "program": {
     "type": "Program",
diff --git a/packages/babel-parser/test/fixtures/es2017/async-functions/allow-await-outside-function-throw/output.json b/packages/babel-parser/test/fixtures/es2017/async-functions/allow-await-outside-function-throw/output.json
index 3f3e1cddf5b1..8f13d165a4be 100644
--- a/packages/babel-parser/test/fixtures/es2017/async-functions/allow-await-outside-function-throw/output.json
+++ b/packages/babel-parser/test/fixtures/es2017/async-functions/allow-await-outside-function-throw/output.json
@@ -2,7 +2,7 @@
   "type": "File",
   "start":0,"end":33,"loc":{"start":{"line":1,"column":0},"end":{"line":3,"column":1}},
   "errors": [
-    "SyntaxError: 'await' is only allowed within async functions and at the top levels of modules (2:9)"
+    "SyntaxError: 'await' is only allowed within async functions (2:9)"
   ],
   "program": {
     "type": "Program",
diff --git a/packages/babel-parser/test/fixtures/es2017/async-functions/await-inside-arrow-expression-disallowed/output.json b/packages/babel-parser/test/fixtures/es2017/async-functions/await-inside-arrow-expression-disallowed/output.json
index b12eebc08943..506ce33b909e 100644
--- a/packages/babel-parser/test/fixtures/es2017/async-functions/await-inside-arrow-expression-disallowed/output.json
+++ b/packages/babel-parser/test/fixtures/es2017/async-functions/await-inside-arrow-expression-disallowed/output.json
@@ -2,7 +2,7 @@
   "type": "File",
   "start":0,"end":17,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":17}},
   "errors": [
-    "SyntaxError: 'await' is only allowed within async functions and at the top levels of modules (1:8)"
+    "SyntaxError: 'await' is only allowed within async functions (1:8)"
   ],
   "program": {
     "type": "Program",
diff --git a/packages/babel-parser/test/fixtures/es2017/async-functions/await-inside-parameters-of-nested-function/output.json b/packages/babel-parser/test/fixtures/es2017/async-functions/await-inside-parameters-of-nested-function/output.json
index c7d4e8fb8241..444930868eef 100644
--- a/packages/babel-parser/test/fixtures/es2017/async-functions/await-inside-parameters-of-nested-function/output.json
+++ b/packages/babel-parser/test/fixtures/es2017/async-functions/await-inside-parameters-of-nested-function/output.json
@@ -2,7 +2,7 @@
   "type": "File",
   "start":0,"end":55,"loc":{"start":{"line":1,"column":0},"end":{"line":3,"column":1}},
   "errors": [
-    "SyntaxError: 'await' is only allowed within async functions and at the top levels of modules (2:19)",
+    "SyntaxError: 'await' is only allowed within async functions (2:19)",
     "SyntaxError: await is not allowed in async function parameters (2:19)"
   ],
   "program": {
diff --git a/packages/babel-parser/test/fixtures/es2017/async-functions/invalid-await-with-object-exp-in-function/output.json b/packages/babel-parser/test/fixtures/es2017/async-functions/invalid-await-with-object-exp-in-function/output.json
index d64bc787b0ab..cd71c7cea376 100644
--- a/packages/babel-parser/test/fixtures/es2017/async-functions/invalid-await-with-object-exp-in-function/output.json
+++ b/packages/babel-parser/test/fixtures/es2017/async-functions/invalid-await-with-object-exp-in-function/output.json
@@ -2,7 +2,7 @@
   "type": "File",
   "start":0,"end":35,"loc":{"start":{"line":1,"column":0},"end":{"line":3,"column":1}},
   "errors": [
-    "SyntaxError: 'await' is only allowed within async functions and at the top levels of modules (2:2)"
+    "SyntaxError: 'await' is only allowed within async functions (2:2)"
   ],
   "program": {
     "type": "Program",
diff --git a/packages/babel-parser/test/fixtures/experimental/class-static-block/invalid-await/output.json b/packages/babel-parser/test/fixtures/experimental/class-static-block/invalid-await/output.json
index 3d29d5376d60..a5c0a305f294 100644
--- a/packages/babel-parser/test/fixtures/experimental/class-static-block/invalid-await/output.json
