Sync pre-release CPython 3.15 branch from GitHub (2026-07-08)

Summary:
Imported python/cpython `3.15.0b3+dev` from upstream rev [`e597358`](https://www.github.com/python/cpython/commit/e597358779cb965a687ba26422b434d70e3cd201) (committed 2026-07-08 01:40:03+00:00).

# Commit Info

- Base: (`3.15.0b3+dev`) - [`017e4e9`](https://www.github.com/python/cpython/commit/017e4e9bb8152bf09acd31b5fcaafceac002d84f) (commit date: 2026-07-07 00:24:44+00:00)
- Imported: (`3.15.0b3+dev`) - [`e597358`](https://www.github.com/python/cpython/commit/e597358779cb965a687ba26422b434d70e3cd201) (commit date: 2026-07-08 01:40:03+00:00)

# Noteworthy file changes

- Test files (1 added)
- Low-signal files (4 added) (NEWS.d, docs, .github)

Complete list of added/removed files: https://www.internalfb.com/intern/everpaste/?color=0&handle=GKynkiEO1CK4nrwFAL8lSt5yoS1Abr0LAAAz

Differential Revision: D110993969

fbshipit-source-id: 2f125926903ef71de6fff4ddcb27dca7af028e54

Author: generatedunixname1734921407115435

.github/workflows/build.yml

@@ -601,7 +601,6 @@ jobs:
         - Thread
         free-threading:
         - false
-        - true
         sanitizer:
         - TSan
         include:
@@ -613,6 +612,17 @@ jobs:
       sanitizer: ${{ matrix.sanitizer }}
       free-threading: ${{ matrix.free-threading }}
 
+  # XXX: Temporarily allow this job to fail to not block PRs.
+  build-san-free-threading:
+    # ${{ '' } is a hack to nest jobs under the same sidebar category.
+    name: Sanitizers${{ '' }}  # zizmor: ignore[obfuscation]
+    needs: build-context
+    if: needs.build-context.outputs.run-ubuntu == 'true'
+    uses: ./.github/workflows/reusable-san.yml
+    with:
+      sanitizer: TSan
+      free-threading: true
+
   cross-build-linux:
     name: Cross build Linux
     runs-on: ubuntu-latest
@@ -716,6 +726,7 @@ jobs:
     - test-hypothesis
     - build-asan
     - build-san
+    - build-san-free-threading
     - cross-build-linux
     - cifuzz
     if: always()
@@ -727,6 +738,7 @@ jobs:
         allowed-failures: >-
           build-android,
           build-emscripten,
+          build-san-free-threading,
           build-windows-msi,
           build-ubuntu-ssltests,
           test-hypothesis,

.github/workflows/reusable-docs.yml

@@ -3,6 +3,17 @@ name: Reusable Docs
 on:
   workflow_call:
   workflow_dispatch:
+  # Pushes to CPython branches seed the pip caches under the exact keys every
+  # docs PR restores from. Without a branch-scoped copy, each PR saves a
+  # duplicate into its own refs/pull/N/merge scope that nothing else can read.
+  push:
+    branches:
+      - main
+      - '3.*'
+    paths:
+      - 'Doc/pylock.toml'
+      - 'Doc/requirements.txt'
+      - '.github/workflows/reusable-docs.yml'
 
 permissions:
   contents: read

Doc/library/string.rst

@@ -971,7 +971,8 @@ attributes:
 
 Alternatively, you can provide the entire regular expression pattern by
 overriding the class attribute *pattern*.  If you do this, the value must be a
-regular expression object with four named capturing groups.  The capturing
+regular expression pattern string, or a compiled regular expression
+object, with four named capturing groups.  The capturing
 groups correspond to the rules given above, along with the invalid placeholder
 rule:
 

Doc/pylock.toml

@@ -2,6 +2,7 @@
 #    uv pip compile Doc/requirements.txt --exclude-newer P14D --exclude-newer-package linklint=PT0S --exclude-newer-package python-docs-theme=PT0S --no-cache --output-file Doc/pylock.toml --python-version 3.12 --universal
 lock-version = "1.0"
 created-by = "uv"
+requires-python = ">=3.12"
 
 [[packages]]
 name = "alabaster"
@@ -23,9 +24,9 @@ wheels = [{ url = "https://files.pythonhosted.org/packages/b4/03/374bd9e31b58e8a
 
