gh-90822: Make `PY_SSIZE_T_MAX` and `PY_SSIZE_T_MIN` constant expression (GH-92071)

Include/pyport.h

@@ -114,17 +114,23 @@ typedef intptr_t        Py_intptr_t;
 /* Py_ssize_t is a signed integral type such that sizeof(Py_ssize_t) ==
  * sizeof(size_t).  C99 doesn't define such a thing directly (size_t is an
  * unsigned integral type).  See PEP 353 for details.
+ * PY_SSIZE_T_MAX is the largest positive value of type Py_ssize_t.
  */
 #ifdef HAVE_PY_SSIZE_T
 
 #elif HAVE_SSIZE_T
 typedef ssize_t         Py_ssize_t;
+#   define PY_SSIZE_T_MAX SSIZE_MAX
 #elif SIZEOF_VOID_P == SIZEOF_SIZE_T
 typedef Py_intptr_t     Py_ssize_t;
+#   define PY_SSIZE_T_MAX INTPTR_MAX
 #else
 #   error "Python needs a typedef for Py_ssize_t in pyport.h."
 #endif
 
+/* Smallest negative value of type Py_ssize_t. */
+#define PY_SSIZE_T_MIN (-PY_SSIZE_T_MAX-1)
+
 /* Py_hash_t is the same size as a pointer. */
 #define SIZEOF_PY_HASH_T SIZEOF_SIZE_T
 typedef Py_ssize_t Py_hash_t;
@@ -138,11 +144,6 @@ typedef Py_ssize_t Py_ssize_clean_t;
 /* Largest possible value of size_t. */
 #define PY_SIZE_MAX SIZE_MAX
 
-/* Largest positive value of type Py_ssize_t. */
-#define PY_SSIZE_T_MAX ((Py_ssize_t)(((size_t)-1)>>1))
-/* Smallest negative value of type Py_ssize_t. */
-#define PY_SSIZE_T_MIN (-PY_SSIZE_T_MAX-1)
-
 /* Macro kept for backward compatibility: use "z" in new code.
  *
  * PY_FORMAT_SIZE_T is a platform-specific modifier for use in a printf

PC/pyconfig.h

@@ -162,8 +162,10 @@ WIN32 is still required for the locale module.
 /* Define like size_t, omitting the "unsigned" */
 #ifdef MS_WIN64
 typedef __int64 Py_ssize_t;
+#   define PY_SSIZE_T_MAX LLONG_MAX
 #else
 typedef _W64 int Py_ssize_t;
+#   define PY_SSIZE_T_MAX INT_MAX
 #endif
 #define HAVE_PY_SSIZE_T 1