From 813ddf7909fc55f0b41580a58d5e2349a2efec32 Mon Sep 17 00:00:00 2001
From: Zzzen <843968788@qq.com>
Date: Thu, 1 Jul 2021 00:43:14 +0800
Subject: [PATCH] ensure export modifier is used before default modifier
 (#44570)

* ensure export modifier is used before default modifier

* gracefully handle `default function`

* Revert "gracefully handle `default function`"

This reverts commit 1d8e2887540f5abaa8b7192fee89ef8935be8640.

* give better error message on default without leading export
---
 src/compiler/checker.ts                       |  3 +++
 src/compiler/parser.ts                        |  5 ++++-
 .../classAbstractManyKeywords.errors.txt      |  4 ++--
 .../defaultKeywordWithoutExport1.errors.txt   | 10 +++++++++
 .../reference/defaultKeywordWithoutExport1.js | 21 +++++++++++++++++++
 .../defaultKeywordWithoutExport1.symbols      |  9 ++++++++
 .../defaultKeywordWithoutExport1.types        |  9 ++++++++
 .../defaultKeywordWithoutExport2.errors.txt   | 12 +++++++++++
 .../reference/defaultKeywordWithoutExport2.js |  8 +++++++
 .../defaultKeywordWithoutExport2.symbols      |  5 +++++
 .../defaultKeywordWithoutExport2.types        |  5 +++++
 .../compiler/defaultKeywordWithoutExport1.ts  |  6 ++++++
 .../compiler/defaultKeywordWithoutExport2.ts  |  3 +++
 13 files changed, 97 insertions(+), 3 deletions(-)
 create mode 100644 tests/baselines/reference/defaultKeywordWithoutExport1.errors.txt
 create mode 100644 tests/baselines/reference/defaultKeywordWithoutExport1.js
 create mode 100644 tests/baselines/reference/defaultKeywordWithoutExport1.symbols
 create mode 100644 tests/baselines/reference/defaultKeywordWithoutExport1.types
 create mode 100644 tests/baselines/reference/defaultKeywordWithoutExport2.errors.txt
 create mode 100644 tests/baselines/reference/defaultKeywordWithoutExport2.js
 create mode 100644 tests/baselines/reference/defaultKeywordWithoutExport2.symbols
 create mode 100644 tests/baselines/reference/defaultKeywordWithoutExport2.types
 create mode 100644 tests/cases/compiler/defaultKeywordWithoutExport1.ts
 create mode 100644 tests/cases/compiler/defaultKeywordWithoutExport2.ts

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index b1d2befee7e..bd576cecbfd 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -41139,6 +41139,9 @@ namespace ts {
                         if (container.kind === SyntaxKind.ModuleDeclaration && !isAmbientModule(container)) {
                             return grammarErrorOnNode(modifier, Diagnostics.A_default_export_can_only_be_used_in_an_ECMAScript_style_module);
                         }
+                        else if (!(flags & ModifierFlags.Export)) {
+                            return grammarErrorOnNode(modifier, Diagnostics._0_modifier_must_precede_1_modifier, "export", "default");
+                        }
 
                         flags |= ModifierFlags.Default;
                         break;
diff --git a/src/compiler/parser.ts b/src/compiler/parser.ts
index f3ac472e122..bc7a23e26e4 100644
--- a/src/compiler/parser.ts
+++ b/src/compiler/parser.ts
@@ -2429,7 +2429,10 @@ namespace ts {
 
