slices should be ignored in __getitem__ settings (for now)

jedi/evaluate/__init__.py

@@ -109,7 +109,7 @@ class Evaluator(object):
             return f.filter_name(scopes)
         return f.find(scopes, resolve_decorator)
 
-    @memoize_default(default=(), evaluator_is_first_arg=True)
+    @memoize_default(default=[], evaluator_is_first_arg=True)
     @recursion.recursion_decorator
     @debug.increase_indent
     def eval_statement(self, stmt, seek_name=None):

jedi/evaluate/finder.py

@@ -11,7 +11,6 @@ would check whether a flow has the form of ``if isinstance(a, type_or_tuple)``.
 Unfortunately every other thing is being ignored (e.g. a == '' would be easy to
 check for -> a is a string). There's big potential in these checks.
 """
-import copy
 import sys
 
 from jedi._compatibility import hasattr, unicode, u, reraise

jedi/evaluate/representation.py

@@ -169,6 +169,12 @@ class Instance(use_metaclass(CachedMetaClass, Executable)):
             return False
 
     def get_index_types(self, indexes=[]):
+        if any([isinstance(i, iterable.Slice) for i in indexes]):
+            # Slice support in Jedi is very marginal, at the moment, so just
+            # ignore them in case of __getitem__.
+            # TODO support slices in a more general way.
+            indexes = []
+
         try:
             return self.execute_subscope_by_name('__getitem__', indexes)
         except KeyError:

test/completion/arrays.py

@@ -30,6 +30,9 @@ b = [6,7]
 #? int()
 b[8-7]
 
+# -----------------
+# Slices
+# -----------------
 #? list()
 b[8:]
 
@@ -37,6 +40,14 @@ b[8:]
 b[int():]
 
 
+class _StrangeSlice():
+    def __getitem__(self, slice):
+        return slice
+
+#? []
+_StrangeSlice()[1:2]
+
+
 # -----------------
 # iterable multiplication
 # -----------------