From 2b6feefcf60ff91e35020deadacf437b2b40939a Mon Sep 17 00:00:00 2001
From: kingwl <kingwenlu@gmail.com>
Date: Sun, 6 Jun 2021 23:33:52 +0800
Subject: [PATCH 1/4] Improve parsing in await and yield context

---
 src/compiler/parser.ts                        |  6 +-
 ...syncOrYieldAsBindingIdentifier1.errors.txt | 68 +++++++++++++
 .../asyncOrYieldAsBindingIdentifier1.js       | 86 +++++++++++++++++
 .../asyncOrYieldAsBindingIdentifier1.symbols  | 84 ++++++++++++++++
 .../asyncOrYieldAsBindingIdentifier1.types    | 96 +++++++++++++++++++
 .../asyncOrYieldAsBindingIdentifier1.ts       | 49 ++++++++++
 6 files changed, 386 insertions(+), 3 deletions(-)
 create mode 100644 tests/baselines/reference/asyncOrYieldAsBindingIdentifier1.errors.txt
 create mode 100644 tests/baselines/reference/asyncOrYieldAsBindingIdentifier1.js
 create mode 100644 tests/baselines/reference/asyncOrYieldAsBindingIdentifier1.symbols
 create mode 100644 tests/baselines/reference/asyncOrYieldAsBindingIdentifier1.types
 create mode 100644 tests/cases/conformance/async/es6/functionDeclarations/asyncOrYieldAsBindingIdentifier1.ts

diff --git a/src/compiler/parser.ts b/src/compiler/parser.ts
index 8a6743090f9dc..fb82b4d603341 100644
--- a/src/compiler/parser.ts
+++ b/src/compiler/parser.ts
@@ -6122,15 +6122,15 @@ namespace ts {
             }
         }
 
-        function nextTokenIsIdentifierOrStartOfDestructuring() {
+        function nextTokenIsBindingIdentifierOrStartOfDestructuring() {
             nextToken();
-            return isIdentifier() || token() === SyntaxKind.OpenBraceToken || token() === SyntaxKind.OpenBracketToken;
+            return isBindingIdentifier() || token() === SyntaxKind.OpenBraceToken || token() === SyntaxKind.OpenBracketToken;
         }
 
         function isLetDeclaration() {
             // In ES6 'let' always starts a lexical declaration if followed by an identifier or {
             // or [.
-            return lookAhead(nextTokenIsIdentifierOrStartOfDestructuring);
+            return lookAhead(nextTokenIsBindingIdentifierOrStartOfDestructuring);
         }
 
