Deprecate module keyword for namespace declarations

src/compiler/checker.ts

@@ -340,6 +340,7 @@ import {
  getNamespaceDeclarationNode,
  getNewTargetContainer,
  getNonAugmentationDeclaration,
+ getNonModifierTokenPosOfNode,
  getNormalizedAbsolutePath,
  getObjectFlags,
  getOriginalNode,
@@ -46365,6 +46366,14 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
 
  if (isIdentifier(node.name)) {
  checkCollisionsForDeclarationName(node, node.name);
+ if (!(node.flags & (NodeFlags.Namespace | NodeFlags.GlobalAugmentation))) {
+ 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),
+ );
+ }
  }
 
  checkExportsOnMergedDeclarations(node);

src/compiler/diagnosticMessages.json

@@ -1797,6 +1797,11 @@
  "category": "Error",
  "code": 1535
  },
+ "A namespace declaration should not be declared using the module keyword. Please use the namespace keyword instead.": {
+ "category": "Suggestion",
+ "code": 1536,
+ "reportsDeprecated": true
+ },
 
  "The types of '{0}' are incompatible between these types.": {
  "category": "Error",

src/compiler/utilities.ts

@@ -1207,6 +1207,16 @@ export function getNonDecoratorTokenPosOfNode(node: Node, sourceFile?: SourceFil
  return skipTrivia((sourceFile || getSourceFileOfNode(node)).text, lastDecorator.end);
 }
 
+/** @internal */
+export function getNonModifierTokenPosOfNode(node: Node, sourceFile?: SourceFileLike): number {
+ const lastModifier = !nodeIsMissing(node) && canHaveModifiers(node) && node.modifiers ? last(node.modifiers) : undefined;
+ if (!lastModifier) {
+ return getTokenPosOfNode(node, sourceFile);
+ }
+
+ return skipTrivia((sourceFile || getSourceFileOfNode(node)).text, lastModifier.end);
+}
+
 /** @internal */
 export function getSourceTextOfNodeFromSourceFile(sourceFile: SourceFile, node: Node, includeTrivia = false): string {
  return getTextOfNodeFromSourceText(sourceFile.text, node, includeTrivia);

tests/cases/fourslash/moduleDeclarationDeprecated_suggestion1.ts

@@ -0,0 +1,41 @@
+///<reference path="fourslash.ts" />
+// @Filename: a.ts
+////[|module|] mod1 { export let x: number }
+////declare [|module|] mod2 { export let x: number }
+////export [|module|] mod3 { export let x: number }
+////export declare [|module|] mod4 { export let x: number }
+////namespace mod5 { export let x: number }
+////declare namespace mod6 { export let x: number }
+////declare global {}
+////mod1.x = 1;
+////mod2.x = 1;
+////mod5.x = 1;
+////mod6.x = 1;
+
+const ranges = test.ranges();
+verify.getSuggestionDiagnostics([
+ {
+ "code": 1536,
+ "message": "A namespace declaration should not be declared using the module keyword. Please use the namespace keyword instead.",
+ "reportsDeprecated": true,
+ "range": ranges[0]
+ },
+ {
+ "code": 1536,
+ "message": "A namespace declaration should not be declared using the module keyword. Please use the namespace keyword instead.",
+ "reportsDeprecated": true,
+ "range": ranges[1]
+ },
+ {
+ "code": 1536,
+ "message": "A namespace declaration should not be declared using the module keyword. Please use the namespace keyword instead.",
+ "reportsDeprecated": true,
+ "range": ranges[2]
+ },
+ {
+ "code": 1536,
+ "message": "A namespace declaration should not be declared using the module keyword. Please use the namespace keyword instead.",
+ "reportsDeprecated": true,
+ "range": ranges[3]
+ },
+])