+++ b/packages/babel-parser/test/fixtures/experimental/class-static-block/invalid-await/output.json
@@ -2,7 +2,7 @@
   "type": "File",
   "start":0,"end":95,"loc":{"start":{"line":1,"column":0},"end":{"line":8,"column":1}},
   "errors": [
-    "SyntaxError: 'await' is only allowed within async functions and at the top levels of modules (5:6)"
+    "SyntaxError: 'await' is only allowed within async functions (5:6)"
   ],
   "program": {
     "type": "Program",

From 6e692092fb40950b3fb38eca716a3ad98d3e57f3 Mon Sep 17 00:00:00 2001
From: sosukesuzuki <aosukeke@gmail.com>
Date: Sun, 10 Jan 2021 13:45:06 +0900
Subject: [PATCH 6/7] Address reviewed points

---
 .../babel-parser/src/parser/expression.js     |  8 +--
 .../options.json                              |  3 -
 .../output.json                               | 58 +++++++++++++++++
 .../inside-class-property/options.json        | 10 +--
 .../inside-class-property/output.json         | 63 +++++++++++++++++++
 .../top-level-await/options.json              |  8 +--
 .../top-level-await/output.json               | 60 ++++++++++++++++++
 7 files changed, 187 insertions(+), 23 deletions(-)
 delete mode 100644 packages/babel-parser/test/fixtures/es2017/async-functions/await-inside-parameters-of-async-arrow-function/options.json
 create mode 100644 packages/babel-parser/test/fixtures/es2017/async-functions/await-inside-parameters-of-async-arrow-function/output.json
 create mode 100644 packages/babel-parser/test/fixtures/experimental/top-level-await/inside-class-property/output.json
 create mode 100644 packages/babel-parser/test/fixtures/typescript/module-namespace/top-level-await/output.json

diff --git a/packages/babel-parser/src/parser/expression.js b/packages/babel-parser/src/parser/expression.js
index 49e4cc181640..6d0677e4695a 100644
--- a/packages/babel-parser/src/parser/expression.js
+++ b/packages/babel-parser/src/parser/expression.js
@@ -537,13 +537,7 @@ export default class ExpressionParser extends LValParser {
     const startsExpr = this.hasPlugin("v8intrinsic")
       ? this.state.type.startsExpr
       : this.state.type.startsExpr && !this.match(tt.modulo);
-    if (
-      isAwait &&
-      startsExpr &&
-      !this.isAmbiguousAwait() &&
-      (this.scope.inFunction ||
-        (this.hasPlugin("topLevelAwait") && !this.inModule))
-    ) {
+    if (isAwait && startsExpr && !this.isAmbiguousAwait()) {
       this.raise(
         startPos,
         this.hasPlugin("topLevelAwait")
diff --git a/packages/babel-parser/test/fixtures/es2017/async-functions/await-inside-parameters-of-async-arrow-function/options.json b/packages/babel-parser/test/fixtures/es2017/async-functions/await-inside-parameters-of-async-arrow-function/options.json
deleted file mode 100644
index ceaee67ee6b4..000000000000
--- a/packages/babel-parser/test/fixtures/es2017/async-functions/await-inside-parameters-of-async-arrow-function/options.json
+++ /dev/null
@@ -1,3 +0,0 @@
-{
-  "throws": "Unexpected token, expected \",\" (1:17)"
-}
diff --git a/packages/babel-parser/test/fixtures/es2017/async-functions/await-inside-parameters-of-async-arrow-function/output.json b/packages/babel-parser/test/fixtures/es2017/async-functions/await-inside-parameters-of-async-arrow-function/output.json
new file mode 100644
index 000000000000..287f8eae4418
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/es2017/async-functions/await-inside-parameters-of-async-arrow-function/output.json
@@ -0,0 +1,58 @@
+{
+  "type": "File",
+  "start":0,"end":26,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":26}},
+  "errors": [
+    "SyntaxError: 'await' is only allowed within async functions (1:11)",
+    "SyntaxError: await is not allowed in async function parameters (1:11)"
+  ],
+  "program": {
+    "type": "Program",
+    "start":0,"end":26,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":26}},
+    "sourceType": "script",
+    "interpreter": null,
+    "body": [
