Fix #20745: Don't silence TypeError raised inside templates.

Thanks to robin for the report and claudep for the review.

django/template/base.py

@@ -3,7 +3,7 @@ from __future__ import unicode_literals
 import re
 from functools import partial
 from importlib import import_module
-from inspect import getargspec
+from inspect import getargspec, getcallargs
 
 from django.conf import settings
 from django.template.context import (BaseContext, Context, RequestContext,
@@ -788,10 +788,13 @@ class Variable(object):
                     else:
                         try: # method call (assuming no args required)
                             current = current()
-                        except TypeError: # arguments *were* required
-                            # GOTCHA: This will also catch any TypeError
-                            # raised in the function itself.
-                            current = settings.TEMPLATE_STRING_IF_INVALID  # invalid method call
+                        except TypeError:
+                            try:
+                                getcallargs(current)
+                            except TypeError: # arguments *were* required
+                                current = settings.TEMPLATE_STRING_IF_INVALID  # invalid method call
+                            else:
+                                raise
         except Exception as e:
             if getattr(e, 'silent_variable_failure', False):
                 current = settings.TEMPLATE_STRING_IF_INVALID

docs/releases/1.7.txt

@@ -282,6 +282,9 @@ Templates
   :setting:`TEMPLATE_DEBUG` is ``True``. This allows template origins to be
   inspected and logged outside of the ``django.template`` infrastructure.
 
+* ``TypeError`` exceptions are not longer silenced when raised during the
+  rendering of a template.
+
 Backwards incompatible changes in 1.7
 =====================================
 

tests/template_tests/tests.py

@@ -98,6 +98,9 @@ class SomeClass:
     def method4(self):
         raise SomeOtherException
 
+    def method5(self):
+        raise TypeError
+
     def __getitem__(self, key):
         if key == 'silent_fail_key':
             raise SomeException
@@ -680,6 +683,9 @@ class TemplateTests(TransRealMixin, TestCase):
             # Fail silently when accessing a non-simple method
             'basic-syntax20': ("{{ var.method2 }}", {"var": SomeClass()}, ("","INVALID")),
 
+            # Don't silence a TypeError if it was raised inside a callable
+            'basic-syntax20b': ("{{ var.method5 }}", {"var": SomeClass()}, TypeError),
+
             # Don't get confused when parsing something that is almost, but not
             # quite, a template tag.
             'basic-syntax21': ("a {{ moo %} b", {}, "a {{ moo %} b"),