From d2dd6f7c709f70f325cad34a4bf283d80e832939 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.
---
 NEWS                      |  1 +
 src/thread/PosixCond.hxx  | 14 +++++++-------
 src/thread/PosixMutex.hxx | 14 +++++++-------
 3 files changed, 15 insertions(+), 14 deletions(-)

diff --git a/NEWS b/NEWS
index a2a9d2523..cf3e788fc 100644
--- a/NEWS
+++ b/NEWS
@@ -1,4 +1,5 @@
 ver 0.19.14 (not yet released)
+* fix build failures on non-glibc builds due to constexpr Mutex
 
 ver 0.19.13 (2016/02/23)
 * tags
diff --git a/src/thread/PosixCond.hxx b/src/thread/PosixCond.hxx
index b3fe204e1..1d4a78985 100644
--- a/src/thread/PosixCond.hxx
+++ b/src/thread/PosixCond.hxx
@@ -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 5805158d5..6afe850f0 100644
--- a/src/thread/PosixMutex.hxx
+++ b/src/thread/PosixMutex.hxx
@@ -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;