> On Jan 16, 2018, at 10:24 AM, Jordan Rose <jordan_r...@apple.com> wrote:
>>> On Jan 12, 2018, at 3:08 PM, Jordan Rose <jordan_r...@apple.com
>>> <mailto:jordan_r...@apple.com>> wrote:
>>>
>>> Okay, I went back to `unknown case` in the proposal, but mentioned Chris's
>>> point very specifically: if the compiler emits an error, we should go with
>>> `case #unknown` instead. (I'm very strongly in the "warning" camp, though.)
>>
>> Thanks!
>>
>> Out of curiosity, why not “unknown default:”? The “warning” behavior is a
>> customization of default, so this seems like a more logical model. It also
>> fits into the existing Swift grammar, unlike “unknown case:” which requires
>> adding a new special case production.
>
> I'm not sure how this fits more into the existing grammar. Both of them
> require custom parsing with one token's worth of lookahead. You're right that
> they suggest different natural modelings in the AST, but that's an
> implementation detail.
The parser has fairly general support for declmodifiers, and my proposal fits
directly into that. The only extension is that ‘default’ isn’t a decl, and I
don’t think we have a statement modifier yet. That said, we’ve always planned
to have them when the need arose.
-Chris
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