Sam Mason <sam(at)samason(dot)me(dot)uk> writes:
> On Wed, Sep 02, 2009 at 02:59:54PM -0500, Kevin Grittner wrote:
>> I'm not sure whether the only place the standard doesn't require a
>> cast is on assignment, but this is one place that the standard clearly
>> does require a cast, and I'm all for that.
> I'm probably missing something obvious again, but where does it say
> that?
They express it as a syntactic constraint not a semantic one. NULL
without decoration is a <contextually typed value specification>
which is allowed in only a limited number of places. One place
it's allowed is inside a <cast specification>, which is reachable
from <value expression>. The latter is allowed in lots of places.
regards, tom lane