feat(commands): support 3.12's type statement and TypeAliasType (#…

…1128)

changelog/1128.feature.rst

@@ -0,0 +1 @@
+|commands| Support Python 3.12's ``type`` statement and :class:`py:typing.TypeAliasType` annotations in command signatures.

disnake/utils.py

@@ -1122,6 +1122,24 @@ def normalise_optional_params(parameters: Iterable[Any]) -> Tuple[Any, ...]:
     return tuple(p for p in parameters if p is not none_cls) + (none_cls,)
 
 
+def _resolve_typealiastype(
+    tp: Any, globals: Dict[str, Any], locals: Dict[str, Any], cache: Dict[str, Any]
+):
+    # Use __module__ to get the (global) namespace in which the type alias was defined.
+    if mod := sys.modules.get(tp.__module__):
+        mod_globals = mod.__dict__
+        if mod_globals is not globals or mod_globals is not locals:
+            # if the namespace changed (usually when a TypeAliasType was imported from a different module),
+            # drop the cache since names can resolve differently now
+            cache = {}
+        globals = locals = mod_globals
+
+    # Accessing `__value__` automatically evaluates the type alias in the annotation scope.
+    # (recurse to resolve possible forwardrefs, aliases, etc.)
+    return evaluate_annotation(tp.__value__, globals, locals, cache)
+
+
+# FIXME: this should be split up into smaller functions for clarity and easier maintenance
 def evaluate_annotation(
     tp: Any,
     globals: Dict[str, Any],
@@ -1147,23 +1165,31 @@ def evaluate_annotation(
         cache[tp] = evaluated
         return evaluated
 
+    # GenericAlias / UnionType
     if hasattr(tp, "__args__"):
-        implicit_str = True
-        is_literal = False
-        orig_args = args = tp.__args__
         if not hasattr(tp, "__origin__"):
             if tp.__class__ is UnionType:
-                converted = Union[args]  # type: ignore
+                converted = Union[tp.__args__]  # type: ignore
                 return evaluate_annotation(converted, globals, locals, cache)
 
             return tp
-        if tp.__origin__ is Union:
+
+        implicit_str = True
+        is_literal = False
+        orig_args = args = tp.__args__
+        orig_origin = origin = tp.__origin__
+
+        # origin can be a TypeAliasType too, resolve it and continue
+        if hasattr(origin, "__value__"):
+            origin = _resolve_typealiastype(origin, globals, locals, cache)
+
+        if origin is Union:
             try:
                 if args.index(type(None)) != len(args) - 1:
                     args = normalise_optional_params(tp.__args__)
             except ValueError:
                 pass
-        if tp.__origin__ is Literal:
+        if origin is Literal:
             if not PY_310:
                 args = flatten_literal_params(tp.__args__)
             implicit_str = False
@@ -1179,13 +1205,21 @@ def evaluate_annotation(
         ):
             raise TypeError("Literal arguments must be of type str, int, bool, or NoneType.")
 
+        if origin != orig_origin:
+            # we can't use `copy_with` in this case, so just skip all of the following logic
+            return origin[evaluated_args]
+
         if evaluated_args == orig_args:
             return tp
 
         try:
             return tp.copy_with(evaluated_args)
         except AttributeError:
-            return tp.__origin__[evaluated_args]
+            return origin[evaluated_args]
+
+    # TypeAliasType, 3.12+
+    if hasattr(tp, "__value__"):
+        return _resolve_typealiastype(tp, globals, locals, cache)
 
     return tp
 

tests/test_utils.py

@@ -9,7 +9,7 @@
 import warnings
 from dataclasses import dataclass
 from datetime import timedelta, timezone
-from typing import Any, Dict, List, Literal, Optional, Tuple, Union
+from typing import TYPE_CHECKING, Any, Dict, List, Literal, Optional, Tuple, TypeVar, Union
 from unittest import mock
 
 import pytest
@@ -18,7 +18,13 @@
 import disnake
 from disnake import utils
 
-from . import helpers
+from . import helpers, utils_helper_module
+
+if TYPE_CHECKING:
+    from typing_extensions import TypeAliasType
+elif sys.version_info >= (3, 12):
+    # non-3.12 tests shouldn't be using this
+    from typing import TypeAliasType
 
 
 def test_missing() -> None:
@@ -785,6 +791,65 @@ def test_resolve_annotation_literal() -> None:
         utils.resolve_annotation(Literal[timezone.utc, 3], globals(), locals(), {})  # type: ignore
 
