Target Python 3.15 using the final upstream reference

Update active version and comparison configuration to Python 3.15.0. Preserve the alpha implementation status, actual bytecode format, and existing libraries pending separate migration. Align generated library-upgrade workflow pins without changing permissions or actions. Assisted-by: OpenAI Codex:model identifier unavailable
youknowone · Oct 11, 2026 · Oct 9, 2026 · Oct 9, 2026 · Oct 9, 2026 · Oct 9, 2026
commit 6c2529800a593fdf7f8cd123b1b17e33be0f03aa
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
@@ -40,8 +40,8 @@ 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 "Cloning CPython v3.15.0 (shallow)..."
+    git clone --depth 1 --branch v3.15.0 https://github.com/python/cpython.git cpython
     echo "CPython source ready."
 else
     echo "CPython source already present."

diff --git a/.github/workflows/pyperformance.yaml b/.github/workflows/pyperformance.yaml
@@ -63,7 +63,7 @@ jobs:
       - uses: actions/setup-python@5fda3b95a4ea91299a34e894583c3862153e4b97 # v7.0.0
         id: cpython
         with:
-          python-version: "3.14"
+          python-version: "3.15"
 
       - 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 @@ on:
       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

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:
@@ -52,7 +52,7 @@ cache:
     - cpython-lib-
 
 env:
-  PYTHON_VERSION: "v3.14.7"
+  PYTHON_VERSION: "v3.15.0"
   ISSUE_ID: "6839"
 ---
 

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/README.md b/README.md
@@ -2,9 +2,11 @@
 
 # [RustPython](https://rustpython.github.io/)
 
-A Python-3 (CPython >= 3.14.0) Interpreter written in Rust :snake: :scream:
+A Python-3 interpreter written in Rust, targeting CPython 3.15 :snake: :scream:
 :metal:.
 
+Python 3.15 compatibility is a work in progress.
+
 [![Build Status](https://github.com/RustPython/RustPython/workflows/CI/badge.svg)](https://github.com/RustPython/RustPython/actions?query=workflow%3ACI)
 [![codecov](https://codecov.io/gh/RustPython/RustPython/branch/main/graph/badge.svg)](https://codecov.io/gh/RustPython/RustPython)
 [![CodSpeed](https://img.shields.io/endpoint?url=https://codspeed.io/badge.json)](https://app.codspeed.io/RustPython/RustPython?utm_source=badge)

diff --git a/crates/vm/build.rs b/crates/vm/build.rs
@@ -22,8 +22,8 @@ fn main() {
     }
     println!("cargo:rerun-if-changed=../../Lib/importlib/_bootstrap.py");
 
-    // = 3.14.0alpha
-    python_version(3, 14, 0, "alpha", 0);
+    // = 3.15.0alpha
+    python_version(3, 15, 0, "alpha", 0);
 