 [[packages]]
 name = "certifi"
-version = "2026.4.22"
-sdist = { url = "https://files.pythonhosted.org/packages/25/ee/6caf7a40c36a1220410afe15a1cc64993a1f864871f698c0f93acb72842a/certifi-2026.4.22.tar.gz", upload-time = 2026-04-22T11:26:11Z, size = 137077, hashes = { sha256 = "8d455352a37b71bf76a79caa83a3d6c25afee4a385d632127b6afb3963f1c580" } }
-wheels = [{ url = "https://files.pythonhosted.org/packages/22/30/7cd8fdcdfbc5b869528b079bfb76dcdf6056b1a2097a662e5e8c04f42965/certifi-2026.4.22-py3-none-any.whl", upload-time = 2026-04-22T11:26:09Z, size = 135707, hashes = { sha256 = "3cb2210c8f88ba2318d29b0388d1023c8492ff72ecdde4ebdaddbb13a31b1c4a" } }]
+version = "2026.6.17"
+sdist = { url = "https://files.pythonhosted.org/packages/c9/c7/424b75da314c1045981bd9777432fad05a9e0c69daa4ed7e308bbaffe405/certifi-2026.6.17.tar.gz", upload-time = 2026-06-17T10:31:07Z, size = 134594, hashes = { sha256 = "024c88eeec92ca068db80f02b8b07c9cef7b9fe261d1d535abfd5abd6f6af432" } }
+wheels = [{ url = "https://files.pythonhosted.org/packages/ef/2f/c5464532e965badff2f4c4c1a3a83f5697f0d7c407ed0cda44aaa99bb451/certifi-2026.6.17-py3-none-any.whl", upload-time = 2026-06-17T10:31:06Z, size = 133289, hashes = { sha256 = "2227dcbaafe0d2f59279d1762ddddc37783ed4354594f194ffc31d20f41fc3db" } }]
 
 [[packages]]
 name = "charset-normalizer"
@@ -114,9 +115,9 @@ wheels = [{ url = "https://files.pythonhosted.org/packages/8f/d7/9322c609343d929
 
 [[packages]]
 name = "idna"
-version = "3.13"
-sdist = { url = "https://files.pythonhosted.org/packages/ce/cc/762dfb036166873f0059f3b7de4565e1b5bc3d6f28a414c13da27e442f99/idna-3.13.tar.gz", upload-time = 2026-04-22T16:42:42Z, size = 194210, hashes = { sha256 = "585ea8fe5d69b9181ec1afba340451fba6ba764af97026f92a91d4eef164a242" } }
-wheels = [{ url = "https://files.pythonhosted.org/packages/5d/13/ad7d7ca3808a898b4612b6fe93cde56b53f3034dcde235acb1f0e1df24c6/idna-3.13-py3-none-any.whl", upload-time = 2026-04-22T16:42:40Z, size = 68629, hashes = { sha256 = "892ea0cde124a99ce773decba204c5552b69c3c67ffd5f232eb7696135bc8bb3" } }]
+version = "3.18"
+sdist = { url = "https://files.pythonhosted.org/packages/cd/63/9496c57188a2ee585e0f1db071d75089a11e98aa86eb99d9d7618fc1edce/idna-3.18.tar.gz", upload-time = 2026-06-02T14:34:07Z, size = 196711, hashes = { sha256 = "ffb385a7e039654cef1ab9ef32c6fafe283c0c0467bba1d9029738ce4a14a848" } }
+wheels = [{ url = "https://files.pythonhosted.org/packages/1e/5e/d4e9f1a599fb8e573b7b87160658329fbf28d19eac2718f51fc3def3aa5a/idna-3.18-py3-none-any.whl", upload-time = 2026-06-02T14:34:06Z, size = 65455, hashes = { sha256 = "7f952cbe720b688055e3f87de14f5c3e5fdaa8bc3928985c4077ca689de849a2" } }]
 
 [[packages]]
 name = "imagesize"
@@ -132,9 +133,9 @@ wheels = [{ url = "https://files.pythonhosted.org/packages/62/a1/3d680cbfd5f4b8f
 
