youknowdot · Oct 9, 2026 · Oct 9, 2026 · Oct 9, 2026 · Oct 9, 2026 · Oct 9, 2026
diff --git a/.claude/scripts/setup-env.sh b/.claude/scripts/setup-env.sh
@@ -16,7 +16,7 @@ if [ "$(printf '%s\n' "3.13" "$CURRENT_PY" | sort -V | head -1)" != "3.13" ]; th
     echo "Upgrading python3 default to 3.13..."
     # Find best available Python >= 3.13
     TARGET=""
-    for ver in python3.14 python3.13; do
+    for ver in python3.15 python3.14 python3.13; do
         if command -v "$ver" &>/dev/null; then
             TARGET=$(command -v "$ver")
             break
@@ -38,13 +38,17 @@ else
     echo "python3 already >= 3.13: $(python3 --version)"
 fi
 
-# 2. Clone CPython source if not present (needed for scripts/update_lib)
-if [ ! -d "cpython" ]; then
-    echo "Cloning CPython v3.14.3 (shallow)..."
-    git clone --depth 1 --branch v3.14.3 https://github.com/python/cpython.git cpython
-    echo "CPython source ready."
+# 2. Ensure the CPython source matches the target (needed for scripts/update_lib)
+PYTHON_VERSION="v3.15.0"
+if [ ! -e "cpython" ]; then
+    git clone --depth 1 --branch "$PYTHON_VERSION" https://github.com/python/cpython.git cpython
+elif [ ! -d "cpython/.git" ] || [ ! -d "cpython/Lib" ] ||
+    [ "$(git -C cpython rev-parse HEAD)" != "$(git -C cpython rev-parse --verify "$PYTHON_VERSION^{commit}" 2>/dev/null)" ] ||
+    [ -n "$(git -C cpython status --porcelain)" ]; then
+    echo "ERROR: cpython must be a clean checkout of $PYTHON_VERSION. Move the existing directory aside and rerun." >&2
+    exit 1
 else
-    echo "CPython source already present."
+    echo "CPython $PYTHON_VERSION source already present."
 fi
 
 echo "=== Setup complete ==="
diff --git a/.github/actions/setup-python/action.yml b/.github/actions/setup-python/action.yml
@@ -0,0 +1,57 @@
+name: Set up reference Python
+description: Install CPython from python-build-standalone with pip available.
+inputs:
+  python-version:
+    description: CPython version to install
+    default: "3.15.0"
+outputs:
+  python-path:
+    description: Path to the installed interpreter
+    value: ${{ steps.python.outputs.python-path }}
+  python-version:
+    description: Installed CPython version
+    value: ${{ steps.python.outputs.python-version }}
+runs:
+  using: composite
+  steps:
+    # uv 0.13.0 includes the final 3.15.0 builds, before setup-python's catalog.
+    - uses: astral-sh/setup-uv@1c37ad07a6a961277cf70c0d37d6f313000f5884 # v10.3.0
+      with:
+        version: "0.13.0"
+        python-version: ${{ inputs.python-version }}
+        activate-environment: true
+        no-project: true
+        venv-path: ${{ runner.temp }}/reference-python
+        enable-cache: false
+      env:
+        UV_VENV_SEED: "true"
+        UV_MANAGED_PYTHON: "true"
+    - id: python
+      shell: bash
+      env:
+        REQUESTED_PYTHON: ${{ inputs.python-version }}
+      run: |
+        python - <<'PY'
+        import os
+        import platform
+        import sys
+
+        if os.environ["REQUESTED_PYTHON"] == "3.15.0":
+            assert sys.version_info[:3] == (3, 15, 0), sys.version
+            assert sys.version_info.releaselevel == "final", sys.version
+        with open(os.environ["GITHUB_OUTPUT"], "a") as output:
+            print(f"python-path={sys.executable}", file=output)
+            print(f"python-version={platform.python_version()}", file=output)
+        with open(os.environ["GITHUB_ENV"], "a") as env:
+            print(f"pythonLocation={sys.base_prefix}", file=env)
+            if sys.platform == "linux":
+                lib = os.path.join(sys.base_prefix, "lib")
+                previous = os.environ.get("LD_LIBRARY_PATH")
+                lib_path = os.pathsep.join([lib, previous] if previous else [lib])
+                print(f"LD_LIBRARY_PATH={lib_path}", file=env)
+        if sys.platform == "win32":
+            with open(os.environ["GITHUB_PATH"], "a") as path:
+                print(sys.base_prefix, file=path)
+                print(os.path.dirname(sys.executable), file=path)
+        print(sys.version)
+        PY
diff --git a/.github/workflows/ci.yaml b/.github/workflows/ci.yaml
@@ -539,7 +539,7 @@
         # Windows runners randomly crashes, https://github.com/actions/cache/issues/1754
         continue-on-error: true
 
-      - uses: actions/setup-python@5fda3b95a4ea91299a34e894583c3862153e4b97 # v7.0.0
+      - uses: ./.github/actions/setup-python
 
