Updating CMake changes to move min version to 3.5.1

CMakeLists.txt

-CMAKE_MINIMUM_REQUIRED(VERSION 3.1.3)
+CMAKE_MINIMUM_REQUIRED(VERSION 3.5.1)
 SET(CMAKE_BUILD_TYPE Release CACHE STRING "Choose the type of build,
 options are: None(CMAKE_CXX_FLAGS or CMAKE_C_FLAGS used) Debug Release
 RelWithDebInfo MinSizeRel.")
@@ -14,26 +14,10 @@ IF (POLICY CMP0074)
     CMAKE_POLICY(SET CMP0074 OLD)
 ENDIF()
 
-# Nektar++ requires C++11. Try to infer this for older CMake versions (less than
-# 3.1.0)
-IF ("${CMAKE_VERSION}" VERSION_LESS "3.1")
-    IF (NOT MSVC)
-        INCLUDE(CheckCXXCompilerFlag)
-        CHECK_CXX_COMPILER_FLAG("-std=c++11" COMPILER_SUPPORTS_CXX11)
-
-        IF (COMPILER_SUPPORTS_CXX11)
-            SET(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11")
-        ELSE()
-            MESSAGE(FATAL_ERROR "Nektar++ requires a compiler with C++11 support.")
-        ENDIF()
-    ELSEIF(CMAKE_CXX_COMPILER_VERSION VERSION_LESS 18.0)
-        MESSAGE(FATAL_ERROR "Nektar++ requires full C++11 support: please upgrade to Visual Studio 2013 or later")
-    ENDIF()
-ELSE()
-    SET(CMAKE_CXX_STANDARD 11)
-    SET(CMAKE_CXX_STANDARD_REQUIRED ON)
-    SET(CMAKE_CXX_EXTENSIONS OFF)
-ENDIF()
+# Nektar++ requires C++11.
+SET(CMAKE_CXX_STANDARD 11)
+SET(CMAKE_CXX_STANDARD_REQUIRED ON)
+SET(CMAKE_CXX_EXTENSIONS OFF)
 
 INCLUDE(CheckLanguage)
 

cmake/ThirdPartyHDF5.cmake

@@ -33,10 +33,6 @@ IF (NEKTAR_USE_HDF5)
         "NEKTAR_USE_HDF5" OFF)
 
     IF(THIRDPARTY_BUILD_HDF5)
-        IF (CMAKE_VERSION VERSION_LESS 3.1.0)
-            MESSAGE(FATAL_ERROR "HDF5 compilation requires CMake 3.1.0 or later.")
-        ENDIF()
-
         INCLUDE(ExternalProject)
         EXTERNALPROJECT_ADD(
             hdf5-1.8.16

cmake/thirdparty-patches/CMakeLists_CCM.txt

-CMAKE_MINIMUM_REQUIRED(VERSION 2.8.7)
+CMAKE_MINIMUM_REQUIRED(VERSION 3.5.1)
 PROJECT(libccmio)
 
 # compile in Release mode by default

templates/executable/CMakeLists.txt

@@ -4,8 +4,7 @@
 # projects are marked below.
 ######################################################
 
-# Require at least CMake 3.1 for CMAKE_CXX_STANDARD.
-CMAKE_MINIMUM_REQUIRED(VERSION 3.1)
+CMAKE_MINIMUM_REQUIRED(VERSION 3.5.1)
 
 # TODO - Put the name of your project here.
 PROJECT(ExampleSolver)