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# GMock uses tuples extensively, but since it is part of tr1 we cannot
# assume it is present - the Fujitsu compilers on K computer is one
# example of a system where it is not, and this is likely the case for many
# embedded systems too.
#
# In general, we can ask gmock to use its own internal implementation by
# defining GTEST_USE_OWN_TR1_TUPLE=1. This is safe for Gromacs, since we do
# not use tr1/tuple.h elsewhere. However, this workaround itself will not
# compile on MSVC - but this is the only architecture we know where it does
# not work. To make things even worse, on MSVC even the standard tr1/tuple
# implementation is not fully compatible, but we can make it work by setting
# _VARIADIC_MAX=10. This is similar to r675 of googletest, which is still not
# present in GMock 1.7.0. See
# https://code.google.com/p/googletest/source/detail?r=675#, but note
# that its summary does not represent its code correctly.
#
# To make all this work without user intervention, we first check what compiler
# we have, and if it is not MSVC we simply use the internal version. If we are
# using MSVC, we rely on the compiler's version, but set the variable necessary
# to make it compatible.
#
# This function should be called to get the compile definitions
# suitable for making sure we have a tuple implementation that works with gmock.
#
# Returns a string of options in VARIABLE
function(GET_GMOCK_TUPLE_WORKAROUND VARIABLE)
    set(${VARIABLE} "")
    if(MSVC OR (WIN32 AND CMAKE_CXX_COMPILER_ID MATCHES "Intel"))
        if(MSVC_VERSION VERSION_EQUAL 1700)
            # Fixes Visual Studio 2012
            set(${VARIABLE} "_VARIADIC_MAX=10")
        endif()
        # For MSVC different from 2012, or Intel on Windows, we reply on tr1/tuple working.
    else()
        # Use the built-in version on all other compilers.
        set(${VARIABLE} "GTEST_USE_OWN_TR1_TUPLE=1")
    endif()
    set(${VARIABLE} ${${VARIABLE}} PARENT_SCOPE)
endfunction()