[transpileDeclaration API][5.5] Type-only import is missing when type is used as arrow function argument

[MichaelMitchell-at]

🔎 Search Terms

transpile declaration api emit missing import

🕗 Version & Regression Information

• This changed in commit or PR Add transpileDeclaration API method #58261 @weswigham

⏯ Playground Link

https://github.com/MichaelMitchell-at/transpile_declaration_bug_repro/tree/bug2

💻 Code

// @strict: true
// @declaration: true
// @showEmit
// @showEmittedFile: a.d.ts
// @showEmittedFile: b.d.ts

// @filename: a.ts
export interface Type {}

// @filename: b.ts
import { type Type } from "./a";

export const foo = (_: Type): void => {};
export const bar = (_: import("./a").Type): void => {};

Workbench Repro

🙁 Actual behavior

Refer to this program which invokes the ts.transpileDeclaration API:
https://github.com/MichaelMitchell-at/transpile_declaration_bug_repro/blob/bug2/transpile.mjs

Basic instructions to invoke it can be found in
https://github.com/MichaelMitchell-at/transpile_declaration_bug_repro/blob/bug2/README.md

When using the API, b.d.ts is emitted as

export declare const foo: (_: Type) => void;
export declare const bar: (_: any) => void;

while when using tsc it gets emitted as

import { type Type } from "./a";
export declare const foo: (_: Type) => void;
export declare const bar: (_: import("./a").Type) => void;

🙂 Expected behavior

Using the API should emit

import { type Type } from "./a";
export declare const foo: (_: Type) => void;
export declare const bar: (_: import("./a").Type) => void;

Additional information about the issue

[robpalme]

The bug description seems to have a typo because the Actual vs Expected code snippets are identical.

[fatcerberus]

I'm guessing the tsc and API output are mistakenly swapped under Actual Behavior.

[MichaelMitchell-at]

The bug description seems to have a typo because the Actual vs Expected code snippets are identical.

Corrected, thanks