Implement TypeScript 6.0 deprecation of module keyword for namespace declarations

src/compiler/checker.ts

@@ -1123,6 +1123,8 @@
     VariableLikeDeclaration,
     VariableStatement,
     VarianceFlags,
+    Version,
+    versionMajorMinor,
     visitEachChild as visitEachChildWorker,
     visitNode,
     visitNodes,
@@ -47998,9 +48000,41 @@
                     const sourceFile = getSourceFileOfNode(node);
                     const pos = getNonModifierTokenPosOfNode(node);
                     const span = getSpanOfTokenAtPosition(sourceFile, pos);
-                    suggestionDiagnostics.add(
-                        createFileDiagnostic(sourceFile, span.start, span.length, Diagnostics.A_namespace_declaration_should_not_be_declared_using_the_module_keyword_Please_use_the_namespace_keyword_instead),
-                    );
+
+                    // Check if we should generate an error (TS 6.0+) or suggestion (older versions)
+                    const currentVersion = new Version(versionMajorMinor);
+                    const errorVersion = new Version("6.0");
+                    const shouldError = currentVersion.compareTo(errorVersion) >= Comparison.EqualTo;
+
+                    // Check if ignoreDeprecations should suppress this error
+                    let shouldSuppress = false;
+                    if (shouldError && compilerOptions.ignoreDeprecations) {
+                        // Only valid ignoreDeprecations values: "5.0" and "6.0"
+                        if (compilerOptions.ignoreDeprecations === "6.0") {
+                            shouldSuppress = true;
+                        }
+                    }
+
+                    if (shouldError && !shouldSuppress) {
+                        // In TypeScript 6.0+, this is an error unless suppressed by ignoreDeprecations
+                        const errorDiagnostic = createFileDiagnostic(
+                            sourceFile,
+                            span.start,
+                            span.length,
+                            Diagnostics.The_module_keyword_is_not_allowed_for_namespace_declarations_Use_the_namespace_keyword_instead,
+                        );
+                        diagnostics.add(errorDiagnostic);
+                    }
+                    else {
+                        // In older versions or when suppressed, keep as suggestion
+                        const suggestionDiagnostic = createFileDiagnostic(
+                            sourceFile,
+                            span.start,
+                            span.length,
+                            Diagnostics.A_namespace_declaration_should_not_be_declared_using_the_module_keyword_Please_use_the_namespace_keyword_instead,
+                        );
+                        suggestionDiagnostics.add(suggestionDiagnostic);
+                    }
                 }
             }
 

src/compiler/diagnosticMessages.json

@@ -1825,6 +1825,10 @@
         "code": 1540,
         "reportsDeprecated": true
     },
+    "The 'module' keyword is not allowed for namespace declarations. Use the 'namespace' keyword instead.": {
+        "category": "Error",
+        "code": 1547
+    },
     "Type-only import of an ECMAScript module from a CommonJS module must have a 'resolution-mode' attribute.": {
         "category": "Error",
         "code": 1541

tests/baselines/reference/AmbientModuleAndAmbientFunctionWithTheSameNameAndCommonRoot.errors.txt

@@ -0,0 +1,17 @@
+module.d.ts(1,9): error TS1547: The 'module' keyword is not allowed for namespace declarations. Use the 'namespace' keyword instead.
+
+
+==== module.d.ts (1 errors) ====
+    declare module Point {
+            ~~~~~~
+!!! error TS1547: The 'module' keyword is not allowed for namespace declarations. Use the 'namespace' keyword instead.
+        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/AmbientModuleAndNonAmbientFunctionWithTheSameNameAndCommonRoot.errors.txt

@@ -0,0 +1,19 @@
+module.d.ts(1,9): error TS1547: The 'module' keyword is not allowed for namespace declarations. Use the 'namespace' keyword instead.
+
+
+==== module.d.ts (1 errors) ====
+    declare module Point {
+            ~~~~~~
+!!! error TS1547: The 'module' keyword is not allowed for namespace declarations. Use the 'namespace' keyword instead.
+        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/ClassAndModuleThatMergeWithModulesExportedStaticFunctionUsingClassPrivateStatics.errors.txt

