Hi internals, I'm a bit concerned about the addition of the "enum" reserved keyword as part of https://wiki.php.net/rfc/enumerations. The problem is that there are quite a few existing enum libraries (such as https://github.com/myclabs/php-enum) that define an Enum class. While the implementation of enums in PHP 8 obsoletes these libraries, it still constitutes a migration problem, especially for libraries supporting more than one PHP version.
I don't believe that the keyword is strictly necessary: We can recognize enum declarations as T_STRING T_STRING, where the former is checked to be equal to "enum" by the parser. It so happens that this is syntactically unambiguous at this time. We may be forced to introduce the keyword at a later time, if it becomes ambiguous. Another possibility would be to recognize T_ENUM in the lexer, but only if it is followed by whitespace and an identifier. This would possibly be friendlier for tooling using token_get_all(). It would not permit comments in between the tokens though. Thoughts? Regards, Nikita
