gh-122931: Include multiarch tuple in abi3t filenames

Doc/whatsnew/3.16.rst

@@ -81,6 +81,16 @@ Other language changes
   they reference) alive indefinitely.
   (Contributed by Łukasz Langa in :gh:`102960`.)
 
+* Stable ABI extensions (with free-threaded compatibility) may now
+  include a multiarch tuple in the filename, e.g.
+  ``foo.abi3t-x86-64-linux-gnu.so``.
+  This permits stable ABI extensions for multiple architectures to be
+  co-installed into the same directory, without clashing with each
+  other, as regular dynamic extensions do. Build tools will generate
+  these multiarch tagged filenames, by default, when targeting
+  compatibility with at least Python 3.15.
+  (Contributed by Stefano Rivera in :gh:`122931`.)
+
 
 New modules
 ===========

Lib/test/pythoninfo.py

@@ -570,6 +570,7 @@ def collect_sysconfig(info_add):
 
     for name in (
         'ABIFLAGS',
+        'ALT_SOABI',
         'ANDROID_API_LEVEL',
         'CC',
         'CCSHARED',
@@ -595,6 +596,7 @@ def collect_sysconfig(info_add):
         'Py_REMOTE_DEBUG',
         'SHELL',
         'SOABI',
+        'SOABI_PLATFORM',
         'TEST_MODULES',
         'VAPTH',
         'abs_builddir',
@@ -1316,6 +1318,12 @@ def collect_system(info_add):
             info_add('system.hardware', hardware)
 
 
+def collect_importlib(info_add):
+    import importlib.machinery
+    info_add('importlib.extension_suffixes',
+             importlib.machinery.EXTENSION_SUFFIXES)
+
+
 def collect_info(info):
     error = False
     info_add = info.add
@@ -1358,6 +1366,7 @@ def collect_info(info):
         collect_zstd,
         collect_libregrtest_utils,
         collect_system,
+        collect_importlib,
 
         # Collecting from tests should be last as they have side effects.
         collect_test_socket,

Lib/test/test_importlib/extension/test_finder.py

@@ -5,6 +5,7 @@
 
 import unittest
 import sys
+import sysconfig
 
 
 class FinderTests(abc.FinderTests):
@@ -61,6 +62,7 @@ def test_failure(self):
 
     def test_abi3_extension_suffixes(self):
         suffixes = self.machinery.EXTENSION_SUFFIXES
+        platform = sysconfig.get_config_var("SOABI_PLATFORM")
         if 'win32' in sys.platform:
             # Either "_d.pyd" or ".pyd" must be in suffixes
             self.assertTrue({"_d.pyd", ".pyd"}.intersection(suffixes))
@@ -71,6 +73,8 @@ def test_abi3_extension_suffixes(self):
                 self.assertNotIn(".abi3.so", suffixes)
             else:
                 self.assertIn(".abi3.so", suffixes)
+            if platform:
+                self.assertIn(f".abi3t-{platform}.so", suffixes)
             self.assertIn(".abi3t.so", suffixes)
 
 

Misc/NEWS.d/next/C_API/2024-08-12-09-48-04.gh-issue-122931.QwHc2l.rst

@@ -0,0 +1 @@
+Linux: Include multiarch tuples in ``abi3t`` stable ABI C extension filenames, e.g. ``foo.abi3t-x86-64-linux-gnu.so``, by default.

Python/dynload_shlib.c

@@ -48,6 +48,9 @@ const char *_PyImport_DynLoadFiletab[] = {
 #ifndef Py_GIL_DISABLED
     ".abi" PYTHON_ABI_STRING ".so",
 #endif  /* Py_GIL_DISABLED */
+#ifdef SOABI_PLATFORM
+    ".abi" PYTHON_ABI_STRING "t-" SOABI_PLATFORM ".so",
+#endif  /* SOABI_PLATFORM */
     ".abi" PYTHON_ABI_STRING "t.so",
     ".so",
 #endif  /* __CYGWIN__ */

configure.ac

@@ -1212,6 +1212,10 @@ AS_CASE([$ac_sys_system],
   [SOABI_PLATFORM=$PLATFORM_TRIPLET]
 )
 
+if test x$SOABI_PLATFORM != x; then
+    AC_DEFINE_UNQUOTED([SOABI_PLATFORM], ["${SOABI_PLATFORM}"], [Platform tag, used in binary module extension filenames.])
+fi
+
 if test x$MULTIARCH != x; then
   MULTIARCH_CPPFLAGS="-DMULTIARCH=\\\"$MULTIARCH\\\""
 fi

pyconfig.h.in

@@ -1938,6 +1938,9 @@
 /* The size of '_Bool', as computed by sizeof. */
 #undef SIZEOF__BOOL
 
+/* Platform tag, used in binary module extension filenames. */
+#undef SOABI_PLATFORM
+
 /* Define to 1 if you have the ANSI C header files. */
 #undef STDC_HEADERS