Fix Qt 5.11 issues with clicking invalid links

See #3661

qutebrowser/browser/webelem.py

@@ -33,7 +33,8 @@ from PyQt5.QtGui import QMouseEvent
 from qutebrowser.config import config
 from qutebrowser.keyinput import modeman
 from qutebrowser.mainwindow import mainwindow
-from qutebrowser.utils import log, usertypes, utils, qtutils, objreg
+from qutebrowser.utils import (log, usertypes, utils, qtutils, objreg,
+                               urlutils, message)
 
 
 Group = enum.Enum('Group', ['all', 'links', 'images', 'url', 'inputs'])
@@ -275,11 +276,13 @@ class AbstractWebElement(collections.abc.MutableMapping):
         """Remove target from link."""
         raise NotImplementedError
 
-    def resolve_url(self, baseurl):
+    def resolve_url(self, baseurl, *, return_invalid=False):
         """Resolve the URL in the element's src/href attribute.
 
         Args:
             baseurl: The URL to base relative URLs on as QUrl.
+            return_invalid: Whether to return an invalid QUrl.
+                            If False, None is returned for invalid URLs.
 
         Return:
             A QUrl with the absolute URL, or None.
@@ -296,7 +299,7 @@ class AbstractWebElement(collections.abc.MutableMapping):
 
         url = QUrl(text)
         if not url.isValid():
-            return None
+            return url if return_invalid else None
         if url.isRelative():
             url = baseurl.resolved(url)
         qtutils.ensure_valid(url)
@@ -404,6 +407,15 @@ class AbstractWebElement(collections.abc.MutableMapping):
             self._click_fake_event(click_target)
             return
 
+        if qtutils.version_check('5.11', compiled=False):
+            # WORKAROUND for https://bugreports.qt.io/browse/QTBUG-63378
+            baseurl = self._tab.url()
+            url = self.resolve_url(baseurl, return_invalid=True)
+            if url is not None and not url.isValid():
+                msg = urlutils.get_errstring(url, "Invalid link clicked")
+                message.error(msg)
+                return
+
         if click_target == usertypes.ClickTarget.normal:
             if self.is_link():
                 log.webelem.debug("Clicking via JS click()")

qutebrowser/browser/webengine/webview.py

@@ -342,6 +342,11 @@ class WebEnginePage(QWebEnginePage):
                                                  navigation_type=type_map[typ],
                                                  is_main_frame=is_main_frame)
         self.navigation_request.emit(navigation)
+
+        if not url.isValid() and qtutils.version_check('5.11', compiled=False):
+            # WORKAROUND for https://bugreports.qt.io/browse/QTBUG-63378
+            return True
+
         return navigation.accepted
 
     @pyqtSlot('QUrl')

tests/unit/browser/webkit/test_webkitelem.py

@@ -872,3 +872,14 @@ def test_resolve_url_relative_base():
     elem = get_webelem(attributes={'href': 'foo'})
     with pytest.raises(ValueError):
         elem.resolve_url(QUrl('base'))
+
+
+@pytest.mark.parametrize('return_invalid', [True, False])
+def test_resolve_url_invalid(return_invalid):
+    elem = get_webelem(attributes={'href': 'what://::'})
+    baseurl = QUrl('http://www.example.com/')
+    resolved = elem.resolve_url(baseurl, return_invalid=return_invalid)
+    if return_invalid:
+        assert not resolved.isValid()
+    else:
+        assert resolved is None