Fix partial signatures for MixedObject

Now a MixedObject return the signatures of its CompiledObject all the time, fixes #1371

jedi/evaluate/compiled/access.py

@@ -175,6 +175,18 @@ def _force_unicode_decorator(func):
     return lambda *args, **kwargs: force_unicode(func(*args, **kwargs))
 
 
+def get_api_type(obj):
+    if inspect.isclass(obj):
+        return u'class'
+    elif inspect.ismodule(obj):
+        return u'module'
+    elif inspect.isbuiltin(obj) or inspect.ismethod(obj) \
+            or inspect.ismethoddescriptor(obj) or inspect.isfunction(obj):
+        return u'function'
+    # Everything else...
+    return u'instance'
+
+
 class DirectObjectAccess(object):
     def __init__(self, evaluator, obj):
         self._evaluator = evaluator
@@ -352,16 +364,7 @@ class DirectObjectAccess(object):
         raise ValueError("Object is type %s and not simple" % type(self._obj))
 
     def get_api_type(self):
-        obj = self._obj
-        if self.is_class():
-            return u'class'
-        elif inspect.ismodule(obj):
-            return u'module'
-        elif inspect.isbuiltin(obj) or inspect.ismethod(obj) \
-                or inspect.ismethoddescriptor(obj) or inspect.isfunction(obj):
-            return u'function'
-        # Everything else...
-        return u'instance'
+        return get_api_type(self._obj)
 
     def get_access_path_tuples(self):
         accesses = [create_access(self._evaluator, o) for o in self._get_objects_path()]

jedi/evaluate/compiled/mixed.py

@@ -18,7 +18,7 @@ from jedi.evaluate.context import ModuleContext
 from jedi.evaluate.cache import evaluator_function_cache
 from jedi.evaluate.compiled.getattr_static import getattr_static
 from jedi.evaluate.compiled.access import compiled_objects_cache, \
-    ALLOWED_GETITEM_TYPES
+    ALLOWED_GETITEM_TYPES, get_api_type
 from jedi.evaluate.compiled.context import create_cached_compiled_object
 from jedi.evaluate.gradual.conversion import to_stub
 
@@ -50,6 +50,11 @@ class MixedObject(ContextWrapper):
     def get_filters(self, *args, **kwargs):
         yield MixedObjectFilter(self.evaluator, self)
 
+    def get_signatures(self):
+        # Prefer `inspect.signature` over somehow analyzing Python code. It
+        # should be very precise, especially for stuff like `partial`.
+        return self.compiled_object.get_signatures()
+
     def py__call__(self, arguments):
         return (to_stub(self._wrapped_context) or self._wrapped_context).py__call__(arguments)
 
@@ -151,6 +156,7 @@ def _get_object_to_check(python_object):
 
 
 def _find_syntax_node_name(evaluator, python_object):
+    original_object = python_object
     try:
         python_object = _get_object_to_check(python_object)
         path = inspect.getsourcefile(python_object)
@@ -214,7 +220,13 @@ def _find_syntax_node_name(evaluator, python_object):
     # completions at some points but will lead to mostly correct type
     # inference, because people tend to define a public name in a module only
     # once.
-    return module_node, names[-1].parent, file_io, code_lines
+    tree_node = names[-1].parent
+    if tree_node.type == 'funcdef' and get_api_type(original_object) == 'instance':
+        # If an instance is given and we're landing on a function (e.g.
+        # partial in 3.5), something is completely wrong and we should not
+        # return that.
+        return None
+    return module_node, tree_node, file_io, code_lines
 
 
 @compiled_objects_cache('mixed_cache')