Re: Issue: TAGBODY-CONTENTS (Version 3)

[Kent M Pitman <KMP@STONY-BROOK.SCRC.Symbolics.COM>]

    Date: Wed, 5 Oct 88  13:36:26 CDT
    From: David N Gray <Gray@DSG.csc.ti.com>

    >  Is anybody concerned about macros that expand to a tagbody with NIL forms?
    > If NIL is a statement in a tagbody then they disappear quietly,
    > especially after a pass by a good compiler.
    > With the current proposal, though, one will get:
    >   "ERROR: Multiple appearances of tag NIL."
    > 
    > I don't know what current practice is, if code like this has 
    > always signalled an error then this is a total non-issue.
    > If not, it might be noted as a possible conversion cost.

    The Explorer permits using NIL as a GO tag, but as a special case, does
    not warn about multiple appearances of NIL.

Hmmm. That suggests another alternative: We could leave NIL being a tag
and just say that it's an error to repeat a tag only if you also GO to
it.  That would mean that other tags could be repeated as well. eg, I
seem to recall that some people put ------ in their tagbodies as
separators between major sections. As long as they didn't also do (GO
-----), their practice would be legitimized.