Ban non-ambient namespaces written with module keyword

src/compiler/checker.ts

@@ -47309,6 +47309,10 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
                 error(node.name, Diagnostics.Augmentations_for_the_global_scope_should_have_declare_modifier_unless_they_appear_in_already_ambient_context);
             }
 
+            if ((node.flags & NodeFlags.Namespace) === NodeFlags.None && node.name.kind !== SyntaxKind.StringLiteral && !isGlobalScopeAugmentation(node)) {
+                error(node.name, Diagnostics.This_syntax_is_not_allowed_when_erasableSyntaxOnly_is_enabled);
+            }
+
             const isAmbientExternalModule: boolean = isAmbientModule(node);
             const contextErrorMessage = isAmbientExternalModule
                 ? Diagnostics.An_ambient_module_declaration_is_only_allowed_at_the_top_level_in_a_file
@@ -47345,9 +47349,6 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
                 && !inAmbientContext
                 && isInstantiatedModule(node, shouldPreserveConstEnums(compilerOptions))
             ) {
-                if (compilerOptions.erasableSyntaxOnly) {
-                    error(node.name, Diagnostics.This_syntax_is_not_allowed_when_erasableSyntaxOnly_is_enabled);
-                }
 
                 if (getIsolatedModules(compilerOptions) && !getSourceFileOfNode(node).externalModuleIndicator) {
                     // This could be loosened a little if needed. The only problem we are trying to avoid is unqualified

tests/baselines/reference/AmbientModuleAndAmbientFunctionWithTheSameNameAndCommonRoot.errors.txt

@@ -0,0 +1,17 @@
+module.d.ts(1,16): error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
+
+
+==== module.d.ts (1 errors) ====
+    declare module Point {
+                   ~~~~~
+!!! error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
+        export var Origin: { x: number; y: number; }
+    }
+
+==== function.d.ts (0 errors) ====
+    declare function Point(): { x: number; y: number; }
+
+==== test.ts (0 errors) ====
+    var cl: { x: number; y: number; }
+    var cl = Point();
+    var cl = Point.Origin;

tests/baselines/reference/AmbientModuleAndAmbientWithSameNameAndCommonRoot.errors.txt

@@ -0,0 +1,35 @@
+class.d.ts(1,16): error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
+module.d.ts(1,16): error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
+module.d.ts(2,19): error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
+
+
+==== module.d.ts (2 errors) ====
+    declare module A {
+                   ~
+!!! error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
+        export module Point {
+                      ~~~~~
+!!! error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
+            export var Origin: {
+                x: number;
+                y: number;
+            }
+        }
+    }
+
+==== class.d.ts (1 errors) ====
+    declare module A {
+                   ~
+!!! error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
+        export class Point {
+            constructor(x: number, y: number);
+            x: number;
+            y: number;
+        }
+    }
+
+==== test.ts (0 errors) ====
+    var p: { x: number; y: number; }
+    var p = A.Point.Origin;
+    var p = new A.Point(0, 0); // unexpected error here, bug 840000
+

tests/baselines/reference/AmbientModuleAndNonAmbientClassWithSameNameAndCommonRoot.errors.txt

@@ -0,0 +1,32 @@
+classPoint.ts(1,8): error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
+module.d.ts(1,16): error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
+module.d.ts(2,19): error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
+
+
+==== module.d.ts (2 errors) ====
+    declare module A {
+                   ~
+!!! error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
+        export module Point {
+                      ~~~~~
+!!! error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
+            export var Origin: {
+                x: number;
+                y: number;
+            }
+        }
+    }
+
+==== classPoint.ts (1 errors) ====
+    module A {
+           ~
+!!! error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
+        export class Point {
+            constructor(public x: number, public y: number) { }
+        }
+    }
+
+==== test.ts (0 errors) ====
+    var p: { x: number; y: number; }
+    var p = A.Point.Origin;
+    var p = new A.Point(0, 0); // unexpected error here, bug 840000

tests/baselines/reference/AmbientModuleAndNonAmbientFunctionWithTheSameNameAndCommonRoot.errors.txt

@@ -0,0 +1,19 @@
+module.d.ts(1,16): error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
+
+
+==== module.d.ts (1 errors) ====
+    declare module Point {
+                   ~~~~~
+!!! error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
+        export var Origin: { x: number; y: number; }
+    }
+
+==== function.ts (0 errors) ====
+    function Point() {
+        return { x: 0, y: 0 };
+    }
+
+==== test.ts (0 errors) ====
+    var cl: { x: number; y: number; }
+    var cl = Point();
+    var cl = Point.Origin;

tests/baselines/reference/ClassAndModuleThatMergeWithModuleMemberThatUsesClassTypeParameter.errors.txt

