Imports in .d.ts files break wildcard modules declarations

TypeScript Version: 3.1.3

Search Terms:

import d.ts wildcard module

Code

main.ts

/// <reference path="./typings.d.ts" />

import template from './template.html';

typings.d.ts

import * as _angular from 'angular';

declare module '*.html' {
  const content : string;
  export default content;
}

{
  "name": "ts-bug",
  "version": "1.0.0",
  "dependencies": {
    "angular": "^1.7.5"
  }
}

Compile with:

tsc main.ts

Expected behavior:

Compiled without errors.

Actual behavior: Compiled with error

main.ts:3:22 - error TS2307: Cannot find module './template.html'.

3 import template from './template.html';
                       ~~~~~~~~~~~~~~~~~

Removing import * as _angular from 'angular'; fixes the issue.

Side Note 1

Regular module declarations work regardless of imports being present.

Side Note 2 import * as _angular from 'angular'; is needed to later do:

declare global {
  const angular : typeof _angular;
}

to workaround https://github.com/Microsoft/TypeScript/issues/10178

[benmosher]

Not sure if this helps others but I was just trying to import to get a type from a dependency, and stumbled into this clearer but not-obvious (to me anyway) alternative. Apparently you can import within the module declarations themselves and this compiles the same (AFAICT) as no-imports declarations. Not sure if this satisfies OP’s desired outcome but this does what I was looking for:

/**
 * GraphQL query files.
 */
declare module "*.gql" {
  // import is tucked into (and scoped only within?) the module declaration
  import { gql } from 'graphql-tag'
  // currently `any` but could be well-defined in a future graphql-tag release
  const doc: ReturnType<typeof gql>
  export = doc
}

[weswigham]

An import makes a file a module, which consequently makes the module statement a module augmentation and not a module declaration. A module augmentation differs in that it only adds to existing modules in the compilation. Maybe we could issue a more useful error (or related span) here? Like “a module augmentation exists which matches this import, however no module file or declaration does”?