in reply to
Re^4: The default hash - accident, coincidence or conspiracy?
in thread The default hash - accident, coincidence or conspiracy?
No, it is illegal, because if you put it in a perl program, the program will not run. You get a fatal error during compilation.
For better or worse, the Perl language (unlike most) is defined by the implementation, not by a document. If the behavior in question isn't documented, that is simply a documentation bug.
ObDisclaimer: This refers to Perl5 (and prec.) only.