JS output contains imports only used in types when `emitDecoratorMetadata: true`

Bug Report

🔎 Search Terms

• emitDecoratorMetadata require
• emitDecoratorMetadata import

🕗 Version & Regression Information

• This is the behavior in every version I tried, and I reviewed the FAQ for entries about 3.3.3, 4.1.3

⏯ Playground Link

Playground link with relevant code

💻 Code

import * as vscode from 'vscode';

function LogMethod(
  target: any,
  propertyKey: string | symbol,
  descriptor: PropertyDescriptor
) {
  console.log(target);
  console.log(propertyKey);
  console.log(descriptor);
}

class Demo {
  @LogMethod
  public foo(bar: vscode.Memento) {
    // do nothing
  }
}

const demo = new Demo();

🙁 Actual behavior

The output contains const vscode = __importStar(require("vscode")); when emitDecoratorMetadata: true but not when emitDecoratorMetadata: false

🙂 Expected behavior

As the type of bar as nothing to do with the compiled JS, the import of vscode should not exist regardless of the value of emitDecoratorMetadata

Start with the linked TypeScript Playground example and compare the generated JavaScript with emitDecoratorMetadata enabled and disabled. The report names no repository files or tests, so locating the compiler path will require reading the relevant implementation. Done means the type-only vscode import is absent in both outputs.