Sync pre-release CPython 3.15 branch from GitHub (2026-06-14)

Summary:
Imported python/cpython `3.15.0b2+dev` from upstream rev [`1b457d3`](https://www.github.com/python/cpython/commit/1b457d3bbc528184f373bdcac47f0951052f90b7) (committed 2026-06-14 18:37:23+00:00).

# Commit Info

- Base: (`3.15.0b2+dev`) - [`75289a9`](https://www.github.com/python/cpython/commit/75289a92dfb460acde427b9f399881a108427b6c) (commit date: 2026-06-13 23:40:19+00:00)
- Imported: (`3.15.0b2+dev`) - [`1b457d3`](https://www.github.com/python/cpython/commit/1b457d3bbc528184f373bdcac47f0951052f90b7) (commit date: 2026-06-14 18:37:23+00:00)

# Noteworthy file changes

- Low-signal files (2 added) (NEWS.d, docs, .github)

Complete list of added/removed files: https://www.internalfb.com/intern/everpaste/?color=0&handle=GNqyAikz87RmOXwDAF8u6j_7PXktbr0LAAAz

Differential Revision: D108576618

fbshipit-source-id: c2f883301985a9b22288493b76b1a765beceb74b

Author: generatedunixname1734921407115435

Doc/library/warnings.rst

@@ -626,9 +626,28 @@ Available Context Managers
     If the *record* argument is :const:`False` (the default) the context manager
     returns :class:`None` on entry. If *record* is :const:`True`, a list is
     returned that is progressively populated with objects as seen by a custom
-    :func:`showwarning` function (which also suppresses output to ``sys.stdout``).
-    Each object in the list has attributes with the same names as the arguments to
-    :func:`showwarning`.
+    :func:`showwarning` function (which also suppresses output to ``sys.stderr``).
+    Each object in the list is guaranteed to have the following attributes:
+
+      - ``message``: the warning message (an instance of :exc:`Warning`)
+      - ``category``: the warning category (a subclass of :exc:`Warning`)
+      - ``filename``: the file name where the warning occurred (:class:`str`)
+      - ``lineno``: the line number in the file (:class:`int`)
+      - ``file``: the file object used for output (if any), or ``None``
+      - ``line``: the line of source code (if available), or ``None``
+      - ``source``: the original object that generated the warning (if
+        available), or ``None``
+      - ``module``: the module name where the warning occurred
+        (:class:`str`), or ``None``
+
+    .. versionchanged:: 3.6
+      The ``source`` attribute was added.
+
+    .. versionchanged:: 3.15
+      The ``module`` attribute was added.
+
+    The type of these objects is not specified and may change; only the
+    presence of these attributes is guaranteed.
 
     The *module* argument takes a module that will be used instead of the
     module returned when you import :mod:`!warnings` whose filter will be

Lib/_pyrepl/utils.py

@@ -259,7 +259,7 @@ def is_soft_keyword_used(*tokens: TI | None) -> bool:
             None | TI(T.NEWLINE) | TI(T.INDENT) | TI(string=":"),
             TI(string="match"),
             TI(T.NUMBER | T.STRING | T.FSTRING_START | T.TSTRING_START)
-            | TI(T.OP, string="(" | "*" | "[" | "{" | "~" | "...")
+            | TI(T.OP, string="(" | "*" | "-" | "+" | "[" | "{" | "~" | "...")
         ):
             return True
         case (

Lib/test/test_json/test_recursion.py

@@ -68,6 +68,7 @@ def default(self, o):
             self.fail("didn't raise ValueError on default recursion")
 
 
+    @support.skip_if_pgo_task  # fails during PGO training w/ some stack sizes
     @support.skip_if_unlimited_stack_size
     @support.skip_emscripten_stack_overflow()
     @support.skip_wasi_stack_overflow()

Lib/test/test_pyrepl/test_utils.py

@@ -125,6 +125,22 @@ def test_gen_colors_keyword_highlighting(self):
                     ("import", "keyword"),
                 ],
             ),
+            (
+                "match +1",
+                [
+                    ("match", "soft_keyword"),
+                    ("+", "op"),
+                    ("1", "number"),
+                ],
+            ),
+            (
+                "match -1",
+                [
+                    ("match", "soft_keyword"),
+                    ("-", "op"),
+                    ("1", "number"),
+                ],
+            ),
         ]
         for code, expected_highlights in cases:
             with self.subTest(code=code):

Lib/test/test_source_encoding.py

@@ -387,8 +387,7 @@ def test_utf8_non_utf8_third_line_error(self):
                b'#third\xa4\n'
                b'raise RuntimeError\n')
         self.check_script_error(src,
-                br"'utf-8' codec can't decode byte|"
-                br"encoding problem: utf8")
+                br"'utf-8' codec can't decode byte")
 
     def test_crlf(self):
         src = (b'print(ascii("""\r\n"""))\n')
@@ -540,6 +539,20 @@ def check_script_error(self, src, expected, lineno=...):
                 line = line.removeprefix('\ufeff')
             self.assertIn(line.encode(), err)
 