         function parseStatement(): Statement {
diff --git a/tests/baselines/reference/asyncOrYieldAsBindingIdentifier1.errors.txt b/tests/baselines/reference/asyncOrYieldAsBindingIdentifier1.errors.txt
new file mode 100644
index 0000000000000..4b18189d9c90b
--- /dev/null
+++ b/tests/baselines/reference/asyncOrYieldAsBindingIdentifier1.errors.txt
@@ -0,0 +1,68 @@
+tests/cases/conformance/async/es6/functionDeclarations/asyncOrYieldAsBindingIdentifier1.ts(14,9): error TS1359: Identifier expected. 'await' is a reserved word that cannot be used here.
+tests/cases/conformance/async/es6/functionDeclarations/asyncOrYieldAsBindingIdentifier1.ts(18,9): error TS1359: Identifier expected. 'await' is a reserved word that cannot be used here.
+tests/cases/conformance/async/es6/functionDeclarations/asyncOrYieldAsBindingIdentifier1.ts(22,11): error TS1359: Identifier expected. 'await' is a reserved word that cannot be used here.
+tests/cases/conformance/async/es6/functionDeclarations/asyncOrYieldAsBindingIdentifier1.ts(38,9): error TS1359: Identifier expected. 'yield' is a reserved word that cannot be used here.
+tests/cases/conformance/async/es6/functionDeclarations/asyncOrYieldAsBindingIdentifier1.ts(42,9): error TS1359: Identifier expected. 'yield' is a reserved word that cannot be used here.
+tests/cases/conformance/async/es6/functionDeclarations/asyncOrYieldAsBindingIdentifier1.ts(46,11): error TS1359: Identifier expected. 'yield' is a reserved word that cannot be used here.
+
+
+==== tests/cases/conformance/async/es6/functionDeclarations/asyncOrYieldAsBindingIdentifier1.ts (6 errors) ====
+    function f_let () {
+        let await = 1
+    }
+    
+    function f1_var () {
+        var await = 1
+    }
+    
+    function f1_const () {
+        const await = 1
+    }
+    
+    async function f2_let () {
+        let await = 1
+            ~~~~~
+!!! error TS1359: Identifier expected. 'await' is a reserved word that cannot be used here.
+    }
+    
+    async function f2_var () {
+        var await = 1
+            ~~~~~
+!!! error TS1359: Identifier expected. 'await' is a reserved word that cannot be used here.
+    }
+    
+    async function f2_const () {
+        const await = 1
+              ~~~~~
+!!! error TS1359: Identifier expected. 'await' is a reserved word that cannot be used here.
+    }
+    
+    function f3_let () {
+        let yield = 2
+    }
+    
+    function f3_var () {
+        var yield = 2
+    }
+    
+    function f3_const () {
+        const yield = 2
+    }
+    
+    function * f4_let () {
+        let yield = 2;
+            ~~~~~
+!!! error TS1359: Identifier expected. 'yield' is a reserved word that cannot be used here.
+    }
+    
+    function * f4_var () {
+        var yield = 2;
+            ~~~~~
+!!! error TS1359: Identifier expected. 'yield' is a reserved word that cannot be used here.
+    }
+    
+    function * f4_const () {
+        const yield = 2;
+              ~~~~~
+!!! error TS1359: Identifier expected. 'yield' is a reserved word that cannot be used here.
+    }
\ No newline at end of file
diff --git a/tests/baselines/reference/asyncOrYieldAsBindingIdentifier1.js b/tests/baselines/reference/asyncOrYieldAsBindingIdentifier1.js
new file mode 100644
index 0000000000000..d770f71ab8a46
--- /dev/null
+++ b/tests/baselines/reference/asyncOrYieldAsBindingIdentifier1.js
@@ -0,0 +1,86 @@
+//// [asyncOrYieldAsBindingIdentifier1.ts]
+function f_let () {
+    let await = 1
+}
+
+function f1_var () {
+    var await = 1
+}
+
+function f1_const () {
+    const await = 1
+}
+
+async function f2_let () {
+    let await = 1
+}
+
+async function f2_var () {
+    var await = 1
+}
+
+async function f2_const () {
+    const await = 1
+}
+
+function f3_let () {
+    let yield = 2
+}
+
+function f3_var () {
+    var yield = 2
+}
+
+function f3_const () {
+    const yield = 2
+}
+
+function * f4_let () {
+    let yield = 2;
+}
+
+function * f4_var () {
+    var yield = 2;
+}
+
+function * f4_const () {
+    const yield = 2;
+}
+
+//// [asyncOrYieldAsBindingIdentifier1.js]
+function f_let() {
+    let await = 1;
+}
+function f1_var() {
+    var await = 1;
+}
+function f1_const() {
+    const await = 1;
+}
+async function f2_let() {
+    let await = 1;
+}
+async function f2_var() {
+    var await = 1;
+}
+async function f2_const() {
+    const await = 1;
+}
+function f3_let() {
+    let yield = 2;
+}
+function f3_var() {
+    var yield = 2;
+}
+function f3_const() {
+    const yield = 2;
+}
+function* f4_let() {
+    let yield = 2;
+}
+function* f4_var() {
+    var yield = 2;
+}
+function* f4_const() {
+    const yield = 2;
+}
diff --git a/tests/baselines/reference/asyncOrYieldAsBindingIdentifier1.symbols b/tests/baselines/reference/asyncOrYieldAsBindingIdentifier1.symbols
new file mode 100644
index 0000000000000..830d08b69ad13
--- /dev/null
+++ b/tests/baselines/reference/asyncOrYieldAsBindingIdentifier1.symbols
@@ -0,0 +1,84 @@
+=== tests/cases/conformance/async/es6/functionDeclarations/asyncOrYieldAsBindingIdentifier1.ts ===
+function f_let () {
+>f_let : Symbol(f_let, Decl(asyncOrYieldAsBindingIdentifier1.ts, 0, 0))
+
+    let await = 1
+>await : Symbol(await, Decl(asyncOrYieldAsBindingIdentifier1.ts, 1, 7))
+}
+
+function f1_var () {
+>f1_var : Symbol(f1_var, Decl(asyncOrYieldAsBindingIdentifier1.ts, 2, 1))
+
+    var await = 1
+>await : Symbol(await, Decl(asyncOrYieldAsBindingIdentifier1.ts, 5, 7))
+}
+
+function f1_const () {
+>f1_const : Symbol(f1_const, Decl(asyncOrYieldAsBindingIdentifier1.ts, 6, 1))
+
+    const await = 1
+>await : Symbol(await, Decl(asyncOrYieldAsBindingIdentifier1.ts, 9, 9))
+}
+
+async function f2_let () {
+>f2_let : Symbol(f2_let, Decl(asyncOrYieldAsBindingIdentifier1.ts, 10, 1))
+
+    let await = 1
+>await : Symbol(await, Decl(asyncOrYieldAsBindingIdentifier1.ts, 13, 7))
+}
+
+async function f2_var () {
+>f2_var : Symbol(f2_var, Decl(asyncOrYieldAsBindingIdentifier1.ts, 14, 1))
+
+    var await = 1
+>await : Symbol(await, Decl(asyncOrYieldAsBindingIdentifier1.ts, 17, 7))
+}
+
+async function f2_const () {
+>f2_const : Symbol(f2_const, Decl(asyncOrYieldAsBindingIdentifier1.ts, 18, 1))
+
+    const await = 1
+>await : Symbol(await, Decl(asyncOrYieldAsBindingIdentifier1.ts, 21, 9))
+}
+
+function f3_let () {
+>f3_let : Symbol(f3_let, Decl(asyncOrYieldAsBindingIdentifier1.ts, 22, 1))
+
+    let yield = 2
+>yield : Symbol(yield, Decl(asyncOrYieldAsBindingIdentifier1.ts, 25, 7))
+}
+
+function f3_var () {
+>f3_var : Symbol(f3_var, Decl(asyncOrYieldAsBindingIdentifier1.ts, 26, 1))
+
+    var yield = 2
+>yield : Symbol(yield, Decl(asyncOrYieldAsBindingIdentifier1.ts, 29, 7))
+}
+
+function f3_const () {
+>f3_const : Symbol(f3_const, Decl(asyncOrYieldAsBindingIdentifier1.ts, 30, 1))
+
+    const yield = 2
+>yield : Symbol(yield, Decl(asyncOrYieldAsBindingIdentifier1.ts, 33, 9))
+}
+
+function * f4_let () {
+>f4_let : Symbol(f4_let, Decl(asyncOrYieldAsBindingIdentifier1.ts, 34, 1))
+
+    let yield = 2;
+>yield : Symbol(yield, Decl(asyncOrYieldAsBindingIdentifier1.ts, 37, 7))
+}
+
+function * f4_var () {
+>f4_var : Symbol(f4_var, Decl(asyncOrYieldAsBindingIdentifier1.ts, 38, 1))
+
+    var yield = 2;
+>yield : Symbol(yield, Decl(asyncOrYieldAsBindingIdentifier1.ts, 41, 7))
+}
+
+function * f4_const () {
+>f4_const : Symbol(f4_const, Decl(asyncOrYieldAsBindingIdentifier1.ts, 42, 1))
+
+    const yield = 2;
+>yield : Symbol(yield, Decl(asyncOrYieldAsBindingIdentifier1.ts, 45, 9))
+}
diff --git a/tests/baselines/reference/asyncOrYieldAsBindingIdentifier1.types b/tests/baselines/reference/asyncOrYieldAsBindingIdentifier1.types
new file mode 100644
index 0000000000000..e887b60eb21e4
--- /dev/null
+++ b/tests/baselines/reference/asyncOrYieldAsBindingIdentifier1.types
@@ -0,0 +1,96 @@
+=== tests/cases/conformance/async/es6/functionDeclarations/asyncOrYieldAsBindingIdentifier1.ts ===
+function f_let () {
+>f_let : () => void
+
+    let await = 1
+>await : number
+>1 : 1
+}
+
+function f1_var () {
+>f1_var : () => void
+
+    var await = 1
+>await : number
+>1 : 1
+}
+
+function f1_const () {
+>f1_const : () => void
+
+    const await = 1
+>await : 1
+>1 : 1
+}
+
+async function f2_let () {
+>f2_let : () => Promise<void>
+
+    let await = 1
+>await : number
+>1 : 1
+}
+
+async function f2_var () {
+>f2_var : () => Promise<void>
+
+    var await = 1
+>await : number
+>1 : 1
+}
+
+async function f2_const () {
+>f2_const : () => Promise<void>
+
+    const await = 1
+>await : 1
+>1 : 1
+}
+
+function f3_let () {
+>f3_let : () => void
+
+    let yield = 2
+>yield : number
+>2 : 2
+}
+
+function f3_var () {
+>f3_var : () => void
+
+    var yield = 2
+>yield : number
+>2 : 2
+}
+
+function f3_const () {
+>f3_const : () => void
+
+    const yield = 2
+>yield : 2
+>2 : 2
+}
+
+function * f4_let () {
+>f4_let : () => Generator<never, void, unknown>
+
+    let yield = 2;
+>yield : number
+>2 : 2
+}
+
+function * f4_var () {
+>f4_var : () => Generator<never, void, unknown>
+
+    var yield = 2;
+>yield : number
+>2 : 2
+}
+
+function * f4_const () {
+>f4_const : () => Generator<never, void, unknown>
+
+    const yield = 2;
+>yield : 2
+>2 : 2
+}
diff --git a/tests/cases/conformance/async/es6/functionDeclarations/asyncOrYieldAsBindingIdentifier1.ts b/tests/cases/conformance/async/es6/functionDeclarations/asyncOrYieldAsBindingIdentifier1.ts
new file mode 100644
index 0000000000000..31c1c4055c531
--- /dev/null
+++ b/tests/cases/conformance/async/es6/functionDeclarations/asyncOrYieldAsBindingIdentifier1.ts
@@ -0,0 +1,49 @@
+// @target: esnext
+
+function f_let () {
+    let await = 1
+}
+
+function f1_var () {
+    var await = 1
+}
+
+function f1_const () {
+    const await = 1
+}
+
+async function f2_let () {
+    let await = 1
+}
+
+async function f2_var () {
+    var await = 1
+}
+
+async function f2_const () {
+    const await = 1
+}
+
+function f3_let () {
+    let yield = 2
+}
+
+function f3_var () {
+    var yield = 2
+}
+
+function f3_const () {
+    const yield = 2
+}
+
+function * f4_let () {
+    let yield = 2;
+}
+
+function * f4_var () {
+    var yield = 2;
+}
+
+function * f4_const () {
+    const yield = 2;
+}
\ No newline at end of file

From 9644859f291840db87de6275f2e4cca7f665bf8a Mon Sep 17 00:00:00 2001
From: kingwl <kingwenlu@gmail.com>
Date: Mon, 21 Jun 2021 15:45:53 +0800
Subject: [PATCH 2/4] Avoid yield and await check in identifier

---
 src/compiler/parser.ts                        |  22 ++--
 .../await_unaryExpression_es2017_3.errors.txt |  16 ++-
 .../await_unaryExpression_es2017_3.js         |   8 +-
 .../await_unaryExpression_es2017_3.types      |  10 +-
 .../await_unaryExpression_es6_3.errors.txt    |  16 ++-
 .../reference/await_unaryExpression_es6_3.js  |   8 +-
 .../await_unaryExpression_es6_3.types         |  10 +-
 .../reference/castOfYield.errors.txt          |   9 +-
 tests/baselines/reference/castOfYield.js      |   6 +-
 tests/baselines/reference/castOfYield.types   |   5 +-
 .../topLevelAwaitErrors.1.errors.txt          | 105 +++++++++++++-----
 .../reference/topLevelAwaitErrors.1.js        |  44 ++++----
 .../reference/topLevelAwaitErrors.1.symbols   |  17 +--
 .../reference/topLevelAwaitErrors.1.types     |  39 ++++---
 14 files changed, 185 insertions(+), 130 deletions(-)

diff --git a/src/compiler/parser.ts b/src/compiler/parser.ts
index fb82b4d603341..17d7bf85b823f 100644
--- a/src/compiler/parser.ts
+++ b/src/compiler/parser.ts
@@ -1510,17 +1510,17 @@ namespace ts {
                 return true;
             }
 
