Merge branch 'main' into stats_cospi_sinpi

Author: rhettinger

Doc/c-api/bytes.rst

@@ -231,6 +231,7 @@ called with a non-bytes parameter.
    Resize a bytes object. *newsize* will be the new length of the bytes object.
    You can think of it as creating a new bytes object and destroying the old
    one, only more efficiently.
+
    Pass the address of an
    existing bytes object as an lvalue (it may be written into), and the new size
    desired.  On success, *\*bytes* holds the resized bytes object and ``0`` is
@@ -239,6 +240,11 @@ called with a non-bytes parameter.
    *\*bytes* is set to ``NULL``, :exc:`MemoryError` is set, and ``-1`` is
    returned.
 
+   While bytes objects are usually immutable in Python, this special C API
+   allows mutating a bytes object in-place. The returned bytes object can still
+   be mutated using :c:func:`PyBytesWriter_GetData`; except if *newsize* is
+   zero in which case it returns the immutable empty bytes string.
+
    .. soft-deprecated:: 3.15
       Use the :c:type:`PyBytesWriter` API instead.
 
@@ -290,10 +296,10 @@ object.
 
 .. c:type:: PyBytesWriter
 
-   A bytes writer instance.
+   A bytes writer object.
 
-   The API is **not thread safe**: a writer should only be used by a single
-   thread at the same time.
+   The API is **not thread safe**. A :c:type:`PyBytesWriter` object must only
+   be used by a single thread, it must not be shared between threads.
 
    The instance must be destroyed by :c:func:`PyBytesWriter_Finish` on
    success, or :c:func:`PyBytesWriter_Discard` on error.
@@ -429,7 +435,7 @@ Low-level API
    On success, return ``0``.
    On error, set an exception and return ``-1``.
 
-   *size* can be negative to shrink the writer.
+   *grow* can be negative to shrink the writer.
 
 .. c:function:: void* PyBytesWriter_GrowAndUpdatePointer(PyBytesWriter *writer, Py_ssize_t size, void *buf)
 

Include/internal/pycore_bytesobject.h

@@ -77,6 +77,10 @@ PyAPI_FUNC(PyObject *) _PyBytes_Repeat(PyObject *self, Py_ssize_t n);
 
 extern int _PyBytes_ResizeKeepOnError(PyObject **pv, Py_ssize_t newsize);
 
+#ifndef NDEBUG
+extern int _PyBytes_IsMutable(PyObject *obj);
+#endif
+
 /* --- PyBytesWriter ------------------------------------------------------ */
 
 struct PyBytesWriter {

Lib/test/test_annotationlib.py

@@ -1869,7 +1869,7 @@ def nested():
         self.assertEqual(type_repr(t'''{ 0
             & 1
             | 2
-        }'''), 't"""{ 0\n            & 1\n            | 2}"""')
+        }'''), 't"""{ 0\n            & 1\n            | 2\n        }"""')
         self.assertEqual(
             type_repr(Template("hi", Interpolation(42, "42"))), "t'hi{42}'"
         )

Lib/test/test_bytes.py

@@ -1130,13 +1130,14 @@ def test_translate(self):
         self.assertRaises(ValueError, b.translate, bytes(range(255)))
 
         c = b.translate(rosetta, b'hello')
-        self.assertEqual(b, b'hello')
-        self.assertIsInstance(c, self.type2test)
+        self.assertEqual(c, b'')
+        self.assertEqual(type(c), self.type2test)
 
         c = b.translate(rosetta)
         d = b.translate(rosetta, b'')
-        self.assertEqual(c, d)
         self.assertEqual(c, b'helle')
+        self.assertEqual(type(c), self.type2test)
+        self.assertEqual(d, b'helle')
 
         c = b.translate(rosetta, b'l')
         self.assertEqual(c, b'hee')

Lib/test/test_capi/test_bytes.py

@@ -461,6 +461,24 @@ def test_grow(self):
         writer.grow(0)  # noop
         self.assertEqual(writer.finish(), b'number=123')
 
