PHP Manual: Uri\WhatWg\Url::_

public function Uri\WhatWg\Url::__construct(string $uri, ?Uri\WhatWg\Url $baseUrl = null, array &$softErrors = null)

Constructs the Uri\WhatWg\Url object.

uri: A URL string to parse, for instance https://example.com/foo. A relative-URL string such as /foo is only accepted when baseUrl is given.
baseUrl: When a string is passed, uri is applied on baseUrl, if uri is a relative-URL string. If either null is passed, or uri is a not a relative-URL string, then baseUrl doesn't have any effect.
softErrors: An array to pass a list of Uri\WhatWg\UrlValidationError instances by reference to provide extended information about the errors triggered during parsing.

If the resulting URL is invalid, a Uri\WhatWg\InvalidUrlException is thrown.

Uri\WhatWg\Url::__construct