Support numba up to 0.65.1 and Python 3.14t

Numba 0.64 and 0.65 keep llvmlite on LLVM 20, so no pass or runtime
changes are needed; this extends the supported range and enables the
free-threaded build that Numba 0.65 introduces.

Packaging:
- Widen the numba requirement to >=0.62, <0.66 in pyproject.toml and
  the conda recipe
- Build cp314t wheels by removing the cibuildwheel skip
- Require numba >=0.65 for free-threaded conda builds via the
  is_freethreading selector (default false in conda_build_config.yaml)
- Raise ImportError at import time on free-threaded Python with
  numba < 0.65

CI:
- Test wheels against numba 0.64.0, 0.65.0 and 0.65.1, and add Python
  3.14t (numba 0.65.x only)
- Build and upload a 3.14t conda package, selecting the free-threaded
  variant with a variant file (freethreading.yaml) because
  `conda build --output` ignores --variants
- Modal GPU tests: match the ABI tag when selecting wheels, so cp314
  no longer also matches cp314t, and test with numba 0.65.1

Docs:
- Update the compatibility matrix to 0.62.x - 0.65.x and note that
  Python 3.14t requires numba 0.65.x

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

Author: ggeorgakoudis

.github/workflows/build-upload-conda.yml

@@ -24,7 +24,7 @@ jobs:
       matrix:
         # TODO: Add windows.
         os: [ubuntu-latest, macos-latest, ubuntu-24.04-arm]
-        python-version: ["3.10", "3.11", "3.12", "3.13", "3.14"]
+        python-version: ["3.10", "3.11", "3.12", "3.13", "3.14", "3.14t"]
     steps:
       - name: Determine conda label
         run: |
@@ -62,15 +62,22 @@ jobs:
           conda config --set anaconda_upload no
           conda build --version
 
+          # Select the python variant; 3.14t needs the free-threaded ABI.
+          if [[ "${{ matrix.python-version }}" == "3.14t" ]]; then
+            PY_ARGS=(--python "3.14.* *_cp314t" -m buildscripts/conda-recipes/pyomp/freethreading.yaml)
+          else
+            PY_ARGS=(--python ${{ matrix.python-version }})
+          fi
+
           # Build the package.
           conda build \
             -c conda-forge \
-            --python ${{ matrix.python-version }} \
+            "${PY_ARGS[@]}" \
             buildscripts/conda-recipes/pyomp
 
           # Get the output file path.
           OUTPUT=$(conda build -c conda-forge --output \
-            --python ${{ matrix.python-version }} \
+            "${PY_ARGS[@]}" \
             buildscripts/conda-recipes/pyomp)
 
           # Upload the package.

.github/workflows/build-upload-wheels.yml

@@ -84,13 +84,24 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-latest, macos-latest, ubuntu-24.04-arm]
-        python-version: ['3.10', '3.11', '3.12', '3.13', '3.14']
-        numba-version: ['0.62.0', '0.62.1', '0.63.0', '0.63.1']
+        python-version: ['3.10', '3.11', '3.12', '3.13', '3.14', '3.14t']
+        numba-version: ['0.62.0', '0.62.1', '0.63.0', '0.63.1', '0.64.0', '0.65.0', '0.65.1']
         exclude:
           - python-version: '3.14'
             numba-version: '0.62.0'
           - python-version: '3.14'
             numba-version: '0.62.1'
+          # Numba supports free-threaded Python starting with 0.65.
+          - python-version: '3.14t'
+            numba-version: '0.62.0'
+          - python-version: '3.14t'
+            numba-version: '0.62.1'
+          - python-version: '3.14t'
+            numba-version: '0.63.0'
+          - python-version: '3.14t'
+            numba-version: '0.63.1'
+          - python-version: '3.14t'
+            numba-version: '0.64.0'
 
     steps:
       - name: Download built wheels

README.md

@@ -45,10 +45,12 @@ conda install -c python-for-hpc -c conda-forge pyomp
 
 | PyOMP | Numba           |
 | ----- | --------------- |
-| 0.5.x | 0.62.x - 0.63.x |
+| 0.5.x | 0.62.x - 0.65.x |
 | 0.4.x | 0.61.x          |
 | 0.3.x | 0.57.x - 0.60.x |
 
+Python 3.14t (free-threaded) requires Numba 0.65.x.
+
 Besides a standard installation, we also provide the following options to
 quickly try out PyOMP online or through a container.
 

