ROW_TYPE and "not assigned to tuple structure"

[adam-p]

When the plpgsql_check.mode = 'every_start' is not present in my config, this SQL works fine:

CREATE TABLE ttt (
  id TEXT
);

CREATE OR REPLACE FUNCTION f() RETURNS TEXT AS $$
DECLARE
  v ttt%ROWTYPE;
BEGIN
  v.id = 'hi';
  RETURN v.id;
END $$ LANGUAGE plpgsql;

SELECT * FROM f():

But when that config line is present, the SQL gives the error:

ERROR:  record "v" is not assigned to tuple structure
CONTEXT:  PL/pgSQL function f() line 5 at assignment to field "id" of variable "v" declared on line 3

That error leads me to this comment in the plpgsql_check source:

Check that there is already a tuple in the record. We need that because records don't have any predefined field structure.

The documentation for RECORD certainly indicates that they "have no predefined structure", but for ROWTYPE it doesn't say that.

I am not a postgres/SQL pro-star, but I was under the impression that ROWTYPE does confer the structure of the table.

So... Am I wrong and my code is bad, or is plpgsql_check being overzealous in throwing an error for ROWTYPE?