[KRRT7]

CPython 3.15.0 is out. This adds 3.15 to BUILD_PYTHON_PY_VERSIONS in python/CMakeLists.txt and raises the README prerequisite to <= v3.15.x. Tracking issue: #4890.

Evidence the bindings work on 3.15

Against the 11.3.0.99 GA libraries (Linux x86_64, CUDA 13.4, nvidia/cuda:13.4.1-devel-ubuntu24.04), the v11.3 bindings build for CPython 3.15.0 with no source changes and the repo's pinned pybind11 v3.0.1:

cmake <TRT_OSS> -G Ninja -DCMAKE_BUILD_TYPE=Release -DCMAKE_PREFIX_PATH=$TRT_ROOT \
  -DBUILD_PYTHON=ON -DBUILD_PLUGINS=OFF -DBUILD_PARSERS=OFF -DBUILD_SAMPLES=OFF \
  -DPython3_EXECUTABLE=<python3.15> -DTRT_BUILD_PYTHON_PY_VERSIONS=3.15 \
  -DTRT_BUILD_PYTHON_EXTERNALS_PATH=<prefix>/include
ninja tensorrt_bindings_tensorrt_3.15

The resulting tensorrt.so, in the official cp314 wheel layout retagged cp315, behaves the same as the official cp314 wheel (on 3.14) in the same container: it imports, reports 34 plugin creators, tensorrt.plugin imports, and pybind11 calls from a non-main thread work. Engine building and inference were not run (no GPU in that environment).

A note on CPython 3.15 ABI that matters for any binding built against 3.15 pre-releases: 3.15.0b4 added a PyThreadState field (last_profiled_frame_seq), which moved gilstate_counter, and pybind11's gil_scoped_acquire touches that field directly. Bindings must be built against 3.15.0b4 or later headers. PyTorch's macOS cp315 2.14.1 wheel was built against earlier headers and segfaults (pytorch/pytorch#201944).

Not changed, but worth a look

• python/requirements.txt pins numpy==1.26.4; python_version >= "3.12". numpy 1.26.4 has no wheels for 3.13, 3.14 or 3.15, so if that file is on a 3.15 build path it will need a newer numpy (2.5.2 is the first with cp315 wheels). It evidently isn't on the 3.13/3.14 path, so I left it alone.
• The wheel-packaging step in the OSS tree can't run because python/packaging/*/pyproject.toml is missing (Python 3.15 bindings: OSS BUILD_PYTHON build works, but wheel packaging fails (missing bindings_wheel/pyproject.toml) and 3.15 is not in the version list #4890). That's independent of this change.