fix(53006): generate let in namespaces for expando (microsoft#53206)

Author: Zzzen

src/compiler/checker.ts

@@ -9460,7 +9460,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
                     else {
                         const statement = factory.createVariableStatement(/*modifiers*/ undefined, factory.createVariableDeclarationList([
                             factory.createVariableDeclaration(varName, /*exclamationToken*/ undefined, serializeTypeForDeclaration(context, typeToSerialize, symbol, enclosingDeclaration, includePrivateSymbol, bundled))
-                        ], NodeFlags.Const));
+                        ], context.enclosingDeclaration?.kind === SyntaxKind.ModuleDeclaration ? NodeFlags.Let : NodeFlags.Const));
                         // Inlined JSON types exported with [module.]exports= will already emit an export=, so should use `declare`.
                         // Otherwise, the type itself should be exported.
                         addResult(statement,

tests/baselines/reference/argumentsReferenceInConstructor5_Js.js

@@ -27,7 +27,7 @@ class A {
 
 //// [a.d.ts]
 declare namespace bar {
-    const arguments: {};
+    let arguments: {};
 }
 declare class A {
     /**

tests/baselines/reference/argumentsReferenceInMethod5_Js.js

@@ -25,7 +25,7 @@ class A {
 
 //// [a.d.ts]
 declare namespace bar {
-    const arguments: {};
+    let arguments: {};
 }
 declare class A {
     /**

tests/baselines/reference/expandoOnAlias.js

@@ -27,7 +27,7 @@ config.y;
 export class Vue {
 }
 export namespace config {
-    const x: number;
+    let x: number;
 }
 //// [test.d.ts]
 export {};

tests/baselines/reference/jsDeclarationsClassExtendsVisibility.js

@@ -65,6 +65,6 @@ declare namespace Foo {
 }
 import Bar = require("./bar");
 declare namespace Strings {
-    const a: string;
-    const b: string;
+    let a: string;
+    let b: string;
 }

tests/baselines/reference/jsDeclarationsClassStatic.js

@@ -63,8 +63,8 @@ declare namespace Handler {
 }
 declare function statische(): void;
 declare namespace Strings {
-    const a: string;
-    const b: string;
+    let a: string;
+    let b: string;
 }
 type HandlerOptions = {
     /**

tests/baselines/reference/jsDeclarationsClassStatic2.js

@@ -0,0 +1,30 @@
+//// [tests/cases/conformance/jsdoc/declarations/jsDeclarationsClassStatic2.ts] ////
+
+//// [Foo.js]
+class Base {
+  static foo = "";
+}
+export class Foo extends Base {}
+Foo.foo = "foo";
+
+//// [Bar.ts]
+import { Foo } from "./Foo.js";
+
+class Bar extends Foo {}
+Bar.foo = "foo";
+
+
+
+
+//// [Foo.d.ts]
+export class Foo extends Base {
+}
+export namespace Foo {
+    let foo: string;
+}
+declare class Base {
+    static foo: string;
+}
+export {};
+//// [Bar.d.ts]
+export {};

tests/baselines/reference/jsDeclarationsClassStatic2.symbols

@@ -0,0 +1,29 @@
+=== tests/cases/conformance/jsdoc/declarations/Foo.js ===
+class Base {
+>Base : Symbol(Base, Decl(Foo.js, 0, 0))
+
+  static foo = "";
+>foo : Symbol(Base.foo, Decl(Foo.js, 0, 12))
+}
+export class Foo extends Base {}
+>Foo : Symbol(Foo, Decl(Foo.js, 2, 1), Decl(Foo.js, 3, 32))
+>Base : Symbol(Base, Decl(Foo.js, 0, 0))
+
+Foo.foo = "foo";
+>Foo.foo : Symbol(Foo.foo, Decl(Foo.js, 3, 32))
+>Foo : Symbol(Foo, Decl(Foo.js, 2, 1), Decl(Foo.js, 3, 32))
+>foo : Symbol(Foo.foo, Decl(Foo.js, 3, 32))
+
+=== tests/cases/conformance/jsdoc/declarations/Bar.ts ===
+import { Foo } from "./Foo.js";
+>Foo : Symbol(Foo, Decl(Bar.ts, 0, 8))
+
+class Bar extends Foo {}
+>Bar : Symbol(Bar, Decl(Bar.ts, 0, 31))
+>Foo : Symbol(Foo, Decl(Bar.ts, 0, 8))
+
+Bar.foo = "foo";
+>Bar.foo : Symbol(Foo.foo, Decl(Foo.js, 3, 32))
+>Bar : Symbol(Bar, Decl(Bar.ts, 0, 31))
+>foo : Symbol(Foo.foo, Decl(Foo.js, 3, 32))
+