 
+@pytest.mark.skipif(sys.version_info < (3, 12), reason="syntax requires py3.12")
+class TestResolveAnnotationTypeAliasType:
+    def test_simple(self) -> None:
+        # this is equivalent to `type CoolList = List[int]`
+        CoolList = TypeAliasType("CoolList", List[int])
+        assert utils.resolve_annotation(CoolList, globals(), locals(), {}) == List[int]
+
+    def test_generic(self) -> None:
+        # this is equivalent to `type CoolList[T] = List[T]; CoolList[int]`
+        T = TypeVar("T")
+        CoolList = TypeAliasType("CoolList", List[T], type_params=(T,))
+
+        annotation = CoolList[int]
+        assert utils.resolve_annotation(annotation, globals(), locals(), {}) == List[int]
+
+    # alias and arg in local scope
+    def test_forwardref_local(self) -> None:
+        T = TypeVar("T")
+        IntOrStr = Union[int, str]
+        CoolList = TypeAliasType("CoolList", List[T], type_params=(T,))
+
+        annotation = CoolList["IntOrStr"]
+        assert utils.resolve_annotation(annotation, globals(), locals(), {}) == List[IntOrStr]
+
+    # alias and arg in other module scope
+    def test_forwardref_module(self) -> None:
+        resolved = utils.resolve_annotation(
+            utils_helper_module.ListWithForwardRefAlias, globals(), locals(), {}
+        )
+        assert resolved == List[Union[int, str]]
+
+    # combination of the previous two, alias in other module scope and arg in local scope
+    def test_forwardref_mixed(self) -> None:
+        LocalIntOrStr = Union[int, str]
+
+        annotation = utils_helper_module.GenericListAlias["LocalIntOrStr"]
+        assert utils.resolve_annotation(annotation, globals(), locals(), {}) == List[LocalIntOrStr]
+
+    # two different forwardrefs with same name
+    def test_forwardref_duplicate(self) -> None:
+        DuplicateAlias = int
+
+        # first, resolve an annotation where `DuplicateAlias` resolves to the local int
+        cache = {}
+        assert (
+            utils.resolve_annotation(List["DuplicateAlias"], globals(), locals(), cache)
+            == List[int]
+        )
+
+        # then, resolve an annotation where the globalns changes and `DuplicateAlias` resolves to something else
+        # (i.e. this should not resolve to `List[int]` despite {"DuplicateAlias": int} in the cache)
+        assert (
+            utils.resolve_annotation(
+                utils_helper_module.ListWithDuplicateAlias, globals(), locals(), cache
+            )
+            == List[str]
+        )
+
+
 @pytest.mark.parametrize(
     ("dt", "style", "expected"),
     [

tests/utils_helper_module.py

@@ -0,0 +1,26 @@
+# SPDX-License-Identifier: MIT
+
+"""Separate module file for some test_utils.py type annotation tests."""
+
+import sys
+from typing import TYPE_CHECKING, List, TypeVar, Union
+
+version = sys.version_info  # assign to variable to trick pyright
+
+if TYPE_CHECKING:
+    from typing_extensions import TypeAliasType
+elif version >= (3, 12):
+    # non-3.12 tests shouldn't be using this
+    from typing import TypeAliasType
+
+if version >= (3, 12):
+    CoolUniqueIntOrStrAlias = Union[int, str]
+    ListWithForwardRefAlias = TypeAliasType(
+        "ListWithForwardRefAlias", List["CoolUniqueIntOrStrAlias"]
+    )
+
+    T = TypeVar("T")
+    GenericListAlias = TypeAliasType("GenericListAlias", List[T], type_params=(T,))
+
+    DuplicateAlias = str
+    ListWithDuplicateAlias = TypeAliasType("ListWithDuplicateAlias", List["DuplicateAlias"])