-            // If we have a 'yield' keyword, and we're in the [yield] context, then 'yield' is
-            // considered a keyword and is not an identifier.
-            if (token() === SyntaxKind.YieldKeyword && inYieldContext()) {
-                return false;
-            }
-
-            // If we have a 'await' keyword, and we're in the [Await] context, then 'await' is
-            // considered a keyword and is not an identifier.
-            if (token() === SyntaxKind.AwaitKeyword && inAwaitContext()) {
-                return false;
-            }
+            // // If we have a 'yield' keyword, and we're in the [yield] context, then 'yield' is
+            // // considered a keyword and is not an identifier.
+            // if (token() === SyntaxKind.YieldKeyword && inYieldContext()) {
+            //     return false;
+            // }
+
+            // // If we have a 'await' keyword, and we're in the [Await] context, then 'await' is
+            // // considered a keyword and is not an identifier.
+            // if (token() === SyntaxKind.AwaitKeyword && inAwaitContext()) {
+            //     return false;
+            // }
 
             return token() > SyntaxKind.LastReservedWord;
         }
diff --git a/tests/baselines/reference/await_unaryExpression_es2017_3.errors.txt b/tests/baselines/reference/await_unaryExpression_es2017_3.errors.txt
index da533765a0788..bffdd1b9a2082 100644
--- a/tests/baselines/reference/await_unaryExpression_es2017_3.errors.txt
+++ b/tests/baselines/reference/await_unaryExpression_es2017_3.errors.txt
@@ -1,18 +1,24 @@
-tests/cases/conformance/async/es2017/await_unaryExpression_es2017_3.ts(2,7): error TS1109: Expression expected.
-tests/cases/conformance/async/es2017/await_unaryExpression_es2017_3.ts(6,7): error TS1109: Expression expected.
+tests/cases/conformance/async/es2017/await_unaryExpression_es2017_3.ts(2,7): error TS2304: Cannot find name 'await'.
+tests/cases/conformance/async/es2017/await_unaryExpression_es2017_3.ts(2,13): error TS1005: ';' expected.
+tests/cases/conformance/async/es2017/await_unaryExpression_es2017_3.ts(6,7): error TS2304: Cannot find name 'await'.
+tests/cases/conformance/async/es2017/await_unaryExpression_es2017_3.ts(6,13): error TS1005: ';' expected.
 
 
-==== tests/cases/conformance/async/es2017/await_unaryExpression_es2017_3.ts (2 errors) ====
+==== tests/cases/conformance/async/es2017/await_unaryExpression_es2017_3.ts (4 errors) ====
     async function bar1() {
         ++await 42; // Error
           ~~~~~
-!!! error TS1109: Expression expected.
+!!! error TS2304: Cannot find name 'await'.
+                ~~
+!!! error TS1005: ';' expected.
     }
     
     async function bar2() {
         --await 42; // Error
           ~~~~~
-!!! error TS1109: Expression expected.
+!!! error TS2304: Cannot find name 'await'.
+                ~~
+!!! error TS1005: ';' expected.
     }
     
     async function bar3() {
diff --git a/tests/baselines/reference/await_unaryExpression_es2017_3.js b/tests/baselines/reference/await_unaryExpression_es2017_3.js
index b2a1593a9d0bd..bbddded1a1d30 100644
--- a/tests/baselines/reference/await_unaryExpression_es2017_3.js
+++ b/tests/baselines/reference/await_unaryExpression_es2017_3.js
@@ -19,12 +19,12 @@ async function bar4() {
 
 //// [await_unaryExpression_es2017_3.js]
 async function bar1() {
-    ++;
-    await 42; // Error
+    ++await;
+    42; // Error
 }
 async function bar2() {
-    --;
-    await 42; // Error
+    --await;
+    42; // Error
 }
 async function bar3() {
     var x = 42;
diff --git a/tests/baselines/reference/await_unaryExpression_es2017_3.types b/tests/baselines/reference/await_unaryExpression_es2017_3.types
index b60ea42b2a0d5..f94d05515d657 100644
--- a/tests/baselines/reference/await_unaryExpression_es2017_3.types
+++ b/tests/baselines/reference/await_unaryExpression_es2017_3.types
@@ -3,9 +3,8 @@ async function bar1() {
 >bar1 : () => Promise<void>
 
     ++await 42; // Error
->++ : number
-> : any
->await 42 : 42
+>++await : number
+>await : any
 >42 : 42
 }
 
@@ -13,9 +12,8 @@ async function bar2() {
 >bar2 : () => Promise<void>
 
     --await 42; // Error
->-- : number
-> : any
->await 42 : 42
+>--await : number
+>await : any
 >42 : 42
 }
 
diff --git a/tests/baselines/reference/await_unaryExpression_es6_3.errors.txt b/tests/baselines/reference/await_unaryExpression_es6_3.errors.txt
index 373e6739461b4..297c8887db945 100644
--- a/tests/baselines/reference/await_unaryExpression_es6_3.errors.txt
+++ b/tests/baselines/reference/await_unaryExpression_es6_3.errors.txt
@@ -1,18 +1,24 @@
-tests/cases/conformance/async/es6/await_unaryExpression_es6_3.ts(2,7): error TS1109: Expression expected.
-tests/cases/conformance/async/es6/await_unaryExpression_es6_3.ts(6,7): error TS1109: Expression expected.
+tests/cases/conformance/async/es6/await_unaryExpression_es6_3.ts(2,7): error TS2304: Cannot find name 'await'.
+tests/cases/conformance/async/es6/await_unaryExpression_es6_3.ts(2,13): error TS1005: ';' expected.
+tests/cases/conformance/async/es6/await_unaryExpression_es6_3.ts(6,7): error TS2304: Cannot find name 'await'.
+tests/cases/conformance/async/es6/await_unaryExpression_es6_3.ts(6,13): error TS1005: ';' expected.
 
 
-==== tests/cases/conformance/async/es6/await_unaryExpression_es6_3.ts (2 errors) ====
+==== tests/cases/conformance/async/es6/await_unaryExpression_es6_3.ts (4 errors) ====
     async function bar1() {
         ++await 42; // Error
           ~~~~~
-!!! error TS1109: Expression expected.
+!!! error TS2304: Cannot find name 'await'.
+                ~~
+!!! error TS1005: ';' expected.
     }
     
     async function bar2() {
         --await 42; // Error
           ~~~~~
-!!! error TS1109: Expression expected.
+!!! error TS2304: Cannot find name 'await'.
+                ~~
+!!! error TS1005: ';' expected.
     }
     
     async function bar3() {
diff --git a/tests/baselines/reference/await_unaryExpression_es6_3.js b/tests/baselines/reference/await_unaryExpression_es6_3.js
index 42643caa262ae..f92401028025d 100644
--- a/tests/baselines/reference/await_unaryExpression_es6_3.js
+++ b/tests/baselines/reference/await_unaryExpression_es6_3.js
@@ -29,14 +29,14 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
 };
 function bar1() {
     return __awaiter(this, void 0, void 0, function* () {
-        ++;
-        yield 42; // Error
+        ++await;
+        42; // Error
     });
 }
 function bar2() {
     return __awaiter(this, void 0, void 0, function* () {
-        --;
-        yield 42; // Error
+        --await;
+        42; // Error
     });
 }
 function bar3() {
diff --git a/tests/baselines/reference/await_unaryExpression_es6_3.types b/tests/baselines/reference/await_unaryExpression_es6_3.types
index db18c88955375..d24149449ac5b 100644
--- a/tests/baselines/reference/await_unaryExpression_es6_3.types
+++ b/tests/baselines/reference/await_unaryExpression_es6_3.types
@@ -3,9 +3,8 @@ async function bar1() {
 >bar1 : () => Promise<void>
 
     ++await 42; // Error
->++ : number
-> : any
->await 42 : 42
+>++await : number
+>await : any
 >42 : 42
 }
 
@@ -13,9 +12,8 @@ async function bar2() {
 >bar2 : () => Promise<void>
 
     --await 42; // Error
->-- : number
-> : any
->await 42 : 42
+>--await : number
+>await : any
 >42 : 42
 }
 
diff --git a/tests/baselines/reference/castOfYield.errors.txt b/tests/baselines/reference/castOfYield.errors.txt
index 0d40a4dcd987d..b7c3035f68e4e 100644
--- a/tests/baselines/reference/castOfYield.errors.txt
+++ b/tests/baselines/reference/castOfYield.errors.txt
@@ -1,14 +1,17 @@
 error TS2318: Cannot find global type 'IterableIterator'.
-tests/cases/compiler/castOfYield.ts(4,14): error TS1109: Expression expected.
+tests/cases/compiler/castOfYield.ts(4,14): error TS2304: Cannot find name 'yield'.
+tests/cases/compiler/castOfYield.ts(4,20): error TS1005: ';' expected.
 
