Support free threaded Python versions like '3.13t' (#973)

* Support free threaded Python versions like '3.13t'

Python wheels, pyenv, and a number of other tools use 't' in the Python
version number to identify free threaded builds. For example, '3.13t',
'3.14.0a1', '3.14t-dev'.

This PR supports that syntax in `actions/setup-python`, strips the "t",
and adds "-freethreading" to the architecture to select the correct
Python version.

See #771

* Add free threading to advanced usage documentation

* Fix desugaring of `3.13.1t` and add test case.

* Add freethreaded input and fix handling of prerelease versions

* Fix lint

* Add 't' suffix to python-version output

* Use distinct cache key for free threaded Python

* Remove support for syntax like '3.14.0a1'

* Clarify use of 't' suffix

* Improve error message when trying to use free threaded Python versions before 3.13

Author: colesbury

README.md

@@ -45,6 +45,16 @@ steps:
 - run: python my_script.py
 ```
 
+**Free threaded Python**
+```yaml
+steps:
+- uses: actions/checkout@v4
+- uses: actions/setup-python@v5
+  with:
+    python-version: '3.13t'
+- run: python my_script.py
+```
+
 The `python-version` input is optional. If not supplied, the action will try to resolve the version from the default `.python-version` file. If the `.python-version` file doesn't exist Python or PyPy version from the PATH will be used. The default version of Python or PyPy in PATH varies between runners and can be changed unexpectedly so we recommend always setting Python version explicitly using the `python-version` or `python-version-file` inputs.
 
 The action will first check the local [tool cache](docs/advanced-usage.md#hosted-tool-cache) for a [semver](https://github.com/npm/node-semver#versions) match. If unable to find a specific version in the tool cache, the action will attempt to download a version of Python from [GitHub Releases](https://github.com/actions/python-versions/releases) and for PyPy from the official [PyPy's dist](https://downloads.python.org/pypy/).

__tests__/find-python.test.ts

@@ -0,0 +1,43 @@
+import {desugarVersion, pythonVersionToSemantic} from '../src/find-python';
+
+describe('desugarVersion', () => {
+  it.each([
+    ['3.13', {version: '3.13', freethreaded: false}],
+    ['3.13t', {version: '3.13', freethreaded: true}],
+    ['3.13.1', {version: '3.13.1', freethreaded: false}],
+    ['3.13.1t', {version: '3.13.1', freethreaded: true}],
+    ['3.14-dev', {version: '~3.14.0-0', freethreaded: false}],
+    ['3.14t-dev', {version: '~3.14.0-0', freethreaded: true}]
+  ])('%s -> %s', (input, expected) => {
+    expect(desugarVersion(input)).toEqual(expected);
+  });
+});
+
+// Test the combined desugarVersion and pythonVersionToSemantic functions
+describe('pythonVersions', () => {
+  it.each([
+    ['3.13', {version: '3.13', freethreaded: false}],
+    ['3.13t', {version: '3.13', freethreaded: true}],
+    ['3.13.1', {version: '3.13.1', freethreaded: false}],
+    ['3.13.1t', {version: '3.13.1', freethreaded: true}],
+    ['3.14-dev', {version: '~3.14.0-0', freethreaded: false}],
+    ['3.14t-dev', {version: '~3.14.0-0', freethreaded: true}]
+  ])('%s -> %s', (input, expected) => {
+    const {version, freethreaded} = desugarVersion(input);
+    const semanticVersionSpec = pythonVersionToSemantic(version, false);
+    expect({version: semanticVersionSpec, freethreaded}).toEqual(expected);
+  });
+
+  it.each([
+    ['3.13', {version: '~3.13.0-0', freethreaded: false}],
+    ['3.13t', {version: '~3.13.0-0', freethreaded: true}],
+    ['3.13.1', {version: '3.13.1', freethreaded: false}],
+    ['3.13.1t', {version: '3.13.1', freethreaded: true}],
+    ['3.14-dev', {version: '~3.14.0-0', freethreaded: false}],
+    ['3.14t-dev', {version: '~3.14.0-0', freethreaded: true}]
+  ])('%s (allowPreReleases=true) -> %s', (input, expected) => {
+    const {version, freethreaded} = desugarVersion(input);
+    const semanticVersionSpec = pythonVersionToSemantic(version, true);
+    expect({version: semanticVersionSpec, freethreaded}).toEqual(expected);
+  });
+});

__tests__/finder.test.ts

@@ -56,7 +56,7 @@ describe('Finder tests', () => {
     await io.mkdirP(pythonDir);
