7.2:9 says "The value is unchanged if it is in the range of enumeration
values of the enumeration type; otherwise the resulting enumeration
value is unspecified".

For a case where C might pick a signed representation, this appears
to be a stronger constraint in C++ than in C, since it implies a C++
implementation must produce an unspecified value (and then carry on)
where C makes no requirement on the implementation (i.e. UB).

Is this an intentional change?  (Obviously, the definition of range
has changed but I believe that is orthogonal here.)  Why doesn't it
just say "the behavior is undefined"?

Stroustrup 3rd edition (4.8, p.77) says "The result of such a
conversion is undefined unless the value is within the range of
the enumeration."  It's not clear whether he means "the result
behavior" or "the result value".  Is there a material difference
between Stroustrup's "undefined" versus the Standard's "unspecified"?

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