 
 !!! error TS2318: Cannot find global type 'IterableIterator'.
-==== tests/cases/compiler/castOfYield.ts (1 errors) ====
+==== tests/cases/compiler/castOfYield.ts (2 errors) ====
     function* f() {
         <number> (yield 0);
         // Unlike await, yield is not allowed to appear in a simple unary expression.
         <number> yield 0;
                  ~~~~~
-!!! error TS1109: Expression expected.
+!!! error TS2304: Cannot find name 'yield'.
+                       ~
+!!! error TS1005: ';' expected.
     }
     
\ No newline at end of file
diff --git a/tests/baselines/reference/castOfYield.js b/tests/baselines/reference/castOfYield.js
index 86d35bedad434..91b1f01a7852f 100644
--- a/tests/baselines/reference/castOfYield.js
+++ b/tests/baselines/reference/castOfYield.js
@@ -41,10 +41,8 @@ function f() {
             case 1:
                 (_a.sent());
                 // Unlike await, yield is not allowed to appear in a simple unary expression.
-                ;
-                return [4 /*yield*/, 0];
-            case 2:
-                _a.sent();
+                yield;
+                0;
                 return [2 /*return*/];
         }
     });
diff --git a/tests/baselines/reference/castOfYield.types b/tests/baselines/reference/castOfYield.types
index c005205609196..008cf646686dd 100644
--- a/tests/baselines/reference/castOfYield.types
+++ b/tests/baselines/reference/castOfYield.types
@@ -10,9 +10,8 @@ function* f() {
 
     // Unlike await, yield is not allowed to appear in a simple unary expression.
     <number> yield 0;
-><number> : number
-> : any
->yield 0 : any
+><number> yield : number
+>yield : any
 >0 : 0
 }
 
diff --git a/tests/baselines/reference/topLevelAwaitErrors.1.errors.txt b/tests/baselines/reference/topLevelAwaitErrors.1.errors.txt
index 773e8446a6fda..525ce18f6d7a2 100644
--- a/tests/baselines/reference/topLevelAwaitErrors.1.errors.txt
+++ b/tests/baselines/reference/topLevelAwaitErrors.1.errors.txt
@@ -4,23 +4,40 @@ tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(5,14): error TS
 tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(5,16): error TS2693: 'string' only refers to a type, but is being used as a value here.
 tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(8,14): error TS1005: '>' expected.
 tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(8,16): error TS2693: 'string' only refers to a type, but is being used as a value here.
-tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(11,17): error TS1109: Expression expected.
-tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(11,22): error TS1109: Expression expected.
-tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(11,23): error TS2693: 'string' only refers to a type, but is being used as a value here.
-tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(11,29): error TS1005: ',' expected.
+tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(11,17): error TS2304: Cannot find name 'await'.
 tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(15,8): error TS1109: Expression expected.
-tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(18,2): error TS1109: Expression expected.
+tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(18,8): error TS1146: Declaration expected.
 tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(18,8): error TS2304: Cannot find name 'x'.
-tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(21,2): error TS1109: Expression expected.
-tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(26,6): error TS1109: Expression expected.
-tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(30,6): error TS1109: Expression expected.
+tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(18,9): error TS1005: ';' expected.
+tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(22,6): error TS1146: Declaration expected.
+tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(22,7): error TS2304: Cannot find name 'C3'.
+tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(22,10): error TS1005: ';' expected.
+tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(26,6): error TS2304: Cannot find name 'await'.
+tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(27,11): error TS1005: ';' expected.
+tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(27,12): error TS1068: Unexpected token. A constructor, method, accessor, or property was expected.
+tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(27,13): error TS1068: Unexpected token. A constructor, method, accessor, or property was expected.
+tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(27,15): error TS1068: Unexpected token. A constructor, method, accessor, or property was expected.
+tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(28,1): error TS1109: Expression expected.
+tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(30,6): error TS2304: Cannot find name 'await'.
+tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(30,13): error TS1005: ';' expected.
 tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(34,12): error TS1109: Expression expected.
-tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(40,14): error TS1109: Expression expected.
-tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(41,14): error TS1109: Expression expected.
+tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(40,14): error TS2304: Cannot find name 'await'.
+tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(40,22): error TS1005: ')' expected.
+tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(40,23): error TS1068: Unexpected token. A constructor, method, accessor, or property was expected.
+tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(40,25): error TS1068: Unexpected token. A constructor, method, accessor, or property was expected.
+tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(41,5): error TS2304: Cannot find name 'method2'.
+tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(41,13): error TS1135: Argument expression expected.
+tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(41,24): error TS2304: Cannot find name 'x'.
+tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(41,28): error TS1005: ';' expected.
+tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(42,5): error TS2304: Cannot find name 'method3'.
+tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(42,13): error TS1135: Argument expression expected.
 tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(42,20): error TS1109: Expression expected.
+tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(42,23): error TS2304: Cannot find name 'x'.
+tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(42,27): error TS1005: ';' expected.
+tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(43,1): error TS1109: Expression expected.
 
 
-==== tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts (20 errors) ====
+==== tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts (37 errors) ====
     export {};
     
     // reparse call as invalid await should error
@@ -45,13 +62,7 @@ tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(42,20): error T
     // reparse class extends clause should fail
     class C extends await<string> {
                     ~~~~~
-!!! error TS1109: Expression expected.
-                         ~
-!!! error TS1109: Expression expected.
-                          ~~~~~~
-!!! error TS2693: 'string' only refers to a type, but is being used as a value here.
-                                ~
-!!! error TS1005: ',' expected.
+!!! error TS2304: Cannot find name 'await'.
     }
     
     // await in class decorators should fail
@@ -61,28 +72,46 @@ tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(42,20): error T
     class C1 {}
     
     @await(x)
-     ~~~~~
-!!! error TS1109: Expression expected.
+           
+!!! error TS1146: Declaration expected.
            ~
 !!! error TS2304: Cannot find name 'x'.
+            ~
+!!! error TS1005: ';' expected.
     class C2 {}
     
     @await
-     ~~~~~
-!!! error TS1109: Expression expected.
     class C3 {}
+         
+!!! error TS1146: Declaration expected.
+          ~~
+!!! error TS2304: Cannot find name 'C3'.
+             ~
+!!! error TS1005: ';' expected.
     
     // await in member decorators should fail
     class C4 {
         @await
          ~~~~~
-!!! error TS1109: Expression expected.
+!!! error TS2304: Cannot find name 'await'.
         ["foo"]() {}
+              ~
+!!! error TS1005: ';' expected.
+               ~
+!!! error TS1068: Unexpected token. A constructor, method, accessor, or property was expected.
+                ~
+!!! error TS1068: Unexpected token. A constructor, method, accessor, or property was expected.
+                  ~
+!!! error TS1068: Unexpected token. A constructor, method, accessor, or property was expected.
     }
+    ~
+!!! error TS1109: Expression expected.
     class C5 {
         @await(1)
          ~~~~~
-!!! error TS1109: Expression expected.
+!!! error TS2304: Cannot find name 'await'.
+                ~
+!!! error TS1005: ';' expected.
         ["foo"]() {}
     }
     class C6 {
@@ -96,12 +125,34 @@ tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(42,20): error T
     class C7 {
         method1(@await [x]) {}
                  ~~~~~
-!!! error TS1109: Expression expected.
+!!! error TS2304: Cannot find name 'await'.
+                         ~
+!!! error TS1005: ')' expected.
+                          ~
+!!! error TS1068: Unexpected token. A constructor, method, accessor, or property was expected.
+                            ~
+!!! error TS1068: Unexpected token. A constructor, method, accessor, or property was expected.
         method2(@await(1) [x]) {}
-                 ~~~~~
-!!! error TS1109: Expression expected.
+        ~~~~~~~
+!!! error TS2304: Cannot find name 'method2'.
+                ~
+!!! error TS1135: Argument expression expected.
+                           ~
+!!! error TS2304: Cannot find name 'x'.
+                               ~
+!!! error TS1005: ';' expected.
         method3(@(await) [x]) {}
+        ~~~~~~~
+!!! error TS2304: Cannot find name 'method3'.
+                ~
+!!! error TS1135: Argument expression expected.
                        ~
 !!! error TS1109: Expression expected.
+                          ~
+!!! error TS2304: Cannot find name 'x'.
+                              ~
+!!! error TS1005: ';' expected.
     }
+    ~
+!!! error TS1109: Expression expected.
     
