Merge pull request #19533 from BvB93/optional2

BUG: Fix an issue wherein importing `numpy.typing` could raise

numpy/typing/_array_like.py

@@ -1,7 +1,15 @@
 from __future__ import annotations
 
 import sys
-from typing import Any, overload, Sequence, TYPE_CHECKING, Union, TypeVar
+from typing import (
+    Any,
+    overload,
+    Sequence,
+    TYPE_CHECKING,
+    Union,
+    TypeVar,
+    Generic,
+)
 
 from numpy import (
     ndarray,
@@ -47,7 +55,8 @@
     class _SupportsArray(Protocol[_DType_co]):
         def __array__(self) -> ndarray[Any, _DType_co]: ...
 else:
-    _SupportsArray = Any
+    class _SupportsArray(Generic[_DType_co]):
+        pass
 
 # TODO: Wait for support for recursive types
 _NestedSequence = Union[

numpy/typing/_dtype_like.py

@@ -67,6 +67,8 @@
     _ObjectCodes,
 )
 
+_DType_co = TypeVar("_DType_co", covariant=True, bound=np.dtype)
+
 _DTypeLikeNested = Any  # TODO: wait for support for recursive types
 
 if TYPE_CHECKING or HAVE_PROTOCOL:
@@ -82,7 +84,6 @@ class _DTypeDict(_DTypeDictBase, total=False):
         itemsize: int
         aligned: bool
 
-    _DType_co = TypeVar("_DType_co", covariant=True, bound=np.dtype)
 
     # A protocol for anything with the dtype attribute
     class _SupportsDType(Protocol[_DType_co]):

numpy/typing/tests/test_typing_extensions.py

@@ -0,0 +1,35 @@
+"""Tests for the optional typing-extensions dependency."""
+
+import sys
+import textwrap
+import subprocess
+
+CODE = textwrap.dedent(r"""
+    import sys
+    import importlib
+
+    assert "typing_extensions" not in sys.modules
+    assert "numpy.typing" not in sys.modules
+
+    # Importing `typing_extensions` will now raise an `ImportError`
+    sys.modules["typing_extensions"] = None
+    assert importlib.import_module("numpy.typing")
+""")
+
+
+def test_no_typing_extensions() -> None:
+    """Import `numpy.typing` in the absence of typing-extensions.
+
+    Notes
+    -----
+    Ideally, we'd just run the normal typing tests in an environment where
+    typing-extensions is not installed, but unfortunatelly this is currently
+    impossible as it is an indirect hard dependency of pytest.
+
+    """
+    p = subprocess.run([sys.executable, '-c', CODE], capture_output=True)
+    if p.returncode:
+        raise AssertionError(
+            f"Non-zero return code: {p.returncode!r}\n\n{p.stderr.decode()}"
+        )
+