From d382b756c2e832bbb8a5778d704c8310ad19ad57 Mon Sep 17 00:00:00 2001
From: Robin Gareus <robin@gareus.org>
Date: Sun, 28 Jul 2019 14:57:51 +0200
Subject: [PATCH] Follow up d8ae3fd
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Depending on implementation, d8ae3fd may only construct the spinlock
once to `sl_init`. Later it is only copy-constructed and that leads to
compile and/or runtmime errors.

e.g. gcc-8.3 fails to compile
error: use of deleted function ‘boost::detail::spinlock::spinlock(const boost::detail::spinlock&)’
---
 libs/pbd/pbd/spinlock.h | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/libs/pbd/pbd/spinlock.h b/libs/pbd/pbd/spinlock.h
index 7173fde594..69b76ce820 100644
--- a/libs/pbd/pbd/spinlock.h
+++ b/libs/pbd/pbd/spinlock.h
@@ -32,11 +32,17 @@ namespace PBD {
  *
  * initialize with BOOST_DETAIL_SPINLOCK_INIT
  */
-static boost::detail::spinlock sl_init = BOOST_DETAIL_SPINLOCK_INIT;
+#ifdef COMPILER_MSVC
+private:
+	static boost::detail::spinlock sl_init = BOOST_DETAIL_SPINLOCK_INIT;
+# define SPINLOCK_INIT sl_init
+#else
+# define SPINLOCK_INIT BOOST_DETAIL_SPINLOCK_INIT
+#endif
 
 struct spinlock_t {
 public:
-	spinlock_t () : l (sl_init) {};
+	spinlock_t () : l (SPINLOCK_INIT) {};
 	void lock () { l.lock (); }
 	void unlock () { l.unlock (); }
 	bool try_lock () { return l.try_lock (); }
@@ -44,6 +50,8 @@ private:
 	boost::detail::spinlock l;
 };
 
+#undef SPINLOCK_INIT
+
 /* RAII wrapper */
 class LIBPBD_API SpinLock {