C++ order of evaluation of operands, arguments

[Jason Merrill]

There's a proposal working through the C++ committee to define the order 
of evaluation of subexpressions that previously had unspecified ordering:

http://www.open-std.org/Jtc1/sc22/wg21/docs/papers/2015/p0145r0.pdf
I agree with much of this, but was concerned about the proposal to 
define order of evaluation of function arguments as left-to-right, since 
GCC does right-to-left on PUSH_ARGS_REVERSED targets, including x86_64.

Any thoughts?

Jason