The problem is actually caused by the error reporting:
https://github.com/rakudo/rakudo/blob/08b951c8f33cfc702c308e64efcb44f3ec725117/src/core/Exception.pm6#L2969
The only heuristic I’ve been able to find so far that the value of $ns{$_}
suddenly is no longer fully qualified if the namespace doesn’t exist. I guess
we can build some heuristic check on that, but it feels fragile. Perhaps nine
/ ugexe / jnthn have a better idea about that.
> On 13 Apr 2018, at 08:34, Martin Barth (via RT)
> <[email protected]> wrote:
>
> # New Ticket Created by Martin Barth
> # Please include the string: [perl #133107]
> # in the subject line of all future correspondence about this issue.
> # <URL: https://rt.perl.org/Ticket/Display.html?id=133107 >
>
>
> requireing a non installed module leads to strange error if the name
> starts with the name of a core module. e.g:
>
>
>> perl6 -e 'require IO::Socket::Async::SSL'
> IO::Socket::Async::SSL is a builtin type, not an external module
> in block <unit> at -e line 1
