From 0b166461ef491b13eaafe9245dcdbcebb8543397 Mon Sep 17 00:00:00 2001
From: Olivier Parcollet <olivier.parcollet@cea.fr>
Date: Tue, 10 Dec 2013 11:53:58 +0100
Subject: [PATCH] Add C++14 detection and flags

- if compiler detected, compile in c++1y mode.
- override with -Dcompiler_is_c14=ON if not detected.
- compilation in c++1y on clang 3.4 ok on OS X
---
 CMakeLists.txt                | 10 ++++++++--
 cmake/FindCompilerCheck.cmake | 20 +++++++++++---------
 2 files changed, 19 insertions(+), 11 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 97c2c435..738f65cf 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -62,8 +62,14 @@ set(CMAKE_INSTALL_RPATH_USE_LINK_PATH TRUE)
 # First check the C++ compiler
 find_package(CompilerCheck)
 
-# Add C11 flag
-SET(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++0x")
+# Add C11 or C14 flag depending on compiler detection
+if (NOT compiler_is_c14)
+ MESSAGE(STATUS "Compiling in C++11 mode")
+ SET(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11")
+else()
+ MESSAGE(STATUS "Compiling in C++14 mode")
+ SET(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++1y")
+endif()
 
 # Include TRIQS cmake macros
 find_package(TriqsMacros)
diff --git a/cmake/FindCompilerCheck.cmake b/cmake/FindCompilerCheck.cmake
index 88ce7a30..9f2d6432 100644
--- a/cmake/FindCompilerCheck.cmake
+++ b/cmake/FindCompilerCheck.cmake
@@ -19,12 +19,11 @@ if ("${CMAKE_CXX_COMPILER_ID}" MATCHES "GNU")
   OUTPUT_VARIABLE _compiler_output RESULT_VARIABLE returncode OUTPUT_STRIP_TRAILING_WHITESPACE)
  set(compiler_version_min "4.8.1")
  set(compiler_name "gcc")
- set(compiler_group 1)
  string(REGEX REPLACE ".*([2-5]\\.[0-9]\\.[0-9]).*" "\\1" compiler_version ${_compiler_output})
 
- #if(compiler_version VERSION_LESS "4.8.0" )
- # set(compiler_is_obsolete_gcc ON)
- #endif()
+ if(NOT compiler_version VERSION_LESS "4.9.0")
+  set (compiler_is_c14 ON)
+ endif()
 
 elseif ("${CMAKE_CXX_COMPILER_ID}" MATCHES "Clang")
 
@@ -32,17 +31,21 @@ elseif ("${CMAKE_CXX_COMPILER_ID}" MATCHES "Clang")
   OUTPUT_VARIABLE _compiler_output RESULT_VARIABLE returncode OUTPUT_STRIP_TRAILING_WHITESPACE)
  set(CMAKE_COMPILER_IS_CLANG TRUE )
  set(compiler_name "clang")
- set(compiler_group 1)
  IF(${CMAKE_SYSTEM_NAME} MATCHES "Darwin")
   # Apple which does not has the official clang version number ... 
   string(REGEX REPLACE ".*LLVM ([2-5]\\.[0-9]).*" "\\1" compiler_version ${_compiler_output})
-  #set( compiler_version_min "3.2")
  else()
- string(REGEX REPLACE ".*([2-5]\\.[0-9]).*" "\\1" compiler_version ${_compiler_output})
- message(STATUS "Compiler version = ${compiler_version}")
+  string(REGEX REPLACE ".*([2-5]\\.[0-9]).*" "\\1" compiler_version ${_compiler_output})
  endif()
+ #message(STATUS "Compiler --version output = ${_compiler_output}")
+ message(STATUS "Compiler version = ${compiler_version}")
  set( compiler_version_min "3.2")
 
+ # does not always work ... To be fixed when clang 3.4 officially released and on OS X.
+ if(NOT compiler_version VERSION_LESS "3.4")
+  set (compiler_is_c14 ON)
+ endif()
+
 elseif ("${CMAKE_CXX_COMPILER_ID}" MATCHES "Intel")
  
  EXECUTE_PROCESS(COMMAND ${CMAKE_CXX_COMPILER} -dumpversion  
@@ -50,7 +53,6 @@ elseif ("${CMAKE_CXX_COMPILER_ID}" MATCHES "Intel")
  set(CMAKE_COMPILER_IS_ICC TRUE )
  set(compiler_version_min "14.0.0")
  set(compiler_name "Intel icc")
- set(compiler_group 3)
  #string(REGEX REPLACE "[^0-9]*([0-9]+\\.[0-9]\\.[0-9]).*" "\\1" compiler_version ${_compiler_output})
 
  # for intel 14.0 /test