+        for size in (self.SMALL_BUFFER, self.LARGE_BUFFER):
+            with self.subTest(size=size):
+                # Truncate the last byte
+                data = b'x' * size
+                writer = self.create_writer(size)
+                writer.write(0, data)
+                self.assertEqual(writer.get_data(), data)
+                writer.grow(-1)
+                self.assertEqual(writer.get_data(), data[:-1])
+                self.assertEqual(writer.finish(),  data[:-1])
+
+                # Make the buffer empty
+                writer = self.create_writer(size)
+                writer.write(0, data)
+                writer.grow(-size)
+                self.assertEqual(writer.get_data(), b'')
+                self.assertEqual(writer.finish(),  b'')
+
         # Switch from small buffer to large buffer
         writer = self.create_writer()
         small, large = self.SMALL_BUFFER, self.LARGE_BUFFER
@@ -476,8 +494,8 @@ def test_grow(self):
             with self.subTest(size=size):
                 writer = self.create_writer()
                 writer.write_bytes(b'x' * size, -1)
-                with self.assertRaisesRegex(ValueError, 'size must be >= 0'):
-                    writer.grow(-1)
+                with self.assertRaisesRegex(ValueError, 'invalid size'):
+                    writer.grow(-size - 1)
                 with self.assertRaises(MemoryError):
                     writer.grow(_testcapi.PY_SSIZE_T_MAX)
                 self.assertEqual(writer.finish(), b'x' * size)

Lib/test/test_fstring.py

@@ -1695,6 +1695,14 @@ def __repr__(self):
         self.assertEqual(f'''{f"{d["a#b"]}"=}''',
                          'f"{d["a#b"]}"=\'42\'')
 
+        result = f'''{(
+            1,  # Force lexer metadata reconstruction.
+            "\"#")=}'''
+        self.assertEqual(
+            result,
+            '(\n            1,  \n            "\\"#")=(1, \'"#\')',
+        )
+
         self.assertEqual(f'{ # some comment goes here
   """hello"""=}',  ' \n  """hello"""=\'hello\'')
         self.assertEqual(f'{"""# this is not a comment

Lib/test/test_io/test_memoryio.py

@@ -5,6 +5,7 @@
 
 import unittest
 from test import support
+from test.support import import_helper
 
 import gc
 import io
@@ -753,6 +754,35 @@ def __buffer__(self, flags):
         self.assertEqual(memio.getvalue(), b"01AAA56789")
         self.assertEqual(memio.tell(), 5)
 
+    def test_memory_error(self):
+        # gh-157242: io.BytesIO() must not close the file on MemoryError
+        _testcapi = import_helper.import_module('_testcapi')
+
+        # write()
+        stream = self.ioclass()
+        stream.write(self.buftype('abc'))
+        with self.assertRaises(MemoryError):
+            try:
+                data = self.buftype('def')
+                _testcapi.set_nomemory(0)
+                stream.write(data)
+            finally:
+                _testcapi.remove_mem_hooks()
+        stream.write(self.buftype('123'))
+        self.assertEqual(stream.getvalue(), self.buftype('abc123'))
+
+        # truncate()
+        data = self.buftype('x' * 100)
+        stream = self.ioclass()
+        stream.write(data)
+        with self.assertRaises(MemoryError):
+            try:
+                _testcapi.set_nomemory(0)
+                stream.truncate(5)
+            finally:
+                _testcapi.remove_mem_hooks()
+        self.assertEqual(stream.getvalue(), data)
+
 
 class TextIOTestMixin:
 

Lib/test/test_tstring.py

@@ -136,10 +136,47 @@ def test_debug_specifier(self):
         # Test white space in debug specifier
         t = t"Value: {value = }"
         self.assertTStringEqual(
-            t, ("Value: value = ", ""), [(value, "value", "r")]
+            t, ("Value: value = ", ""), [(value, "value ", "r")]
         )
         self.assertEqual(fstring(t), "Value: value = 42")
 
