Track nesting depth correctly when drilling down into RECORD Vars.

expandRecordVariable() failed to adjust the parse nesting structure
correctly when recursing to inspect an outer-level Var.  This could
result in assertion failures or core dumps in corner cases.

Likewise, get_name_for_var_field() failed to adjust the deparse
namespace stack correctly when recursing to inspect an outer-level
Var.  In this case the likely result was a "bogus varno" error
while deparsing a view.

Per bug #18077 from Jingzhou Fu.  Back-patch to all supported
branches.

Richard Guo, with some adjustments by me

Discussion: https://postgr.es/m/18077-b9db97c6e0ab45d8@postgresql.org

src/test/regress/expected/rowtypes.out

@@ -1209,6 +1209,66 @@ select r, r is null as isnull, r is not null as isnotnull from r;
  (,)         | t      | f
 (6 rows)
 
+--
+-- Check parsing of indirect references to composite values (bug #18077)
+--
+explain (verbose, costs off)
+with cte(c) as materialized (select row(1, 2)),
+     cte2(c) as (select * from cte)
+select * from cte2 as t
+where (select * from (select c as c1) s
+       where (select (c1).f1 > 0)) is not null;
+                 QUERY PLAN                 
+--------------------------------------------
+ CTE Scan on cte
+   Output: cte.c
+   Filter: ((SubPlan 3) IS NOT NULL)
+   CTE cte
+     ->  Result
+           Output: '(1,2)'::record
+   SubPlan 3
+     ->  Result
+           Output: cte.c
+           One-Time Filter: $2
+           InitPlan 2 (returns $2)
+             ->  Result
+                   Output: ((cte.c).f1 > 0)
+(13 rows)
+
+with cte(c) as materialized (select row(1, 2)),
+     cte2(c) as (select * from cte)
+select * from cte2 as t
+where (select * from (select c as c1) s
+       where (select (c1).f1 > 0)) is not null;
+   c   
+-------
+ (1,2)
+(1 row)
+
+-- Also check deparsing of such cases
+create view composite_v as
+with cte(c) as materialized (select row(1, 2)),
+     cte2(c) as (select * from cte)
+select 1 as one from cte2 as t
+where (select * from (select c as c1) s
+       where (select (c1).f1 > 0)) is not null;
+select pg_get_viewdef('composite_v', true);
+                     pg_get_viewdef                     
+--------------------------------------------------------
+  WITH cte(c) AS MATERIALIZED (                        +
+          SELECT ROW(1, 2) AS "row"                    +
+         ), cte2(c) AS (                               +
+          SELECT cte.c                                 +
+            FROM cte                                   +
+         )                                             +
+  SELECT 1 AS one                                      +
+    FROM cte2 t                                        +
+   WHERE (( SELECT s.c1                                +
+            FROM ( SELECT t.c AS c1) s                 +
+           WHERE ( SELECT (s.c1).f1 > 0))) IS NOT NULL;
+(1 row)
+
+drop view composite_v;
 --
 -- Tests for component access / FieldSelect
 --

src/test/regress/sql/rowtypes.sql

@@ -487,6 +487,31 @@ with r(a,b) as materialized
           (null,row(1,2)), (null,row(null,null)), (null,null) )
 select r, r is null as isnull, r is not null as isnotnull from r;
 
+--
+-- Check parsing of indirect references to composite values (bug #18077)
+--
+explain (verbose, costs off)
+with cte(c) as materialized (select row(1, 2)),
+     cte2(c) as (select * from cte)
+select * from cte2 as t
+where (select * from (select c as c1) s
+       where (select (c1).f1 > 0)) is not null;
+
+with cte(c) as materialized (select row(1, 2)),
+     cte2(c) as (select * from cte)
+select * from cte2 as t
+where (select * from (select c as c1) s
+       where (select (c1).f1 > 0)) is not null;
+
+-- Also check deparsing of such cases
+create view composite_v as
+with cte(c) as materialized (select row(1, 2)),
+     cte2(c) as (select * from cte)
+select 1 as one from cte2 as t
+where (select * from (select c as c1) s
+       where (select (c1).f1 > 0)) is not null;
+select pg_get_viewdef('composite_v', true);
+drop view composite_v;
 
 --
 -- Tests for component access / FieldSelect