Make sure docstrings can always be inferred for builtins modules, fixes #1432

jedi/inference/syntax_tree.py

@@ -45,7 +45,16 @@ def _limit_value_infers(func):
         inference_state = context.inference_state
         try:
             inference_state.inferred_element_counts[n] += 1
-            if inference_state.inferred_element_counts[n] > 300:
+            maximum = 300
+            if context.parent_context is None \
+                    and context.get_value() is inference_state.builtins_module:
+                # Builtins should have a more generous inference limit.
+                # It is important that builtins can be executed, otherwise some
+                # functions that depend on certain builtins features would be
+                # broken, see e.g. GH #1432
+                maximum *= 100
+
+            if inference_state.inferred_element_counts[n] > maximum:
                 debug.warning('In value %s there were too many inferences.', n)
                 return NO_VALUES
         except KeyError:

jedi/inference/value/instance.py

@@ -518,7 +518,7 @@ class InstanceClassFilter(AbstractFilter):
         ]
 
     def __repr__(self):
-        return '<%s for %s>' % (self.__class__.__name__, self._class_filter.context)
+        return '<%s for %s>' % (self.__class__.__name__, self._class_filter)
 
 
 class SelfAttributeFilter(ClassFilter):

test/test_api/test_api.py

@@ -10,6 +10,7 @@ import pytest
 from pytest import raises
 from parso import cache
 
+from jedi._compatibility import unicode
 from jedi import preload_module
 from jedi.inference.gradual import typeshed
 
@@ -311,3 +312,8 @@ def test_goto_follow_builtin_imports(Script):
     assert d.in_builtin_module() is True
     d, = s.goto_assignments(follow_imports=True, follow_builtin_imports=True)
     assert d.in_builtin_module() is True
+
+
+def test_docstrings_for_completions(Script):
+    for c in Script('').completions():
+        assert isinstance(c.docstring(), (str, unicode))