From 42a5f0c4435757505bd515b68c2a27e8f7565f34 Mon Sep 17 00:00:00 2001
From: Max Kellermann <max@duempel.org>
Date: Tue, 25 Aug 2015 12:46:12 +0200
Subject: [PATCH] thread/Posix{Mutex,Cond}: use "constexpr" only with glibc

Apparently all other C libraries are not compatible with "constexpr".
Those which are not will get a performance penalty, but at least they
work at all.

[Thomas: taken from upstream commit 75dff6445063d9b49cca126fd661c9abbd680977.]
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
---
 src/thread/PosixCond.hxx  | 16 ++++++++--------
 src/thread/PosixMutex.hxx | 16 ++++++++--------
 2 files changed, 16 insertions(+), 16 deletions(-)

diff --git a/src/thread/PosixCond.hxx b/src/thread/PosixCond.hxx
index b3fe204..73dbe02 100644
--- a/src/thread/PosixCond.hxx
+++ b/src/thread/PosixCond.hxx
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2009-2013 Max Kellermann <max@duempel.org>
+ * Copyright (C) 2009-2015 Max Kellermann <max@duempel.org>
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -41,9 +41,13 @@ class PosixCond {
 	pthread_cond_t cond;
 
 public:
-#if defined(__NetBSD__) || defined(__BIONIC__)
-	/* NetBSD's PTHREAD_COND_INITIALIZER is not compatible with
-	   "constexpr" */
+#ifdef __GLIBC__
+	/* optimized constexpr constructor for pthread implementations
+	   that support it */
+	constexpr PosixCond():cond(PTHREAD_COND_INITIALIZER) {}
+#else
+	/* slow fallback for pthread implementations that are not
+	   compatible with "constexpr" */
 	PosixCond() {
 		pthread_cond_init(&cond, nullptr);
 	}
@@ -51,10 +55,6 @@ public:
 	~PosixCond() {
 		pthread_cond_destroy(&cond);
 	}
-#else
-	/* optimized constexpr constructor for sane POSIX
-	   implementations */
-	constexpr PosixCond():cond(PTHREAD_COND_INITIALIZER) {}
 #endif
 
 	PosixCond(const PosixCond &other) = delete;
diff --git a/src/thread/PosixMutex.hxx b/src/thread/PosixMutex.hxx
index 5805158..e0fd614 100644
--- a/src/thread/PosixMutex.hxx
+++ b/src/thread/PosixMutex.hxx
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2009-2013 Max Kellermann <max@duempel.org>
+ * Copyright (C) 2009-2015 Max Kellermann <max@duempel.org>
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -41,9 +41,13 @@ class PosixMutex {
 	pthread_mutex_t mutex;
 
 public:
-#if defined(__NetBSD__) || defined(__BIONIC__)
-	/* NetBSD's PTHREAD_MUTEX_INITIALIZER is not compatible with
-	   "constexpr" */
+#ifdef __GLIBC__
+	/* optimized constexpr constructor for pthread implementations
+	   that support it */
+	constexpr PosixMutex():mutex(PTHREAD_MUTEX_INITIALIZER) {}
+#else
+	/* slow fallback for pthread implementations that are not
+	   compatible with "constexpr" */
 	PosixMutex() {
 		pthread_mutex_init(&mutex, nullptr);
 	}
@@ -51,10 +55,6 @@ public:
 	~PosixMutex() {
 		pthread_mutex_destroy(&mutex);
 	}
-#else
-	/* optimized constexpr constructor for sane POSIX
-	   implementations */
-	constexpr PosixMutex():mutex(PTHREAD_MUTEX_INITIALIZER) {}
 #endif
 
 	PosixMutex(const PosixMutex &other) = delete;
-- 
2.6.4