Hitoshi Harada <umi(dot)tanuki(at)gmail(dot)com> writes:
> DEFAULT is disallowed now in such VALUES list, but we can explain it
> is allowed in a "simple" VALUES of INSERT case.
I don't think we really need to explain anything. This is per spec;
if you trace the way that a DEFAULT expression can appear in INSERT,
it's treated as a <contextually typed value specification>,
which appears in <contextually typed table value constructor>,
which is VALUES and nothing else.
regards, tom lane