From 4c25f321e09b05c311b70c5c8fbdc5f021d95d6a Mon Sep 17 00:00:00 2001
From: andrewgsavage <andrewgsavage@gmail.com>
Date: Fri, 21 Jun 2024 14:24:44 +0100
Subject: [PATCH] support 3.9 (#2019)

changed matplotlib test to use a build that has a pypi wheel available for python3.10
changed TypeAlias import for 3.9 compat
changed min versions
---
 .github/workflows/ci.yml                           | 8 ++++----
 CHANGES                                            | 4 ++--
 docs/user/log_units.rst                            | 6 +++---
 pint/compat.py                                     | 6 +++++-
 pint/delegates/formatter/_compound_unit_helpers.py | 3 +--
 pyproject.toml                                     | 3 ++-
 6 files changed, 17 insertions(+), 13 deletions(-)

diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 0797decb5..24f001b43 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -7,18 +7,18 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        python-version: ["3.10", "3.11", "3.12"]
+        python-version: ["3.9", "3.10", "3.11", "3.12"]
         numpy: [null, "numpy>=1.23,<2.0.0", "numpy>=2.0.0rc1"]
         uncertainties: [null, "uncertainties==3.1.6", "uncertainties>=3.1.6,<4.0.0"]
         extras: [null]
         include:
           - python-version: "3.10" # Minimal versions
-            numpy: "numpy"
-            extras: matplotlib==2.2.5
+            numpy: "numpy>=1.23,<2.0.0"
+            extras: matplotlib==3.5.3
           - python-version: "3.10"
             numpy: "numpy"
             uncertainties: "uncertainties"
-            extras: "sparse xarray netCDF4 dask[complete]==2023.4.0 graphviz babel==2.8 mip>=1.13"
+            extras: "sparse xarray netCDF4 dask[complete]==2024.5.1 graphviz babel==2.8 mip>=1.13"
     runs-on: ubuntu-latest
 
     env:
diff --git a/CHANGES b/CHANGES
index 8e59b4803..588e7f5b7 100644
--- a/CHANGES
+++ b/CHANGES
@@ -1,11 +1,11 @@
 Pint Changelog
 ==============
 
-0.25 (unreleased)
+0.24.1 (unreleased)
 -----------------
 
 - Fix custom formatter needing the registry object. (PR #2011)
-
+- Support python 3.9 following difficulties installing with NumPy 2. (PR #2019)
 
 0.24 (2024-06-07)
 -----------------
diff --git a/docs/user/log_units.rst b/docs/user/log_units.rst
index 03e007914..096397350 100644
--- a/docs/user/log_units.rst
+++ b/docs/user/log_units.rst
@@ -111,16 +111,16 @@ will not work:
 .. doctest::
 
     >>> -161.0 * ureg('dBm/Hz') == (-161.0 * ureg.dBm / ureg.Hz)
-    False
+    np.False_
 
 But this will:
 
 .. doctest::
 
     >>> ureg('-161.0 dBm/Hz') == (-161.0 * ureg.dBm / ureg.Hz)
-    True
+    np.True_
     >>> Q_(-161.0, 'dBm') / ureg.Hz == (-161.0 * ureg.dBm / ureg.Hz)
-    True
+    np.True_
 
 To begin using this feature while avoiding problems, define logarithmic units
 as single-unit quantities and convert them to their base units as quickly as
diff --git a/pint/compat.py b/pint/compat.py
index 277662410..32ad04afb 100644
--- a/pint/compat.py
+++ b/pint/compat.py
@@ -19,9 +19,13 @@
 from typing import (
     Any,
     NoReturn,
-    TypeAlias,  # noqa
 )
 
+if sys.version_info >= (3, 10):
+    from typing import TypeAlias  # noqa
+else:
+    from typing_extensions import TypeAlias  # noqa
+
 if sys.version_info >= (3, 11):
     from typing import Self  # noqa
 else:
diff --git a/pint/delegates/formatter/_compound_unit_helpers.py b/pint/delegates/formatter/_compound_unit_helpers.py
index 89bda87a2..7631a94ef 100644
--- a/pint/delegates/formatter/_compound_unit_helpers.py
+++ b/pint/delegates/formatter/_compound_unit_helpers.py
@@ -20,12 +20,11 @@
     TYPE_CHECKING,
     Any,
     Literal,
-    TypeAlias,
     TypedDict,
     TypeVar,
 )
 
-from ...compat import babel_parse
+from ...compat import TypeAlias, babel_parse
 from ...util import UnitsContainer
 
 T = TypeVar("T")
diff --git a/pyproject.toml b/pyproject.toml
index a376bd6a4..9f29f8f92 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -22,11 +22,12 @@ classifiers = [
     "Programming Language :: Python",
     "Topic :: Scientific/Engineering",
     "Topic :: Software Development :: Libraries",
+    "Programming Language :: Python :: 3.9",
     "Programming Language :: Python :: 3.10",
     "Programming Language :: Python :: 3.11",
     "Programming Language :: Python :: 3.12",
 ]
-requires-python = ">=3.10"
+requires-python = ">=3.9"
 dynamic = ["version", "dependencies"]
 
 [tool.setuptools.package-data]