[Issue 199] Label causes scope to collapse into parent

[d-bugmail at puremagic.com]

http://d.puremagic.com/issues/show_bug.cgi?id=199



--- Comment #27 from Nick Treleaven <ntrel-public at yahoo.co.uk> 2013-05-30 08:41:41 PDT ---
(In reply to comment #16)
> (In reply to comment #15)
> > Walter Bright, comment #6:
> > > I don't want to change this because it could break existing code
> > 
> > We could deprecate having a BlockStatement after a label, with a message
> > suggesting to move the label within the block. That way no code gets broken.
> 
> Wait. What? Deprecate having a block statement after a label? Why would we do
> that? That's completely arbitrary. Plus, that would *definitely* break more
> code than what we'd break with a straight up fix.

In order not to break code. I'm skeptical that a solution which causes any
existing, debugged working code to silently break will be accepted, and I think
that opinion makes sense.

If we are to avoid all possible code breakage, it's simple to just deprecate
non-empty block statements after a label, since there are two workarounds (see
comment 15) which do not require changing existing scope semantics. The
deprecation message can advise the user of the workarounds.

I omitted to mention that an empty block statement after a label should still
be allowed, as that is not bug-prone.

Maybe I wasn't clear - by deprecating I mean permanent deprecation without
removal, essentially a warning that you can turn off if you really want to by
silencing deprecation messages.

> This behavior was never according to spec anyways. I say we just fix it.

It's a trade off between either breaking working code or annoying users with
deprecation messages that need small fixes to their code.

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