     println!("cargo:rustc-env=RUSTPYTHON_GIT_HASH={}", git_hash());
     println!(

diff --git a/crates/vm/src/stdlib/_ast.rs b/crates/vm/src/stdlib/_ast.rs
@@ -1804,7 +1804,7 @@ pub(crate) fn parse<E: From<CompileError>>(
 ) -> Result<PyObjectRef, E> {
     let source_file = SourceFileBuilder::new(filename.to_owned(), source.to_owned()).finish();
     let mut options = parser::ParseOptions::from(mode);
-    let target_version = target_version.unwrap_or(ast::PythonVersion::PY314);
+    let target_version = target_version.unwrap_or(ast::PythonVersion::PY315);
     if let Some(error) = feature_version_syntax_error(source, &source_file, target_version) {
         return Err(error.into());
     }
@@ -2045,7 +2045,7 @@ pub(crate) fn parse_func_type<E: From<CompileError>>(
     let parse_expr = |expr_src: &str| -> Result<ast::Expr, CompileError> {
         let source_file = SourceFileBuilder::new(filename.to_owned(), expr_src.to_owned()).finish();
         let options = parser::ParseOptions::from(parser::Mode::Expression)
-            .with_target_version(target_version.unwrap_or(ast::PythonVersion::PY314));
+            .with_target_version(target_version.unwrap_or(ast::PythonVersion::PY315));
         let parsed = parser::parse(expr_src, options).map_err(|parse_error| {
             let range = text_range_to_source_range(&source_file, parse_error.location);
             CompileError::from(ParseError {
@@ -2080,7 +2080,7 @@ pub(crate) fn parse_func_type<E: From<CompileError>>(
         let call_source = format!("{ARG_PREFIX}{inner})");
         let source_file = SourceFileBuilder::new(filename.to_owned(), call_source.clone()).finish();
         let options = parser::ParseOptions::from(parser::Mode::Expression)
-            .with_target_version(target_version.unwrap_or(ast::PythonVersion::PY314));
+            .with_target_version(target_version.unwrap_or(ast::PythonVersion::PY315));
         let parsed = parser::parse(&call_source, options).map_err(|parse_error| {
             let range = text_range_to_source_range(&source_file, parse_error.location);
             CompileError::from(ParseError {

diff --git a/crates/vm/src/vm/mod.rs b/crates/vm/src/vm/mod.rs
@@ -1607,7 +1607,7 @@ impl VirtualMachine {
     /// ```no_run
     /// use rustpython_vm::Interpreter;
     /// Interpreter::without_stdlib(Default::default()).enter(|vm| {
-    ///     let bytes = std::fs::read("__pycache__/<input>.rustpython-314.pyc").unwrap();
+    ///     let bytes = std::fs::read("__pycache__/<input>.rustpython-315.pyc").unwrap();
     ///     let main_scope = vm.new_scope_with_main().unwrap();
     ///     vm.run_pyc_bytes(&bytes, main_scope);
     /// });

diff --git a/extra_tests/snippets/stdlib_sys.py b/extra_tests/snippets/stdlib_sys.py
@@ -25,6 +25,12 @@
 assert isinstance(sys.implementation.name, str)
 assert isinstance(sys.implementation.cache_tag, str)
 
+if sys.implementation.name == "rustpython":
+    assert sys.version_info == (3, 15, 0, "alpha", 0)
+    assert sys.hexversion == 0x030F00A0
+    assert sys.version.startswith("3.15.0.alpha (")
+    assert sys.implementation.cache_tag == "rustpython-315"
+
 assert sys.getfilesystemencoding() == "utf-8"
 assert sys.getfilesystemencodeerrors().startswith("surrogate")
 

diff --git a/scripts/libc_posix.py b/scripts/libc_posix.py
@@ -8,7 +8,7 @@
 
 import tomllib
 
-CPYTHON_VERSION = "3.14"
+CPYTHON_VERSION = "3.15"
 
 CONSTS_PATTERN = re.compile(r"\b_*[A-Z]+(?:_+[A-Z]+)*_*\b")
 

diff --git a/scripts/whats_left.py b/scripts/whats_left.py
@@ -1,6 +1,6 @@
 #!/usr/bin/env -S python3 -I
 # /// script
-# requires-python = ">=3.14"
+# requires-python = ">=3.15.0"
 # ///
 
 # This script generates Lib/snippets/whats_left_data.py with these variables defined:
@@ -39,9 +39,9 @@
 implementation = platform.python_implementation()
 if implementation != "CPython":
     sys.exit(f"whats_left.py must be run under CPython, got {implementation} instead")
-if sys.version_info[:2] < (3, 14):
+if sys.version_info[:2] < (3, 15):
     sys.exit(
-        f"whats_left.py must be run under CPython 3.14 or newer, got {implementation} {sys.version} instead. If you have uv, try `uv run python -I scripts/whats_left.py` to select a proper Python interpreter easier."
+        f"whats_left.py must be run under CPython 3.15 or newer, got {implementation} {sys.version} instead. If you have uv, try `uv run python -I scripts/whats_left.py` to select a proper Python interpreter easier."
     )