From 16eea45fbd3b7c3d1b222b7eb7a5d7ee427f70bd Mon Sep 17 00:00:00 2001
From: Felix Yan <felixonmars@archlinux.org>
Date: Thu, 16 Jul 2020 04:22:23 +0800
Subject: [PATCH] [3.8] bpo-41302: Support system libmpdec 2.5 for Python 3.8
 (GH-21488)

Define UNUSED only when mpdecimal.h doesn't define it. This would support
building with system libmpdec 2.5 while retaining compatibility with system
libmpdec 2.4 or the vendored copy.

Tested to build fine with either system libmpdec or the vendored one.
---
diff --git a/Modules/_decimal/_decimal.c b/Modules/_decimal/_decimal.c
index df7c6e254bcf2..eb1f1a01feeca 100644
--- a/Modules/_decimal/_decimal.c
+++ b/Modules/_decimal/_decimal.c
@@ -58,6 +58,13 @@
 
 #define BOUNDS_CHECK(x, MIN, MAX) x = (x < MIN || MAX < x) ? MAX : x
 
+#ifndef UNUSED
+#if defined(__GNUC__) && !defined(__INTEL_COMPILER)
+  #define UNUSED __attribute__((unused))
+#else
+  #define UNUSED
+#endif
+#endif
 
 /* _Py_DEC_MINALLOC >= MPD_MINALLOC */
 #define _Py_DEC_MINALLOC 4