@@ -1,7 +1,8 @@
+ClassAndModuleThatMergeWithModulesExportedStaticFunctionUsingClassPrivateStatics.ts(8,1): error TS1547: The 'module' keyword is not allowed for namespace declarations. Use the 'namespace' keyword instead.
 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 TS1547: The 'module' keyword is not allowed for namespace declarations. Use the 'namespace' keyword instead.
         // error: duplicate identifier expected
         export function fn<T>(x: T, y: T): number {
             return clodule.sfn('a');

tests/baselines/reference/EnumAndModuleWithSameNameAndCommonRoot.errors.txt

@@ -0,0 +1,22 @@
+EnumAndModuleWithSameNameAndCommonRoot.ts(5,1): error TS1547: The 'module' keyword is not allowed for namespace declarations. Use the 'namespace' keyword instead.
+
+
+==== EnumAndModuleWithSameNameAndCommonRoot.ts (1 errors) ====
+    enum enumdule {
+        Red, Blue
+    }
+
+    module enumdule {
+    ~~~~~~
+!!! error TS1547: The 'module' keyword is not allowed for namespace declarations. Use the 'namespace' keyword instead.
+
+        export class Point {
+            constructor(public x: number, public y: number) { }
+        }
+    }
+
+    var x: enumdule;
+    var x = enumdule.Red;
+
+    var y: { x: number; y: number };
+    var y = new enumdule.Point(0, 0);

tests/baselines/reference/ExportClassWhichExtendsInterfaceWithInaccessibleType.errors.txt

@@ -0,0 +1,25 @@
+ExportClassWhichExtendsInterfaceWithInaccessibleType.ts(1,1): error TS1547: The 'module' keyword is not allowed for namespace declarations. Use the 'namespace' keyword instead.
+
+
+==== ExportClassWhichExtendsInterfaceWithInaccessibleType.ts (1 errors) ====
+    module A {
+    ~~~~~~
+!!! error TS1547: The 'module' keyword is not allowed for namespace declarations. Use the 'namespace' keyword instead.
+
+        interface Point {
+            x: number;
+            y: number;
+
+            fromOrigin(p: Point): number;
+        }
+
+        export class Point2d implements Point {
+            constructor(public x: number, public y: number) { }
+
+            fromOrigin(p: Point) {
+                return 1;
+            }
+        }
+    }
+
+

tests/baselines/reference/ExportFunctionWithAccessibleTypesInParameterAndReturnTypeAnnotation.errors.txt

@@ -0,0 +1,21 @@
+ExportFunctionWithAccessibleTypesInParameterAndReturnTypeAnnotation.ts(1,1): error TS1547: The 'module' keyword is not allowed for namespace declarations. Use the 'namespace' keyword instead.
+
+
+==== ExportFunctionWithAccessibleTypesInParameterAndReturnTypeAnnotation.ts (1 errors) ====
+    module A {
+    ~~~~~~
+!!! error TS1547: The 'module' keyword is not allowed for namespace declarations. Use the 'namespace' keyword instead.
+
+        export class Point {
+            x: number;
+            y: number;
+        }
+
+        export class Line {
+            constructor(public start: Point, public end: Point) { }
+        }
+
+        export function fromOrigin(p: Point): Line {
+            return new Line({ x: 0, y: 0 }, p);
+        }
+    }

tests/baselines/reference/ExportFunctionWithInaccessibleTypesInParameterTypeAnnotation.errors.txt

@@ -0,0 +1,21 @@
+ExportFunctionWithInaccessibleTypesInParameterTypeAnnotation.ts(1,1): error TS1547: The 'module' keyword is not allowed for namespace declarations. Use the 'namespace' keyword instead.
+
+
+==== ExportFunctionWithInaccessibleTypesInParameterTypeAnnotation.ts (1 errors) ====
+    module A {
+    ~~~~~~
+!!! error TS1547: The 'module' keyword is not allowed for namespace declarations. Use the 'namespace' keyword instead.
+
+        class Point {
+            x: number;
+            y: number;
+        }
+
+        export class Line {
+            constructor(public start: Point, public end: Point) { }
+        }
+
+        export function fromOrigin(p: Point): Line {
+            return new Line({ x: 0, y: 0 }, p);
+        }
+    }

tests/baselines/reference/ExportFunctionWithInaccessibleTypesInReturnTypeAnnotation.errors.txt

