From ac03a3c1043cb21785c53c8acd50c6dd71a2e5f0 Mon Sep 17 00:00:00 2001
From: Jim DeLaHunt <from+project_by_git@jdlh.com>
Date: Tue, 25 May 2021 23:28:20 -0700
Subject: [PATCH] Fix compile error for Qt clients on macOS, FC_QT5_CXXFLAGS
 -std=c++11

In m4/qt5-darwin.m4, add flag " -std=c++11" to test and to
definition of FC_QT5_CXXFLAGS . This fixes a compilation error on macOS.
macOS 10.13.6 High Sierra uses the Apple LLVM version 10.0.0
(clang-1000.11.45.5) compiler, rather than gcc. This compiler conforms
to the c++98 standard by default, while gcc conforms to the c++11
standard. The Qt5 code requires features from the c++11 standard.
"-std=c++11" makes the clang compiler conform to the correct standard.
---
 m4/qt5-darwin.m4 | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/m4/qt5-darwin.m4 b/m4/qt5-darwin.m4
index 9a0b57c7f2..6d185651da 100644
--- a/m4/qt5-darwin.m4
+++ b/m4/qt5-darwin.m4
@@ -54,12 +54,12 @@ AC_DEFUN([FC_QT5_DARWIN_COMPILETEST],
     [qt5_headers=yes
      FC_QT5_CPPFLAGS="${FC_QT5_CPPFLAGS}${CPPFADD}"],
     [CXXFLAGS_SAVE="${CXXFLAGS}"
-     CXXFLAGS="${CXXFLAGS} -fPIC"
+     CXXFLAGS="${CXXFLAGS} -fPIC -std=c++11"
      AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[#include <QApplication>]],
 [[int a; QApplication app(a, 0);]])],
       [qt5_headers=yes
        FC_QT5_CPPFLAGS="${FC_QT5_CPPFLAGS}${CPPFADD}"
-       FC_QT5_CXXFLAGS="${FC_QT5_CXXFLAGS} -fPIC"])
+       FC_QT5_CXXFLAGS="${FC_QT5_CXXFLAGS} -fPIC -std=c++11"])
      CXXFLAGS="${CXXFLAGS_SAVE}"])
 
   CPPFLAGS="$CPPFLAGS_SAVE"
-- 
2.31.1