From b749782cf5253bc1dccb8cdaef32d26c2e96c6ac Mon Sep 17 00:00:00 2001
From: Lysandros Nikolaou <lisandrosnik@gmail.com>
Date: Wed, 28 May 2025 13:30:12 +0200
Subject: [PATCH] Mark extensions as free-threading-compatible and build wheels

---
 .github/workflows/ci.yml   | 2 ++
 CHANGELOG.rst              | 2 ++
 src/isal/_isalmodule.c     | 5 +++++
 src/isal/igzip_libmodule.c | 5 +++++
 src/isal/isal_zlibmodule.c | 4 ++++
 5 files changed, 18 insertions(+)

diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index b886a730..104b11db 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -59,6 +59,7 @@ jobs:
           - "3.11"
           - "3.12"
           - "3.13"
+          - "3.13t"
           - "pypy-3.9"
           - "pypy-3.10"
         os: ["ubuntu-latest"]
@@ -215,6 +216,7 @@ jobs:
         run: cibuildwheel --output-dir dist
         env:
           CIBW_SKIP: "*-win32 *-manylinux_i686 cp38-macosx_*arm64 cp39-macosx_*arm64"  # Skip 32 bit and problematic mac builds.
+          CIBW_ENABLE: "cpython-freethreading"
           CIBW_ARCHS_LINUX: ${{ matrix.cibw_archs_linux }}
           CIBW_BEFORE_ALL_LINUX: ${{ matrix.cibw_before_all_linux }}
           # Fully test the build wheels again.
diff --git a/CHANGELOG.rst b/CHANGELOG.rst
index c49acba7..c20a0a5f 100644
--- a/CHANGELOG.rst
+++ b/CHANGELOG.rst
@@ -16,6 +16,8 @@ version 1.8.0-dev
 + Include test packages in the source distribution, so source distribution
   installations can be verified.
 + Fix an issue where some tests failed because they ignored PYTHONPATH.
++ Enable support for free-threading and build free-threaded wheels for
+  CPython 3.13.
 
 version 1.7.2
 -----------------
diff --git a/src/isal/_isalmodule.c b/src/isal/_isalmodule.c
index a429d3a7..55f43917 100644
--- a/src/isal/_isalmodule.c
+++ b/src/isal/_isalmodule.c
@@ -31,6 +31,11 @@ PyInit__isal(void)
     if (m == NULL) {
         return NULL;
     }
+
+#ifdef Py_GIL_DISABLED
+    PyUnstable_Module_SetGIL(m, Py_MOD_GIL_NOT_USED);
+#endif
+
     PyModule_AddIntMacro(m, ISAL_MAJOR_VERSION);
     PyModule_AddIntMacro(m, ISAL_MINOR_VERSION);
     PyModule_AddIntMacro(m, ISAL_PATCH_VERSION);
diff --git a/src/isal/igzip_libmodule.c b/src/isal/igzip_libmodule.c
index de94ab01..d498145f 100644
--- a/src/isal/igzip_libmodule.c
+++ b/src/isal/igzip_libmodule.c
@@ -617,6 +617,11 @@ PyInit_igzip_lib(void)
     if (m == NULL)
         return NULL;
 
+#ifdef Py_GIL_DISABLED
+    PyUnstable_Module_SetGIL(m, Py_MOD_GIL_NOT_USED);
+#endif
+
+
     IsalError = PyErr_NewException("igzip_lib.IsalError", NULL, NULL);
     if (IsalError == NULL) {
         return NULL;
diff --git a/src/isal/isal_zlibmodule.c b/src/isal/isal_zlibmodule.c
index 67547be9..3a280ec8 100644
--- a/src/isal/isal_zlibmodule.c
+++ b/src/isal/isal_zlibmodule.c
@@ -2183,6 +2183,10 @@ PyInit_isal_zlib(void)
         return NULL;
     }
 
+#ifdef Py_GIL_DISABLED
+    PyUnstable_Module_SetGIL(m, Py_MOD_GIL_NOT_USED);
+#endif
+
     PyObject *igzip_lib_module = PyImport_ImportModule("isal.igzip_lib");
     if (igzip_lib_module == NULL) {
         return NULL;