@@ -0,0 +1,21 @@
+ExportFunctionWithInaccessibleTypesInReturnTypeAnnotation.ts(1,1): error TS1547: The 'module' keyword is not allowed for namespace declarations. Use the 'namespace' keyword instead.
+
+
+==== ExportFunctionWithInaccessibleTypesInReturnTypeAnnotation.ts (1 errors) ====
+    module A {
+    ~~~~~~
+!!! error TS1547: The 'module' keyword is not allowed for namespace declarations. Use the 'namespace' keyword instead.
+
+        export class Point {
+            x: number;
+            y: number;
+        }
+
+        class Line {
+            constructor(public start: Point, public end: Point) { }
+        }
+
+        export function fromOrigin(p: Point): Line {
+            return new Line({ x: 0, y: 0 }, p);
+        }
+    }

tests/baselines/reference/ExportObjectLiteralAndObjectTypeLiteralWithAccessibleTypesInNestedMemberTypeAnnotations.errors.txt

@@ -0,0 +1,17 @@
+ExportObjectLiteralAndObjectTypeLiteralWithAccessibleTypesInNestedMemberTypeAnnotations.ts(1,1): error TS1547: The 'module' keyword is not allowed for namespace declarations. Use the 'namespace' keyword instead.
+
+
+==== ExportObjectLiteralAndObjectTypeLiteralWithAccessibleTypesInNestedMemberTypeAnnotations.ts (1 errors) ====
+    module A {
+    ~~~~~~
+!!! error TS1547: The 'module' keyword is not allowed for namespace declarations. Use the 'namespace' keyword instead.
+
+        class Point {
+            constructor(public x: number, public y: number) { }
+        }
+
+        export var UnitSquare : {
+            top: { left: Point, right: Point },
+            bottom: { left: Point, right: Point }
+        } = null;
+    }

tests/baselines/reference/ExportVariableWithInaccessibleTypeInTypeAnnotation.errors.txt

@@ -0,0 +1,24 @@
+ExportVariableWithInaccessibleTypeInTypeAnnotation.ts(1,1): error TS1547: The 'module' keyword is not allowed for namespace declarations. Use the 'namespace' keyword instead.
+
+
+==== ExportVariableWithInaccessibleTypeInTypeAnnotation.ts (1 errors) ====
+    module A {
+    ~~~~~~
+!!! error TS1547: The 'module' keyword is not allowed for namespace declarations. Use the 'namespace' keyword instead.
+
+        export interface Point {
+            x: number;
+            y: number;
+        }
+
+        // valid since Point is exported
+        export var Origin: Point = { x: 0, y: 0 };
+
+        interface Point3d extends Point {
+            z: number;
+        }
+
+        // invalid Point3d is not exported
+        export var Origin3d: Point3d = { x: 0, y: 0, z: 0 };
+    }
+

tests/baselines/reference/FunctionAndModuleWithSameNameAndDifferentCommonRoot.errors.txt

@@ -0,0 +1,32 @@
+function.ts(1,1): error TS1547: The 'module' keyword is not allowed for namespace declarations. Use the 'namespace' keyword instead.
+module.ts(1,1): error TS1547: The 'module' keyword is not allowed for namespace declarations. Use the 'namespace' keyword instead.
+module.ts(2,12): error TS1547: The 'module' keyword is not allowed for namespace declarations. Use the 'namespace' keyword instead.
+
+
+==== function.ts (1 errors) ====
+    module A {
+    ~~~~~~
+!!! error TS1547: The 'module' keyword is not allowed for namespace declarations. Use the 'namespace' keyword instead.
+        export function Point() {
+            return { x: 0, y: 0 };
+        }
+    }
+
+==== module.ts (2 errors) ====
+    module B {
+    ~~~~~~
+!!! error TS1547: The 'module' keyword is not allowed for namespace declarations. Use the 'namespace' keyword instead.
+        export module Point {
+               ~~~~~~
+!!! error TS1547: The 'module' keyword is not allowed for namespace declarations. Use the 'namespace' keyword instead.
+            export var Origin = { x: 0, y: 0 };
+        }
+    }
+
+==== test.ts (0 errors) ====
+    var fn: () => { x: number; y: number };
+    var fn = A.Point;
+
+    var cl: { x: number; y: number; }
+    var cl = B.Point.Origin;
+

