fix: Windows and 32-bit Linux default to 32-bit integers in sums and …

…prods UNLESS it's NumPy 2.0 (#3068)

* fix: determine Windows dtype from NumPy, because it depends on NumPy 1.x vs 2.0

* test NumPy 2.0 on all platforms

* fall back to second-guessing NumPy

* package name

.github/workflows/test.yml

@@ -65,6 +65,14 @@ jobs:
             python-architecture: x64
             runs-on: ubuntu-latest
             dependencies-kind: numpy2
+          - python-version: '3.11'
+            python-architecture: x64
+            runs-on: macos-11
+            dependencies-kind: numpy2
+          - python-version: '3.11'
+            python-architecture: x64
+            runs-on: windows-latest
+            dependencies-kind: numpy2
 
     runs-on: ${{ matrix.runs-on }}
 

src/awkward/_reducers.py

@@ -62,13 +62,15 @@ def _dtype_for_kernel(cls, dtype: DTypeLike) -> DTypeLike:
         else:
             return dtype
 
+    _use32 = (ak._util.win or ak._util.bits32) and not ak._util.numpy2
+
     @classmethod
     def _promote_integer_rank(cls, given_dtype: DTypeLike) -> DTypeLike:
         if given_dtype in (np.bool_, np.int8, np.int16, np.int32):
-            return np.int32 if ak._util.win or ak._util.bits32 else np.int64
+            return np.int32 if cls._use32 else np.int64
 
         elif given_dtype in (np.uint8, np.uint16, np.uint32):
-            return np.uint32 if ak._util.win or ak._util.bits32 else np.uint64
+            return np.uint32 if cls._use32 else np.uint64
 
         else:
             return given_dtype

src/awkward/_util.py

@@ -8,10 +8,15 @@
 import sys
 from collections.abc import Collection
 
+import numpy as np  # noqa: TID251
+import packaging.version
+
 from awkward._typing import TypeVar
 
 win = os.name == "nt"
 bits32 = struct.calcsize("P") * 8 == 32
+numpy2 = packaging.version.parse(np.__version__) >= packaging.version.Version("2.0.0b1")
+
 
 # matches include/awkward/common.h
 kMaxInt8 = 127  # 2**7  - 1