+      {
+        "type": "ExpressionStatement",
+        "start":0,"end":26,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":26}},
+        "expression": {
+          "type": "ArrowFunctionExpression",
+          "start":0,"end":25,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":25}},
+          "id": null,
+          "generator": false,
+          "async": true,
+          "params": [
+            {
+              "type": "AssignmentPattern",
+              "start":7,"end":18,"loc":{"start":{"line":1,"column":7},"end":{"line":1,"column":18}},
+              "left": {
+                "type": "Identifier",
+                "start":7,"end":8,"loc":{"start":{"line":1,"column":7},"end":{"line":1,"column":8},"identifierName":"x"},
+                "name": "x"
+              },
+              "right": {
+                "type": "AwaitExpression",
+                "start":11,"end":18,"loc":{"start":{"line":1,"column":11},"end":{"line":1,"column":18}},
+                "argument": {
+                  "type": "NumericLiteral",
+                  "start":17,"end":18,"loc":{"start":{"line":1,"column":17},"end":{"line":1,"column":18}},
+                  "extra": {
+                    "rawValue": 2,
+                    "raw": "2"
+                  },
+                  "value": 2
+                }
+              }
+            }
+          ],
+          "body": {
+            "type": "BlockStatement",
+            "start":23,"end":25,"loc":{"start":{"line":1,"column":23},"end":{"line":1,"column":25}},
+            "body": [],
+            "directives": []
+          }
+        }
+      }
+    ],
+    "directives": []
+  }
+}
\ No newline at end of file
diff --git a/packages/babel-parser/test/fixtures/experimental/top-level-await/inside-class-property/options.json b/packages/babel-parser/test/fixtures/experimental/top-level-await/inside-class-property/options.json
index 0688c012b357..ac03e3ac9677 100644
--- a/packages/babel-parser/test/fixtures/experimental/top-level-await/inside-class-property/options.json
+++ b/packages/babel-parser/test/fixtures/experimental/top-level-await/inside-class-property/options.json
@@ -1,8 +1,4 @@
 {
-  "plugins": [
-    "topLevelAwait",
-    "classProperties"
-  ],
-  "sourceType": "module",
-  "throws": "Unexpected token, expected \";\" (2:12)"
-}
\ No newline at end of file
+  "plugins": ["topLevelAwati", "classProperties"],
+  "sourceType": "module"
+}
diff --git a/packages/babel-parser/test/fixtures/experimental/top-level-await/inside-class-property/output.json b/packages/babel-parser/test/fixtures/experimental/top-level-await/inside-class-property/output.json
new file mode 100644
index 000000000000..8cdb6c704f02
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/experimental/top-level-await/inside-class-property/output.json
@@ -0,0 +1,63 @@
+{
+  "type": "File",
+  "start":0,"end":33,"loc":{"start":{"line":1,"column":0},"end":{"line":3,"column":1}},
+  "errors": [
+    "SyntaxError: 'await' is only allowed within async functions (2:6)",
+    "SyntaxError: 'await' is only allowed within async functions (2:6)"
+  ],
+  "program": {
+    "type": "Program",
+    "start":0,"end":33,"loc":{"start":{"line":1,"column":0},"end":{"line":3,"column":1}},
+    "sourceType": "module",
+    "interpreter": null,
+    "body": [
+      {
+        "type": "ExportNamedDeclaration",
+        "start":0,"end":33,"loc":{"start":{"line":1,"column":0},"end":{"line":3,"column":1}},
+        "specifiers": [],
+        "source": null,
+        "declaration": {
+          "type": "ClassDeclaration",
+          "start":7,"end":33,"loc":{"start":{"line":1,"column":7},"end":{"line":3,"column":1}},
+          "id": {
+            "type": "Identifier",
+            "start":13,"end":14,"loc":{"start":{"line":1,"column":13},"end":{"line":1,"column":14},"identifierName":"C"},
+            "name": "C"
+          },
+          "superClass": null,