     fs.writeFileSync(`${pythonDir}.complete`, 'hello');
     // This will throw if it doesn't find it in the cache and in the manifest (because no such version exists)
-    await finder.useCpythonVersion('3.x', 'x64', true, false, false);
+    await finder.useCpythonVersion('3.x', 'x64', true, false, false, false);
     expect(spyCoreAddPath).toHaveBeenCalled();
     expect(spyCoreExportVariable).toHaveBeenCalledWith(
       'pythonLocation',
@@ -73,7 +73,7 @@ describe('Finder tests', () => {
     await io.mkdirP(pythonDir);
     fs.writeFileSync(`${pythonDir}.complete`, 'hello');
     // This will throw if it doesn't find it in the cache and in the manifest (because no such version exists)
-    await finder.useCpythonVersion('3.x', 'x64', false, false, false);
+    await finder.useCpythonVersion('3.x', 'x64', false, false, false, false);
     expect(spyCoreAddPath).not.toHaveBeenCalled();
     expect(spyCoreExportVariable).not.toHaveBeenCalled();
   });
@@ -96,7 +96,7 @@ describe('Finder tests', () => {
     });
     // This will throw if it doesn't find it in the cache and in the manifest (because no such version exists)
     await expect(
-      finder.useCpythonVersion('1.2.3', 'x64', true, false, false)
+      finder.useCpythonVersion('1.2.3', 'x64', true, false, false, false)
     ).resolves.toEqual({
       impl: 'CPython',
       version: '1.2.3'
@@ -135,7 +135,14 @@ describe('Finder tests', () => {
     });
     // This will throw if it doesn't find it in the manifest (because no such version exists)
     await expect(
-      finder.useCpythonVersion('1.2.4-beta.2', 'x64', false, false, false)
+      finder.useCpythonVersion(
+        '1.2.4-beta.2',
+        'x64',
+        false,
+        false,
+        false,
+        false
+      )
     ).resolves.toEqual({
       impl: 'CPython',
       version: '1.2.4-beta.2'
@@ -186,7 +193,7 @@ describe('Finder tests', () => {
 
     fs.writeFileSync(`${pythonDir}.complete`, 'hello');
     // This will throw if it doesn't find it in the cache and in the manifest (because no such version exists)
-    await finder.useCpythonVersion('1.2', 'x64', true, true, false);
+    await finder.useCpythonVersion('1.2', 'x64', true, true, false, false);
 
     expect(infoSpy).toHaveBeenCalledWith("Resolved as '1.2.3'");
     expect(infoSpy).toHaveBeenCalledWith(
@@ -197,7 +204,14 @@ describe('Finder tests', () => {
     );
     expect(installSpy).toHaveBeenCalled();
     expect(addPathSpy).toHaveBeenCalledWith(expPath);
-    await finder.useCpythonVersion('1.2.4-beta.2', 'x64', false, true, false);
+    await finder.useCpythonVersion(
+      '1.2.4-beta.2',
+      'x64',
+      false,
+      true,
+      false,
+      false
+    );
     expect(spyCoreAddPath).toHaveBeenCalled();
     expect(spyCoreExportVariable).toHaveBeenCalledWith(
       'pythonLocation',
@@ -224,7 +238,7 @@ describe('Finder tests', () => {
     });
     // This will throw if it doesn't find it in the cache and in the manifest (because no such version exists)
     await expect(
-      finder.useCpythonVersion('1.2', 'x64', false, false, false)
+      finder.useCpythonVersion('1.2', 'x64', false, false, false, false)
     ).resolves.toEqual({
       impl: 'CPython',
       version: '1.2.3'
@@ -251,25 +265,32 @@ describe('Finder tests', () => {
     });
     // This will throw if it doesn't find it in the cache and in the manifest (because no such version exists)
     await expect(
-      finder.useCpythonVersion('1.1', 'x64', false, false, false)
+      finder.useCpythonVersion('1.1', 'x64', false, false, false, false)
     ).rejects.toThrow();
     await expect(
-      finder.useCpythonVersion('1.1', 'x64', false, false, true)
+      finder.useCpythonVersion('1.1', 'x64', false, false, true, false)
     ).resolves.toEqual({
       impl: 'CPython',
       version: '1.1.0-beta.2'
     });
     // Check 1.1.0 version specifier does not fallback to '1.1.0-beta.2'
     await expect(
-      finder.useCpythonVersion('1.1.0', 'x64', false, false, true)
+      finder.useCpythonVersion('1.1.0', 'x64', false, false, true, false)
     ).rejects.toThrow();
   });
 
   it('Errors if Python is not installed', async () => {
