Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com> writes:
> I have a problem - every call of mvarcharin is with typmod = -1.
Sure your typmod_in function works?
Also, there are a bunch of scenarios where we rely on a cast function to
apply the typmod rather than passing it to the input function initially.
I'm not sure if the particular case you're checking here falls into that
category, but you definitely should have a "length conversion cast"
function in pg_cast if you expect to do anything useful with typmod.
regards, tom lane