+          "body": {
+            "type": "ClassBody",
+            "start":15,"end":33,"loc":{"start":{"line":1,"column":15},"end":{"line":3,"column":1}},
+            "body": [
+              {
+                "type": "ClassProperty",
+                "start":19,"end":31,"loc":{"start":{"line":2,"column":2},"end":{"line":2,"column":14}},
+                "static": false,
+                "key": {
+                  "type": "Identifier",
+                  "start":19,"end":20,"loc":{"start":{"line":2,"column":2},"end":{"line":2,"column":3},"identifierName":"p"},
+                  "name": "p"
+                },
+                "computed": false,
+                "value": {
+                  "type": "AwaitExpression",
+                  "start":23,"end":30,"loc":{"start":{"line":2,"column":6},"end":{"line":2,"column":13}},
+                  "argument": {
+                    "type": "NumericLiteral",
+                    "start":29,"end":30,"loc":{"start":{"line":2,"column":12},"end":{"line":2,"column":13}},
+                    "extra": {
+                      "rawValue": 0,
+                      "raw": "0"
+                    },
+                    "value": 0
+                  }
+                }
+              }
+            ]
+          }
+        }
+      }
+    ],
+    "directives": []
+  }
+}
\ No newline at end of file
diff --git a/packages/babel-parser/test/fixtures/typescript/module-namespace/top-level-await/options.json b/packages/babel-parser/test/fixtures/typescript/module-namespace/top-level-await/options.json
index ba579946562a..6328ffd5bc9e 100644
--- a/packages/babel-parser/test/fixtures/typescript/module-namespace/top-level-await/options.json
+++ b/packages/babel-parser/test/fixtures/typescript/module-namespace/top-level-await/options.json
@@ -1,8 +1,4 @@
 {
   "sourceType": "module",
-  "plugins": [
-    "typescript",
-    "topLevelAwait"
-  ],
-  "throws": "Unexpected token, expected \";\" (2:20)"
-}
\ No newline at end of file
+  "plugins": ["typescript", "topLevelAwait"]
+}
diff --git a/packages/babel-parser/test/fixtures/typescript/module-namespace/top-level-await/output.json b/packages/babel-parser/test/fixtures/typescript/module-namespace/top-level-await/output.json
new file mode 100644
index 000000000000..a99125a44c6f
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/typescript/module-namespace/top-level-await/output.json
@@ -0,0 +1,60 @@
+{
+  "type": "File",
+  "start":0,"end":39,"loc":{"start":{"line":1,"column":0},"end":{"line":3,"column":1}},
+  "errors": [
+    "SyntaxError: 'await' is only allowed within async functions and at the top levels of modules (2:14)"
+  ],
+  "program": {
+    "type": "Program",
+    "start":0,"end":39,"loc":{"start":{"line":1,"column":0},"end":{"line":3,"column":1}},
+    "sourceType": "module",
+    "interpreter": null,
+    "body": [
+      {
+        "type": "TSModuleDeclaration",
+        "start":0,"end":39,"loc":{"start":{"line":1,"column":0},"end":{"line":3,"column":1}},
+        "id": {
+          "type": "Identifier",
+          "start":10,"end":11,"loc":{"start":{"line":1,"column":10},"end":{"line":1,"column":11},"identifierName":"N"},
+          "name": "N"
+        },
+        "body": {
+          "type": "TSModuleBlock",
+          "start":12,"end":39,"loc":{"start":{"line":1,"column":12},"end":{"line":3,"column":1}},
+          "body": [
+            {
+              "type": "VariableDeclaration",
+              "start":18,"end":37,"loc":{"start":{"line":2,"column":4},"end":{"line":2,"column":23}},
+              "declarations": [
+                {
+                  "type": "VariableDeclarator",
+                  "start":24,"end":36,"loc":{"start":{"line":2,"column":10},"end":{"line":2,"column":22}},
+                  "id": {
+                    "type": "Identifier",
+                    "start":24,"end":25,"loc":{"start":{"line":2,"column":10},"end":{"line":2,"column":11},"identifierName":"x"},