\ No newline at end of file
diff --git a/tests/baselines/reference/topLevelAwaitErrors.1.js b/tests/baselines/reference/topLevelAwaitErrors.1.js
index 175321a0513f8..b535c95dca4eb 100644
--- a/tests/baselines/reference/topLevelAwaitErrors.1.js
+++ b/tests/baselines/reference/topLevelAwaitErrors.1.js
@@ -51,7 +51,7 @@ await , string > (1);
 // reparse tagged template as invalid await should error
 await , string > ``;
 // reparse class extends clause should fail
-class C extends string {
+class C extends await {
 }
 // await in class decorators should fail
 let C1 = class C1 {
@@ -59,27 +59,27 @@ let C1 = class C1 {
 C1 = __decorate([
     (await )
 ], C1);
-let C2 = class C2 {
-};
-C2 = __decorate([
-    (x)
-], C2);
-let C3 = class C3 {
-};
-C3 = __decorate([
-], C3);
+x;
+;
+class C2 {
+}
+C3;
+{ }
 // await in member decorators should fail
 class C4 {
-    ["foo"]() { }
+    "foo";
 }
 __decorate([
-], C4.prototype, "foo", null);
+    await
+], C4.prototype, "foo", void 0);
+;
 class C5 {
+    1;
     ["foo"]() { }
 }
 __decorate([
-    (1)
-], C5.prototype, "foo", null);
+    await
+], C5.prototype, 1, void 0);
 class C6 {
     ["foo"]() { }
 }
@@ -88,17 +88,13 @@ __decorate([
 ], C6.prototype, "foo", null);
 // await in parameter decorators should fail
 class C7 {
-    method1([x]) { }
-    method2([x]) { }
-    method3([x]) { }
 }
 __decorate([
-    __param(0, )
+    __param(0, await)
 ], C7.prototype, "method1", null);
-__decorate([
-    __param(0, (1))
-], C7.prototype, "method2", null);
-__decorate([
-    __param(0, (await ))
-], C7.prototype, "method3", null);
+method2(await (1)[x]);
+{ }
+method3((await )[x]);
+{ }
+;
 export {};
diff --git a/tests/baselines/reference/topLevelAwaitErrors.1.symbols b/tests/baselines/reference/topLevelAwaitErrors.1.symbols
index c414127bbe691..0384c15c740e2 100644
--- a/tests/baselines/reference/topLevelAwaitErrors.1.symbols
+++ b/tests/baselines/reference/topLevelAwaitErrors.1.symbols
@@ -20,11 +20,10 @@ class C1 {}
 
 @await(x)
 class C2 {}
->C2 : Symbol(C2, Decl(topLevelAwaitErrors.1.ts, 15, 11))
+>C2 : Symbol(C2, Decl(topLevelAwaitErrors.1.ts, 17, 9))
 
 @await
 class C3 {}
->C3 : Symbol(C3, Decl(topLevelAwaitErrors.1.ts, 18, 11))
 
 // await in member decorators should fail
 class C4 {
@@ -32,16 +31,17 @@ class C4 {
 
     @await
     ["foo"]() {}
->["foo"] : Symbol(C4["foo"], Decl(topLevelAwaitErrors.1.ts, 24, 10))
 >"foo" : Symbol(C4["foo"], Decl(topLevelAwaitErrors.1.ts, 24, 10))
 }
 class C5 {
 >C5 : Symbol(C5, Decl(topLevelAwaitErrors.1.ts, 27, 1))
 
     @await(1)
+>1 : Symbol(C5[1], Decl(topLevelAwaitErrors.1.ts, 28, 10))
+
     ["foo"]() {}
->["foo"] : Symbol(C5["foo"], Decl(topLevelAwaitErrors.1.ts, 28, 10))
->"foo" : Symbol(C5["foo"], Decl(topLevelAwaitErrors.1.ts, 28, 10))
+>["foo"] : Symbol(C5["foo"], Decl(topLevelAwaitErrors.1.ts, 29, 13))
+>"foo" : Symbol(C5["foo"], Decl(topLevelAwaitErrors.1.ts, 29, 13))
 }
 class C6 {
 >C6 : Symbol(C6, Decl(topLevelAwaitErrors.1.ts, 31, 1))
@@ -58,14 +58,9 @@ class C7 {
 
     method1(@await [x]) {}
 >method1 : Symbol(C7.method1, Decl(topLevelAwaitErrors.1.ts, 38, 10))
->x : Symbol(x, Decl(topLevelAwaitErrors.1.ts, 39, 20))
+>x : Symbol(x, Decl(topLevelAwaitErrors.1.ts, 39, 12))
 
     method2(@await(1) [x]) {}
->method2 : Symbol(C7.method2, Decl(topLevelAwaitErrors.1.ts, 39, 26))
->x : Symbol(x, Decl(topLevelAwaitErrors.1.ts, 40, 23))
-
     method3(@(await) [x]) {}
->method3 : Symbol(C7.method3, Decl(topLevelAwaitErrors.1.ts, 40, 29))
->x : Symbol(x, Decl(topLevelAwaitErrors.1.ts, 41, 22))
 }
 
diff --git a/tests/baselines/reference/topLevelAwaitErrors.1.types b/tests/baselines/reference/topLevelAwaitErrors.1.types
index 7e8efc49dce7f..3ce38b5cca110 100644
--- a/tests/baselines/reference/topLevelAwaitErrors.1.types
+++ b/tests/baselines/reference/topLevelAwaitErrors.1.types
@@ -32,7 +32,7 @@ await <number, string> ``;
 // reparse class extends clause should fail
 class C extends await<string> {
 >C : C
->string : any
+>await : any
 }
 
 // await in class decorators should fail
@@ -45,37 +45,37 @@ class C1 {}
 >C1 : C1
 
 @await(x)
->await(x) : any
-> : any
+>await : any
 >x : any
+> : any
 
 class C2 {}
 >C2 : C2
 
 @await
-> : any
+>await : any
 
 class C3 {}
->C3 : C3
+>C3 : any
 
 // await in member decorators should fail
 class C4 {
 >C4 : C4
 
     @await
-> : any
+>await : any
 
     ["foo"]() {}
->["foo"] : () => void
->"foo" : "foo"
+>"foo" : any
 }
+> : any
+
 class C5 {
 >C5 : C5
 
     @await(1)
->await(1) : any
-> : any
->1 : 1
+>await : any
+>1 : any
 
     ["foo"]() {}
 >["foo"] : () => void
@@ -99,22 +99,27 @@ class C7 {
 >C7 : C7
 
     method1(@await [x]) {}
->method1 : ([x]: [any]) => void
-> : any
+>method1 : (x: any) => any
+>await : any
 >x : any
 
     method2(@await(1) [x]) {}
->method2 : ([x]: [any]) => void
->await(1) : any
-> : any
+>method2(@await(1) [x]) : any
+>method2 : any
+>await(1) [x] : any
+>(1) [x] : any
+>(1) : 1
 >1 : 1
 >x : any
 
     method3(@(await) [x]) {}
->method3 : ([x]: [any]) => void
+>method3(@(await) [x]) : any
+>method3 : any
+>(await) [x] : any
 >(await) : any
 >await : any
 > : any
 >x : any
 }
+> : any
 

From 347094c9978659dc3def758308f829b99bb822ef Mon Sep 17 00:00:00 2001
From: kingwl <kingwenlu@gmail.com>
Date: Mon, 21 Jun 2021 15:46:00 +0800
Subject: [PATCH 3/4] Revert "Avoid yield and awaitt check in identifier"

This reverts commit 9644859f291840db87de6275f2e4cca7f665bf8a.
---
 src/compiler/parser.ts                        |  22 ++--
 .../await_unaryExpression_es2017_3.errors.txt |  16 +--
 .../await_unaryExpression_es2017_3.js         |   8 +-
 .../await_unaryExpression_es2017_3.types      |  10 +-
 .../await_unaryExpression_es6_3.errors.txt    |  16 +--
 .../reference/await_unaryExpression_es6_3.js  |   8 +-
 .../await_unaryExpression_es6_3.types         |  10 +-
 .../reference/castOfYield.errors.txt          |   9 +-
 tests/baselines/reference/castOfYield.js      |   6 +-
 tests/baselines/reference/castOfYield.types   |   5 +-
 .../topLevelAwaitErrors.1.errors.txt          | 105 +++++-------------
 .../reference/topLevelAwaitErrors.1.js        |  44 ++++----
 .../reference/topLevelAwaitErrors.1.symbols   |  17 ++-
 .../reference/topLevelAwaitErrors.1.types     |  39 +++----
 14 files changed, 130 insertions(+), 185 deletions(-)

diff --git a/src/compiler/parser.ts b/src/compiler/parser.ts
index 17d7bf85b823f..fb82b4d603341 100644
--- a/src/compiler/parser.ts
+++ b/src/compiler/parser.ts
@@ -1510,17 +1510,17 @@ namespace ts {
                 return true;
             }
 
