Re: array_in sub function ReadArrayDimensions error message

On Mon, Jul 8, 2024 at 10:42 PM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>
> jian he <jian(dot)universality(at)gmail(dot)com> writes:
> > while reviewing the json query doc,
> > I found out the following error message was not quite right.
>
> > select '[1,2]'::int[];
> > ERROR: malformed array literal: "[1,2]"
> > LINE 1: select '[1,2]'::int[];
> > ^
> > DETAIL: Missing "]" after array dimensions.
>
> > should it be:
> > "Missing delimiter ":" while specifying array dimensions."
>
> That's presuming quite a lot about the nature of the error.
> All the code knows is that what follows the "1" should be
> either ":" or "]", and when it sees "," instead it throws
> this error. I agree the existing message isn't great, but
> trying to be more specific could confuse people even more
> if the more-specific message doesn't apply either.
>
> One possibility could be
>
> if (*p != ']')
> ereturn(escontext, false,
> (errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
> errmsg("malformed array literal: \"%s\"", origStr),
> + (strchr(p, ']') != NULL) ?
> + errdetail("Array dimensions have invalid syntax.") :
> errdetail("Missing \"%s\" after array dimensions.",
> "]")));
>
> that is, only say "Missing "]"" if there's no ']' anywhere, and
> otherwise just say the dimensions are wrong. This could be fooled
> by a ']' that's part of some string in the data, but even then the
> errdetail isn't wrong.
>
> Or we could just say "Array dimensions have invalid syntax."
> unconditionally.
>
> regards, tom lane

we can
if (*p == ':')
{
....

if (*p != ']')
ereturn(escontext, false,
(errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
errmsg("malformed array literal: \"%s\"", origStr),
errdetail("Missing \"%s\" after array dimensions.",
"]")));
}
else
{
if (*p != ']')
ereturn(escontext, false,
(errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
errmsg("malformed array literal: \"%s\"", origStr),
errdetail("Missing delimiter \"%s\" while specifying array dimensions.",
":")));
}

different error message in IF ELSE blocks.
please check attached.