Add codemod to fix variadic callable annotations (#1269)

* add fix variadic callable codemod

* format

libcst/codemod/commands/fix_variadic_callable.py

@@ -0,0 +1,40 @@
+# Copyright (c) Meta Platforms, Inc. and affiliates.
+#
+# This source code is licensed under the MIT license found in the
+# LICENSE file in the root directory of this source tree.
+#
+# pyre-strict
+
+import libcst as cst
+import libcst.matchers as m
+from libcst.codemod import VisitorBasedCodemodCommand
+from libcst.metadata import QualifiedName, QualifiedNameProvider, QualifiedNameSource
+
+
+class FixVariadicCallableCommmand(VisitorBasedCodemodCommand):
+    DESCRIPTION: str = (
+        "Fix incorrect variadic callable type annotations from `Callable[[...], T]` to `Callable[..., T]``"
+    )
+
+    METADATA_DEPENDENCIES = (QualifiedNameProvider,)
+
+    def leave_Subscript(
+        self, original_node: cst.Subscript, updated_node: cst.Subscript
+    ) -> cst.BaseExpression:
+        if QualifiedNameProvider.has_name(
+            self,
+            original_node,
+            QualifiedName(name="typing.Callable", source=QualifiedNameSource.IMPORT),
+        ):
+            node_matches = len(updated_node.slice) == 2 and m.matches(
+                updated_node.slice[0],
+                m.SubscriptElement(
+                    slice=m.Index(value=m.List(elements=[m.Element(m.Ellipsis())]))
+                ),
+            )
+
+            if node_matches:
+                slices = list(updated_node.slice)
+                slices[0] = cst.SubscriptElement(cst.Index(cst.Ellipsis()))
+                return updated_node.with_changes(slice=slices)
+        return updated_node

libcst/codemod/commands/tests/test_fix_variadic_callable.py

@@ -0,0 +1,92 @@
+# Copyright (c) Meta Platforms, Inc. and affiliates.
+#
+# This source code is licensed under the MIT license found in the
+# LICENSE file in the root directory of this source tree.
+#
+# pyre-strict
+
+from libcst.codemod import CodemodTest
+from libcst.codemod.commands.fix_variadic_callable import FixVariadicCallableCommmand
+
+
+class TestFixVariadicCallableCommmand(CodemodTest):
+    TRANSFORM = FixVariadicCallableCommmand
+
+    def test_callable_typing(self) -> None:
+        before = """
+            from typing import Callable
+            x: Callable[[...], int] = ...
+        """
+        after = """
+            from typing import Callable
+            x: Callable[..., int] = ...
+        """
+        self.assertCodemod(before, after)
+
+    def test_callable_typing_alias(self) -> None:
+        before = """
+            import typing as t
+            x: t.Callable[[...], int] = ...
+        """
+        after = """
+            import typing as t
+            x: t.Callable[..., int] = ...
+        """
+        self.assertCodemod(before, after)
+
+    def test_callable_import_alias(self) -> None:
+        before = """
+            from typing import Callable as C
+            x: C[[...], int] = ...
+        """
+        after = """
+            from typing import Callable as C
+            x: C[..., int] = ...
+        """
+        self.assertCodemod(before, after)
+
+    def test_callable_with_optional(self) -> None:
+        before = """
+            from typing import Callable
+            def foo(bar: Optional[Callable[[...], int]]) -> Callable[[...], int]:
+                ...
+        """
+        after = """
+            from typing import Callable
+            def foo(bar: Optional[Callable[..., int]]) -> Callable[..., int]:
+                ...
+        """
+        self.assertCodemod(before, after)
+
+    def test_callable_with_arguments(self) -> None:
+        before = """
+            from typing import Callable
+            x: Callable[[int], int]
+        """
+        after = """
+            from typing import Callable
+            x: Callable[[int], int]
+        """
+        self.assertCodemod(before, after)
+
+    def test_callable_with_variadic_arguments(self) -> None:
+        before = """
+            from typing import Callable
+            x: Callable[[int, int, ...], int]
+        """
+        after = """
+            from typing import Callable
+            x: Callable[[int, int, ...], int]
+        """
+        self.assertCodemod(before, after)
+
+    def test_callable_no_arguments(self) -> None:
+        before = """
+            from typing import Callable
+            x: Callable
+        """
+        after = """
+            from typing import Callable
+            x: Callable
+        """
+        self.assertCodemod(before, after)