gh-59705: Make PYTHREAD_NAME_MAXLEN macro private (#128945)

Rename PYTHREAD_NAME_MAXLEN to _PYTHREAD_NAME_MAXLEN.

Author: vstinner

Diff for: Modules/_threadmodule.c

@@ -2450,12 +2450,12 @@ _thread_set_name_impl(PyObject *module, PyObject *name_obj)
         return NULL;
     }
 
-#ifdef PYTHREAD_NAME_MAXLEN
-    // Truncate to PYTHREAD_NAME_MAXLEN bytes + the NUL byte if needed
-    if (PyBytes_GET_SIZE(name_encoded) > PYTHREAD_NAME_MAXLEN) {
+#ifdef _PYTHREAD_NAME_MAXLEN
+    // Truncate to _PYTHREAD_NAME_MAXLEN bytes + the NUL byte if needed
+    if (PyBytes_GET_SIZE(name_encoded) > _PYTHREAD_NAME_MAXLEN) {
         PyObject *truncated;
         truncated = PyBytes_FromStringAndSize(PyBytes_AS_STRING(name_encoded),
-                                              PYTHREAD_NAME_MAXLEN);
+                                              _PYTHREAD_NAME_MAXLEN);
         if (truncated == NULL) {
             Py_DECREF(name_encoded);
             return NULL;
@@ -2490,14 +2490,14 @@ _thread_set_name_impl(PyObject *module, PyObject *name_obj)
         return NULL;
     }
 
-    if (len > PYTHREAD_NAME_MAXLEN) {
+    if (len > _PYTHREAD_NAME_MAXLEN) {
         // Truncate the name
-        Py_UCS4 ch = name[PYTHREAD_NAME_MAXLEN-1];
+        Py_UCS4 ch = name[_PYTHREAD_NAME_MAXLEN-1];
         if (Py_UNICODE_IS_HIGH_SURROGATE(ch)) {
-            name[PYTHREAD_NAME_MAXLEN-1] = 0;
+            name[_PYTHREAD_NAME_MAXLEN-1] = 0;
         }
         else {
-            name[PYTHREAD_NAME_MAXLEN] = 0;
+            name[_PYTHREAD_NAME_MAXLEN] = 0;
         }
     }
 
@@ -2645,9 +2645,9 @@ thread_module_exec(PyObject *module)
 
     llist_init(&state->shutdown_handles);
 
-#ifdef PYTHREAD_NAME_MAXLEN
+#ifdef _PYTHREAD_NAME_MAXLEN
     if (PyModule_AddIntConstant(module, "_NAME_MAXLEN",
-                                PYTHREAD_NAME_MAXLEN) < 0) {
+                                _PYTHREAD_NAME_MAXLEN) < 0) {
         return -1;
     }
 #endif

Diff for: PC/pyconfig.h.in

@@ -753,8 +753,7 @@ Py_NO_ENABLE_SHARED to find out.  Also support MS_NO_COREDLL for b/w compat */
 /* Define if libssl has X509_VERIFY_PARAM_set1_host and related function */
 #define HAVE_X509_VERIFY_PARAM_SET1_HOST 1
 
-// Truncate the thread name to 64 characters. The OS limit is 32766 wide
-// characters, but long names aren't of practical use.
-#define PYTHREAD_NAME_MAXLEN 32766
+// Truncate the thread name to 32766 characters.
+#define _PYTHREAD_NAME_MAXLEN 32766
 
 #endif /* !Py_CONFIG_H */

Diff for: configure

@@ -7539,19 +7539,19 @@ _RESTORE_VAR([CPPFLAGS])
 
 # gh-59705: Maximum length in bytes of a thread name
 case "$ac_sys_system" in
-  Linux*) PYTHREAD_NAME_MAXLEN=15;;  # Linux and Android
-  SunOS*) PYTHREAD_NAME_MAXLEN=31;;
-  NetBSD*) PYTHREAD_NAME_MAXLEN=31;;
-  Darwin) PYTHREAD_NAME_MAXLEN=63;;
-  iOS) PYTHREAD_NAME_MAXLEN=63;;
-  FreeBSD*) PYTHREAD_NAME_MAXLEN=98;;
-  *) PYTHREAD_NAME_MAXLEN=;;
+  Linux*) _PYTHREAD_NAME_MAXLEN=15;;  # Linux and Android
+  SunOS*) _PYTHREAD_NAME_MAXLEN=31;;
+  NetBSD*) _PYTHREAD_NAME_MAXLEN=31;;
+  Darwin) _PYTHREAD_NAME_MAXLEN=63;;
+  iOS) _PYTHREAD_NAME_MAXLEN=63;;
+  FreeBSD*) _PYTHREAD_NAME_MAXLEN=98;;
+  *) _PYTHREAD_NAME_MAXLEN=;;
 esac
-if test -n "$PYTHREAD_NAME_MAXLEN"; then
-    AC_DEFINE_UNQUOTED([PYTHREAD_NAME_MAXLEN], [$PYTHREAD_NAME_MAXLEN],
+if test -n "$_PYTHREAD_NAME_MAXLEN"; then
+    AC_DEFINE_UNQUOTED([_PYTHREAD_NAME_MAXLEN], [$_PYTHREAD_NAME_MAXLEN],
                        [Maximum length in bytes of a thread name])
 fi
-AC_SUBST([PYTHREAD_NAME_MAXLEN])
+AC_SUBST([_PYTHREAD_NAME_MAXLEN])
 
 
 # stdlib

Diff for: configure.ac

@@ -1662,9 +1662,6 @@
 /* Define as the preferred size in bits of long digits */
 #undef PYLONG_BITS_IN_DIGIT
 
-/* Maximum length in bytes of a thread name */
-#undef PYTHREAD_NAME_MAXLEN
-
 /* enabled builtin hash modules */
 #undef PY_BUILTIN_HASHLIB_HASHES
 
@@ -1980,6 +1977,9 @@
 /* framework name */
 #undef _PYTHONFRAMEWORK
 
+/* Maximum length in bytes of a thread name */
+#undef _PYTHREAD_NAME_MAXLEN
+
 /* Define to force use of thread-safe errno, h_errno, and other functions */
 #undef _REENTRANT