-            // // If we have a 'yield' keyword, and we're in the [yield] context, then 'yield' is
-            // // considered a keyword and is not an identifier.
-            // if (token() === SyntaxKind.YieldKeyword && inYieldContext()) {
-            //     return false;
-            // }
-
-            // // If we have a 'await' keyword, and we're in the [Await] context, then 'await' is
-            // // considered a keyword and is not an identifier.
-            // if (token() === SyntaxKind.AwaitKeyword && inAwaitContext()) {
-            //     return false;
-            // }
+            // If we have a 'yield' keyword, and we're in the [yield] context, then 'yield' is
+            // considered a keyword and is not an identifier.
+            if (token() === SyntaxKind.YieldKeyword && inYieldContext()) {
+                return false;
+            }
+
+            // If we have a 'await' keyword, and we're in the [Await] context, then 'await' is
+            // considered a keyword and is not an identifier.
+            if (token() === SyntaxKind.AwaitKeyword && inAwaitContext()) {
+                return false;
+            }
 
             return token() > SyntaxKind.LastReservedWord;
         }
diff --git a/tests/baselines/reference/await_unaryExpression_es2017_3.errors.txt b/tests/baselines/reference/await_unaryExpression_es2017_3.errors.txt
index bffdd1b9a2082..da533765a0788 100644
--- a/tests/baselines/reference/await_unaryExpression_es2017_3.errors.txt
+++ b/tests/baselines/reference/await_unaryExpression_es2017_3.errors.txt
@@ -1,24 +1,18 @@
-tests/cases/conformance/async/es2017/await_unaryExpression_es2017_3.ts(2,7): error TS2304: Cannot find name 'await'.
-tests/cases/conformance/async/es2017/await_unaryExpression_es2017_3.ts(2,13): error TS1005: ';' expected.
-tests/cases/conformance/async/es2017/await_unaryExpression_es2017_3.ts(6,7): error TS2304: Cannot find name 'await'.
-tests/cases/conformance/async/es2017/await_unaryExpression_es2017_3.ts(6,13): error TS1005: ';' expected.
+tests/cases/conformance/async/es2017/await_unaryExpression_es2017_3.ts(2,7): error TS1109: Expression expected.
+tests/cases/conformance/async/es2017/await_unaryExpression_es2017_3.ts(6,7): error TS1109: Expression expected.
 
 
-==== tests/cases/conformance/async/es2017/await_unaryExpression_es2017_3.ts (4 errors) ====
+==== tests/cases/conformance/async/es2017/await_unaryExpression_es2017_3.ts (2 errors) ====
     async function bar1() {
         ++await 42; // Error
           ~~~~~
-!!! error TS2304: Cannot find name 'await'.
-                ~~
-!!! error TS1005: ';' expected.
+!!! error TS1109: Expression expected.
     }
     
     async function bar2() {
         --await 42; // Error
           ~~~~~
-!!! error TS2304: Cannot find name 'await'.
-                ~~
-!!! error TS1005: ';' expected.
+!!! error TS1109: Expression expected.
     }
     
     async function bar3() {
diff --git a/tests/baselines/reference/await_unaryExpression_es2017_3.js b/tests/baselines/reference/await_unaryExpression_es2017_3.js
index bbddded1a1d30..b2a1593a9d0bd 100644
--- a/tests/baselines/reference/await_unaryExpression_es2017_3.js
+++ b/tests/baselines/reference/await_unaryExpression_es2017_3.js
@@ -19,12 +19,12 @@ async function bar4() {
 
 //// [await_unaryExpression_es2017_3.js]
 async function bar1() {
-    ++await;
-    42; // Error
+    ++;
+    await 42; // Error
 }
 async function bar2() {
-    --await;
-    42; // Error
+    --;
+    await 42; // Error
 }
 async function bar3() {
     var x = 42;
diff --git a/tests/baselines/reference/await_unaryExpression_es2017_3.types b/tests/baselines/reference/await_unaryExpression_es2017_3.types
index f94d05515d657..b60ea42b2a0d5 100644
--- a/tests/baselines/reference/await_unaryExpression_es2017_3.types
+++ b/tests/baselines/reference/await_unaryExpression_es2017_3.types
@@ -3,8 +3,9 @@ async function bar1() {
 >bar1 : () => Promise<void>
 
     ++await 42; // Error
->++await : number
->await : any
+>++ : number
+> : any
+>await 42 : 42
 >42 : 42
 }
 
@@ -12,8 +13,9 @@ async function bar2() {
 >bar2 : () => Promise<void>
 
     --await 42; // Error
->--await : number
->await : any
+>-- : number
+> : any
+>await 42 : 42
 >42 : 42
 }
 
diff --git a/tests/baselines/reference/await_unaryExpression_es6_3.errors.txt b/tests/baselines/reference/await_unaryExpression_es6_3.errors.txt
index 297c8887db945..373e6739461b4 100644
--- a/tests/baselines/reference/await_unaryExpression_es6_3.errors.txt
+++ b/tests/baselines/reference/await_unaryExpression_es6_3.errors.txt
@@ -1,24 +1,18 @@
-tests/cases/conformance/async/es6/await_unaryExpression_es6_3.ts(2,7): error TS2304: Cannot find name 'await'.
-tests/cases/conformance/async/es6/await_unaryExpression_es6_3.ts(2,13): error TS1005: ';' expected.
-tests/cases/conformance/async/es6/await_unaryExpression_es6_3.ts(6,7): error TS2304: Cannot find name 'await'.
-tests/cases/conformance/async/es6/await_unaryExpression_es6_3.ts(6,13): error TS1005: ';' expected.
+tests/cases/conformance/async/es6/await_unaryExpression_es6_3.ts(2,7): error TS1109: Expression expected.
+tests/cases/conformance/async/es6/await_unaryExpression_es6_3.ts(6,7): error TS1109: Expression expected.
 
 
-==== tests/cases/conformance/async/es6/await_unaryExpression_es6_3.ts (4 errors) ====
+==== tests/cases/conformance/async/es6/await_unaryExpression_es6_3.ts (2 errors) ====
     async function bar1() {
         ++await 42; // Error
           ~~~~~
-!!! error TS2304: Cannot find name 'await'.
-                ~~
-!!! error TS1005: ';' expected.
+!!! error TS1109: Expression expected.
     }
     
     async function bar2() {
         --await 42; // Error
           ~~~~~
-!!! error TS2304: Cannot find name 'await'.
-                ~~
-!!! error TS1005: ';' expected.
+!!! error TS1109: Expression expected.
     }
     
     async function bar3() {
diff --git a/tests/baselines/reference/await_unaryExpression_es6_3.js b/tests/baselines/reference/await_unaryExpression_es6_3.js
index f92401028025d..42643caa262ae 100644
--- a/tests/baselines/reference/await_unaryExpression_es6_3.js
+++ b/tests/baselines/reference/await_unaryExpression_es6_3.js
@@ -29,14 +29,14 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
 };
 function bar1() {
     return __awaiter(this, void 0, void 0, function* () {
-        ++await;
-        42; // Error
+        ++;
+        yield 42; // Error
     });
 }
 function bar2() {
     return __awaiter(this, void 0, void 0, function* () {
-        --await;
-        42; // Error
+        --;
+        yield 42; // Error
     });
 }
 function bar3() {
diff --git a/tests/baselines/reference/await_unaryExpression_es6_3.types b/tests/baselines/reference/await_unaryExpression_es6_3.types
index d24149449ac5b..db18c88955375 100644
--- a/tests/baselines/reference/await_unaryExpression_es6_3.types
+++ b/tests/baselines/reference/await_unaryExpression_es6_3.types
@@ -3,8 +3,9 @@ async function bar1() {
 >bar1 : () => Promise<void>
 
     ++await 42; // Error
->++await : number
->await : any
+>++ : number
+> : any
+>await 42 : 42
 >42 : 42
 }
 
@@ -12,8 +13,9 @@ async function bar2() {
 >bar2 : () => Promise<void>
 
     --await 42; // Error
->--await : number
->await : any
+>-- : number
+> : any
+>await 42 : 42
 >42 : 42
 }
 
diff --git a/tests/baselines/reference/castOfYield.errors.txt b/tests/baselines/reference/castOfYield.errors.txt
index b7c3035f68e4e..0d40a4dcd987d 100644
--- a/tests/baselines/reference/castOfYield.errors.txt
+++ b/tests/baselines/reference/castOfYield.errors.txt
@@ -1,17 +1,14 @@
 error TS2318: Cannot find global type 'IterableIterator'.
-tests/cases/compiler/castOfYield.ts(4,14): error TS2304: Cannot find name 'yield'.
-tests/cases/compiler/castOfYield.ts(4,20): error TS1005: ';' expected.
+tests/cases/compiler/castOfYield.ts(4,14): error TS1109: Expression expected.
 
