From 3c69386a197d7d773d7fa03cced18cb114ee0555 Mon Sep 17 00:00:00 2001
From: vsr <vsr@opencascade.com>
Date: Mon, 14 Sep 2020 11:33:05 +0300
Subject: [PATCH] Add option to choose C++ standard; default value is set to 11
 (requries CMake minimal version 3.1)

---
 cmake/SalomeMacros.cmake        |  1 +
 cmake/SalomeSetupPlatform.cmake | 11 ++++++++++-
 2 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/cmake/SalomeMacros.cmake b/cmake/SalomeMacros.cmake
index 33078a9..d24b042 100644
--- a/cmake/SalomeMacros.cmake
+++ b/cmake/SalomeMacros.cmake
@@ -27,6 +27,7 @@ IF(WIN32)
   CMAKE_POLICY(SET CMP0020 OLD) # Disable automatic linking to qtmain.lib
 ENDIF(WIN32)
 CMAKE_POLICY(SET CMP0053 NEW)   # For correct Qt 5 detection procedure
+CMAKE_POLICY(SET CMP0057 NEW)   # For IF(IN_LIST) operator
 IF(CMAKE_VERSION VERSION_GREATER_EQUAL 3.12)
   CMAKE_POLICY(SET CMP0074 NEW) # Use ROOT variables when detecting packages
 ENDIF()
diff --git a/cmake/SalomeSetupPlatform.cmake b/cmake/SalomeSetupPlatform.cmake
index abfb734..a5f713a 100644
--- a/cmake/SalomeSetupPlatform.cmake
+++ b/cmake/SalomeSetupPlatform.cmake
@@ -106,7 +106,16 @@ IF(COMPILER_SUPPORTS_NO_OPERATOR_NAMES)
   SET(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fno-operator-names")
 ENDIF()
 
-SET(CMAKE_CXX_STANDARD 17)
+# C++ standard to use; NOTE: extensions are not allowed!
+SET(SALOME_CXX_STANDARD 11 CACHE STRING "C++ standard to use")
+SET(_supported_standards 11 14 17 20)
+IF(NOT ${SALOME_CXX_STANDARD} IN_LIST _supported_standards)
+  MESSAGE(FATAL_ERROR "Unsupported C++ standard: ${SALOME_CXX_STANDARD}; allowed values: ${_supported_standards}")
+ENDIF()
+UNSET(_supported_standards)
+MESSAGE(STATUS "Setting C++ standard to ${SALOME_CXX_STANDARD}")
+SET(CMAKE_CXX_STANDARD ${SALOME_CXX_STANDARD})
+SET(CMAKE_CXX_EXTENSIONS OFF)
 SET(CMAKE_CXX_STANDARD_REQUIRED ON)
 
 # Fight warnings
-- 
2.39.2