`export as namespace` still allows access via properties in module files

TypeScript Version: 3.8.0-dev.20200119

Search Terms: export as namespace

Code

someModule.d.ts:

export function foo (bar: string): void;
export as namespace someModule;

index.ts:

import { foo } from './someModule';

someModule.foo;
window.someModule.foo;
globalThis.someModule.foo;

Expected behavior:

All of the attempts to access someModule as a global namespace in index.ts should result in compile-time errors, as index.ts is not a script file.

Actual behavior:

window.someModule.foo and globalThis.someModule.foo do NOT result in compile-time errors.

Playground Link: N/A (requires multiple files)

Related Issues: None found

使用报告的 TypeScript 版本或当前构建，利用显示的两个文件 someModule.d.ts 和 index.ts 重现该问题。比较直接访问、通过 window 访问以及通过 globalThis 访问时的诊断结果，然后跟踪编译器对 export as namespace 的处理。完成标准是：模块文件中的三个全局命名空间访问都会产生编译时错误。