@@ -1,11 +1,15 @@
+ClassAndModuleThatMergeWithModuleMemberThatUsesClassTypeParameter.ts(9,8): error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
 ClassAndModuleThatMergeWithModuleMemberThatUsesClassTypeParameter.ts(10,19): error TS2304: Cannot find name 'T'.
+ClassAndModuleThatMergeWithModuleMemberThatUsesClassTypeParameter.ts(19,8): error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
 ClassAndModuleThatMergeWithModuleMemberThatUsesClassTypeParameter.ts(20,12): error TS2304: Cannot find name 'T'.
 ClassAndModuleThatMergeWithModuleMemberThatUsesClassTypeParameter.ts(22,23): error TS2304: Cannot find name 'T'.
+ClassAndModuleThatMergeWithModuleMemberThatUsesClassTypeParameter.ts(34,8): error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
 ClassAndModuleThatMergeWithModuleMemberThatUsesClassTypeParameter.ts(35,26): error TS2304: Cannot find name 'T'.
+ClassAndModuleThatMergeWithModuleMemberThatUsesClassTypeParameter.ts(44,8): error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
 ClassAndModuleThatMergeWithModuleMemberThatUsesClassTypeParameter.ts(46,15): error TS2304: Cannot find name 'T'.
 
 
-==== ClassAndModuleThatMergeWithModuleMemberThatUsesClassTypeParameter.ts (5 errors) ====
+==== ClassAndModuleThatMergeWithModuleMemberThatUsesClassTypeParameter.ts (9 errors) ====
     // all expected to be errors
 
     class clodule1<T>{
@@ -15,6 +19,8 @@ ClassAndModuleThatMergeWithModuleMemberThatUsesClassTypeParameter.ts(46,15): err
     }
 
     module clodule1 {
+           ~~~~~~~~
+!!! error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
         function f(x: T) { }
                       ~
 !!! error TS2304: Cannot find name 'T'.
@@ -27,6 +33,8 @@ ClassAndModuleThatMergeWithModuleMemberThatUsesClassTypeParameter.ts(46,15): err
     }
 
     module clodule2 {
+           ~~~~~~~~
+!!! error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
         var x: T;
                ~
 !!! error TS2304: Cannot find name 'T'.
@@ -46,6 +54,8 @@ ClassAndModuleThatMergeWithModuleMemberThatUsesClassTypeParameter.ts(46,15): err
     }
 
     module clodule3 {
+           ~~~~~~~~
+!!! error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
         export var y = { id: T };
                              ~
 !!! error TS2304: Cannot find name 'T'.
@@ -58,6 +68,8 @@ ClassAndModuleThatMergeWithModuleMemberThatUsesClassTypeParameter.ts(46,15): err
     }
 
     module clodule4 {
+           ~~~~~~~~
+!!! error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
         class D {
             name: T;
                   ~

tests/baselines/reference/ClassAndModuleThatMergeWithModulesExportedGenericFunctionAndGenericClassStaticFunctionOfTheSameName.errors.txt

@@ -1,8 +1,9 @@
 ClassAndModuleThatMergeWithModulesExportedGenericFunctionAndGenericClassStaticFunctionOfTheSameName.ts(5,12): error TS2300: Duplicate identifier 'fn'.
+ClassAndModuleThatMergeWithModulesExportedGenericFunctionAndGenericClassStaticFunctionOfTheSameName.ts(8,8): error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
 ClassAndModuleThatMergeWithModulesExportedGenericFunctionAndGenericClassStaticFunctionOfTheSameName.ts(10,21): error TS2300: Duplicate identifier 'fn'.
 
 
-==== ClassAndModuleThatMergeWithModulesExportedGenericFunctionAndGenericClassStaticFunctionOfTheSameName.ts (2 errors) ====
+==== ClassAndModuleThatMergeWithModulesExportedGenericFunctionAndGenericClassStaticFunctionOfTheSameName.ts (3 errors) ====
     class clodule<T> {
         id: string;
         value: T;
@@ -13,6 +14,8 @@ ClassAndModuleThatMergeWithModulesExportedGenericFunctionAndGenericClassStaticFu
     }
 
