Work around QUrl::query() not being available with PyQt 5.9.1

See https://www.riverbankcomputing.com/pipermail/pyqt/2017-November/039702.html

doc/changelog.asciidoc

@@ -64,6 +64,8 @@ Fixed
 - Sites like `qute://help` now redirect to `qute://help/` to make sure links
   work properly.
 - Fixes for the size calculation of pinned tabs in the tab bar.
+- Worked around a crash with PyQt 5.9.1 compiled against Qt < 5.9.1 when using
+  :yank or qute:// URLs.
 
 Deprecated
 ~~~~~~~~~~

qutebrowser/browser/commands.py

@@ -814,7 +814,7 @@ class CommandDispatcher:
             flags |= QUrl.FullyEncoded
         url = QUrl(self._current_url())
         url_query = QUrlQuery()
-        url_query_str = url.query()
+        url_query_str = urlutils.query_string(url)
         if '&' not in url_query_str and ';' in url_query_str:
             url_query.setQueryDelimiters('=', ';')
         url_query.setQuery(url_query_str)

qutebrowser/browser/qutescheme.py

@@ -36,7 +36,7 @@ from PyQt5.QtCore import QUrlQuery, QUrl
 import qutebrowser
 from qutebrowser.config import config, configdata, configexc, configdiff
 from qutebrowser.utils import (version, utils, jinja, log, message, docutils,
-                               objreg)
+                               objreg, urlutils)
 from qutebrowser.misc import objects
 
 
@@ -137,7 +137,7 @@ def data_for_url(url):
     """
     path = url.path()
     host = url.host()
-    query = url.query()
+    query = urlutils.query_string(url)
     # A url like "qute:foo" is split as "scheme:path", not "scheme:host".
     log.misc.debug("url: {}, path: {}, host {}".format(
         url.toDisplayString(), path, host))

qutebrowser/utils/urlutils.py

@@ -26,7 +26,7 @@ import ipaddress
 import posixpath
 import urllib.parse
 
-from PyQt5.QtCore import QUrl
+from PyQt5.QtCore import QUrl, QUrlQuery
 from PyQt5.QtNetwork import QHostInfo, QHostAddress, QNetworkProxy
 
 from qutebrowser.config import config
@@ -615,6 +615,18 @@ def safe_display_string(qurl):
     return qurl.toDisplayString()
 
 
+def query_string(qurl):
+    """Get a query string for the given URL.
+
+    This is a WORKAROUND for:
+    https://www.riverbankcomputing.com/pipermail/pyqt/2017-November/039702.html
+    """
+    try:
+        return qurl.query()
+    except AttributeError:  # pragma: no cover
+        return QUrlQuery(qurl).query()
+
+
 class InvalidProxyTypeError(Exception):
 
     """Error raised when proxy_from_url gets an unknown proxy type."""

tests/unit/utils/test_urlutils.py

@@ -758,6 +758,11 @@ def test_safe_display_string_invalid():
         urlutils.safe_display_string(QUrl())
 
 
+def test_query_string():
+    url = QUrl('https://www.example.com/?foo=bar')
+    assert urlutils.query_string(url) == 'foo=bar'
+
+
 class TestProxyFromUrl:
 
     @pytest.mark.parametrize('url, expected', [