NEP-29 - enforce minimum Python version 3.10 (quantumlib#6591)

- Raise exception if running with Python <= 3.9.x
- Clean up checks and notes relevant for old Pythons
- Bump up to numpy~=1.22 which is effectively the minimum version
  that works with Python 3.10.  We are a bit more permissive than
  NEP 29 which suggests numpy-1.23+.

Fixes: quantumlib#6463
Ref: https://numpy.org/neps/nep-0029-deprecation_policy.html

Author: pavoljuhas

cirq/_version.py

@@ -13,16 +13,16 @@
 # limitations under the License.
 
 """Define version number here, read it from setup.py automatically,
-and warn users that the latest version of cirq uses python 3.9+"""
+and warn users that the latest version of cirq uses python 3.10+"""
 
 import sys
 
-if sys.version_info < (3, 9, 0):  # pragma: no cover
+if sys.version_info < (3, 10, 0):  # pragma: no cover
     raise SystemError(
-        "You installed the latest version of cirq but aren't on python 3.9+.\n"
+        "You installed the latest version of cirq but aren't on python 3.10+.\n"
         'To fix this error, you need to either:\n'
         '\n'
-        'A) Update to python 3.9 or later.\n'
+        'A) Update to python 3.10 or later.\n'
         '- OR -\n'
         'B) Explicitly install an older deprecated-but-compatible version '
         'of cirq (e.g. "python -m pip install cirq==1.1.*")'

cirq/ops/qid_util.py

@@ -41,8 +41,7 @@ def q(*args: Union[int, str]) -> Union['cirq.LineQubit', 'cirq.GridQubit', 'cirq
     >>> cirq.q("foo") == cirq.NamedQubit("foo")
     True
 
-    Note that arguments should be treated as positional only, even
-    though this is only enforceable in python 3.8 or later.
+    Note that arguments should be treated as positional only.
 
     Args:
         *args: One or two ints, or a single str, as described above.

cirq/protocols/json_serialization_test.py

@@ -11,6 +11,7 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
+
 import contextlib
 import dataclasses
 import datetime
@@ -19,7 +20,6 @@
 import json
 import os
 import pathlib
-import sys
 import warnings
 from typing import Dict, List, Optional, Tuple, Type
 from unittest import mock
@@ -56,12 +56,6 @@ class _ModuleDeprecation:
 }
 
 
-# pyQuil 3.0, necessary for cirq_rigetti module requires
-# python >= 3.9
-if sys.version_info < (3, 9):  # pragma: no cover
-    del TESTED_MODULES['cirq_rigetti']
-
-
 def _get_testspecs_for_modules() -> List[ModuleJsonTestSpec]:
     modules = []
     for m in TESTED_MODULES.keys():

requirements.txt

@@ -4,7 +4,7 @@ attrs
 duet>=0.2.8
 matplotlib~=3.0
 networkx>=2.4
-numpy~=1.16
+numpy~=1.22
 pandas
 sortedcontainers~=2.0
 scipy<1.13.0

setup.py

@@ -63,7 +63,7 @@
     url='http://github.com/quantumlib/cirq',
     author='The Cirq Developers',
     author_email='[email protected]',
-    python_requires=('>=3.9.0'),
+    python_requires=('>=3.10.0'),
     install_requires=requirements,
     extras_require={'contrib': contrib_requirements},
     license='Apache 2',