     module clodule {
+           ~~~~~~~
+!!! error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
         // error: duplicate identifier expected
         export function fn<T>(x: T, y: T): T {
                         ~~

tests/baselines/reference/ClassAndModuleThatMergeWithModulesExportedGenericFunctionAndNonGenericClassStaticFunctionOfTheSameName.errors.txt

@@ -1,8 +1,9 @@
 ClassAndModuleThatMergeWithModulesExportedGenericFunctionAndNonGenericClassStaticFunctionOfTheSameName.ts(5,12): error TS2300: Duplicate identifier 'fn'.
+ClassAndModuleThatMergeWithModulesExportedGenericFunctionAndNonGenericClassStaticFunctionOfTheSameName.ts(8,8): error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
 ClassAndModuleThatMergeWithModulesExportedGenericFunctionAndNonGenericClassStaticFunctionOfTheSameName.ts(10,21): error TS2300: Duplicate identifier 'fn'.
 
 
-==== ClassAndModuleThatMergeWithModulesExportedGenericFunctionAndNonGenericClassStaticFunctionOfTheSameName.ts (2 errors) ====
+==== ClassAndModuleThatMergeWithModulesExportedGenericFunctionAndNonGenericClassStaticFunctionOfTheSameName.ts (3 errors) ====
     class clodule<T> {
         id: string;
         value: T;
@@ -13,6 +14,8 @@ ClassAndModuleThatMergeWithModulesExportedGenericFunctionAndNonGenericClassStati
     }
 
     module clodule {
+           ~~~~~~~
+!!! error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
         // error: duplicate identifier expected
         export function fn<T>(x: T, y: T): T {
                         ~~

tests/baselines/reference/ClassAndModuleThatMergeWithModulesExportedStaticFunctionUsingClassPrivateStatics.errors.txt

@@ -1,7 +1,8 @@
+ClassAndModuleThatMergeWithModulesExportedStaticFunctionUsingClassPrivateStatics.ts(8,8): error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
 ClassAndModuleThatMergeWithModulesExportedStaticFunctionUsingClassPrivateStatics.ts(11,24): error TS2341: Property 'sfn' is private and only accessible within class 'clodule<T>'.
 
 
-==== ClassAndModuleThatMergeWithModulesExportedStaticFunctionUsingClassPrivateStatics.ts (1 errors) ====
+==== ClassAndModuleThatMergeWithModulesExportedStaticFunctionUsingClassPrivateStatics.ts (2 errors) ====
     class clodule<T> {
         id: string;
         value: T;
@@ -10,6 +11,8 @@ ClassAndModuleThatMergeWithModulesExportedStaticFunctionUsingClassPrivateStatics
     }
 
     module clodule {
+           ~~~~~~~
+!!! error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
         // error: duplicate identifier expected
         export function fn<T>(x: T, y: T): number {
             return clodule.sfn('a');

tests/baselines/reference/ClassAndModuleThatMergeWithStaticFunctionAndExportedFunctionThatShareAName.errors.txt

@@ -1,10 +1,13 @@
 ClassAndModuleThatMergeWithStaticFunctionAndExportedFunctionThatShareAName.ts(4,12): error TS2300: Duplicate identifier 'Origin'.
+ClassAndModuleThatMergeWithStaticFunctionAndExportedFunctionThatShareAName.ts(7,8): error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
 ClassAndModuleThatMergeWithStaticFunctionAndExportedFunctionThatShareAName.ts(8,21): error TS2300: Duplicate identifier 'Origin'.
+ClassAndModuleThatMergeWithStaticFunctionAndExportedFunctionThatShareAName.ts(12,8): error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
 ClassAndModuleThatMergeWithStaticFunctionAndExportedFunctionThatShareAName.ts(16,16): error TS2300: Duplicate identifier 'Origin'.
+ClassAndModuleThatMergeWithStaticFunctionAndExportedFunctionThatShareAName.ts(19,19): error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
 ClassAndModuleThatMergeWithStaticFunctionAndExportedFunctionThatShareAName.ts(20,25): error TS2300: Duplicate identifier 'Origin'.
 
 
-==== ClassAndModuleThatMergeWithStaticFunctionAndExportedFunctionThatShareAName.ts (4 errors) ====
+==== ClassAndModuleThatMergeWithStaticFunctionAndExportedFunctionThatShareAName.ts (7 errors) ====
     class Point {
         constructor(public x: number, public y: number) { }
 
@@ -14,13 +17,17 @@ ClassAndModuleThatMergeWithStaticFunctionAndExportedFunctionThatShareAName.ts(20
     }
 
     module Point {
+           ~~~~~
+!!! error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
         export function Origin() { return null; } //expected duplicate identifier error
                         ~~~~~~
 !!! error TS2300: Duplicate identifier 'Origin'.
     }
 
 
     module A {
+           ~
+!!! error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
         export class Point {
             constructor(public x: number, public y: number) { }
 