 [[packages]]
 name = "linklint"
-version = "1.0.0"
-sdist = { url = "https://files.pythonhosted.org/packages/f3/59/a2bb261b3fc0e3bfdc9d3e6f8a37bdf1fb6eca8d992f23f55a83bf19acb1/linklint-1.0.0.tar.gz", upload-time = 2026-05-02T11:39:39Z, size = 21310, hashes = { sha256 = "52dc292f27b7eb4f3825d23ec1222d4a17bd116945b77c486406d97bb936e6c2" } }
-wheels = [{ url = "https://files.pythonhosted.org/packages/7b/78/98e52e4262416060a0eedc2e5514035cfcfc2fd962d09b84e27848c1aef3/linklint-1.0.0-py3-none-any.whl", upload-time = 2026-05-02T11:39:37Z, size = 12521, hashes = { sha256 = "bbb3f589ab65709cf23655ef6097bdc25180f80c0d42a4d9a1714366d2d3edab" } }]
+version = "1.0.1"
+sdist = { url = "https://files.pythonhosted.org/packages/62/22/c65a97b2192c3c317c472058bf52d7ca88e421998fa8d5c183b2280ab5d4/linklint-1.0.1.tar.gz", upload-time = 2026-06-09T12:30:47Z, size = 22412, hashes = { sha256 = "10201b4366edecfbeb3281883aff857dbe77d40bb56f16f212d372f597342d5f" } }
+wheels = [{ url = "https://files.pythonhosted.org/packages/7b/d8/b2f1708f55f4dd5358b48d28be07ff8e0dadd6d23e41ead2ed1424e90256/linklint-1.0.1-py3-none-any.whl", upload-time = 2026-06-09T12:30:46Z, size = 12828, hashes = { sha256 = "c931f110482f1d17808aa2df78b116adc44d7a14e9e79922c57bf9a7cba40a2d" } }]
 
 [[packages]]
 name = "markupsafe"
@@ -162,8 +163,7 @@ wheels = [{ url = "https://files.pythonhosted.org/packages/88/ef/eb23f262cca3c0c
 [[packages]]
 name = "pygments"
 version = "2.20.0"
-sdist = { url = "https://files.pythonhosted.org/packages/c3/b2/bc9c9196916376152d655522fdcebac55e66de6603a76a02bca1b6414f6c/pygments-2.20.0.tar.gz", upload-time = 2026-03-29T13:29:33Z, size = 4955991, hashes = { sha256 = "6757cd03768053ff99f3039c1a36d6c0aa0b263438fcab17520b30a303a82b5f" } }
-wheels = [{ url = "https://files.pythonhosted.org/packages/f4/7e/a72dd26f3b0f4f2bf1dd8923c85f7ceb43172af56d63c7383eb62b332364/pygments-2.20.0-py3-none-any.whl", upload-time = 2026-03-29T13:29:30Z, size = 1231151, hashes = { sha256 = "81a9e26dd42fd28a23a2d169d86d7ac03b46e2f8b59ed4698fb4785f946d0176" } }]
+archive = { url = "https://github.com/pygments/pygments/archive/2cad2642058441b59782a6a18f03c98c42d081f1.tar.gz", hashes = { sha256 = "e6ae46831285e86355eabb969bf2d0520655b001dd882147637f4bc500e56bfb" } }
 
 [[packages]]
 name = "python-docs-theme"
@@ -173,9 +173,9 @@ wheels = [{ url = "https://files.pythonhosted.org/packages/db/05/b9298eb9330c70a
 
 [[packages]]
 name = "requests"
-version = "2.33.1"
-sdist = { url = "https://files.pythonhosted.org/packages/5f/a4/98b9c7c6428a668bf7e42ebb7c79d576a1c3c1e3ae2d47e674b468388871/requests-2.33.1.tar.gz", upload-time = 2026-03-30T16:09:15Z, size = 134120, hashes = { sha256 = "18817f8c57c6263968bc123d237e3b8b08ac046f5456bd1e307ee8f4250d3517" } }
-wheels = [{ url = "https://files.pythonhosted.org/packages/d7/8e/7540e8a2036f79a125c1d2ebadf69ed7901608859186c856fa0388ef4197/requests-2.33.1-py3-none-any.whl", upload-time = 2026-03-30T16:09:13Z, size = 64947, hashes = { sha256 = "4e6d1ef462f3626a1f0a0a9c42dd93c63bad33f9f1c1937509b8c5c8718ab56a" } }]
+version = "2.34.2"
+sdist = { url = "https://files.pythonhosted.org/packages/ac/c3/e2a2b89f2d3e2179abd6d00ebd70bff6273f37fb3e0cc209f48b39d00cbf/requests-2.34.2.tar.gz", upload-time = 2026-05-14T19:25:27Z, size = 142856, hashes = { sha256 = "f288924cae4e29463698d6d60bc6a4da69c89185ad1e0bcc4104f584e960b9ed" } }
+wheels = [{ url = "https://files.pythonhosted.org/packages/a0/f4/c67b0b3f1b9245e8d266f0f112c500d50e5b4e83cb6f3b71b6528104182a/requests-2.34.2-py3-none-any.whl", upload-time = 2026-05-14T19:25:26Z, size = 73075, hashes = { sha256 = "2a0d60c172f83ac6ab31e4554906c0f3b3588d37b5cb939b1c061f4907e278e0" } }]
 
