Re: [Json] Unpaired surrogates in JSON strings

[Paul Hoffman <[e-mail]>]

<definitely no hat>

On Jun 5, 2013, at 10:46 AM, Douglas Crockford <[e-mail]> wrote:

> On 6/5/2013 9:22 AM, John Cowan wrote:
>> RFC 4627 Section 1 says:
>> 
>>     A string is a sequence of zero or more Unicode characters.
>> 
>> However, the grammar of strings permits things like "foo\uDC00bar",
>> which contains an escape sequence that does not correspond to any
>> Unicode character.  This provides backward compatibility with JavaScript,
>> where a string is not a sequence of characters but a sequence of UTF-16
>> code units.
>> 
>> If Section 1 is normative, then there is a contradiction with Section 4,
>> which says:
>> 
>>     A JSON parser MUST accept all texts that conform to the JSON
>>     grammar.
>> 
>> In my view, JSONbis processors should be REQUIRED to produce only strings
>> that conform to Section 1.
>> 
> Such a requirement will be breaking. Breaking changes are out of scope.

How is that "breaking"? Section 1 has a definition of strings, and Section 4 says that the parser must accept all texts that conform to the grammar. Surrogate code points are not characters, according to the Unicode spec.

> I like the suggestion that section 1 should be talking about code points instead of characters.

That seems like a significant change that would cause parsers that currently follow Section 1 to fail.

--Paul Hoffman