Implement support for TypeVar inference for __new__

CHANGELOG.rst

@@ -10,7 +10,9 @@ Unreleased
 - Removed support for Python 3.8 and 3.9
 - Upgraded Typeshed
 - Better support for Final/ClassVar
-- ``__new__`` is now also recognized as a signature
+- ``__new__`` is now also recognized as a signature and TypeVar inference
+- Support for ``Self``
+- Support for ``TypeAlias``, generics for ``type[...]`` and ``tuple[...]``
 
 0.19.2 (2024-11-10)
 +++++++++++++++++++

jedi/inference/value/instance.py

@@ -17,7 +17,7 @@ from jedi.inference.arguments import ValuesArguments, TreeArgumentsWrapper
 from jedi.inference.value.function import \
     FunctionValue, FunctionMixin, OverloadedFunctionValue, \
     BaseFunctionExecutionContext, FunctionExecutionContext, FunctionNameInClass
-from jedi.inference.value.klass import ClassFilter
+from jedi.inference.value.klass import ClassFilter, init_or_new_func
 from jedi.inference.value.dynamic_arrays import get_dynamic_array_instance
 from jedi.parser_utils import function_is_staticmethod, function_is_classmethod
 
@@ -327,7 +327,7 @@ class TreeInstance(_BaseTreeInstance):
             infer_type_vars_for_execution
 
         args = InstanceArguments(self, self._arguments)
-        for signature in self.class_value.py__getattribute__('__init__').get_signatures():
+        for signature in init_or_new_func(self.class_value).get_signatures():
             # Just take the first result, it should always be one, because we
             # control the typeshed code.
             funcdef = signature.value.tree_node

jedi/inference/value/klass.py

@@ -376,19 +376,8 @@ class ClassMixin:
             if sigs:
                 return sigs
         args = ValuesArguments([])
-        init_funcs = self.py__call__(args).py__getattribute__('__init__')
+        instance = self.py__call__(args)
-        if len(init_funcs) == 1:
+        init_funcs = init_or_new_func(instance)
-            init = next(iter(init_funcs))
-            try:
-                class_context = init.class_context
-            except AttributeError:
-                pass
-            else:
-                # In the case where we are on object.__init__, we try to use
-                # __new__.
-                if class_context.get_root_context().is_builtins_module() \
-                        and init.class_context.name.string_name == "object":
-                    init_funcs = self.py__call__(args).py__getattribute__('__new__')
 
         dataclass_sigs = self._get_dataclass_transform_signatures()
         if dataclass_sigs:
@@ -481,6 +470,23 @@ class ClassMixin:
         return ValueSet({self})
 
 
+def init_or_new_func(value):
+    init_funcs = value.py__getattribute__('__init__')
+    if len(init_funcs) == 1:
+        init = next(iter(init_funcs))
+        try:
+            class_context = init.class_context
+        except AttributeError:
+            pass
+        else:
+            # In the case where we are on object.__init__, we try to use
+            # __new__.
+            if class_context.get_root_context().is_builtins_module() \
+                    and init.class_context.name.string_name == "object":
+                return value.py__getattribute__('__new__')
+    return init_funcs
+
+
 class DataclassParamName(BaseTreeParamName):
     """
     Represent a field declaration on a class with dataclass semantics.

test/completion/arrays.py

@@ -435,9 +435,9 @@ list(set(list(set(a))))[1]
 list(set(set(a)))[1]
 
 # frozenset
-##? int() str()
+#? int() str()
 list(frozenset(a))[1]
-##? int() str()
+#? int() str()
 list(set(frozenset(a)))[1]
 
 # iter

test/completion/pep0484_generic_parameters.py

@@ -11,6 +11,7 @@ from typing import (
     TypeVar,
     Union,
     Sequence,
+    Self,
 )
 
 K = TypeVar('K')
@@ -395,3 +396,11 @@ def generic_func2(arg: T) -> Union[int, str, T]: pass
 generic_func1(b"hello")
 #? int() str() bytes()
 generic_func2(b"hello")
+
+class CustomGeneric2(Generic[T_co]):
+    val: T_co
+    def __init__(cls, val: T_co) -> Self:
+        raise NotImplementedError
+
+#? int()
+CustomGeneric2(1).val

test/static_analysis/comprehensions.py

@@ -8,8 +8,6 @@
 #! 12 type-error-not-iterable
 [a for a in 1]
 
-# TODO wrong?
-#! 10 type-error-too-many-arguments
 tuple(str(a) for a in [1])
 
 #! 8 type-error-operation