await fetch is dropped in 1.14.0

[kenrick95]

• Rollup Version: 1.14.0
• Operating System (or Browser): Windows 10 1809
• Node Version: v10.15.3

How Do We Reproduce?

REPL

main.js

import fetchAndDecode from './util.js';

fetchAndDecode();

util.js

export default async function fetchAndDecode() {
	const response = await fetch('https://example.com');
	return response.json();
}

Expected Behavior

await is not dropped. This is the UMD output from Rollup 1.13.0. REPL

(function (factory) {
	typeof define === 'function' && define.amd ? define(factory) :
	factory();
}(function () { 'use strict';

	async function fetchAndDecode() {
		const response = await fetch('https://example.com');
	 	return response.json();
	}

	fetchAndDecode();

}));

Actual Behavior

This is the UMD output in Rollup 1.14.0

(function (factory) {
	typeof define === 'function' && define.amd ? define(factory) :
	factory();
}(function () { 'use strict';

	async function fetchAndDecode() {
		const response; // <-- the `await` is dropped, creating a Syntax Error
	 	return response.json();
	}

	fetchAndDecode();

}));

[RomanHotsiy]

I'm seeing a similar more generic issue on 1.14.0:

REPL

main.js

export async function handler() {
	await test();
}

async function test() {
	console.log('test');
}

Expected Behavior

CJS output from rollup 1.14.0:

'use strict';

Object.defineProperty(exports, '__esModule', { value: true });

async function handler() {
	 await test();
}

async function test() {
	console.log('test');
}

exports.handler = handler;

Actual Behavior

CJS output from rollup 1.13.1:

'use strict';

Object.defineProperty(exports, '__esModule', { value: true });

async function handler() {
	 await test();
}

exports.handler = handler;

The test function is dropped!

[lukastaegert]

Fix at #2899

[RomanHotsiy]

That was fast 🔥! Thanks!

[lukastaegert]

Sorry for the inconvenience, should be fixed in 1.14.1 now.

[kenrick95]

Thanks a lot!