+        # Explicit line continuations after the debug marker are part of
+        # the debug text, not the interpolation expression.
+        for template, strings, interpolation, rendered in (
+            (
+                t"""Value: {value =\
+}""",
+                ("Value: value =\\\n", ""),
+                (value, "value ", "r"),
+                "Value: value =\\\n42",
+            ),
+            (
+                t"""Value: {value =\
+!r}""",
+                ("Value: value =\\\n", ""),
+                (value, "value ", "r"),
+                "Value: value =\\\n42",
+            ),
+            (
+                t"""Value: {value =\
+:04}""",
+                ("Value: value =\\\n", ""),
+                (value, "value ", None, "04"),
+                "Value: value =\\\n0042",
+            ),
+            (
+                t"""Value: {value =\
+\
+}""",
+                ("Value: value =\\\n\\\n", ""),
+                (value, "value ", "r"),
+                "Value: value =\\\n\\\n42",
+            ),
+        ):
+            with self.subTest(template=template):
+                self.assertTStringEqual(template, strings, [interpolation])
+                self.assertEqual(fstring(template), rendered)
+
         class C:
             def __format__(self, spec):
                 return f"FORMAT-{spec}"
@@ -149,6 +186,41 @@ def __format__(self, spec):
         self.assertEqual(t.interpolations[0].format_spec,
                          "FORMAT-value=42")
 
+    def test_interpolation_expression_whitespace(self):
+        x = 42
+        for template, expected in (
+            (t"{x}", "x"),
+            (t"{x }", "x "),
+            (t"{ x}", " x"),
+            (t"{ x }", " x "),
+            (t"{  x  }", "  x  "),
+            (t"""{
+  x
+}""", "\n  x\n"),
+            (t"{ x !r}", " x "),
+            (t"{ x :.2f}", " x "),
+            (t"{ x = }", " x "),
+            (t"{ x = !r}", " x "),
+            (t"{ x = :.2f}", " x "),
+            (t"{x == 42 = }", "x == 42 "),
+        ):
+            with self.subTest(template=template):
+                self.assertEqual(
+                    template.interpolations[0].expression,
+                    expected,
+                )
+
+    def test_interpolation_expression_with_reconstructed_metadata(self):
+        regular = t'''{(
+            1,  # Force lexer metadata reconstruction.
+            "\"#")}'''
+        debug = t'''{(
+            1,  # Force lexer metadata reconstruction.
+            "\"#")=}'''
+        expected = '(\n            1,  \n            "\\"#")'
+        self.assertEqual(regular.interpolations[0].expression, expected)
+        self.assertEqual(debug.interpolations[0].expression, expected)
+
     def test_raw_tstrings(self):
         path = r"C:\Users"
         t = rt"{path}\Documents"
@@ -314,12 +386,12 @@ def test_triple_quoted(self):
 
         t = t'{"""a""""#" # outside
 }'
-        self.assertEqual(t.interpolations[0].expression, '"""a""""#"')
+        self.assertEqual(t.interpolations[0].expression, '"""a""""#" \n')
 
         x, y = 1, 2
         t = t'{x != y # outside
 }'
-        self.assertEqual(t.interpolations[0].expression, 'x != y')
+        self.assertEqual(t.interpolations[0].expression, 'x != y \n')
 
         d = {'a#b': 42}
         t = t'''{f"{d["a#b"]}"}'''

Lib/test/test_unparse.py

@@ -216,6 +216,15 @@ def test_tstrings(self):
         self.check_ast_roundtrip('t""')
         self.check_ast_roundtrip("t'{(lambda x: x)}'")
         self.check_ast_roundtrip("t'{t'{x}'}'")
+        self.check_ast_roundtrip(
+            r"""t'''{(
+                1,  # Force lexer metadata reconstruction.
+                "\"#")}'''"""
+        )
+        self.check_ast_roundtrip(
+            r'''t"""Value: {value =\
+}"""'''
+        )
 
     def test_tstring_with_nonsensical_str_field(self):
         # `value` suggests that the original code is `t'{test1}`, but `str` suggests otherwise

Misc/NEWS.d/next/Core_and_Builtins/2026-07-27-17-20-49.gh-issue-154719.eI88Gs.rst

@@ -0,0 +1,5 @@
+Trailing whitespace in a t-string interpolation expression is now preserved
+in :attr:`string.templatelib.Interpolation.expression`, up to the closing ``}``
+or the conversion (``!``), format (``:``), or debug (``=``) delimiter.
+Explicit line continuations following a debug ``=`` remain part of the debug
+text and are excluded from :attr:`~string.templatelib.Interpolation.expression`.