Merge 'origin/main' into gh-131253-pystats-ft

Author: nascheme

Doc/library/array.rst

@@ -24,7 +24,7 @@ defined:
 +-----------+--------------------+-------------------+-----------------------+-------+
 | ``'u'``   | wchar_t            | Unicode character | 2                     | \(1)  |
 +-----------+--------------------+-------------------+-----------------------+-------+
-| ``'w'``   | Py_UCS4            | Unicode character | 4                     |       |
+| ``'w'``   | Py_UCS4            | Unicode character | 4                     | \(2)  |
 +-----------+--------------------+-------------------+-----------------------+-------+
 | ``'h'``   | signed short       | int               | 2                     |       |
 +-----------+--------------------+-------------------+-----------------------+-------+
@@ -60,6 +60,9 @@ Notes:
    .. deprecated-removed:: 3.3 3.16
       Please migrate to ``'w'`` typecode.
 
+(2)
+   .. versionadded:: 3.13
+
 
 The actual representation of values is determined by the machine architecture
 (strictly speaking, by the C implementation).  The actual size can be accessed

Doc/whatsnew/3.14.rst

@@ -1081,6 +1081,18 @@ The behavior of :func:`!gc.collect` changes slightly:
 
 (Contributed by Mark Shannon in :gh:`108362`.)
 
+Platform support
+================
+
+* :pep:`776`: Emscripten is now an officially supported platform at
+  :pep:`tier 3 <11#tier-3>`. As a part of this effort, more than 25 bugs in
+  `Emscripten libc`__ were fixed. Emscripten now includes support
+  for :mod:`ctypes`, :mod:`termios`, and :mod:`fcntl`, as well as
+  experimental support for :ref:`PyREPL <tut-interactive>`.
+
+  (Contributed by R. Hood Chatham in :gh:`127146`, :gh:`127683`, and :gh:`136931`.)
+
+  __ https://emscripten.org/docs/porting/emscripten-runtime-environment.html
 
 Other language changes
 ======================

Include/internal/pycore_traceback.h

@@ -100,6 +100,7 @@ extern int _Py_WriteIndentedMargin(int, const char*, PyObject *);
 extern int _Py_WriteIndent(int, PyObject *);
 
 // Export for the faulthandler module
+PyAPI_FUNC(void) _Py_InitDumpStack(void);
 PyAPI_FUNC(void) _Py_DumpStack(int fd);
 
 #ifdef __cplusplus

Lib/test/test_pyrepl/test_pyrepl.py

@@ -51,6 +51,7 @@ def run_repl(
         cwd: str | None = None,
         skip: bool = False,
         timeout: float = SHORT_TIMEOUT,
+        exit_on_output: str | None = None,
     ) -> tuple[str, int]:
         temp_dir = None
         if cwd is None:
@@ -64,6 +65,7 @@ def run_repl(
                 cwd=cwd,
                 skip=skip,
                 timeout=timeout,
+                exit_on_output=exit_on_output,
             )
         finally:
             if temp_dir is not None:
@@ -78,6 +80,7 @@ def _run_repl(
         cwd: str,
         skip: bool,
         timeout: float,
+        exit_on_output: str | None,
     ) -> tuple[str, int]:
         assert pty
         master_fd, slave_fd = pty.openpty()
@@ -123,6 +126,11 @@ def _run_repl(
             except OSError:
                 break
             output.append(data)
+            if exit_on_output is not None:
+                output = ["".join(output)]
+                if exit_on_output in output[0]:
+                    process.kill()
+                    break
         else:
             os.close(master_fd)
             process.kill()
@@ -1718,18 +1726,24 @@ def test_history_survive_crash(self):
 
             commands = "1\n2\n3\nexit()\n"
             output, exit_code = self.run_repl(commands, env=env, skip=True)
+            self.assertEqual(exit_code, 0)
 
-            commands = "spam\nimport time\ntime.sleep(1000)\nquit\n"
-            try:
-                self.run_repl(commands, env=env, timeout=3)
-            except AssertionError:
-                pass
+            # Run until "0xcafe" is printed (as "51966") and then kill the
+            # process to simulate a crash. Note that the output also includes
+            # the echoed input commands.
+            commands = "spam\nimport time\n0xcafe\ntime.sleep(1000)\nquit\n"
+            output, exit_code = self.run_repl(commands, env=env,
+                                              exit_on_output="51966")
+            self.assertNotEqual(exit_code, 0)
 
             history = pathlib.Path(hfile.name).read_text()
             self.assertIn("2", history)
             self.assertIn("exit()", history)
             self.assertIn("spam", history)
             self.assertIn("import time", history)
+            # History is written after each command's output is printed to the
+            # console, so depending on how quickly the process is killed,
+            # the last command may or may not be written to the history file.
             self.assertNotIn("sleep", history)
             self.assertNotIn("quit", history)
 

Misc/NEWS.d/next/Library/2025-07-28-20-48-32.gh-issue-137185.fgI7-B.rst

@@ -0,0 +1,2 @@
+Fix a potential async-signal-safety issue in :mod:`faulthandler` when
+printing C stack traces.

Modules/faulthandler.c

@@ -524,6 +524,11 @@ faulthandler_enable(void)
     }
 #endif
 
+    // gh-137185: Initialize C stack trace dumping outside of the signal
+    // handler. Specifically, we call backtrace() to ensure that libgcc is
+    // dynamically loaded outside of the signal handler.
+    _Py_InitDumpStack();
+
     for (size_t i=0; i < faulthandler_nsignals; i++) {
         fault_handler_t *handler;
         int err;

Python/traceback.c

@@ -1326,3 +1326,13 @@ _Py_DumpStack(int fd)
     PUTS(fd, "  <cannot get C stack on this system>\n");
 }
 #endif
+
+void
+_Py_InitDumpStack(void)
+{
+#ifdef CAN_C_BACKTRACE
+    // gh-137185: Call backtrace() once to force libgcc to be loaded early.
+    void *callstack[1];
+    (void)backtrace(callstack, 1);
+#endif
+}