Non-exported classes in type declaration files leaking value names

TypeScript Version: 3.5.2

Search Terms: ambient module declaration export declare class type name

Code

In a file called classes.d.ts:

declare class A {}
export declare class B extends A {}

In a file called test.js:

let a = require('classes').A;

In a file called test.ts:

import { A } from './types/classes';

[NEW] Assumptions:
The following is a list of assumptions I had when originally opening this issue:

1. Type Declaration Files work like modules: once you use import or export [on a top-level declaration], only explicitly exported declarations are visible externally.
2. Type names declared in a Declaration File are always accessible via import types (at least those that are used by exported types.
   • E.g. export class B extends A exports the type names A and B, even if A was not directly exported.
3. Value names declared in a module-style Declaration File (see #1 above) are only accessible if explicitly exported.

These assumptions are the result of reading the documentation and working with declaration files. Note that the documentation does not mention:

1. All declarations in a declaration file are implicitly exported.
2. Special [and undocumented?] export {}; syntax causes only explicitly exported declarations to be available by consumers of the declaration file.

I list them here to provide context for the Expected Behavior section.

Expected behavior:
In both cases , an Error that name 'A' could be found in module 'classes'.

I expect in this case that TypeScript is capable of resolving the following from the declaration file:

1. The Value "B".
2. The Types "A" and "B".

In other words, I should be able to use import types to resolve class A, but attempts to use them should fail.

Actual behavior:
No compiler error in either case. TypeScript-powered IDEs (e.g. VSCode) happily show that the full non-exported class A is available.

In short, a non-exported, declared class should resolve in the same way as an interface.

As things stand today, TypeScript erroneously resolves the Value "A".

Playground Link: NA

Related Issues: NA

Tái hiện hành vi bằng cách sử dụng các ví dụ classes.d.ts, test.js và test.ts trong issue, sau đó theo dõi quá trình phân giải module và symbol của các tệp khai báo trong TypeScript compiler. Công việc được xem là hoàn tất khi class A không được export không bị lộ ra dưới dạng value, trong khi các tham chiếu kiểu cần thiết bởi class B được export vẫn tiếp tục được phân giải, với độ bao phủ hồi quy cho cả hai ví dụ.