# New Ticket Created by "Carl Mäsak" # Please include the string: [perl #123583] # in the subject line of all future correspondence about this issue. # <URL: https://rt.perl.org/Ticket/Display.html?id=123583 >
<masak> here: https://gist.github.com/masak/406d687c3e4e0684c013 Inlined here for your benefit: $ cat X.pm enum X is export <A B>; $ cat Y.pm enum Y is export <B W>; $ perl6 -I. -e 'use X; use Y' ===SORRY!=== Merging GLOBAL symbols failed: duplicate definition of symbol B <masak> by my reading of S12, this should work, but then you're not allowed to refer to just `B`; you have to say `X::B` or `Y::B`. <masak> (and if you also import a `sub B { ... }` from somewhere, it takes precedence and "un-poisons" the slot for itself) <moritz> that takes slot &B <masak> no doubt -- but I'm talking about what happens when you write `B` in code after that. <masak> if the sub has been imported, that's a call to `&B`. <moritz> that should resolve to &B, yes * moritz skims S12 <masak> but if it hasn't, then it's still a compile-time error, because it's not clear if you're referring to `X::B` or `Y::B`. <moritz> Since there is an enum C<OK>, the function C<OK> may only be <moritz> called using parentheses, never in list operator form. <moritz> so you'd be able to call B() when the B slot is poisoned, but not just 'B args', iiuc <moritz> ah yes <moritz> "If there is <moritz> a collision on two enum values that cancels them both, the function <moritz> still may only be called with parentheses, since the enum key <moritz> is "poisoned"." <masak> right. <masak> that's the only reference to the concept of poisoning I've found. <masak> it mentions the effect in passing, but it's pretty clear about it. * masak submits rakudobug <moritz> masak: S12 doesn't talk about in which circumstances poisoning, so I'd assume it happens everywhere <moritz> so, also in importation/exportation <masak> moritz: ah, you mean between any two imported symbols? <masak> moritz: that's very possible. <moritz> masak: no <masak> moritz: but enum values are a bit special in that they're essentially short-form aliases for their real unambiguous names. <masak> moritz: like, `True` is short for `Bool::True`. <moritz> yes <moritz> masak: I mean between two imported enum items vs. two declared-here enum items <masak> moritz: oh, that's entirely possible, yes. <masak> moritz: though I could equally well argue that the declared-here enum value takes precedence... <moritz> with "everywhere" I meant "at declaration and at {ex,im}portation" <masak> declaring something feels like much more of a "conscious act" than importation. <masak> like, you might not know you're importing a `B`, but you definitely know you're declaring one! To summarize: the error message "Merging GLOBAL symbols failed: duplicate definition of symbol B" on importing Y.pm is wrong. That should work without an error. Referring to `B` after that in code should be a (compile-time) error, though. This is the "poisoning" effect referred to by S12. The rest of the discussion is pertinent, but doesn't figure in the closability of this ticket.
