from P0298R2: http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2016/p0298r2.pdf
> Motivation and Scope
> Many programs require byte-oriented access to memory. ...

Could you please show examples of such programs?


As I read N4623 (WG21 2016-11 Issaquah Minutes) and saw that the
proposal was about to pass through, I want to understand more concretely
what is going.

I suspect that such programs do something like obtaining unsigned char*
which points to an int object via reinterpret_cast and iterating through
it as if the pointer points to an element of unsigned char[sizeof(int)],
as I personally have seen many such programs.

However, AFAIK, the current standard doesn't (or fails to) give
well-defined behavior to such byte-oriented access on objects of
arbitrary types.
N4618 5.7 [expr.add] p6 says:
> For addition or subtraction, if the expressions P or Q have type
> "pointer to cv T", where T and the array element type are not similar
> (4.5), the behavior is undefined.

Then, if "Many programs require ..." is saying what I suspect, I think
defining such byte-oriented accesses should be done before (or within)
the proposal. It will also resolve CWG issue 1701:
"Array vs sequence in object representation"
http://wg21.cmeerw.net/cwg/issue1701

--
k_satoda

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