+    def test_coding_spec_unknown_encoding(self):
+        src = (b'# coding: c1252\n'
+               b'print("Hi!")\n')
+        self.check_script_error(src, br"unknown encoding: c1252")
+
+    def test_coding_spec_decode_error(self):
+        src = (b'# coding: shift-jis\n'
+               b'print("\xc4\x85")\n')
+        self.check_script_error(src, br"'shift_jis' codec can't decode byte")
+
+    def test_coding_spec_non_text_encoding(self):
+        src = (b'# coding: hex_codec\n'
+               b'print("eggs")\n')
+        self.check_script_error(src, br"'hex_codec' is not a text encoding")
 
 
 if __name__ == "__main__":

Misc/NEWS.d/next/Core_and_Builtins/2026-06-14-05-05-15.gh-issue-151461.5q0s88.rst

@@ -0,0 +1,3 @@
+Fix direct execution of files with invalid source encodings to report the
+underlying codec lookup or decoding error instead of the generic
+``SyntaxError: encoding problem`` message. Patch by Bartosz Sławecki.

Misc/NEWS.d/next/Library/2026-06-12-07-20-08.gh-issue-151390.CmYN9EeJ.rst

@@ -0,0 +1 @@
+Colorize ``match`` in the :term:`REPL` when followed by a unary ``+`` or ``-`` operator. Patch by Bartosz Sławecki.

Parser/pegen.c

@@ -9,6 +9,7 @@
 
 #include "lexer/lexer.h"
 #include "tokenizer/tokenizer.h"
+#include "tokenizer/helpers.h"
 #include "pegen.h"
 
 // Internal parser functions
@@ -993,7 +994,7 @@ _PyPegen_run_parser_from_file_pointer(FILE *fp, int start_rule, PyObject *filena
     struct tok_state *tok = _PyTokenizer_FromFile(fp, enc, ps1, ps2);
     if (tok == NULL) {
         if (PyErr_Occurred()) {
-            _PyPegen_raise_tokenizer_init_error(filename_ob);
+            _PyTokenizer_raise_init_error(filename_ob);
             return NULL;
         }
         return NULL;
@@ -1051,7 +1052,7 @@ _PyPegen_run_parser_from_string(const char *str, int start_rule, PyObject *filen
     }
     if (tok == NULL) {
         if (PyErr_Occurred()) {
-            _PyPegen_raise_tokenizer_init_error(filename_ob);
+            _PyTokenizer_raise_init_error(filename_ob);
         }
         return NULL;
     }

Parser/pegen.h

@@ -174,7 +174,6 @@ typedef enum {
 } TARGETS_TYPE;
 
 int _Pypegen_raise_decode_error(Parser *p);
-void _PyPegen_raise_tokenizer_init_error(PyObject *filename);
 int _Pypegen_tokenizer_error(Parser *p);
 void *_PyPegen_raise_error(Parser *p, PyObject *errtype, int use_mark, const char *errmsg, ...);
 void *_PyPegen_raise_error_known_location(Parser *p, PyObject *errtype,

Parser/pegen_errors.c

@@ -10,53 +10,6 @@
 
 // TOKENIZER ERRORS
 
-void
-_PyPegen_raise_tokenizer_init_error(PyObject *filename)
-{
-    if (!(PyErr_ExceptionMatches(PyExc_LookupError)
-          || PyErr_ExceptionMatches(PyExc_SyntaxError)
-          || PyErr_ExceptionMatches(PyExc_ValueError)
-          || PyErr_ExceptionMatches(PyExc_UnicodeDecodeError))) {
-        return;
-    }
-    PyObject *errstr = NULL;
-    PyObject *tuple = NULL;
-    PyObject *type;
-    PyObject *value;
-    PyObject *tback;
-    PyErr_Fetch(&type, &value, &tback);
-    if (PyErr_GivenExceptionMatches(value, PyExc_SyntaxError)) {
-        if (PyObject_SetAttr(value, &_Py_ID(filename), filename)) {
-            goto error;
-        }
-        PyErr_Restore(type, value, tback);
-        return;
-    }
-    errstr = PyObject_Str(value);
-    if (!errstr) {
-        goto error;
-    }
-
-    PyObject *tmp = Py_BuildValue("(OiiO)", filename, 0, -1, Py_None);
-    if (!tmp) {
-        goto error;
-    }
-
-    tuple = _PyTuple_FromPair(errstr, tmp);
-    Py_DECREF(tmp);
-    if (!tuple) {
-        goto error;
-    }
-    PyErr_SetObject(PyExc_SyntaxError, tuple);
-
-error:
-    Py_XDECREF(type);
-    Py_XDECREF(value);
-    Py_XDECREF(tback);
-    Py_XDECREF(errstr);
-    Py_XDECREF(tuple);
-}
-
 static inline void
 raise_unclosed_parentheses_error(Parser *p) {
        int error_lineno = p->tok->parenlinenostack[p->tok->level-1];