[psteinroe]

Stacked on #894.

Follow-up to #864 for the comparison case, plus a nested-subquery case from #857.

= (subquery) stays together

#864 kept exists (, in (, = any ( and > all ( on one line, but a scalar subquery compared with an operator still broke between the operator and (. With the config reported in #857 (layout: expanded, clauseBodyStyle: compact, logicalOperatorPlacement: leading):

-- before
using (
  org_id =
  (
    select org_id
    ...
-- after
using (
  org_id = (
    select org_id
    from members
    where user_id = auth.uid()
  )
);

The default config did the same, t.owner_id = followed by (select …) on its own line. A binary operator now puts a plain space before a right-hand (subquery) or array(subquery), and the subquery breaks inside its parentheses as it does after in (. Other right-hand operands still break after the operator when they don't fit.

Subqueries with clauses expand inside a select-list-only subquery

Since #857, a subquery made of a select list alone, such as (select auth.uid()), uses fit layout in expanded mode, because there are no clauses to break between. That fit layout applied to everything inside it, so a subquery with FROM/WHERE nested in it stayed on one line in expanded mode:

-- layout: expanded, clauseBodyStyle: compact
select * from t where a = (select coalesce((select max(x) from y where y.id = t.id), 0));

The emitter now remembers the configured layout, and a nested subquery with clauses switches back to it, so the inner select max(x) / from y / where ... expands again.

Snapshot changes

All reviewed; one category: x =\n( / x <>\n( / x <\n( / <>\narray( → x = (, x <> (, x < (, <> array(. When the subquery is short enough to fit on the next line, it now sits indented inside the parentheses instead (relnamespace = (\n select oid from pg_namespace where ...\n)). Affected: create_cast, create_index, create_view, namespace, opr_sanity, rangefuncs, reloptions, tablespace, type_sanity, with.

New fixtures scalar_subquery.sql and scalar_subquery_expanded.sql (the #857 reporter's config) cover a policy, = with a multi-clause subquery, = array(subquery), the nested-coalesce case and a short = (select 1). New subquery_layout.rs tests cover both findings.

Not covered

With clauseBodyStyle: compact, a WHERE condition keeps its indent for its own continuation lines, so a subquery that opens on the where line is indented two levels and closes one level in:

where a = (
    select ...
  );

That is the same for where exists ( today and is a separate change to the compact layout.

Follow-ups: The compact WHERE indentation is fixed in #938.