@@ -30,6 +37,8 @@ ClassAndModuleThatMergeWithStaticFunctionAndExportedFunctionThatShareAName.ts(20
         }
 
         export module Point {
+                      ~~~~~
+!!! error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
             export function Origin() { return ""; }//expected duplicate identifier error
                             ~~~~~~
 !!! error TS2300: Duplicate identifier 'Origin'.

tests/baselines/reference/ClassAndModuleThatMergeWithStaticFunctionAndNonExportedFunctionThatShareAName.errors.txt

@@ -0,0 +1,34 @@
+ClassAndModuleThatMergeWithStaticFunctionAndNonExportedFunctionThatShareAName.ts(7,8): error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
+ClassAndModuleThatMergeWithStaticFunctionAndNonExportedFunctionThatShareAName.ts(12,8): error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
+ClassAndModuleThatMergeWithStaticFunctionAndNonExportedFunctionThatShareAName.ts(19,19): error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
+
+
+==== ClassAndModuleThatMergeWithStaticFunctionAndNonExportedFunctionThatShareAName.ts (3 errors) ====
+    class Point {
+        constructor(public x: number, public y: number) { }
+
+        static Origin(): Point { return { x: 0, y: 0 }; }
+    }
+
+    module Point {
+           ~~~~~
+!!! error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
+        function Origin() { return ""; }// not an error, since not exported
+    }
+
+
+    module A {
+           ~
+!!! error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
+        export class Point {
+            constructor(public x: number, public y: number) { }
+
+            static Origin(): Point { return { x: 0, y: 0 }; }
+        }
+
+        export module Point {
+                      ~~~~~
+!!! error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
+            function Origin() { return ""; }// not an error since not exported
+        }
+    }

tests/baselines/reference/ClassAndModuleThatMergeWithStaticVariableAndExportedVarThatShareAName.errors.txt

@@ -1,10 +1,13 @@
 ClassAndModuleThatMergeWithStaticVariableAndExportedVarThatShareAName.ts(4,12): error TS2300: Duplicate identifier 'Origin'.
+ClassAndModuleThatMergeWithStaticVariableAndExportedVarThatShareAName.ts(7,8): error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
 ClassAndModuleThatMergeWithStaticVariableAndExportedVarThatShareAName.ts(8,16): error TS2300: Duplicate identifier 'Origin'.
+ClassAndModuleThatMergeWithStaticVariableAndExportedVarThatShareAName.ts(12,8): error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
 ClassAndModuleThatMergeWithStaticVariableAndExportedVarThatShareAName.ts(16,16): error TS2300: Duplicate identifier 'Origin'.
+ClassAndModuleThatMergeWithStaticVariableAndExportedVarThatShareAName.ts(19,19): error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
 ClassAndModuleThatMergeWithStaticVariableAndExportedVarThatShareAName.ts(20,20): error TS2300: Duplicate identifier 'Origin'.
 
 
-==== ClassAndModuleThatMergeWithStaticVariableAndExportedVarThatShareAName.ts (4 errors) ====
+==== ClassAndModuleThatMergeWithStaticVariableAndExportedVarThatShareAName.ts (7 errors) ====
     class Point {
         constructor(public x: number, public y: number) { }
 
@@ -14,13 +17,17 @@ ClassAndModuleThatMergeWithStaticVariableAndExportedVarThatShareAName.ts(20,20):
     }
 
     module Point {
+           ~~~~~
+!!! error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
         export var Origin = ""; //expected duplicate identifier error
                    ~~~~~~
 !!! error TS2300: Duplicate identifier 'Origin'.
     }
 
 
     module A {
+           ~
+!!! error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
         export class Point {
             constructor(public x: number, public y: number) { }
 
@@ -30,6 +37,8 @@ ClassAndModuleThatMergeWithStaticVariableAndExportedVarThatShareAName.ts(20,20):
         }
 
         export module Point {
+                      ~~~~~
+!!! error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
             export var Origin = ""; //expected duplicate identifier error
                        ~~~~~~
 !!! error TS2300: Duplicate identifier 'Origin'.

tests/baselines/reference/ClassAndModuleThatMergeWithStaticVariableAndNonExportedVarThatShareAName.errors.txt

@@ -0,0 +1,34 @@
+ClassAndModuleThatMergeWithStaticVariableAndNonExportedVarThatShareAName.ts(7,8): error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
+ClassAndModuleThatMergeWithStaticVariableAndNonExportedVarThatShareAName.ts(12,8): error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
+ClassAndModuleThatMergeWithStaticVariableAndNonExportedVarThatShareAName.ts(19,19): error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
+
+
+==== ClassAndModuleThatMergeWithStaticVariableAndNonExportedVarThatShareAName.ts (3 errors) ====
+    class Point {
+        constructor(public x: number, public y: number) { }
+
+        static Origin: Point = { x: 0, y: 0 };
+    }
+
+    module Point {
+           ~~~~~
+!!! error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
+        var Origin = ""; // not an error, since not exported
+    }
+
+
+    module A {
+           ~
+!!! error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
+        export class Point {
+            constructor(public x: number, public y: number) { }
+
+            static Origin: Point = { x: 0, y: 0 };
+        }
+
+        export module Point {
+                      ~~~~~
+!!! error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
+            var Origin = ""; // not an error since not exported
+        }
+    }