[intro.memory] What is an address?

[TymianekPL]

Reference (section label): [intro.memory]

Link to reflector thread (if any): cplusplus/draft#8491

Issue description:

The term address is not defined by C++, yet it is used a lot, for instance when defining the act of representing an address or that each byte has a unique address.

Suggested resolution:

Solution 1: Italicise address

- Every byte has a unique address.
+ Every byte has a unique \defn{address}.

[intro.memory]/1

Solution 2: Define an address as a concept that describes storage for an object

+ An \defnx{address}{address!byte} identifies the storage of each \term{byte} of storage $b$.

[intro.memory]/6

Solution 3: Define an address as the placement of the object representation of an object

  The \defnx{object representation}{representation!object}
  of a complete object type \tcode{T} is the
  sequence of \placeholder{N} \tcode{\keyword{unsigned} \keyword{char}} objects taken up
  by a non-bit-field complete object of type \tcode{T},
  where \placeholder{N} equals
  \tcode{\keyword{sizeof}(T)}.
+ Each object in the sequence is assigned a unique \defn{address} associated with that object.

[basic.types.general]/4

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Implementing that could also mean changing every reference of a byte & address to a reference to their definitions.

[eisenwave]

Solution 3 would make the address not globally unique. Remember that an array and its first element are located at the same address, and your third option seems to make an address unique between the bytes of an object, but not (obviously) unique per byte of storage, globally.

I wouldn't try talking about objects at all, but about bytes.

Personally, I'd be fine with option 1, which is arguably editorial.

Not sure about option 2.

[frederick-vs-ja]

I think we should also define "address of storage" in some way not relying on the address of an object, as suggested by [intro.object] p12.

Logically, a new storage region and its address need to exist first, and then can objects be (implicitly) created at that address. However, the current wording doesn't seem able to refer to such an address without talking about an object.