DROP TABLE IF EXISTS hoge;

CREATE TABLE hoge
(
  id int primary key,
  name text
);

CREATE OR REPLACE FUNCTION hoge_upd_func()
  RETURNS TRIGGER
  LANGUAGE plpgsql
AS $$
BEGIN
  RAISE WARNING 'old table = %, new table = %', (SELECT string_agg(id || '=' || name, ',') FROM d), (SELECT string_agg(id || '=' || name, ',') FROM i);
  RETURN NULL;
END;
$$;

CREATE TRIGGER hoge_upd_trigger
  AFTER UPDATE ON hoge
  REFERENCING OLD TABLE AS d NEW TABLE AS i
  FOR EACH STATEMENT EXECUTE PROCEDURE hoge_upd_func();

insert into hoge values (1, '1'), (2, '2'), (3, '3');
update hoge set name = name || name;

-- now change 'name' to an integer to see what happens...
alter table hoge alter column name type int using name::integer;
update hoge set name = (name::text || name::text)::integer;

-- at this point we get an error message:
-- ERROR:  attribute 2 has wrong type
-- DETAIL:  Table has type integer, but query expects text.

-- That error ^ can be cleared by recreating the function hoge_upd_func.

-- now drop column 'name' 
alter table hoge drop column name;
update hoge set id = id;

-- segfault!