       - name: Install macOS dependencies
         uses: ./.github/actions/install-macos-deps
@@ -752,7 +752,7 @@
         with:
           persist-credentials: false
 
-      - uses: actions/setup-python@5fda3b95a4ea91299a34e894583c3862153e4b97 # v7.0.0
+      - uses: ./.github/actions/setup-python
 
       - uses: dtolnay/rust-toolchain@stable
         with:
@@ -781,18 +781,14 @@
       - name: prek run
         run: prek run --show-diff-on-failure --color=always --all-files
 
-      - name: Get target CPython version
-        id: cpython-version
-        run: |
-          version=$(cat .python-version)
-          echo "version=${version}" >> "$GITHUB_OUTPUT"
-
-      - name: Clone CPython
+      - name: Clone CPython opcode metadata source
         uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
         with:
           repository: python/cpython
           path: cpython
-          ref: "v${{ steps.cpython-version.outputs.version }}"
+          # RustPython still uses the 3.14 bytecode format; this source is only
+          # for opcode metadata, independent of the 3.15 runtime target.
+          ref: "v3.14.7"
           persist-credentials: false
 
       - name: prek run (manual stage)
@@ -918,7 +914,7 @@
           mkdir geckodriver
           tar -xzf geckodriver-v0.36.0-linux64.tar.gz -C geckodriver
 
-      - uses: actions/setup-python@5fda3b95a4ea91299a34e894583c3862153e4b97 # v7.0.0
+      - uses: ./.github/actions/setup-python
 
       - run: python -m pip install -r requirements.txt
         working-directory: ./wasm/tests

diff --git a/.github/workflows/codspeed.yaml b/.github/workflows/codspeed.yaml
@@ -49,7 +49,7 @@
       - uses: dtolnay/rust-toolchain@stable
 
       # The benchmarks are linked against libpython through the pyo3 dev-dependency.
-      - uses: actions/setup-python@5fda3b95a4ea91299a34e894583c3862153e4b97 # v7.0.0
+      - uses: ./.github/actions/setup-python
 
       - name: Restore the machine main last measured on
         # A recording that cannot be fetched is read as "none yet", which the step

diff --git a/.github/workflows/cron-ci.yaml b/.github/workflows/cron-ci.yaml
@@ -37,7 +37,7 @@
         with:
           tool: cargo-llvm-cov
 
-      - uses: actions/setup-python@5fda3b95a4ea91299a34e894583c3862153e4b97 # v7.0.0
+      - uses: ./.github/actions/setup-python
 
       - run: sudo apt-get update && sudo apt-get -y install lcov
 
@@ -110,7 +110,7 @@
 
       - uses: dtolnay/rust-toolchain@stable
 
-      - uses: actions/setup-python@5fda3b95a4ea91299a34e894583c3862153e4b97 # v7.0.0
+      - uses: ./.github/actions/setup-python
 
       - name: build rustpython
         run: cargo build --release --verbose --features sqlite
@@ -170,7 +170,7 @@
 
       - uses: dtolnay/rust-toolchain@stable
 
-      - uses: actions/setup-python@5fda3b95a4ea91299a34e894583c3862153e4b97 # v7.0.0
+      - uses: ./.github/actions/setup-python
 
       - run: cargo install cargo-criterion
 

diff --git a/.github/workflows/lib-deps-check.yaml b/.github/workflows/lib-deps-check.yaml
@@ -107,7 +107,7 @@
 
       - name: Setup Python
         if: steps.changed-files.outputs.modules != ''
-        uses: actions/setup-python@5fda3b95a4ea91299a34e894583c3862153e4b97 # v7.0.0
+        uses: ./.github/actions/setup-python
 
       - name: Run deps check
         if: steps.changed-files.outputs.modules != ''

diff --git a/.github/workflows/pyperformance.yaml b/.github/workflows/pyperformance.yaml
@@ -60,10 +60,10 @@
       # Both the third interpreter under test and the host pyperformance
       # itself runs on (it only runs under a real CPython; RustPython is just
       # the `--python` target it drives).
-      - uses: actions/setup-python@5fda3b95a4ea91299a34e894583c3862153e4b97 # v7.0.0
+      - uses: ./.github/actions/setup-python
         id: cpython
         with:
-          python-version: "3.14"
+          python-version: "3.15.0"
 
       - name: Restore cache
         uses: actions/cache/restore@55cc8345863c7cc4c66a329aec7e433d2d1c52a9 # v6.1.0

diff --git a/.github/workflows/update-doc-db.yml b/.github/workflows/update-doc-db.yml
@@ -8,7 +8,7 @@
       python-version:
         description: Target python version to generate doc db for
         type: string
-        default: "3.14.7"
+        default: "3.15.0"
       base-ref:
         description: Base branch to create the update branch from
         type: string
@@ -35,8 +35,9 @@
           persist-credentials: false
           sparse-checkout: |
             crates/doc
+            .github/actions/setup-python
 
