From 4e10abb4c14df2ffc162a0eb017229dfa2bab1fb Mon Sep 17 00:00:00 2001
From: Ulf Hermann <ulf.hermann@qt.io>
Date: Mon, 12 Oct 2020 15:13:05 +0200
Subject: [PATCH] Add externConstexpr to MSVC compile options

We want this in order to be able to export constexpr members.

Change-Id: I33ba7964ebee54fe656df983985d8d6fa0b99358
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>
Reviewed-by: Lars Knoll <lars.knoll@qt.io>
---
 cmake/QtInternalTargets.cmake    | 5 +++++
 mkspecs/common/msvc-version.conf | 1 +
 2 files changed, 6 insertions(+)

diff --git a/cmake/QtInternalTargets.cmake b/cmake/QtInternalTargets.cmake
index 1485726f0fd..91a75983ea1 100644
--- a/cmake/QtInternalTargets.cmake
+++ b/cmake/QtInternalTargets.cmake
@@ -186,6 +186,11 @@ if (MSVC)
             -Zc:referenceBinding
         )
     endif()
+    if (MSVC_VERSION GREATER_EQUAL 1919)
+        target_compile_options(PlatformCommonInternal INTERFACE
+            -Zc:externConstexpr
+        )
+    endif()
 
     target_compile_options(PlatformCommonInternal INTERFACE -Zc:wchar_t)
 
diff --git a/mkspecs/common/msvc-version.conf b/mkspecs/common/msvc-version.conf
index 046f803b756..eee5cc0dd53 100644
--- a/mkspecs/common/msvc-version.conf
+++ b/mkspecs/common/msvc-version.conf
@@ -119,6 +119,7 @@ greaterThan(QMAKE_MSC_VER, 1919) {
     MSVC_VER            = 16.0
     QMAKE_CXXFLAGS_CXX2A = -std:c++latest
 
+    QMAKE_CXXFLAGS     += -Zc:externConstexpr
 }
 
 !isEmpty(COMPAT_MKSPEC):!$$COMPAT_MKSPEC: CONFIG += $$COMPAT_MKSPEC