Is there a sequence point between the two assignments in the following code:
f(f(x=1,1),x=2);
There are sequence points at the beginning of a function call and at it's end. However because the order of operations on function arguments is implementation defined you can't gaurantee that f(x=1,1) will be executed before x=2.
Also note that the , in the function call case is not the comma operator that introduces a sequence point.