-      - uses: actions/setup-python@5fda3b95a4ea91299a34e894583c3862153e4b97 # v7.0.0
+      - uses: ./.github/actions/setup-python
         with:
           python-version: ${{ inputs.python-version }}
 

diff --git a/.github/workflows/upgrade-pylib.lock.yml b/.github/workflows/upgrade-pylib.lock.yml
diff --git a/.github/workflows/upgrade-pylib.md b/.github/workflows/upgrade-pylib.md
@@ -28,7 +28,7 @@ engine: copilot
 
 runtimes:
   python:
-    version: "3.14"
+    version: "3.15"
 
 tools:
   bash:
@@ -48,11 +48,9 @@ safe-outputs:
 cache:
   key: cpython-lib-${{ env.PYTHON_VERSION }}
   path: cpython
-  restore-keys:
-    - cpython-lib-
 
 env:
-  PYTHON_VERSION: "v3.14.7"
+  PYTHON_VERSION: "v3.15.0"
   ISSUE_ID: "6839"
 ---
 
@@ -65,10 +63,15 @@ You are an automated maintenance agent for RustPython, a Python 3 interpreter wr
 The CPython source may already be cached. Check if the `cpython` directory exists and has the correct version:
 
 ```bash
-if [ -d "cpython/Lib" ]; then
-    echo "CPython cache hit, skipping clone"
-else
+if [ ! -e "cpython" ]; then
     git clone --depth 1 --branch "$PYTHON_VERSION" https://github.com/python/cpython.git cpython
+elif [ ! -d "cpython/.git" ] || [ ! -d "cpython/Lib" ] ||
+    [ "$(git -C cpython rev-parse HEAD)" != "$(git -C cpython rev-parse --verify "$PYTHON_VERSION^{commit}" 2>/dev/null)" ] ||
+    [ -n "$(git -C cpython status --porcelain)" ]; then
+    echo "ERROR: cpython must be a clean checkout of $PYTHON_VERSION. Move the existing directory aside and rerun." >&2
+    exit 1
+else
+    echo "CPython $PYTHON_VERSION source already present."
 fi
 ```
 

diff --git a/.python-version b/.python-version
@@ -1 +1 @@
-3.14.7
+3.15.0
diff --git a/AGENTS.md b/AGENTS.md
@@ -4,7 +4,7 @@ This document provides guidelines for AI coding agents (GitHub Copilot, Claude C
 
 ## Project Overview
 
-RustPython is a Python 3 interpreter written in Rust, implementing Python 3.14.0+ compatibility. The project aims to provide:
+RustPython is a Python 3 interpreter written in Rust, targeting Python 3.15 with compatibility work in progress. The project aims to provide:
 
 - A complete Python-3 environment entirely in Rust (not CPython bindings)
 - A clean implementation without compatibility hacks

diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
@@ -49,7 +49,7 @@ RustPython requires the following:
       stable version: `rustup update stable`
     - If you do not have Rust installed, use [rustup](https://rustup.rs/) to
       do so.
-- CPython version 3.14 or higher
+- CPython version 3.15 or higher
     - CPython can be installed by your operating system's package manager,
       from the [Python website](https://www.python.org/downloads/), or
       using a third-party distribution, such as 

diff --git a/Lib/sysconfig/__init__.py b/Lib/sysconfig/__init__.py
@@ -219,18 +219,7 @@ def _safe_realpath(path):
 if "_PYTHON_PROJECT_BASE" in os.environ:
     _PROJECT_BASE = _safe_realpath(os.environ["_PYTHON_PROJECT_BASE"])
 
-def is_python_build(check_home=None):
-    if check_home is not None:
-        import warnings
-        warnings.warn(
-            (
-                'The check_home argument of sysconfig.is_python_build is '
-                'deprecated and its value is ignored. '
-                'It will be removed in Python 3.15.'
-            ),
-            DeprecationWarning,
-            stacklevel=2,
-        )
+def is_python_build():
     for fn in ("Setup", "Setup.local"):
         if os.path.isfile(os.path.join(_PROJECT_BASE, "Modules", fn)):
             return True

diff --git a/Lib/test/pickletester.py b/Lib/test/pickletester.py
@@ -4394,6 +4394,8 @@ def test_fast_save_enter_frozenset(self):
     def test_fast_save_enter_set(self):
         self.fast_save_enter(lambda i: set([i]))
 
+    # TODO: RUSTPYTHON; frozendict support: https://github.com/RustPython/RustPython/pull/8951
+    @unittest.expectedFailure
     def test_fast_save_enter_frozendict(self):
         if self.py_version < (3, 15):
             self.skipTest('need frozendict')
@@ -4441,6 +4443,8 @@ def test_deep_nested_struct_set(self):
                                 depth=FAST_NESTING_LIMIT+1,
                                 compare_equal=False)
 
+    # TODO: RUSTPYTHON; frozendict support: https://github.com/RustPython/RustPython/pull/8951
+    @unittest.expectedFailure
     def test_deep_nested_struct_frozendict(self):
         if self.py_version < (3, 15):
             self.skipTest('need frozendict')