bpo-41617: Add _Py__has_builtin() macro (GH-23260)
Fix building pycore_bitutils.h internal header on old clang version
without __builtin_bswap16() (ex: Xcode 4.6.3 on Mac OS X 10.7).
Add a new private _Py__has_builtin() macro to check for availability
of a preprocessor builtin function.
Co-Authored-By: Joshua Root <jmr@macports.org>
Co-authored-by: Joshua Root <jmr@macports.org>
diff --git a/Include/pyport.h b/Include/pyport.h
index 79fc7c4..6687849 100644
--- a/Include/pyport.h
+++ b/Include/pyport.h
@@ -869,4 +869,16 @@ extern _invalid_parameter_handler _Py_silent_invalid_parameter_handler;
# define _Py_NO_RETURN
#endif
+
+// Preprocessor check for a builtin preprocessor function. Always return 0
+// if __has_builtin() macro is not defined.
+//
+// __has_builtin() is available on clang and GCC 10.
+#ifdef __has_builtin
+# define _Py__has_builtin(x) __has_builtin(x)
+#else
+# define _Py__has_builtin(x) 0
+#endif
+
+
#endif /* Py_PYPORT_H */