Fix #4070, #4111: crashes when the warning message contains format strings (again)

CHANGES

@@ -22,6 +22,7 @@ Bugs fixed
 * #4100: Remove debug print from autodoc extension
 * #3987: Changing theme from alabaster causes HTML build to fail
 * #4096: C++, don't crash when using the wrong role type. Thanks to mitya57.
+* #4070, #4111: crashes when the warning message contains format strings (again)
 
 Testing
 --------

sphinx/util/logging.py

@@ -356,11 +356,15 @@ class WarningIsErrorFilter(logging.Filter):
             return True
         elif self.app.warningiserror:
             location = getattr(record, 'location', '')
-            message = record.msg.replace('%', '%%')
+            try:
+                message = record.msg % record.args
+            except TypeError:
+                message = record.msg  # use record.msg itself
+
             if location:
-                raise SphinxWarning(location + ":" + message % record.args)
+                raise SphinxWarning(location + ":" + message)
             else:
-                raise SphinxWarning(message % record.args)
+                raise SphinxWarning(message)
         else:
             return True
 

tests/test_util_logging.py

@@ -165,7 +165,11 @@ def test_warningiserror(app, status, warning):
     # if True, warning raises SphinxWarning exception
     app.warningiserror = True
     with pytest.raises(SphinxWarning):
-        logger.warning('message')
+        logger.warning('message: %s', 'arg')
+
+    # message contains format string (refs: #4070)
+    with pytest.raises(SphinxWarning):
+        logger.warning('%s')
 
 
 def test_warning_location(app, status, warning):