mypy: Turn on warn_unreachable

mypy.ini

@@ -17,6 +17,7 @@ disallow_untyped_decorators = True
 # check_untyped_defs = True
 # no_implicit_optional = True
 # warn_return_any = True
+warn_unreachable = True
 
 # Other strictness flags
 strict_equality = True

qutebrowser/browser/webkit/webkitelem.py

@@ -172,7 +172,8 @@ class WebKitElement(webelem.AbstractWebElement):
     def _parent(self) -> typing.Optional['WebKitElement']:
         """Get the parent element of this element."""
         self._check_vanished()
-        elem = self._elem.parent()
+        elem = typing.cast(typing.Optional[QWebElement],
+                           self._elem.parent())
         if elem is None or elem.isNull():
             return None
         return WebKitElement(elem, tab=self._tab)

qutebrowser/mainwindow/tabwidget.py

@@ -19,6 +19,7 @@
 
 """The tab widget used for TabbedBrowser from browser.py."""
 
+import typing
 import functools
 import contextlib
 
@@ -347,7 +348,8 @@ class TabWidget(QTabWidget):
 
     def setTabIcon(self, idx: int, icon: QIcon):
         """Always show tab icons for pinned tabs in some circumstances."""
-        tab = self.widget(idx)
+        tab = typing.cast(typing.Optional[browsertab.AbstractTab],
+                          self.widget(idx))
         if (icon.isNull() and
                 config.cache['tabs.favicons.show'] != 'never' and
                 config.cache['tabs.pinned.shrink'] and

qutebrowser/misc/checkpyver.py

@@ -49,7 +49,8 @@ def check_python_version():
         version_str = '.'.join(map(str, sys.version_info[:3]))
         text = ("At least Python 3.5 is required to run qutebrowser, but " +
                 "it's running with " + version_str + ".\n")
-        if Tk and '--no-err-windows' not in sys.argv:  # pragma: no cover
+        if (Tk and  # type: ignore
+                '--no-err-windows' not in sys.argv):  # pragma: no cover
             root = Tk()
             root.withdraw()
             messagebox.showerror("qutebrowser: Fatal error!", text)

qutebrowser/misc/crashsignal.py

@@ -172,7 +172,7 @@ class CrashHandler(QObject):
         if sys.__stderr__ is not None:
             faulthandler.enable(sys.__stderr__)
         else:
-            faulthandler.disable()
+            faulthandler.disable()  # type: ignore
         try:
             self._crash_log_file.close()
             os.remove(self._crash_log_file.name)

qutebrowser/utils/log.py

@@ -259,7 +259,7 @@ def _init_handlers(level, color, force_color, json_logging, ram_capacity):
         level, color, force_color, json_logging)
 
     if sys.stderr is None:
-        console_handler = None
+        console_handler = None  # type: ignore
     else:
         strip = False if force_color else None
         if use_colorama:
@@ -313,7 +313,7 @@ def _init_formatters(level, color, force_color, json_logging):
     html_formatter = HTMLFormatter(EXTENDED_FMT_HTML, DATEFMT,
                                    log_colors=LOG_COLORS)
     if sys.stderr is None:
-        return None, ram_formatter, html_formatter, False
+        return None, ram_formatter, html_formatter, False  # type: ignore
 
     if json_logging:
         console_formatter = JSONFormatter()

qutebrowser/utils/version.py

@@ -352,9 +352,9 @@ def _chromium_version():
     Also see https://www.chromium.org/developers/calendar
     and https://chromereleases.googleblog.com/
     """
-    if webenginesettings is None or QWebEngineProfile is None:
+    if webenginesettings is None or QWebEngineProfile is None:  # type: ignore
         # This should never happen
-        return 'unavailable'
+        return 'unavailable'  # type: ignore
     ua = webenginesettings.default_user_agent
     if ua is None:
         profile = QWebEngineProfile.defaultProfile()