From 07da1cef239de905b7c1a2e0378efad631a2d5e5 Mon Sep 17 00:00:00 2001
From: Marco Clemencic <marco.clemencic@cern.ch>
Date: Mon, 30 Sep 2024 10:34:50 +0200
Subject: [PATCH] Use C++20 when building with gcc>=13 or clang>=16
---
cmake/Modules/LHCbSettings.cmake | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)
diff --git a/cmake/Modules/LHCbSettings.cmake b/cmake/Modules/LHCbSettings.cmake
index b156427620..d182604847 100644
--- a/cmake/Modules/LHCbSettings.cmake
+++ b/cmake/Modules/LHCbSettings.cmake
@@ -1,5 +1,5 @@
###############################################################################
-# (c) Copyright 2021 CERN for the benefit of the LHCb Collaboration #
+# (c) Copyright 2021-2024 CERN for the benefit of the LHCb Collaboration #
# #
# This software is distributed under the terms of the GNU General Public #
# Licence version 3 (GPL Version 3), copied verbatim in the file "COPYING". #
@@ -19,7 +19,13 @@ find_data_package(Geant4Files ${Geant4_VERSION_MAJOR}${Geant4_VERSION_MINOR}.0)
# FIXME: this should match the version used by ROOT (LCG version + compiler version)
-set(GEANT4_BUILD_CXXSTD 17 CACHE STRING "C++ Standard")
+if( (CMAKE_CXX_COMPILER_ID STREQUAL "GNU" AND CMAKE_CXX_COMPILER_VERSION VERSION_LESS "13.0")
+ OR (CMAKE_CXX_COMPILER_ID STREQUAL "Clang" AND CMAKE_CXX_COMPILER_VERSION VERSION_LESS "16.0") )
+ set(LHCB_DEFAULT_CXXSTD 17)
+else()
+ set(LHCB_DEFAULT_CXXSTD 20)
+endif()
+set(GEANT4_BUILD_CXXSTD ${LHCB_DEFAULT_CXXSTD} CACHE STRING "C++ Standard")
set(OpenGL_GL_PREFERENCE "GLVND" CACHE STRING
"Preferred GL library to use (see https://cmake.org/cmake/help/v3.12/policy/CMP0072.html)")
--
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