 
 !!! error TS2318: Cannot find global type 'IterableIterator'.
-==== tests/cases/compiler/castOfYield.ts (2 errors) ====
+==== tests/cases/compiler/castOfYield.ts (1 errors) ====
     function* f() {
         <number> (yield 0);
         // Unlike await, yield is not allowed to appear in a simple unary expression.
         <number> yield 0;
                  ~~~~~
-!!! error TS2304: Cannot find name 'yield'.
-                       ~
-!!! error TS1005: ';' expected.
+!!! error TS1109: Expression expected.
     }
     
\ No newline at end of file
diff --git a/tests/baselines/reference/castOfYield.js b/tests/baselines/reference/castOfYield.js
index 91b1f01a7852f..86d35bedad434 100644
--- a/tests/baselines/reference/castOfYield.js
+++ b/tests/baselines/reference/castOfYield.js
@@ -41,8 +41,10 @@ function f() {
             case 1:
                 (_a.sent());
                 // Unlike await, yield is not allowed to appear in a simple unary expression.
-                yield;
-                0;
+                ;
+                return [4 /*yield*/, 0];
+            case 2:
+                _a.sent();
                 return [2 /*return*/];
         }
     });
diff --git a/tests/baselines/reference/castOfYield.types b/tests/baselines/reference/castOfYield.types
index 008cf646686dd..c005205609196 100644
--- a/tests/baselines/reference/castOfYield.types
+++ b/tests/baselines/reference/castOfYield.types
@@ -10,8 +10,9 @@ function* f() {
 
     // Unlike await, yield is not allowed to appear in a simple unary expression.
     <number> yield 0;
-><number> yield : number
->yield : any
+><number> : number
+> : any
+>yield 0 : any
 >0 : 0
 }
 
diff --git a/tests/baselines/reference/topLevelAwaitErrors.1.errors.txt b/tests/baselines/reference/topLevelAwaitErrors.1.errors.txt
index 525ce18f6d7a2..773e8446a6fda 100644
--- a/tests/baselines/reference/topLevelAwaitErrors.1.errors.txt
+++ b/tests/baselines/reference/topLevelAwaitErrors.1.errors.txt
@@ -4,40 +4,23 @@ tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(5,14): error TS
 tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(5,16): error TS2693: 'string' only refers to a type, but is being used as a value here.
 tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(8,14): error TS1005: '>' expected.
 tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(8,16): error TS2693: 'string' only refers to a type, but is being used as a value here.
-tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(11,17): error TS2304: Cannot find name 'await'.
+tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(11,17): error TS1109: Expression expected.
+tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(11,22): error TS1109: Expression expected.
+tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(11,23): error TS2693: 'string' only refers to a type, but is being used as a value here.
+tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(11,29): error TS1005: ',' expected.
 tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(15,8): error TS1109: Expression expected.
-tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(18,8): error TS1146: Declaration expected.
+tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(18,2): error TS1109: Expression expected.
 tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(18,8): error TS2304: Cannot find name 'x'.
-tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(18,9): error TS1005: ';' expected.
-tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(22,6): error TS1146: Declaration expected.
-tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(22,7): error TS2304: Cannot find name 'C3'.
-tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(22,10): error TS1005: ';' expected.
-tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(26,6): error TS2304: Cannot find name 'await'.
-tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(27,11): error TS1005: ';' expected.
-tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(27,12): error TS1068: Unexpected token. A constructor, method, accessor, or property was expected.
-tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(27,13): error TS1068: Unexpected token. A constructor, method, accessor, or property was expected.
-tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(27,15): error TS1068: Unexpected token. A constructor, method, accessor, or property was expected.
-tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(28,1): error TS1109: Expression expected.
-tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(30,6): error TS2304: Cannot find name 'await'.
-tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(30,13): error TS1005: ';' expected.
+tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(21,2): error TS1109: Expression expected.
+tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(26,6): error TS1109: Expression expected.
+tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(30,6): error TS1109: Expression expected.
 tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(34,12): error TS1109: Expression expected.
-tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(40,14): error TS2304: Cannot find name 'await'.
-tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(40,22): error TS1005: ')' expected.
-tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(40,23): error TS1068: Unexpected token. A constructor, method, accessor, or property was expected.
-tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(40,25): error TS1068: Unexpected token. A constructor, method, accessor, or property was expected.
-tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(41,5): error TS2304: Cannot find name 'method2'.
-tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(41,13): error TS1135: Argument expression expected.
-tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(41,24): error TS2304: Cannot find name 'x'.
-tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(41,28): error TS1005: ';' expected.
-tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(42,5): error TS2304: Cannot find name 'method3'.
-tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(42,13): error TS1135: Argument expression expected.
+tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(40,14): error TS1109: Expression expected.
+tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(41,14): error TS1109: Expression expected.
 tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(42,20): error TS1109: Expression expected.
-tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(42,23): error TS2304: Cannot find name 'x'.
-tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(42,27): error TS1005: ';' expected.
-tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(43,1): error TS1109: Expression expected.
 
 
-==== tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts (37 errors) ====
+==== tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts (20 errors) ====
     export {};
     
     // reparse call as invalid await should error
@@ -62,7 +45,13 @@ tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(43,1): error TS
     // reparse class extends clause should fail
     class C extends await<string> {
                     ~~~~~
-!!! error TS2304: Cannot find name 'await'.
+!!! error TS1109: Expression expected.
+                         ~
+!!! error TS1109: Expression expected.
+                          ~~~~~~
+!!! error TS2693: 'string' only refers to a type, but is being used as a value here.
+                                ~
+!!! error TS1005: ',' expected.
     }
     
     // await in class decorators should fail
@@ -72,46 +61,28 @@ tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(43,1): error TS
     class C1 {}
     
     @await(x)
-           
-!!! error TS1146: Declaration expected.
+     ~~~~~
+!!! error TS1109: Expression expected.
            ~
 !!! error TS2304: Cannot find name 'x'.
-            ~
-!!! error TS1005: ';' expected.
     class C2 {}
     
     @await
+     ~~~~~
+!!! error TS1109: Expression expected.
     class C3 {}
-         
-!!! error TS1146: Declaration expected.
-          ~~
-!!! error TS2304: Cannot find name 'C3'.
-             ~
-!!! error TS1005: ';' expected.
     
     // await in member decorators should fail
     class C4 {
         @await
          ~~~~~
-!!! error TS2304: Cannot find name 'await'.
+!!! error TS1109: Expression expected.
         ["foo"]() {}
-              ~
-!!! error TS1005: ';' expected.
-               ~
-!!! error TS1068: Unexpected token. A constructor, method, accessor, or property was expected.
-                ~
-!!! error TS1068: Unexpected token. A constructor, method, accessor, or property was expected.
-                  ~
-!!! error TS1068: Unexpected token. A constructor, method, accessor, or property was expected.
     }
-    ~
-!!! error TS1109: Expression expected.
     class C5 {
         @await(1)
          ~~~~~
-!!! error TS2304: Cannot find name 'await'.
-                ~
-!!! error TS1005: ';' expected.
+!!! error TS1109: Expression expected.
         ["foo"]() {}
     }
     class C6 {
@@ -125,34 +96,12 @@ tests/cases/conformance/externalModules/topLevelAwaitErrors.1.ts(43,1): error TS
     class C7 {
         method1(@await [x]) {}
                  ~~~~~
-!!! error TS2304: Cannot find name 'await'.
-                         ~
-!!! error TS1005: ')' expected.
-                          ~
-!!! error TS1068: Unexpected token. A constructor, method, accessor, or property was expected.
-                            ~
-!!! error TS1068: Unexpected token. A constructor, method, accessor, or property was expected.
+!!! error TS1109: Expression expected.
         method2(@await(1) [x]) {}
-        ~~~~~~~
-!!! error TS2304: Cannot find name 'method2'.
-                ~
-!!! error TS1135: Argument expression expected.
-                           ~
-!!! error TS2304: Cannot find name 'x'.
-                               ~
-!!! error TS1005: ';' expected.
+                 ~~~~~
+!!! error TS1109: Expression expected.
         method3(@(await) [x]) {}
-        ~~~~~~~
-!!! error TS2304: Cannot find name 'method3'.
-                ~
-!!! error TS1135: Argument expression expected.
                        ~
 !!! error TS1109: Expression expected.
-                          ~
-!!! error TS2304: Cannot find name 'x'.
-                              ~
-!!! error TS1005: ';' expected.
     }
-    ~
-!!! error TS1109: Expression expected.
     