         function parsingContextErrors(context: ParsingContext) {
             switch (context) {
-                case ParsingContext.SourceElements: return parseErrorAtCurrentToken(Diagnostics.Declaration_or_statement_expected);
+                case ParsingContext.SourceElements:
+                    return token() === SyntaxKind.DefaultKeyword
+                        ? parseErrorAtCurrentToken(Diagnostics._0_expected, tokenToString(SyntaxKind.ExportKeyword))
+                        : parseErrorAtCurrentToken(Diagnostics.Declaration_or_statement_expected);
                 case ParsingContext.BlockStatements: return parseErrorAtCurrentToken(Diagnostics.Declaration_or_statement_expected);
                 case ParsingContext.SwitchClauses: return parseErrorAtCurrentToken(Diagnostics.case_or_default_expected);
                 case ParsingContext.SwitchClauseStatements: return parseErrorAtCurrentToken(Diagnostics.Statement_expected);
diff --git a/tests/baselines/reference/classAbstractManyKeywords.errors.txt b/tests/baselines/reference/classAbstractManyKeywords.errors.txt
index 1b23bfac982..364b19186ab 100644
--- a/tests/baselines/reference/classAbstractManyKeywords.errors.txt
+++ b/tests/baselines/reference/classAbstractManyKeywords.errors.txt
@@ -1,4 +1,4 @@
-tests/cases/conformance/classes/classDeclarations/classAbstractKeyword/classAbstractManyKeywords.ts(3,1): error TS1128: Declaration or statement expected.
+tests/cases/conformance/classes/classDeclarations/classAbstractKeyword/classAbstractManyKeywords.ts(3,1): error TS1005: 'export' expected.
 tests/cases/conformance/classes/classDeclarations/classAbstractKeyword/classAbstractManyKeywords.ts(4,17): error TS1005: '=' expected.
 