tests/baselines/reference/jsDeclarationsClassStatic2.types

@@ -0,0 +1,34 @@
+=== tests/cases/conformance/jsdoc/declarations/Foo.js ===
+class Base {
+>Base : Base
+
+  static foo = "";
+>foo : string
+>"" : ""
+}
+export class Foo extends Base {}
+>Foo : Foo
+>Base : Base
+
+Foo.foo = "foo";
+>Foo.foo = "foo" : "foo"
+>Foo.foo : string
+>Foo : typeof Foo
+>foo : string
+>"foo" : "foo"
+
+=== tests/cases/conformance/jsdoc/declarations/Bar.ts ===
+import { Foo } from "./Foo.js";
+>Foo : typeof Foo
+
+class Bar extends Foo {}
+>Bar : Bar
+>Foo : Foo
+
+Bar.foo = "foo";
+>Bar.foo = "foo" : "foo"
+>Bar.foo : string
+>Bar : typeof Bar
+>foo : string
+>"foo" : "foo"
+

tests/baselines/reference/jsDeclarationsClassStaticMethodAugmentation.js

@@ -25,6 +25,6 @@ export class Clazz {
 export namespace Clazz {
     function method(): void;
     namespace method {
-        const prop: number;
+        let prop: number;
     }
 }

tests/baselines/reference/jsDeclarationsConstsAsNamespacesWithReferences.js

@@ -18,7 +18,7 @@ export const brandColors = {
 
 //// [index.d.ts]
 export namespace colors {
-    const royalBlue: string;
+    let royalBlue: string;
 }
 export namespace brandColors {
     import purple = colors.royalBlue;

tests/baselines/reference/jsDeclarationsEnumTag.js

@@ -113,15 +113,15 @@ export function consume(t: Target, s: Second, f: Fs): void;
 export function ff(s: string): any;
 export type Target = string;
 export namespace Target {
-    const START: string;
-    const MIDDLE: string;
-    const END: string;
-    const OK_I_GUESS: number;
+    let START: string;
+    let MIDDLE: string;
+    let END: string;
+    let OK_I_GUESS: number;
 }
 export type Second = number;
 export namespace Second {
-    const OK: number;
-    const FINE: number;
+    let OK: number;
+    let FINE: number;
 }
 export type Fs = (arg0: number) => number;
 export namespace Fs {

tests/baselines/reference/jsDeclarationsExportAssignedClassInstance3.js

@@ -21,5 +21,5 @@ module.exports.additional = 20;
 
 
 //// [index.d.ts]
-export const member: number;
-export const additional: 20;
+export let member: number;
+export let additional: 20;

tests/baselines/reference/jsDeclarationsExportAssignmentExpressionPlusSecondary.js

@@ -30,11 +30,11 @@ module.exports.Strings = Strings;
 
 //// [index.d.ts]
 export namespace Strings {
-    const a: string;
-    const b: string;
+    let a: string;
+    let b: string;
 }
-export declare const thing: string;
-export declare const also: string;
+export declare let thing: string;
+export declare let also: string;
 export declare namespace desc {
-    const item: string;
+    let item: string;
 }

tests/baselines/reference/jsDeclarationsExportAssignmentWithKeywordName.js

@@ -21,8 +21,8 @@ module.exports = {
 
 //// [index.d.ts]
 export var x: number;
-declare const _extends: string;
+declare let _extends: string;
 export declare namespace more {
-    const others: string[];
+    let others: string[];
 }
 export { _extends as extends };

tests/baselines/reference/jsDeclarationsExportDefinePropertyEmit.js

@@ -114,7 +114,7 @@ Object.defineProperty(module.exports, "j", { value: function j() { } });
 export function a(): void;
 export function b(): void;
 export namespace b {
-    const cat: string;
+    let cat: string;
 }
 /**
  * @param {number} a

tests/baselines/reference/jsDeclarationsExportSubAssignments.js

@@ -29,6 +29,6 @@ declare namespace Foo {
     export { Strings };
 }
 declare namespace Strings {
-    const a: string;
-    const b: string;
+    let a: string;
+    let b: string;
 }

tests/baselines/reference/jsDeclarationsFunctionKeywordProp.js

@@ -24,18 +24,18 @@ baz.normal = false;
 //// [source.d.ts]
 declare function foo(): void;
 declare namespace foo {
-    const _null: boolean;
+    let _null: boolean;
     export { _null as null };
 }
 declare function bar(): void;
 declare namespace bar {
-    const async: boolean;
-    const normal: boolean;
+    let async: boolean;
+    let normal: boolean;
 }
 declare function baz(): void;
 declare namespace baz {
-    const _class: boolean;
+    let _class: boolean;
     export { _class as class };
-    const normal_1: boolean;
+    let normal_1: boolean;
     export { normal_1 as normal };
 }