Make it possible to infer Callable TypeVars, fixes #1449

jedi/inference/gradual/annotation.py

@@ -277,6 +277,39 @@ def infer_type_vars_for_execution(function, arguments, annotation_dict):
     return annotation_variable_results
 
 
+def infer_return_for_callable(arguments, param_values, result_values):
+    result = NO_VALUES
+    for pv in param_values:
+        if pv.array_type == 'list':
+            type_var_dict = infer_type_vars_for_callable(arguments, pv.py__iter__())
+
+            result |= ValueSet.from_sets(
+                v.define_generics(type_var_dict)
+                if isinstance(v, (DefineGenericBase, TypeVar)) else ValueSet({v})
+                for v in result_values
+            ).execute_annotation()
+    return result
+
+
+def infer_type_vars_for_callable(arguments, lazy_params):
+    """
+    Infers type vars for the Calllable class:
+
+        def x() -> Callable[[Callable[..., _T]], _T]: ...
+    """
+    annotation_variable_results = {}
+    for (_, lazy_value), lazy_callable_param in zip(arguments.unpack(), lazy_params):
+        callable_param_values = lazy_callable_param.infer()
+        # Infer unknown type var
+        actual_value_set = lazy_value.infer()
+        for v in callable_param_values:
+            _merge_type_var_dicts(
+                annotation_variable_results,
+                _infer_type_vars(v, actual_value_set),
+            )
+    return annotation_variable_results
+
+
 def _merge_type_var_dicts(base_dict, new_dict):
     for type_var_name, values in new_dict.items():
         if values:
@@ -419,16 +452,21 @@ def find_unknown_type_vars(context, node):
                 for subscript_node in _unpack_subscriptlist(trailer.children[1]):
                     check_node(subscript_node)
         else:
-            type_var_set = context.infer_node(node)
+            found[:] = _filter_type_vars(context.infer_node(node), found)
-            for type_var in type_var_set:
-                if isinstance(type_var, TypeVar) and type_var not in found:
-                    found.append(type_var)
 
     found = []  # We're not using a set, because the order matters.
     check_node(node)
     return found
 
 
+def _filter_type_vars(value_set, found=()):
+    new_found = list(found)
+    for type_var in value_set:
+        if isinstance(type_var, TypeVar) and type_var not in found:
+            new_found.append(type_var)
+    return new_found
+
+
 def _unpack_subscriptlist(subscriptlist):
     if subscriptlist.type == 'subscriptlist':
         for subscript in subscriptlist.children[::2]:

jedi/inference/gradual/base.py

@@ -297,6 +297,9 @@ class BaseTypingValue(LazyValueWrapper):
     def _get_wrapped_value(self):
         return _PseudoTreeNameClass(self.parent_context, self._tree_name)
 
+    def __repr__(self):
+        return '%s(%s)' % (self.__class__.__name__, self._tree_name.value)
+
 
 class BaseTypingValueWithGenerics(DefineGenericBase):
     def __init__(self, parent_context, tree_name, generics_manager):
@@ -307,3 +310,7 @@ class BaseTypingValueWithGenerics(DefineGenericBase):
 
     def _get_wrapped_value(self):
         return _PseudoTreeNameClass(self.parent_context, self._tree_name)
+
+    def __repr__(self):
+        return '%s(%s%s)' % (self.__class__.__name__, self._tree_name.value,
+                             self._generics_manager)

jedi/inference/gradual/generics.py

@@ -74,6 +74,9 @@ class LazyGenericManager(_AbstractGenericManager):
                 return True
         return False
 
+    def __repr__(self):
+        return '<LazyG>[%s]' % (', '.join(repr(x) for x in self.to_tuple()))
+
 
 class TupleGenericManager(_AbstractGenericManager):
     def __init__(self, tup):
@@ -90,3 +93,6 @@ class TupleGenericManager(_AbstractGenericManager):
 
     def is_homogenous_tuple(self):
         return False
+
+    def __repr__(self):
+        return '<TupG>[%s]' % (', '.join(repr(x) for x in self.to_tuple()))

jedi/inference/gradual/typing.py

@@ -216,8 +216,19 @@ class TypeAlias(LazyValueWrapper):
 
 class Callable(BaseTypingValueWithGenerics):
     def py__call__(self, arguments):
+        """
+            def x() -> Callable[[Callable[..., _T]], _T]: ...
+        """
         # The 0th index are the arguments.
-        return self._generics_manager.get_index_and_execute(1)
+        try:
+            param_values = self._generics_manager[0]
+            result_values = self._generics_manager[1]
+        except IndexError:
+            debug.warning('Callable[...] defined without two arguments')
+            return NO_VALUES
+        else:
+            from jedi.inference.gradual.annotation import infer_return_for_callable
+            return infer_return_for_callable(arguments, param_values, result_values)
 
 
 class Tuple(LazyValueWrapper):

test/completion/pep0484_typing.py

@@ -420,6 +420,19 @@ xxx([0])[1]
 #?
 xxx([0])[2]
 
+def call_pls() -> typing.Callable[[TYPE_VARX], TYPE_VARX]: ...
+#? int()
+call_pls()(1)
+
+def call2_pls() -> typing.Callable[[str, typing.Callable[[int], TYPE_VARX]], TYPE_VARX]: ...
+#? float()
+call2_pls('')(1, lambda x: 3.0)
+
+def call3_pls() -> typing.Callable[[typing.Callable[[int], TYPE_VARX]], typing.List[TYPE_VARX]]: ...
+def the_callable() -> float: ...
+#? float()
+call3_pls()(the_callable)[0]
+
 # -------------------------
 # TYPE_CHECKING
 # -------------------------

test/completion/stdlib.py

@@ -329,3 +329,24 @@ X.attr_y.value
 X().name
 #? float()
 X().attr_x.attr_y.value
+
+
+# -----------------
+# functools Python 3.8
+# -----------------
+
+# python >= 3.8
+
+@functools.lru_cache
+def x() -> int: ...
+@functools.lru_cache()
+def y() -> float: ...
+@functools.lru_cache(8)
+def z() -> str: ...
+
+#? int()
+x()
+#? float()
+y()
+#? str()
+z()