 
@@ -7,7 +7,7 @@ tests/cases/conformance/classes/classDeclarations/classAbstractKeyword/classAbst
     export abstract class B {}
     default abstract class C {}
     ~~~~~~~
-!!! error TS1128: Declaration or statement expected.
+!!! error TS1005: 'export' expected.
     import abstract class D {}
                     ~~~~~
 !!! error TS1005: '=' expected.
\ No newline at end of file
diff --git a/tests/baselines/reference/defaultKeywordWithoutExport1.errors.txt b/tests/baselines/reference/defaultKeywordWithoutExport1.errors.txt
new file mode 100644
index 00000000000..d970e7053d7
--- /dev/null
+++ b/tests/baselines/reference/defaultKeywordWithoutExport1.errors.txt
@@ -0,0 +1,10 @@
+tests/cases/compiler/defaultKeywordWithoutExport1.ts(4,1): error TS1029: 'export' modifier must precede 'default' modifier.
+
+
+==== tests/cases/compiler/defaultKeywordWithoutExport1.ts (1 errors) ====
+    declare function decorator(constructor: any): any;
+    
+    @decorator
+    default class {}
+    ~~~~~~~
+!!! error TS1029: 'export' modifier must precede 'default' modifier.
\ No newline at end of file
diff --git a/tests/baselines/reference/defaultKeywordWithoutExport1.js b/tests/baselines/reference/defaultKeywordWithoutExport1.js
new file mode 100644
index 00000000000..f9a93e262d1
--- /dev/null
+++ b/tests/baselines/reference/defaultKeywordWithoutExport1.js
@@ -0,0 +1,21 @@
+//// [defaultKeywordWithoutExport1.ts]
+declare function decorator(constructor: any): any;
+
+@decorator
+default class {}
+
+//// [defaultKeywordWithoutExport1.js]
+var __decorate = (this && this.__decorate) || function (decorators, target, key, desc) {
+    var c = arguments.length, r = c < 3 ? target : desc === null ? desc = Object.getOwnPropertyDescriptor(target, key) : desc, d;
+    if (typeof Reflect === "object" && typeof Reflect.decorate === "function") r = Reflect.decorate(decorators, target, key, desc);
+    else for (var i = decorators.length - 1; i >= 0; i--) if (d = decorators[i]) r = (c < 3 ? d(r) : c > 3 ? d(target, key, r) : d(target, key)) || r;
+    return c > 3 && r && Object.defineProperty(target, key, r), r;
+};
+var default_1 = /** @class */ (function () {
+    function default_1() {
+    }
+    default_1 = __decorate([
+        decorator
+    ], default_1);
+    return default_1;
+}());
diff --git a/tests/baselines/reference/defaultKeywordWithoutExport1.symbols b/tests/baselines/reference/defaultKeywordWithoutExport1.symbols
new file mode 100644
index 00000000000..b7318b2744a
--- /dev/null
+++ b/tests/baselines/reference/defaultKeywordWithoutExport1.symbols
@@ -0,0 +1,9 @@
+=== tests/cases/compiler/defaultKeywordWithoutExport1.ts ===
+declare function decorator(constructor: any): any;
+>decorator : Symbol(decorator, Decl(defaultKeywordWithoutExport1.ts, 0, 0))
+>constructor : Symbol(constructor, Decl(defaultKeywordWithoutExport1.ts, 0, 27))
+
+@decorator
+>decorator : Symbol(decorator, Decl(defaultKeywordWithoutExport1.ts, 0, 0))
+
+default class {}
diff --git a/tests/baselines/reference/defaultKeywordWithoutExport1.types b/tests/baselines/reference/defaultKeywordWithoutExport1.types
new file mode 100644
index 00000000000..c9866c9eb66
--- /dev/null
+++ b/tests/baselines/reference/defaultKeywordWithoutExport1.types
@@ -0,0 +1,9 @@
+=== tests/cases/compiler/defaultKeywordWithoutExport1.ts ===
+declare function decorator(constructor: any): any;
+>decorator : (constructor: any) => any
+>constructor : any
+
+@decorator
+>decorator : (constructor: any) => any
+
+default class {}
diff --git a/tests/baselines/reference/defaultKeywordWithoutExport2.errors.txt b/tests/baselines/reference/defaultKeywordWithoutExport2.errors.txt
new file mode 100644
index 00000000000..c5072379b30
--- /dev/null
+++ b/tests/baselines/reference/defaultKeywordWithoutExport2.errors.txt
@@ -0,0 +1,12 @@
+tests/cases/compiler/defaultKeywordWithoutExport2.ts(1,1): error TS1005: 'export' expected.
+tests/cases/compiler/defaultKeywordWithoutExport2.ts(1,18): error TS1003: Identifier expected.
+
+
+==== tests/cases/compiler/defaultKeywordWithoutExport2.ts (2 errors) ====
+    default function () {
+    ~~~~~~~
+!!! error TS1005: 'export' expected.
+                     ~
+!!! error TS1003: Identifier expected.
+    
+    }
\ No newline at end of file
diff --git a/tests/baselines/reference/defaultKeywordWithoutExport2.js b/tests/baselines/reference/defaultKeywordWithoutExport2.js
new file mode 100644
index 00000000000..0f5dfe5d2a7
--- /dev/null
+++ b/tests/baselines/reference/defaultKeywordWithoutExport2.js
@@ -0,0 +1,8 @@
+//// [defaultKeywordWithoutExport2.ts]
+default function () {
+
+}
+
+//// [defaultKeywordWithoutExport2.js]
+function () {
+}
diff --git a/tests/baselines/reference/defaultKeywordWithoutExport2.symbols b/tests/baselines/reference/defaultKeywordWithoutExport2.symbols
new file mode 100644
index 00000000000..fb8a0ec6ce7
--- /dev/null
+++ b/tests/baselines/reference/defaultKeywordWithoutExport2.symbols
@@ -0,0 +1,5 @@
+=== tests/cases/compiler/defaultKeywordWithoutExport2.ts ===
+default function () {
+> : Symbol((Missing), Decl(defaultKeywordWithoutExport2.ts, 0, 7))
+
+}
diff --git a/tests/baselines/reference/defaultKeywordWithoutExport2.types b/tests/baselines/reference/defaultKeywordWithoutExport2.types
new file mode 100644
index 00000000000..3272127383e
--- /dev/null
+++ b/tests/baselines/reference/defaultKeywordWithoutExport2.types
@@ -0,0 +1,5 @@
+=== tests/cases/compiler/defaultKeywordWithoutExport2.ts ===
+default function () {
+> : () => void
+
+}
diff --git a/tests/cases/compiler/defaultKeywordWithoutExport1.ts b/tests/cases/compiler/defaultKeywordWithoutExport1.ts
new file mode 100644
index 00000000000..f80dbebe2e2
--- /dev/null
+++ b/tests/cases/compiler/defaultKeywordWithoutExport1.ts
@@ -0,0 +1,6 @@
+// @experimentaldecorators: true
+
+declare function decorator(constructor: any): any;
+
+@decorator
+default class {}
\ No newline at end of file
diff --git a/tests/cases/compiler/defaultKeywordWithoutExport2.ts b/tests/cases/compiler/defaultKeywordWithoutExport2.ts
new file mode 100644
index 00000000000..22e62b2a5ad
--- /dev/null
+++ b/tests/cases/compiler/defaultKeywordWithoutExport2.ts
@@ -0,0 +1,3 @@
+default function () {
+
+}
\ No newline at end of file