Add free-threaded Python support (#2310)

Co-authored-by: Nathan Goldbaum <[email protected]>

.github/workflows/test.yml

@@ -12,7 +12,7 @@ on:
   workflow_dispatch:
 
 concurrency:
-  group: ${{ github.workflow }}-${{ github.ref_name }}-${{ github.event.pull_request.number }}
+  group: ${{ github.workflow }}-${{ github.ref_name }}-${{ github.event.action }}-${{ github.event.pull_request.number }}
   cancel-in-progress: true
 
 jobs:
@@ -43,9 +43,10 @@ jobs:
           - macos-14
           - windows-latest
         python-version:
-          - '3.9'
-          - '3.13'
-          - 'pypy3.10'
+          - "3.9"
+          - "3.13"
+          - "3.13t"
+          - "pypy3.10"
         exclude:
           # Skip PyPy on macOS M1 runner because they are built for x86_64
           - os: macos-14
@@ -81,7 +82,7 @@ jobs:
           auto-activate-base: "false"
           activate-environment: ""
           miniconda-version: "latest"
-      - uses: actions/setup-python@v5
+      - uses: Quansight-Labs/setup-python@v5
         with:
           python-version: ${{ matrix.python-version }}
       - name: Set PYTHON_VERSION env var
@@ -96,7 +97,10 @@ jobs:
         run: |
           uv tool install virtualenv
           uv tool install twine
-          uv pip install --system "ziglang>=0.10.0,<0.13.0" uniffi-bindgen==0.28.0
+          uv tool install uniffi-bindgen==0.28.0
+      - uses: mlugg/setup-zig@v1
+        with:
+          version: 0.12.1
       - uses: dtolnay/rust-toolchain@stable
         id: rustup
         with:

src/auditwheel/audit.rs

@@ -17,7 +17,7 @@ use std::{fmt, io};
 use thiserror::Error;
 
 static IS_LIBPYTHON: Lazy<Regex> =
-    Lazy::new(|| Regex::new(r"^libpython3\.\d+m?u?\.so\.\d+\.\d+$").unwrap());
+    Lazy::new(|| Regex::new(r"^libpython3\.\d+m?u?t?\.so\.\d+\.\d+$").unwrap());
 
 /// Error raised during auditing an elf file for manylinux/musllinux compatibility
 #[derive(Error, Debug)]

src/build_options.rs

@@ -274,6 +274,10 @@ impl BuildOptions {
                             .get("ABIFLAGS")
                             .map(ToString::to_string)
                             .unwrap_or_default();
+                        let gil_disabled = sysconfig_data
+                            .get("Py_GIL_DISABLED")
+                            .map(|x| x == "1")
+                            .unwrap_or_default();
                         let ext_suffix = sysconfig_data
                             .get("EXT_SUFFIX")
                             .context("syconfig didn't define an `EXT_SUFFIX` ಠ_ಠ")?;
@@ -299,6 +303,7 @@ impl BuildOptions {
                                 abiflags,
                                 ext_suffix: ext_suffix.to_string(),
                                 pointer_width: None,
+                                gil_disabled,
                             },
                             executable: PathBuf::new(),
                             platform: None,
@@ -376,6 +381,7 @@ impl BuildOptions {
                                 abiflags: "".to_string(),
                                 ext_suffix: ".pyd".to_string(),
                                 pointer_width: None,
+                                gil_disabled: false,
                             },
                             executable: PathBuf::new(),
                             platform: None,
@@ -402,6 +408,7 @@ impl BuildOptions {
                                 abiflags: "".to_string(),
                                 ext_suffix: ".pyd".to_string(),
                                 pointer_width: None,
+                                gil_disabled: false,
                             },
                             executable: PathBuf::new(),
                             platform: None,
@@ -441,6 +448,7 @@ impl BuildOptions {
                                 abiflags: "".to_string(),
                                 ext_suffix: "".to_string(),
                                 pointer_width: None,
+                                gil_disabled: false,
                             },
                             executable: PathBuf::new(),
                             platform: None,
@@ -1244,26 +1252,35 @@ fn find_interpreter_in_sysconfig(
     let mut interpreters = Vec::new();
     for interp in interpreter {
         let python = interp.display().to_string();
-        let (python_impl, python_ver) = if let Some(ver) = python.strip_prefix("pypy") {
-            (InterpreterKind::PyPy, ver.strip_prefix('-').unwrap_or(ver))
-        } else if let Some(ver) = python.strip_prefix("graalpy") {
+        let (python_impl, python_ver, abiflags) = if let Some(ver) = python.strip_prefix("pypy") {
             (
-                InterpreterKind::GraalPy,
+                InterpreterKind::PyPy,
                 ver.strip_prefix('-').unwrap_or(ver),
+                "",
             )
-        } else if let Some(ver) = python.strip_prefix("python") {
+        } else if let Some(ver) = python.strip_prefix("graalpy") {
             (
-                InterpreterKind::CPython,
+                InterpreterKind::GraalPy,
                 ver.strip_prefix('-').unwrap_or(ver),
+                "",
             )
+        } else if let Some(ver) = python.strip_prefix("python") {
+            // Also accept things like `python3.13t` for free-threaded python
+            let (ver, abiflags) =
+                if let Some(ver) = ver.strip_prefix('-').unwrap_or(ver).strip_suffix('t') {
+                    (ver, "t")
+                } else {
+                    (ver, "")
+                };
+            (InterpreterKind::CPython, ver, abiflags)
         } else if python
             .chars()
             .next()
             .map(|c| c.is_ascii_digit())
             .unwrap_or(false)
         {
             // Eg: -i 3.9 without interpreter kind, assume it's CPython
-            (InterpreterKind::CPython, &*python)
+            (InterpreterKind::CPython, &*python, "")
         } else {
             // if interpreter not known
             if std::path::Path::new(&python).is_file() {
@@ -1284,7 +1301,12 @@ fn find_interpreter_in_sysconfig(
         let ver_minor = ver_minor.parse::<usize>().with_context(|| {
             format!("Invalid python interpreter minor version '{ver_minor}', expect a digit")
         })?;
-        let sysconfig = InterpreterConfig::lookup_one(target, python_impl, (ver_major, ver_minor))
+
+        if (ver_major, ver_minor) < (3, 13) && abiflags == "t" {
+            bail!("Free-threaded Python interpreter is only supported on 3.13 and later.");
+        }
+
+        let sysconfig = InterpreterConfig::lookup_one(target, python_impl, (ver_major, ver_minor), abiflags)
             .with_context(|| {
                 format!("Failed to find a {python_impl} {ver_major}.{ver_minor} interpreter in known sysconfig")
             })?;

src/cross_compile.rs

@@ -52,6 +52,7 @@ KEYS = [
     "ABIFLAGS",
     "EXT_SUFFIX",
     "SOABI",
+    "Py_GIL_DISABLED",
 ]
 for key in KEYS:
     print(key, build_time_vars.get(key, ""))