From 97c8b970cdeae405018fdaaee12bf4cea59fb23f Mon Sep 17 00:00:00 2001
From: Kai Koehne <kai.koehne@qt.io>
Date: Wed, 30 May 2018 15:29:50 +0200
Subject: Revert "Atomics: remove qatomic_msvc.h"

This reverts commit 90493e16b8dd9edc6176d0abc255422edbbb05c3.
The change broke static builds with MSVC.

[ChangeLog][Visual Studio] Reverted a change that caused static
binaries compiled with Visual Studio 2015 to crash on start-up. Note
that this does not apply to Visual Studio 2017 static binaries, even
though the crash stack traces are very similar: with 2017, the problem
is compiler regression and requires updating to version 15.8 for the
fix.

Task-number: QTBUG-68514
Change-Id: I67ea8e1ef442cecab83e7d8d74efc9617e02da35
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
---
 src/corelib/thread/qbasicatomic.h | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

(limited to 'src/corelib/thread/qbasicatomic.h')

diff --git a/src/corelib/thread/qbasicatomic.h b/src/corelib/thread/qbasicatomic.h
index aacd12f2208..a0304697b88 100644
--- a/src/corelib/thread/qbasicatomic.h
+++ b/src/corelib/thread/qbasicatomic.h
@@ -45,8 +45,20 @@
 
 #if defined(QT_BOOTSTRAPPED)
 #  include <QtCore/qatomic_bootstrap.h>
-#else
+
+// If C++11 atomics are supported, use them!
+// Note that constexpr support is sometimes disabled in QNX builds but its
+// library has <atomic>.
+#elif defined(Q_COMPILER_ATOMICS) && (defined(Q_COMPILER_CONSTEXPR) || defined(Q_OS_QNX))
 #  include <QtCore/qatomic_cxx11.h>
+
+// We only support one fallback: MSVC, because even on version 2015, it lacks full constexpr support
+#elif defined(Q_CC_MSVC)
+#  include <QtCore/qatomic_msvc.h>
+
+// No fallback
+#else
+#  error "Qt requires C++11 support"
 #endif
 
 QT_WARNING_PUSH
-- 
cgit v1.2.3