From: Felix Yan <felixonmars@archlinux.org>
Date: Wed, 15 Jul 2020 20:22:23 +0000 (+0800)
Subject: [3.8] bpo-41302: Support system libmpdec 2.5 for Python 3.8 (GH-21488)
X-Git-Tag: v3.8.5~13
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=16eea45fbd3b7c3d1b222b7eb7a5d7ee427f70bd;p=thirdparty%2FPython%2Fcpython.git

[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/Misc/NEWS.d/next/Build/2020-07-15-17-56-32.bpo-41302.S3o-x9.rst b/Misc/NEWS.d/next/Build/2020-07-15-17-56-32.bpo-41302.S3o-x9.rst
new file mode 100644
index 000000000000..2f1301740e74
--- /dev/null
+++ b/Misc/NEWS.d/next/Build/2020-07-15-17-56-32.bpo-41302.S3o-x9.rst
@@ -0,0 +1 @@
+Enable building Python 3.8 with libmpdec-2.5.0 to ease maintenance for Linux distributions. Patch by Felix Yan.
\ No newline at end of file
diff --git a/Modules/_decimal/_decimal.c b/Modules/_decimal/_decimal.c
index df7c6e254bcf..eb1f1a01feec 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