Should a distinct array/string be required when an empty array/string is created?

*(This PR is an action item resulting from a TG discussion on slicing.)*

The Standard currently *requires* that string *literals* in the *same* assembly which have the same value, as determined by string equality (§12.12.8), *must* be represented by the same object (§6.4.5.6). Note this only applies to string literals and not strings created dynamically, and as a single program may consist of multiple assemblies does not mean that the same string literal is the same object everywhere in a program.

It is known that at least one implementation uses a single object for each zero-length array and empty string it creates. In particular taking a slice of an array/string though is to return a “new” object, but in this particular implementation may not do so if the resultant slice is empty.

Questions to answer:

- Does this behavior need to be explicitly allowed by the Standard for such an implementation to be conformant?
- If so should it be?
- Are there other cases where a “new“ object is specified in the Standard but where an implementation can provide all the correct semantics, apart from the object reference being distinct, which should be explicitly supported?