gh-121647: Define _Py_TYPEOF macro on more compilers

Extend the _Py_TYPEOF macro to more implementations of __typeof__ and standardized equivalents on C23 and C++11.
On MSVC, __typeof__ is enabled through _MSC_VER check; for others, an autoconf probe is implemented.

Author: fuhsnn

Include/pyport.h

@@ -554,9 +554,14 @@ extern "C" {
 //
 // Example: _Py_TYPEOF(x) x_copy = (x);
 //
-// The macro is only defined if GCC or clang compiler is used.
-#if defined(__GNUC__) || defined(__clang__)
+// Defined if __typeof__ or its equivalents are available.
+#if defined(__GNUC__) || defined(__clang__) || defined(HAVE_TYPEOF) || \
+    (defined(_MSC_VER) && _MSC_VER >= 1939)
 #  define _Py_TYPEOF(expr) __typeof__(expr)
+#elif defined(__STDC_VERSION__) && __STDC_VERSION__ >= 202311L
+#  define _Py_TYPEOF(expr) typeof(expr)
+#elif defined(__cplusplus) && __cplusplus >= 201103
+#  define _Py_TYPEOF(expr) decltype(expr)
 #endif
 
 

configure

@@ -6983,6 +6983,19 @@ case "$ac_cv_computed_gotos" in yes*)
   [Define if the C compiler supports computed gotos.])
 esac
 
+AC_CACHE_CHECK([whether $CC supports __typeof__], [ac_cv_typeof],
+AC_COMPILE_IFELSE([AC_LANG_SOURCE([[
+int i;
+__typeof__(i) *p = &i;
+]])],
+[ac_cv_typeof=yes],
+[ac_cv_typeof=no]))
+if test "$ac_cv_typeof" = yes
+then
+  AC_DEFINE([HAVE_TYPEOF], [1],
+  [Define if the C compiler supports  __typeof__(expr)])
+fi
+
 case $ac_sys_system in
 AIX*)
   AC_DEFINE([HAVE_BROKEN_PIPE_BUF], [1],

configure.ac

@@ -1498,6 +1498,9 @@
 /* Define to 1 if you have the `ttyname' function. */
 #undef HAVE_TTYNAME
 
+/* Define if the C compiler supports __typeof__(expr) */
+#undef HAVE_TYPEOF
+
 /* Define to 1 if you don't have `tm_zone' but do have the external array
    `tzname'. */
 #undef HAVE_TZNAME