Bug pylint 2588

ChangeLog

@@ -6,6 +6,9 @@ What's New in astroid 2.2.0?
 ============================
 Release Date: TBA
 
+* Fix a bug where a call to a function that has been previously called via functools.partial was wrongly inferred
+
+  Close PyCQA/pylint#2588
 
 * Fix a recursion error caused by inferring the ``slice`` builtin.
 

astroid/brain/brain_functools.py

@@ -12,6 +12,7 @@
 from astroid import helpers
 from astroid.interpreter import objectmodel
 from astroid import MANAGER
+from astroid import objects
 
 
 LRU_CACHE = "functools.lru_cache"
@@ -98,31 +99,8 @@ def _functools_partial_inference(node, context=None):
             "wrapped function received unknown parameters"
         )
 
-    # Return a wrapped() object that can be used further for inference
-    class PartialFunction(astroid.FunctionDef):
-
-        filled_positionals = len(call.positional_arguments[1:])
-        filled_keywords = list(call.keyword_arguments)
-
-        def infer_call_result(self, caller=None, context=None):
-            nonlocal call
-            filled_args = call.positional_arguments[1:]
-            filled_keywords = call.keyword_arguments
-
-            if context:
-                current_passed_keywords = {
-                    keyword for (keyword, _) in context.callcontext.keywords
-                }
-                for keyword, value in filled_keywords.items():
-                    if keyword not in current_passed_keywords:
-                        context.callcontext.keywords.append((keyword, value))
-
-                call_context_args = context.callcontext.args or []
-                context.callcontext.args = filled_args + call_context_args
-
-            return super().infer_call_result(caller=caller, context=context)
-
-    partial_function = PartialFunction(
+    partial_function = objects.PartialFunction(
+        call,
         name=inferred_wrapped_function.name,
         doc=inferred_wrapped_function.doc,
         lineno=inferred_wrapped_function.lineno,

astroid/node_classes.py

@@ -1217,8 +1217,16 @@ def _filter_stmts(self, stmts, frame, offset):
                 # want to clear previous assignments if any (hence the test on
                 # optional_assign)
                 if not (optional_assign or are_exclusive(_stmts[pindex], node)):
-                    del _stmt_parents[pindex]
-                    del _stmts[pindex]
+                    if (
+                        # In case of partial function node, if the statement is different
+                        # from the origin function then it can be deleted otherwise it should
+                        # remain to be able to correctly infer the call to origin function.
+                        not node.is_function
+                        or node.qname() != "PartialFunction"
+                        or node.name != _stmts[pindex].name
+                    ):
+                        del _stmt_parents[pindex]
+                        del _stmts[pindex]
             if isinstance(node, AssignName):
                 if not optional_assign and stmt.parent is mystmt.parent:
                     _stmts = []

astroid/objects.py

@@ -248,6 +248,35 @@ class DictValues(bases.Proxy):
     __repr__ = node_classes.NodeNG.__repr__
 
 
+class PartialFunction(scoped_nodes.FunctionDef):
+    """A class representing partial function obtained via functools.partial"""
+
+    def __init__(
+        self, call, name=None, doc=None, lineno=None, col_offset=None, parent=None
+    ):
+        super().__init__(name, doc, lineno, col_offset, parent)
+        self.filled_positionals = len(call.positional_arguments[1:])
+        self.filled_args = call.positional_arguments[1:]
+        self.filled_keywords = call.keyword_arguments
+
+    def infer_call_result(self, caller=None, context=None):
+        if context:
+            current_passed_keywords = {
+                keyword for (keyword, _) in context.callcontext.keywords
+            }
+            for keyword, value in self.filled_keywords.items():
+                if keyword not in current_passed_keywords:
+                    context.callcontext.keywords.append((keyword, value))
+
+            call_context_args = context.callcontext.args or []
+            context.callcontext.args = self.filled_args + call_context_args
+
+        return super().infer_call_result(caller=caller, context=context)
+
+    def qname(self):
+        return self.__class__.__name__
+
+
 # TODO: Hack to solve the circular import problem between node_classes and objects
 # This is not needed in 2.0, which has a cleaner design overall
 node_classes.Dict.__bases__ = (node_classes.NodeNG, DictInstance)

astroid/tests/unittest_brain.py

@@ -1776,9 +1776,12 @@ def other_test(a, b, *, c=1):
         partial(other_test, c=4)(1, 3) #@
         partial(other_test, 4, c=4)(4) #@
         partial(other_test, 4, c=4)(b=5) #@
+        test(1, 2) #@
+        partial(other_test, 1, 2)(c=3) #@
+        partial(test, b=4)(a=3) #@
         """
         )
-        expected_values = [4, 7, 7, 3, 12, 16, 32, 36]
+        expected_values = [4, 7, 7, 3, 12, 16, 32, 36, 3, 9, 7]
         for node, expected_value in zip(ast_nodes, expected_values):
             inferred = next(node.infer())
             assert isinstance(inferred, astroid.Const)