     // This will throw if it doesn't find it in the cache and in the manifest (because no such version exists)
     let thrown = false;
     try {
-      await finder.useCpythonVersion('3.300000', 'x64', true, false, false);
+      await finder.useCpythonVersion(
+        '3.300000',
+        'x64',
+        true,
+        false,
+        false,
+        false
+      );
     } catch {
       thrown = true;
     }

action.yml

@@ -26,6 +26,9 @@ inputs:
   allow-prereleases:
     description: "When 'true', a version range passed to 'python-version' input will match prerelease versions if no GA versions are found. Only 'x.y' version range is supported for CPython."
     default: false
+  freethreaded:
+    description: "When 'true', use the freethreaded version of Python."
+    default: false
 outputs:
   python-version:
     description: "The installed Python or PyPy version. Useful when given a version range as input."

dist/setup/index.js

@@ -99514,7 +99514,7 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
     });
 };
 Object.defineProperty(exports, "__esModule", ({ value: true }));
-exports.pythonVersionToSemantic = exports.useCpythonVersion = void 0;
+exports.pythonVersionToSemantic = exports.desugarVersion = exports.useCpythonVersion = void 0;
 const os = __importStar(__nccwpck_require__(857));
 const path = __importStar(__nccwpck_require__(6928));
 const utils_1 = __nccwpck_require__(1798);
@@ -99542,13 +99542,22 @@ function binDir(installDir) {
         return path.join(installDir, 'bin');
     }
 }
-function useCpythonVersion(version, architecture, updateEnvironment, checkLatest, allowPreReleases) {
+function useCpythonVersion(version, architecture, updateEnvironment, checkLatest, allowPreReleases, freethreaded) {
     return __awaiter(this, void 0, void 0, function* () {
         var _a;
         let manifest = null;
-        const desugaredVersionSpec = desugarDevVersion(version);
+        const { version: desugaredVersionSpec, freethreaded: versionFreethreaded } = desugarVersion(version);
         let semanticVersionSpec = pythonVersionToSemantic(desugaredVersionSpec, allowPreReleases);
+        if (versionFreethreaded) {
+            // Use the freethreaded version if it was specified in the input, e.g., 3.13t
+            freethreaded = true;
+        }
         core.debug(`Semantic version spec of ${version} is ${semanticVersionSpec}`);
+        if (freethreaded) {
+            // Free threaded versions use an architecture suffix like `x64-freethreaded`
+            core.debug(`Using freethreaded version of ${semanticVersionSpec}`);
+            architecture += '-freethreaded';
+        }
         if (checkLatest) {
             manifest = yield installer.getManifest();
             const resolvedVersion = (_a = (yield installer.findReleaseFromManifest(semanticVersionSpec, architecture, manifest))) === null || _a === void 0 ? void 0 : _a.version;
@@ -99572,12 +99581,16 @@ function useCpythonVersion(version, architecture, updateEnvironment, checkLatest
         }
         if (!installDir) {
             const osInfo = yield (0, utils_1.getOSInfo)();
-            throw new Error([
+            const msg = [
                 `The version '${version}' with architecture '${architecture}' was not found for ${osInfo
                     ? `${osInfo.osName} ${osInfo.osVersion}`
-                    : 'this operating system'}.`,
-                `The list of all available versions can be found here: ${installer.MANIFEST_URL}`
-            ].join(os.EOL));
+                    : 'this operating system'}.`
+            ];
+            if (freethreaded) {
+                msg.push(`Free threaded versions are only available for Python 3.13.0 and later.`);
+            }
+            msg.push(`The list of all available versions can be found here: ${installer.MANIFEST_URL}`);
+            throw new Error(msg.join(os.EOL));
         }
         const _binDir = binDir(installDir);
         const binaryExtension = utils_1.IS_WINDOWS ? '.exe' : '';
@@ -99617,12 +99630,39 @@ function useCpythonVersion(version, architecture, updateEnvironment, checkLatest
             // On Linux and macOS, pip will create the --user directory and add it to PATH as needed.
         }
         const installed = versionFromPath(installDir);
