chiaki ISHIKAWA writes: > (2014/04/07 10:16), Karl Tomlinson wrote: >> because enumeration types may hold values that don't match any of >> their enumerator values. > > Is this allowed by C (or C++) specification today?
It is allowed in N3242. I think the relevant sections are 5.2.9 Static cast 10 A value of integral or enumeration type can be explicitly converted to an enumeration type. The value is unchanged if the original value is within the range of the enumeration values (7.2). Otherwise, the resulting enumeration value is unspecified. 7.2 Enumeration declarations 7 For an enumeration whose underlying type is fixed, the values of the enumeration are the values of the underlying type. Otherwise, for an enumeration where e min is the smallest enumerator and e max is the largest, the values of the enumeration are the values in the range b min to b max , defined as follows: Let K be 1 for a two’s complement representation and 0 for a one’s complement or sign-magnitude representation. b max is the smallest value greater than or equal to max(|e min | − K, |e max |) and equal to 2 M − 1, where M is a non-negative integer. b min is zero if e min is non-negative and −(b max + K) otherwise. The size of the smallest bit-field large enough to hold all the values of the enumeration type is max(M, 1) if b min is zero and M + 1 otherwise. It is possible to define an enumeration that has values not defined by any of its enumerators. If the enumerator-list is empty, the values of the enumeration are as if the enumeration had a single enumerator with value 0. _______________________________________________ dev-platform mailing list dev-platform@lists.mozilla.org https://lists.mozilla.org/listinfo/dev-platform
