functions.retrieve with args: [] returns the wrong overload for zero-argument functions

[hsusul]

Describe the bug

PostgresMeta.functions.retrieve({ schema, name, args: [] }) is supposed to select the zero-argument overload of a function. When the name is overloaded, the empty args array currently skips the proargtypes filter, so the query returns an arbitrary overload (data[0]).

functions.create() calls retrieve() after creating the function, so creating a zero-argument overload of an existing name can also return the wrong function.

To Reproduce

Using the fixtures in test/db/00-init.sql:

create or replace function public.polymorphic_function_with_no_params_or_unnamed() returns int language sql as 'SELECT 1';
create or replace function public.polymorphic_function_with_no_params_or_unnamed(bool) returns int language sql as 'SELECT 2';
create or replace function public.polymorphic_function_with_no_params_or_unnamed(text) returns text language sql as $$ SELECT 'foo' $$;

await pgMeta.functions.retrieve({
  schema: 'public',
  name: 'polymorphic_function_with_no_params_or_unnamed',
  args: [],
})

Expected behavior

The zero-argument overload is returned (argument_types === '', return_type === 'integer').

If no zero-argument overload exists, retrieve should return the existing "cannot find function" error.

Actual behavior

A different overload is returned. On the test fixtures this is the text overload (argument_types === 'text').

Root cause

In FUNCTIONS_SQL, an empty args array takes the args.length > 0 false branch and emits no p.proargtypes predicate. The inner "''" comparison for the empty-oidvector case is therefore dead code. retrieve() always passes args (default []), so name-based lookup never filters zero-argument functions.

Additional context

Existing tests only cover args: [] for a uniquely named zero-argument function (function_returning_set_of_rows), which hides the bug.

• Library: @supabase/postgres-meta
• Branch analyzed: master (641831e)