-        core.setOutput('python-version', installed);
+        let pythonVersion = installed;
+        if (freethreaded) {
+            // Add the freethreaded suffix to the version (e.g., 3.13.1t)
+            pythonVersion += 't';
+        }
+        core.setOutput('python-version', pythonVersion);
         core.setOutput('python-path', pythonPath);
-        return { impl: 'CPython', version: installed };
+        return { impl: 'CPython', version: pythonVersion };
     });
 }
 exports.useCpythonVersion = useCpythonVersion;
+/* Desugar free threaded and dev versions */
+function desugarVersion(versionSpec) {
+    const { version, freethreaded } = desugarFreeThreadedVersion(versionSpec);
+    return { version: desugarDevVersion(version), freethreaded };
+}
+exports.desugarVersion = desugarVersion;
+/* Identify freethreaded versions like, 3.13t, 3.13.1t, 3.13t-dev.
+ * Returns the version without the `t` and the architectures suffix, if freethreaded */
+function desugarFreeThreadedVersion(versionSpec) {
+    const majorMinor = /^(\d+\.\d+(\.\d+)?)(t)$/;
+    if (majorMinor.test(versionSpec)) {
+        return { version: versionSpec.replace(majorMinor, '$1'), freethreaded: true };
+    }
+    const devVersion = /^(\d+\.\d+)(t)(-dev)$/;
+    if (devVersion.test(versionSpec)) {
+        return {
+            version: versionSpec.replace(devVersion, '$1$3'),
+            freethreaded: true
+        };
+    }
+    return { version: versionSpec, freethreaded: false };
+}
 /** Convert versions like `3.8-dev` to a version like `~3.8.0-0`. */
 function desugarDevVersion(versionSpec) {
     const devVersion = /^(\d+)\.(\d+)-dev$/;
@@ -100365,6 +100405,7 @@ function run() {
             const versions = resolveVersionInput();
             const checkLatest = core.getBooleanInput('check-latest');
             const allowPreReleases = core.getBooleanInput('allow-prereleases');
+            const freethreaded = core.getBooleanInput('freethreaded');
             if (versions.length) {
                 let pythonVersion = '';
                 const arch = core.getInput('architecture') || os.arch();
@@ -100385,7 +100426,7 @@ function run() {
                         if (version.startsWith('2')) {
                             core.warning('The support for python 2.7 was removed on June 19, 2023. Related issue: https://github.com/actions/setup-python/issues/672');
                         }
-                        const installed = yield finder.useCpythonVersion(version, arch, updateEnvironment, checkLatest, allowPreReleases);
+                        const installed = yield finder.useCpythonVersion(version, arch, updateEnvironment, checkLatest, allowPreReleases, freethreaded);
                         pythonVersion = installed.version;
                         core.info(`Successfully set up ${installed.impl} (${pythonVersion})`);
                     }

docs/advanced-usage.md

@@ -77,6 +77,31 @@ steps:
 - run: python my_script.py
 ```
 
+You can specify the [free threading](https://docs.python.org/3/howto/free-threading-python.html) version of Python by setting the `freethreaded` input to `true` or by using the special **t** suffix in some cases.
+You can use the **t** suffix when specifying the major and minor version (e.g., `3.13t`), with a patch version (e.g., `3.13.1t`), or with the **x.y-dev syntax** (e.g., `3.14t-dev`).
+Free threaded Python is only available starting with the 3.13 release.
+
+```yaml
+steps:
+- uses: actions/checkout@v4
+- uses: actions/setup-python@v5
+  with:
+    python-version: '3.13t'
+- run: python my_script.py
+```
+
+Note that the **t** suffix is not `semver` syntax. If you wish to specify a range, you must use the `freethreaded` input instead of the `t` suffix.
+
+```yaml
+steps:
+- uses: actions/checkout@v4
+- uses: actions/setup-python@v5
+  with:
+    python-version: '>=3.13'
+    freethreaded: true
+- run: python my_script.py
+```
+
 You can also use several types of ranges that are specified in [semver](https://github.com/npm/node-semver#ranges), for instance:
 
 - **[ranges](https://github.com/npm/node-semver#ranges)** to download and set up the latest available version of Python satisfying a range: