Re: array_in sub function ReadArrayDimensions error message

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