 [[packages]]
 name = "roman-numerals"
@@ -251,6 +251,6 @@ wheels = [{ url = "https://files.pythonhosted.org/packages/bf/a4/66c1fd4f8fab88f
 
 [[packages]]
 name = "urllib3"
-version = "2.6.3"
-sdist = { url = "https://files.pythonhosted.org/packages/c7/24/5f1b3bdffd70275f6661c76461e25f024d5a38a46f04aaca912426a2b1d3/urllib3-2.6.3.tar.gz", upload-time = 2026-01-07T16:24:43Z, size = 435556, hashes = { sha256 = "1b62b6884944a57dbe321509ab94fd4d3b307075e0c2eae991ac71ee15ad38ed" } }
-wheels = [{ url = "https://files.pythonhosted.org/packages/39/08/aaaad47bc4e9dc8c725e68f9d04865dbcb2052843ff09c97b08904852d84/urllib3-2.6.3-py3-none-any.whl", upload-time = 2026-01-07T16:24:42Z, size = 131584, hashes = { sha256 = "bf272323e553dfb2e87d9bfd225ca7b0f467b919d7bbd355436d3fd37cb0acd4" } }]
+version = "2.7.0"
+sdist = { url = "https://files.pythonhosted.org/packages/53/0c/06f8b233b8fd13b9e5ee11424ef85419ba0d8ba0b3138bf360be2ff56953/urllib3-2.7.0.tar.gz", upload-time = 2026-05-07T16:13:18Z, size = 433602, hashes = { sha256 = "231e0ec3b63ceb14667c67be60f2f2c40a518cb38b03af60abc813da26505f4c" } }
+wheels = [{ url = "https://files.pythonhosted.org/packages/7f/3e/5db95bcf282c52709639744ca2a8b149baccf648e39c8cc87553df9eae0c/urllib3-2.7.0-py3-none-any.whl", upload-time = 2026-05-07T16:13:17Z, size = 131087, hashes = { sha256 = "9fb4c81ebbb1ce9531cce37674bbc6f1360472bc18ca9a553ede278ef7276897" } }]

Doc/requirements.txt

@@ -9,6 +9,10 @@
 # Keep this version in sync with ``Doc/conf.py``.
 sphinx<9.0.0
 
+# Temporary direct requirement, pending release of Pygments > 2.20.0
+# https://github.com/pygments/pygments/discussions/3145
+pygments @ https://github.com/pygments/pygments/archive/2cad2642058441b59782a6a18f03c98c42d081f1.tar.gz
+
 blurb
 
 sphinxext-opengraph~=0.13.0

Lib/string/__init__.py

@@ -83,7 +83,14 @@ def __init_subclass__(cls):
     def _compile_pattern(cls):
         import re  # deferred import, for performance
 
+        # `pattern` may be the `_TemplatePattern` sentinel (not yet compiled), an
+        # already-compiled regular expression object (as documented), or a string
+        # regular expression.  An already-compiled object is returned as-is; the
+        # other two are compiled and cached back on the class.
         pattern = cls.__dict__.get('pattern', _TemplatePattern)
+        if isinstance(pattern, re.Pattern):
+            # re.compile() rejects flags on an already-compiled pattern.
+            return pattern
         if pattern is _TemplatePattern:
             delim = re.escape(cls.delimiter)
             id = cls.idpattern

Lib/test/test_array.py

@@ -5,7 +5,7 @@
 import collections.abc
 import unittest
 from test import support
-from test.support import import_helper
+from test.support import import_helper, script_helper
 from test.support import os_helper
 from test.support import _2G
 from test.support import subTests
@@ -38,6 +38,11 @@ def __init__(self, typecode, newarg=None):
 
 class MiscTest(unittest.TestCase):
 
+    def test_array_type_importable(self):
+        from array import ArrayType
+
+        self.assertIs(array.array, ArrayType)
+
     def test_array_is_sequence(self):
         self.assertIsInstance(array.array("B"), collections.abc.MutableSequence)
         self.assertIsInstance(array.array("B"), collections.abc.Reversible)
@@ -49,6 +54,23 @@ def test_bad_constructor(self):
         self.assertRaises(ValueError, array.array, 'x')
         self.assertRaises(ValueError, array.array, 'Z')
 
+    @support.cpython_only
+    def test_does_not_crash_on_broken_imports(self):
+        # gh-153210
+        code = """if 1:
+            import collections.abc
+
+            del collections.abc.MutableSequence
+
+            try:
+                import array  # it used to crash before
+            except AttributeError:
+                pass
+            else:
+                raise AssertionError('AttributeError was not raised')
+        """
+        script_helper.assert_python_ok('-c', code)
+
     @support.cpython_only
     def test_disallow_instantiation(self):
         my_array = array.array("I")