+                    "name": "x"
+                  },
+                  "init": {
+                    "type": "AwaitExpression",
+                    "start":28,"end":36,"loc":{"start":{"line":2,"column":14},"end":{"line":2,"column":22}},
+                    "argument": {
+                      "type": "NumericLiteral",
+                      "start":34,"end":36,"loc":{"start":{"line":2,"column":20},"end":{"line":2,"column":22}},
+                      "extra": {
+                        "rawValue": 42,
+                        "raw": "42"
+                      },
+                      "value": 42
+                    }
+                  }
+                }
+              ],
+              "kind": "const"
+            }
+          ]
+        }
+      }
+    ],
+    "directives": []
+  }
+}
\ No newline at end of file

From 6d3b9c54291a098a4100c3247453eb2c094f27fe Mon Sep 17 00:00:00 2001
From: sosukesuzuki <aosukeke@gmail.com>
Date: Mon, 11 Jan 2021 10:58:12 +0900
Subject: [PATCH 7/7] Avoid duplicate errors

---
 packages/babel-parser/src/parser/expression.js    | 15 +++++++++------
 packages/babel-parser/src/tokenizer/state.js      |  3 +++
 .../inside-class-property/output.json             |  1 -
 3 files changed, 12 insertions(+), 7 deletions(-)

diff --git a/packages/babel-parser/src/parser/expression.js b/packages/babel-parser/src/parser/expression.js
index 6d0677e4695a..b50aed34e682 100644
--- a/packages/babel-parser/src/parser/expression.js
+++ b/packages/babel-parser/src/parser/expression.js
@@ -538,12 +538,14 @@ export default class ExpressionParser extends LValParser {
       ? this.state.type.startsExpr
       : this.state.type.startsExpr && !this.match(tt.modulo);
     if (isAwait && startsExpr && !this.isAmbiguousAwait()) {
-      this.raise(
-        startPos,
-        this.hasPlugin("topLevelAwait")
-          ? Errors.AwaitNotInAsyncContext
-          : Errors.AwaitNotInAsyncFunction,
-      );
+      if (!this.state.invalidAwaitErrors.has(startPos)) {
+        this.raise(
+          startPos,
+          this.hasPlugin("topLevelAwait")
+            ? Errors.AwaitNotInAsyncContext
+            : Errors.AwaitNotInAsyncFunction,
+        );
+      }
       return this.parseAwait(startPos, startLoc);
     }
 
@@ -2353,6 +2355,7 @@ export default class ExpressionParser extends LValParser {
             ? Errors.AwaitNotInAsyncContext
             : Errors.AwaitNotInAsyncFunction,
         );
+        this.state.invalidAwaitErrors.add(startLoc);
       } else {
         this.raise(startLoc, Errors.UnexpectedReservedWord, word);
       }
diff --git a/packages/babel-parser/src/tokenizer/state.js b/packages/babel-parser/src/tokenizer/state.js
index ef61fde4eaa8..4f42b15faed0 100644
--- a/packages/babel-parser/src/tokenizer/state.js
+++ b/packages/babel-parser/src/tokenizer/state.js
@@ -154,6 +154,9 @@ export default class State {
   // Tokens length in token store
   tokensLength: number = 0;
 
+  // Positions of invalid await errors
+  invalidAwaitErrors: Set<number> = new Set();
+
   curPosition(): Position {
     return new Position(this.curLine, this.pos - this.lineStart);
   }
diff --git a/packages/babel-parser/test/fixtures/experimental/top-level-await/inside-class-property/output.json b/packages/babel-parser/test/fixtures/experimental/top-level-await/inside-class-property/output.json
index 8cdb6c704f02..71e47b18fa76 100644
--- a/packages/babel-parser/test/fixtures/experimental/top-level-await/inside-class-property/output.json
+++ b/packages/babel-parser/test/fixtures/experimental/top-level-await/inside-class-property/output.json
@@ -2,7 +2,6 @@
   "type": "File",
   "start":0,"end":33,"loc":{"start":{"line":1,"column":0},"end":{"line":3,"column":1}},
   "errors": [
-    "SyntaxError: 'await' is only allowed within async functions (2:6)",
     "SyntaxError: 'await' is only allowed within async functions (2:6)"
   ],
   "program": {