Exiv2

In the discussion in #1187, Taras proposed the following change to CMakeLists.txt:

...
OPTION( EXIV2_ENABLE_CURL          "USE Libcurl for HttpIo"                                ON  )
OPTION( EXIV2_ENABLE_SSH           "USE Libssh for SshIo"                                  ON  )

+include(CheckCXXCompilerFlag)
+CHECK_CXX_COMPILER_FLAG("-std=c++11" COMPILER_SUPPORTS_CXX11)
+CHECK_CXX_COMPILER_FLAG("-std=c++0x" COMPILER_SUPPORTS_CXX0X)
+if(COMPILER_SUPPORTS_CXX11)
+  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11 -stdlib=libc++")
+  message(STATUS "Using C++11")
+elseif(COMPILER_SUPPORTS_CXX0X)
+  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++0x -stdlib=libc++")
+  message(STATUS "Using C++0x")
+else()
+  message(STATUS "The compiler ${CMAKE_CXX_COMPILER} has no C++11 support. Please use a different C++ compiler.")
+endif()
+
+
IF( MINGW OR UNIX ) ...

1. C++11 support for GCC/Clang and various editions of CL (msvc)
2. add an option for C++11 for ./configure, cmake and configure.py (msvc)
3. build with C++11 occasionally on the buildserver (once a week or so)

This seems like very good candidate feature for v0.27. http://dev.exiv2.org/news/3

CMake 3.1 and later has already some support for C++11. Instead of testing on your own (and missing of msvc) have a look at CMAKE_CXX_STANDARD in CMake doc.

So
SET(CMAKE_CXX_STANDARD 11)
in CMakeLists.txt activates the support for C++11 if available by the compiler. Otherwise it will fall back to the lower C++ standard.
If you want to control the behavior wrap it into an if statement.
(Only drawback you will need to update the
CMAKE_MINIMUM_REQUIRED( VERSION 3.1 )
But this should not be a problem as CMake is currently at 3.5.2.)

Thanks. As you know, I am not a fan of CMake and will not be working on this issue until v0.26 ships. If you'd like to contribute to this, I will be delighted to accept your help. I have no issue with setting the minimum CMake version to 3.1.

At least under OS X 10.10.5 it's not enough just to add

SET(CMAKE_CXX_STANDARD 11)

since "-stdlib=libc++" parameter will not be added to CXX_FLAGS. That was the reason I've added bunch of duplicating stuff.

My CMAKE version is quite recent if not the most recent.

> /Applications/CMake.app/Contents/bin/cmake --version
cmake version 3.5.2

CMake suite maintained and supported by Kitware (kitware.com/cmake).

The problem is that --stdlib can be ommited by design, while it's vital to have in compiler flags.

Does it help when you add
set(CMAKE_XCODE_ATTRIBUTE_CLANG_CXX_LIBRARY "libc++")
to CMake?