tests/baselines/reference/ModuleAndEnumWithSameNameAndCommonRoot.errors.txt

@@ -0,0 +1,22 @@
+ModuleAndEnumWithSameNameAndCommonRoot.ts(1,1): error TS1547: The 'module' keyword is not allowed for namespace declarations. Use the 'namespace' keyword instead.
+
+
+==== ModuleAndEnumWithSameNameAndCommonRoot.ts (1 errors) ====
+    module enumdule {
+    ~~~~~~
+!!! error TS1547: The 'module' keyword is not allowed for namespace declarations. Use the 'namespace' keyword instead.
+
+        export class Point {
+            constructor(public x: number, public y: number) { }
+        }
+    }
+
+    enum enumdule {
+        Red, Blue
+    }
+
+    var x: enumdule;
+    var x = enumdule.Red;
+
+    var y: { x: number; y: number };
+    var y = new enumdule.Point(0, 0);

tests/baselines/reference/ModuleWithExportedAndNonExportedImportAlias.errors.txt

@@ -1,8 +1,13 @@
+ModuleWithExportedAndNonExportedImportAlias.ts(1,1): error TS1547: The 'module' keyword is not allowed for namespace declarations. Use the 'namespace' keyword instead.
+ModuleWithExportedAndNonExportedImportAlias.ts(12,1): error TS1547: The 'module' keyword is not allowed for namespace declarations. Use the 'namespace' keyword instead.
+ModuleWithExportedAndNonExportedImportAlias.ts(18,1): error TS1547: The 'module' keyword is not allowed for namespace declarations. Use the 'namespace' keyword instead.
 ModuleWithExportedAndNonExportedImportAlias.ts(37,21): error TS2339: Property 'Lines' does not exist on type 'typeof Geometry'.
 
 
-==== ModuleWithExportedAndNonExportedImportAlias.ts (1 errors) ====
+==== ModuleWithExportedAndNonExportedImportAlias.ts (4 errors) ====
     module A {
+    ~~~~~~
+!!! error TS1547: The 'module' keyword is not allowed for namespace declarations. Use the 'namespace' keyword instead.
         export interface Point {
             x: number;
             y: number;
@@ -14,12 +19,16 @@ ModuleWithExportedAndNonExportedImportAlias.ts(37,21): error TS2339: Property 'L
     }
 
     module B {
+    ~~~~~~
+!!! error TS1547: The 'module' keyword is not allowed for namespace declarations. Use the 'namespace' keyword instead.
         export class Line {
             constructor(public start: A.Point, public end: A.Point) { }
         }
     }
 
     module Geometry {
+    ~~~~~~
+!!! error TS1547: The 'module' keyword is not allowed for namespace declarations. Use the 'namespace' keyword instead.
         export import Points = A;
         import Lines = B;
 

tests/baselines/reference/accessorsInAmbientContext.errors.txt

@@ -1,3 +1,4 @@
+accessorsInAmbientContext.ts(1,9): error TS1547: The 'module' keyword is not allowed for namespace declarations. Use the 'namespace' keyword instead.
 accessorsInAmbientContext.ts(3,17): error TS1183: An implementation cannot be declared in ambient contexts.
 accessorsInAmbientContext.ts(4,18): error TS1183: An implementation cannot be declared in ambient contexts.
 accessorsInAmbientContext.ts(6,24): error TS1183: An implementation cannot be declared in ambient contexts.
@@ -8,8 +9,10 @@ accessorsInAmbientContext.ts(15,20): error TS1183: An implementation cannot be d
 accessorsInAmbientContext.ts(16,21): error TS1183: An implementation cannot be declared in ambient contexts.
 
 
-==== accessorsInAmbientContext.ts (8 errors) ====
+==== accessorsInAmbientContext.ts (9 errors) ====
     declare module M {
+            ~~~~~~
+!!! error TS1547: The 'module' keyword is not allowed for namespace declarations. Use the 'namespace' keyword instead.
         class C {
             get X() { return 1; }
                     ~