buildscripts/conda-recipes/pyomp/conda_build_config.yaml

@@ -1,3 +1,8 @@
+# --- Free-threading ---
+# Default for the is_freethreading selector in meta.yaml; override for 3.14t.
+is_freethreading:
+  - false
+
 # --- Compilers ---
 c_compiler_version:
   - 9                       # [linux]

buildscripts/conda-recipes/pyomp/freethreading.yaml

@@ -0,0 +1,4 @@
+# Variant for free-threaded Python (3.14t) builds, passed with -m. Use this
+# instead of --variants, which `conda build --output` ignores.
+is_freethreading:
+  - true

buildscripts/conda-recipes/pyomp/meta.yaml

@@ -45,7 +45,8 @@ requirements:
     - sysroot_linux-aarch64  # [aarch64]
     - setuptools
     - setuptools_scm
-    - numba >=0.62, <0.64
+    - numba >=0.62, <0.66
+    - numba >=0.65, <0.66  # [is_freethreading]
     - clang {{ LLVM_VERSION }}
     - clangxx {{ LLVM_VERSION }}
     - clang-tools {{ LLVM_VERSION }}
@@ -59,7 +60,8 @@ requirements:
   run:
     - python
     - setuptools
-    - numba >=0.62, <0.64
+    - numba >=0.62, <0.66
+    - numba >=0.65, <0.66  # [is_freethreading]
     # require llvm-openmp for the openmp cpu runtime.
     - llvm-openmp 21.1.8.* # [osx]
     - llvm-openmp {{ LLVM_VERSION }} # [not osx]

buildscripts/modal/test_gpu.py

@@ -8,7 +8,7 @@
 
 
 PYTHON_VERSIONS = ("3.10", "3.11", "3.12", "3.13", "3.14")
-NUMBA_VERSION = "0.63.1"
+NUMBA_VERSION = "0.65.1"
 MINIFORGE_VERSION = "26.3.2-3"
 MINIFORGE_SHA256 = "848194851a98903134187fbb4ab50efe87b003e0c0f808f97644b7524a62bf2c"
 WHEEL_DIRECTORY = (
@@ -26,7 +26,8 @@ def find_linux_wheels() -> dict[str, Path]:
     wheels = {}
     for python_version in PYTHON_VERSIONS:
         abi = python_version.replace(".", "")
-        matches = sorted(WHEEL_DIRECTORY.glob(f"*cp{abi}-*x86_64.whl"))
+        # Match the ABI tag too, so cp314 does not also match cp314t wheels.
+        matches = sorted(WHEEL_DIRECTORY.glob(f"*-cp{abi}-cp{abi}-*x86_64.whl"))
         if len(matches) != 1:
             raise RuntimeError(
                 f"Expected one cp{abi} Linux x86-64 wheel in {WHEEL_DIRECTORY}, "

docs/source/installation.rst

@@ -24,13 +24,15 @@ supported.
 +--------+---------------------+
 | PyOMP  | Numba               |
 +========+=====================+
-| 0.5.x  | 0.62.x - 0.63.x     |
+| 0.5.x  | 0.62.x - 0.65.x     |
 +--------+---------------------+
 | 0.4.x  | 0.61.x              |
 +--------+---------------------+
 | 0.3.x  | 0.57.x - 0.60.x     |
 +--------+---------------------+
 
+Python 3.14t (free-threaded) requires Numba 0.65.x.
+
 Additional options
 ------------------
 

pyproject.toml

@@ -17,7 +17,7 @@ classifiers = [
     "Intended Audience :: Developers",
     "Topic :: Software Development :: Compilers",
 ]
-dependencies = ["numba>=0.62, <0.64", "lark", "cffi", "setuptools"]
+dependencies = ["numba>=0.62, <0.66", "lark", "cffi", "setuptools"]
 maintainers = [
     { name = "Giorgis Georgakoudis", email = "georgakoudis1@llnl.gov" },
 ]
@@ -42,8 +42,7 @@ archs = ["native"]
 environment-pass = ["LLVM_VERSION"]
 # We use miniconda3 to get the clang/llvm toolchain on Linux.
 before-build = ["rm -rf build dist src/*.egg-info"]
-# Skip building 3.14t wheels as they are not supported by the current numba/llvmlite version.
-skip = ["*-musllinux_*", "cp38-*", "cp314t-*"]
+skip = ["*-musllinux_*", "cp38-*"]
 test-command = [
     # Run host OpenMP tests.
     "RUN_TARGET=0 python -m numba.runtests -v -- numba.openmp.tests.test_openmp",

src/numba/openmp/__init__.py

@@ -1,5 +1,17 @@
 import llvmlite.binding as ll
 import sys
+import sysconfig
+
+import numba
+
+# Numba supports free-threaded Python starting with 0.65.
+if sysconfig.get_config_var("Py_GIL_DISABLED") and tuple(
+    int(x) for x in numba.__version__.split(".")[:2]
+) < (0, 65):
+    raise ImportError(
+        f"PyOMP on free-threaded Python requires numba>=0.65, found {numba.__version__}"
+    )
+
 from ._version import version as __version__  # noqa: F401
 
 from .config import (