STRICTMULTIASSIGNMENT would detect most cases of this, except that the condition is checked too late. We'd need to count the fields *before* trying to assign values, not after.
I use some fragments of this routine. But the problem was so I did implicit unnesting, although plpgsql doesn't do this
postgres=# create or replace function broken_into() returns void as $$ declare v typ2; begin -- should to fail select (10,20)::typ2 into v; -- should be ok select ((10,20)::typ2).* into v; -- should to fail execute 'select (10,20)::typ2' into v; -- should be ok execute 'select ((10,20)::typ2).*' into v; end; $$ language plpgsql; CREATE FUNCTION postgres=# select * from plpgsql_check_function('broken_into', fatal_errors => false); ┌────────────────────────────────────────────────────────────────────────────────────────────────────────────┐ │ plpgsql_check_function │ ╞════════════════════════════════════════════════════════════════════════════════════════════════════════════╡ │ error:42804:5:SQL statement:cannot cast composite value of "typ2" type to a scalar value of "integer" type │ │ warning:00000:5:SQL statement:too few attributes for composite variable │ │ error:42804:9:EXECUTE:cannot cast composite value of "typ2" type to a scalar value of "integer" type │ │ warning:00000:9:EXECUTE:too few attributes for composite variable │ │ warning extra:00000:2:DECLARE:never read variable "v" │ └────────────────────────────────────────────────────────────────────────────────────────────────────────────┘ (5 rows)
Regards
Pavel
In the meantime, it does seem like the docs could be more explicit about this, and perhaps give an example showing the (x).* solution.