Lib/test/test_free_threading/test_string_template_race.py

@@ -0,0 +1,35 @@
+import string
+import unittest
+from string import Template
+
+from test.support import threading_helper
+
+
+@threading_helper.requires_working_threading()
+class TestTemplateCompileRace(unittest.TestCase):
+    def test_concurrent_first_use(self):
+        # Racing the lazy pattern compile must not raise a spurious ValueError
+        # from recompiling an already-compiled pattern.  A throwaway subclass,
+        # re-armed to the sentinel each round, keeps string.Template unmutated
+        # (subclasses precompile eagerly in __init_subclass__).
+        uncompiled = string._TemplatePattern
+        errors = []
+
+        def use_template(cls):
+            try:
+                cls("$x and ${y}").substitute(x=1, y=2)
+            except Exception as e:
+                errors.append(e)
+
+        for _ in range(20):
+            class T(Template):
+                pass
+            T.pattern = uncompiled
+            T.flags = None
+            threading_helper.run_concurrently(use_template, nthreads=10, args=(T,))
+
+        self.assertEqual(errors, [], msg=f"unexpected errors: {errors}")
+
+
+if __name__ == "__main__":
+    unittest.main()

Lib/test/test_ssl.py

@@ -1606,19 +1606,24 @@ def dummycallback(sock, servername, ctx, cycle=ctx):
         gc.collect()
         self.assertIs(wr(), None)
 
-    @unittest.skipUnless(support.Py_GIL_DISABLED,
-                         "test is only useful if the GIL is disabled")
     @threading_helper.requires_working_threading()
     def test_sni_callback_race(self):
-        # Replacing sni_callback while handshakes are in-flight must not
+        # Replacing sni_callback while a handshake is in-flight must not
         # crash (use-after-free on the callback in free-threaded builds).
+        #
+        # Use a single handshake thread: OpenSSL has internal data races
+        # on shared SSL_CTX state when multiple handshakes run
+        # concurrently against the same context (gh-150191). Concurrency
+        # on the *setter* is what exercises the fix from gh-149816, so
+        # multiple toggler threads race against each other and against
+        # the one handshake worker.
         client_ctx, server_ctx, hostname = testing_context()
 
         server_ctx.sni_callback = lambda *a: None
-        done = threading.Event()
+        deadline = time.monotonic() + 0.1
 
         def do_handshakes():
-            while not done.is_set():
+            while time.monotonic() < deadline:
                 c_in = ssl.MemoryBIO()
                 c_out = ssl.MemoryBIO()
                 s_in = ssl.MemoryBIO()
@@ -1645,19 +1650,11 @@ def do_handshakes():
                         c_in.write(s_out.read())
 
         def toggle_callback():
-            while not done.is_set():
+            while time.monotonic() < deadline:
                 server_ctx.sni_callback = lambda *a: None
                 server_ctx.sni_callback = None
 
-        workers = max(4, (os.cpu_count() or 4) * 2)
-        threads = [threading.Thread(target=do_handshakes)
-                   for _ in range(workers)]
-        threads.append(threading.Thread(target=toggle_callback))
-
-        with threading_helper.catch_threading_exception() as cm:
-            with threading_helper.start_threads(threads):
-                done.set()
-            self.assertIsNone(cm.exc_value)
+        threading_helper.run_concurrently([do_handshakes] + 4 * [toggle_callback])
 
     def test_cert_store_stats(self):
         ctx = ssl.SSLContext(ssl.PROTOCOL_TLS_CLIENT)

Lib/test/test_string/test_string.py

@@ -299,6 +299,20 @@ def test_SafeTemplate(self):
         eq(s.safe_substitute(dict(who='tim', what='ham', meal='dinner')),
            'tim likes ham for dinner')
 
+    def test_precompiled_pattern(self):
+        # A subclass may supply an already-compiled pattern; it must be reused,
+        # not recompiled (re.compile() rejects flags on a compiled pattern).
+        import re
+        compiled = re.compile(
+            r'\$(?:(?P<escaped>\$)|(?P<named>[a-z]+)|'
+            r'\{(?P<braced>[a-z]+)\}|(?P<invalid>))')
+        class MyTemplate(Template):
+            pattern = compiled
+        self.assertIs(MyTemplate.pattern, compiled)
+        self.assertEqual(
+            MyTemplate('$who likes $what').substitute(who='tim', what='ham'),
+            'tim likes ham')
+
     def test_invalid_placeholders(self):
         raises = self.assertRaises
         s = Template('$who likes $')