\ No newline at end of file
diff --git a/tests/baselines/reference/topLevelAwaitErrors.1.js b/tests/baselines/reference/topLevelAwaitErrors.1.js
index b535c95dca4eb..175321a0513f8 100644
--- a/tests/baselines/reference/topLevelAwaitErrors.1.js
+++ b/tests/baselines/reference/topLevelAwaitErrors.1.js
@@ -51,7 +51,7 @@ await , string > (1);
 // reparse tagged template as invalid await should error
 await , string > ``;
 // reparse class extends clause should fail
-class C extends await {
+class C extends string {
 }
 // await in class decorators should fail
 let C1 = class C1 {
@@ -59,27 +59,27 @@ let C1 = class C1 {
 C1 = __decorate([
     (await )
 ], C1);
-x;
-;
-class C2 {
-}
-C3;
-{ }
+let C2 = class C2 {
+};
+C2 = __decorate([
+    (x)
+], C2);
+let C3 = class C3 {
+};
+C3 = __decorate([
+], C3);
 // await in member decorators should fail
 class C4 {
-    "foo";
+    ["foo"]() { }
 }
 __decorate([
-    await
-], C4.prototype, "foo", void 0);
-;
+], C4.prototype, "foo", null);
 class C5 {
-    1;
     ["foo"]() { }
 }
 __decorate([
-    await
-], C5.prototype, 1, void 0);
+    (1)
+], C5.prototype, "foo", null);
 class C6 {
     ["foo"]() { }
 }
@@ -88,13 +88,17 @@ __decorate([
 ], C6.prototype, "foo", null);
 // await in parameter decorators should fail
 class C7 {
+    method1([x]) { }
+    method2([x]) { }
+    method3([x]) { }
 }
 __decorate([
-    __param(0, await)
+    __param(0, )
 ], C7.prototype, "method1", null);
-method2(await (1)[x]);
-{ }
-method3((await )[x]);
-{ }
-;
+__decorate([
+    __param(0, (1))
+], C7.prototype, "method2", null);
+__decorate([
+    __param(0, (await ))
+], C7.prototype, "method3", null);
 export {};
diff --git a/tests/baselines/reference/topLevelAwaitErrors.1.symbols b/tests/baselines/reference/topLevelAwaitErrors.1.symbols
index 0384c15c740e2..c414127bbe691 100644
--- a/tests/baselines/reference/topLevelAwaitErrors.1.symbols
+++ b/tests/baselines/reference/topLevelAwaitErrors.1.symbols
@@ -20,10 +20,11 @@ class C1 {}
 
 @await(x)
 class C2 {}
->C2 : Symbol(C2, Decl(topLevelAwaitErrors.1.ts, 17, 9))
+>C2 : Symbol(C2, Decl(topLevelAwaitErrors.1.ts, 15, 11))
 
 @await
 class C3 {}
+>C3 : Symbol(C3, Decl(topLevelAwaitErrors.1.ts, 18, 11))
 
 // await in member decorators should fail
 class C4 {
@@ -31,17 +32,16 @@ class C4 {
 
     @await
     ["foo"]() {}
+>["foo"] : Symbol(C4["foo"], Decl(topLevelAwaitErrors.1.ts, 24, 10))
 >"foo" : Symbol(C4["foo"], Decl(topLevelAwaitErrors.1.ts, 24, 10))
 }
 class C5 {
 >C5 : Symbol(C5, Decl(topLevelAwaitErrors.1.ts, 27, 1))
 
     @await(1)
->1 : Symbol(C5[1], Decl(topLevelAwaitErrors.1.ts, 28, 10))
-
     ["foo"]() {}
->["foo"] : Symbol(C5["foo"], Decl(topLevelAwaitErrors.1.ts, 29, 13))
->"foo" : Symbol(C5["foo"], Decl(topLevelAwaitErrors.1.ts, 29, 13))
+>["foo"] : Symbol(C5["foo"], Decl(topLevelAwaitErrors.1.ts, 28, 10))
+>"foo" : Symbol(C5["foo"], Decl(topLevelAwaitErrors.1.ts, 28, 10))
 }
 class C6 {
 >C6 : Symbol(C6, Decl(topLevelAwaitErrors.1.ts, 31, 1))
@@ -58,9 +58,14 @@ class C7 {
 
     method1(@await [x]) {}
 >method1 : Symbol(C7.method1, Decl(topLevelAwaitErrors.1.ts, 38, 10))
->x : Symbol(x, Decl(topLevelAwaitErrors.1.ts, 39, 12))
+>x : Symbol(x, Decl(topLevelAwaitErrors.1.ts, 39, 20))
 
     method2(@await(1) [x]) {}
+>method2 : Symbol(C7.method2, Decl(topLevelAwaitErrors.1.ts, 39, 26))
+>x : Symbol(x, Decl(topLevelAwaitErrors.1.ts, 40, 23))
+
     method3(@(await) [x]) {}
+>method3 : Symbol(C7.method3, Decl(topLevelAwaitErrors.1.ts, 40, 29))
+>x : Symbol(x, Decl(topLevelAwaitErrors.1.ts, 41, 22))
 }
 
diff --git a/tests/baselines/reference/topLevelAwaitErrors.1.types b/tests/baselines/reference/topLevelAwaitErrors.1.types
index 3ce38b5cca110..7e8efc49dce7f 100644
--- a/tests/baselines/reference/topLevelAwaitErrors.1.types
+++ b/tests/baselines/reference/topLevelAwaitErrors.1.types
@@ -32,7 +32,7 @@ await <number, string> ``;
 // reparse class extends clause should fail
 class C extends await<string> {
 >C : C
->await : any
+>string : any
 }
 
 // await in class decorators should fail
@@ -45,37 +45,37 @@ class C1 {}
 >C1 : C1
 
 @await(x)
->await : any
->x : any
+>await(x) : any
 > : any
+>x : any
 
 class C2 {}
 >C2 : C2
 
 @await
->await : any
+> : any
 
 class C3 {}
->C3 : any
+>C3 : C3
 
 // await in member decorators should fail
 class C4 {
 >C4 : C4
 
     @await
->await : any
+> : any
 
     ["foo"]() {}
->"foo" : any
+>["foo"] : () => void
+>"foo" : "foo"
 }
-> : any
-
 class C5 {
 >C5 : C5
 
     @await(1)
->await : any
->1 : any
+>await(1) : any
+> : any
+>1 : 1
 
     ["foo"]() {}
 >["foo"] : () => void
@@ -99,27 +99,22 @@ class C7 {
 >C7 : C7
 
     method1(@await [x]) {}
->method1 : (x: any) => any
->await : any
+>method1 : ([x]: [any]) => void
+> : any
 >x : any
 
     method2(@await(1) [x]) {}
->method2(@await(1) [x]) : any
->method2 : any
->await(1) [x] : any
->(1) [x] : any
->(1) : 1
+>method2 : ([x]: [any]) => void
+>await(1) : any
+> : any
 >1 : 1
 >x : any
 
     method3(@(await) [x]) {}
->method3(@(await) [x]) : any
->method3 : any
->(await) [x] : any
+>method3 : ([x]: [any]) => void
 >(await) : any
 >await : any
 > : any
 >x : any
 }
-> : any
 

From 23cd5e97023a3798e81520d4a9b0285736d2b240 Mon Sep 17 00:00:00 2001
From: kingwl <kingwenlu@gmail.com>
Date: Mon, 21 Jun 2021 15:48:53 +0800
Subject: [PATCH 4/4] Add some comments

---
 src/compiler/parser.ts | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/compiler/parser.ts b/src/compiler/parser.ts
index fb82b4d603341..4ba7f4fad5804 100644
--- a/src/compiler/parser.ts
+++ b/src/compiler/parser.ts
@@ -1501,6 +1501,8 @@ namespace ts {
             if (token() === SyntaxKind.Identifier) {
                 return true;
             }
+
+            // `let await`/`let yield` in [Yield] or [Await] are allowed here and disallowed in the binder.
             return token() > SyntaxKind.LastReservedWord;
         }