Rollup 2.36.* produces invalid output

[IronGeek]

• Rollup Version: >=2.36.0 (including the latest 2.36.1)
• Operating System (or Browser): any
• Node Version (if applicable):
• Link to reproduction (IMPORTANT, read below): repl

Rollup >=2.36.0 produces invalid output when used to bundle the following code:

const LANGUAGE_DEFAULT = 'en';
let _isWindows = false;
let _isMacintosh = false;
let _isLinux = false;
let _isNative = false;
let _isWeb = false;
let _isIOS = false;
let _locale = undefined;
let _language = LANGUAGE_DEFAULT;
let _translationsConfigFile = undefined;
let _userAgent = undefined;
const isElectronRenderer = (typeof process !== 'undefined' && typeof process.versions !== 'undefined' && typeof process.versions.electron !== 'undefined' && process.type === 'renderer');
// OS detection
if (typeof navigator === 'object' && !isElectronRenderer) {
    _userAgent = navigator.userAgent;
    _isWindows = _userAgent.indexOf('Windows') >= 0;
    _isMacintosh = _userAgent.indexOf('Macintosh') >= 0;
    _isIOS = (_userAgent.indexOf('Macintosh') >= 0 || _userAgent.indexOf('iPad') >= 0 || _userAgent.indexOf('iPhone') >= 0) && !!navigator.maxTouchPoints && navigator.maxTouchPoints > 0;
    _isLinux = _userAgent.indexOf('Linux') >= 0;
    _isWeb = true;
    _locale = navigator.language;
    _language = _locale;
}
else if (typeof process === 'object') {
    _isWindows = (process.platform === 'win32');
    _isMacintosh = (process.platform === 'darwin');
    _isLinux = (process.platform === 'linux');
    _locale = LANGUAGE_DEFAULT;
    _language = LANGUAGE_DEFAULT;    
    _isNative = true;
}
...

Expected Behavior

Produce valid output (rollup v2.35.1 produces this valid result)

...
if (typeof navigator === 'object' && !isElectronRenderer) {
  _userAgent = navigator.userAgent;
  _isWindows = _userAgent.indexOf('Windows') >= 0;
  _isMacintosh = _userAgent.indexOf('Macintosh') >= 0;
  _isIOS = (_userAgent.indexOf('Macintosh') >= 0 || _userAgent.indexOf('iPad') >= 0 || _userAgent.indexOf('iPhone') >= 0) && !!navigator.maxTouchPoints && navigator.maxTouchPoints > 0;
  _isLinux = _userAgent.indexOf('Linux') >= 0;
}
else if (typeof process === 'object') {
  _isWindows = (process.platform === 'win32');
  _isMacintosh = (process.platform === 'darwin');
  _isLinux = (process.platform === 'linux');
}
...

Actual Behavior

Produce invalid output:

...
if (typeof navigator === 'object' && !isElectronRenderer) {
  _userAgent = navigator.userAgent;
  _userAgent.indexOf('Windows') >= 0;
  _userAgent.indexOf('Macintosh') >= 0;
  (_userAgent.indexOf('Macintosh') >= 0 || _userAgent.indexOf('iPad') >= 0 || _userAgent.indexOf('iPhone') >= 0) && !!navigator.maxTouchPoints && navigator.maxTouchPoints > 0;
  _userAgent.indexOf('Linux') >= 0;
}
else if (typeof process === 'object') {
  process.platform === 'win32');
  process.platform === 'darwin');
  process.platform === 'linux');
}
...

[lukastaegert]

Could you please clarify further what is the invalid part? Wrong parentheses? Code removed that is essential?

[IronGeek]

Yes, part of the code is removed which resulted in syntax error.
Result in repro here might be slightly different, but in my real project it produces the following code:

else if (typeof process === 'object') {
        _isWindows = (process.platform === 'win32');
        _isMacintosh = (process.platform === 'darwin');
        process.platform === 'linux');  // <--- here 
        _locale = LANGUAGE_DEFAULT;
        _language = LANGUAGE_DEFAULT;
...

notice that the line is missing an opening parenthesis and variable assignment

[lukastaegert]

Thanks! I will investigate.

[lukastaegert]

Fix at #3926