Build whole-row Vars the same way during parsing and planning.

makeWholeRowVar() has different rules for constructing a
whole-row Var depending on the kind of RTE it's representing.
This turns out to be problematic because the rewriter and planner
can convert view RTEs and set-returning-function RTEs into
subquery RTEs; so a whole-row Var made during planning might
look different from one made by the parser.  In isolation this
doesn't cause any problem, but if a query contains Vars made
both ways for the same varno, there are cross-checks in the
executor that will complain.  This manifests for UPDATE, DELETE,
and MERGE queries that use whole-row table references.

To fix, we need makeWholeRowVar() to produce the same result
from an inlined RTE as it would have for the original.  For
an inlined view, we can use RangeTblEntry.relid to detect
that this had been a view RTE.  For inlined SRFs, make a
data structure definition change akin to commit 47bb9db75,
and say that we won't clear RangeTblEntry.functions until
the end of planning.  That allows makeWholeRowVar() to
repeat what it would have done with the unmodified RTE.

Reported-by: Duncan Sands <duncan.sands@deepbluecap.com>
Reported-by: Dean Rasheed <dean.a.rasheed@gmail.com>
Diagnosed-by: Tender Wang <tndrwang@gmail.com>
Author: Tom Lane <tgl@sss.pgh.pa.us>
Reviewed-by: Dean Rasheed <dean.a.rasheed@gmail.com>
Discussion: https://postgr.es/m/3518c50a-ab18-482f-b916-a37263622501@deepbluecap.com
Backpatch-through: 13

src/test/regress/expected/returning.out

@@ -286,6 +286,63 @@ SELECT * FROM voo;
  16 | zoo2
 (2 rows)
 
+-- Check use of a whole-row variable for an un-flattenable view
+CREATE TEMP VIEW foo_v AS SELECT * FROM foo OFFSET 0;
+UPDATE foo SET f2 = foo_v.f2 FROM foo_v WHERE foo_v.f1 = foo.f1
+  RETURNING foo_v;
+      foo_v      
+-----------------
+ (2,more,42,141)
+ (16,zoo2,57,99)
+(2 rows)
+
+SELECT * FROM foo;
+ f1 |  f2  | f3 | f4  
+----+------+----+-----
+  2 | more | 42 | 141
+ 16 | zoo2 | 57 |  99
+(2 rows)
+
+-- Check use of a whole-row variable for an inlined set-returning function
+CREATE FUNCTION foo_f() RETURNS SETOF foo AS
+  $$ SELECT * FROM foo OFFSET 0 $$ LANGUAGE sql STABLE;
+UPDATE foo SET f2 = foo_f.f2 FROM foo_f() WHERE foo_f.f1 = foo.f1
+  RETURNING foo_f;
+      foo_f      
+-----------------
+ (2,more,42,141)
+ (16,zoo2,57,99)
+(2 rows)
+
+SELECT * FROM foo;
+ f1 |  f2  | f3 | f4  
+----+------+----+-----
+  2 | more | 42 | 141
+ 16 | zoo2 | 57 |  99
+(2 rows)
+
+DROP FUNCTION foo_f();
+-- As above, but SRF is defined to return a composite type
+CREATE TYPE foo_t AS (f1 int, f2 text, f3 int, f4 int8);
+CREATE FUNCTION foo_f() RETURNS SETOF foo_t AS
+  $$ SELECT * FROM foo OFFSET 0 $$ LANGUAGE sql STABLE;
+UPDATE foo SET f2 = foo_f.f2 FROM foo_f() WHERE foo_f.f1 = foo.f1
+  RETURNING foo_f;
+      foo_f      
+-----------------
+ (2,more,42,141)
+ (16,zoo2,57,99)
+(2 rows)
+
+SELECT * FROM foo;
+ f1 |  f2  | f3 | f4  
+----+------+----+-----
+  2 | more | 42 | 141
+ 16 | zoo2 | 57 |  99
+(2 rows)
+
+DROP FUNCTION foo_f();
+DROP TYPE foo_t;
 -- Try a join case
 CREATE TEMP TABLE joinme (f2j text, other int);
 INSERT INTO joinme VALUES('more', 12345);
@@ -726,8 +783,9 @@ NOTICE:  UPDATE: (3,zoo2,58,99,54321) -> (3,zoo2,59,7,54321)
 
 -- Test wholerow & dropped column handling
 ALTER TABLE foo DROP COLUMN f3 CASCADE;
-NOTICE:  drop cascades to 3 other objects
+NOTICE:  drop cascades to 4 other objects
 DETAIL:  drop cascades to rule voo_i on view voo
+drop cascades to view foo_v
 drop cascades to view joinview
 drop cascades to rule foo_del_rule on table foo
 UPDATE foo SET f4 = f4 + 1 RETURNING old.f3;  -- should fail

src/test/regress/sql/returning.sql

@@ -132,6 +132,30 @@ DELETE FROM foo WHERE f2 = 'zit' RETURNING *;
 SELECT * FROM foo;
 SELECT * FROM voo;
 
+-- Check use of a whole-row variable for an un-flattenable view
+CREATE TEMP VIEW foo_v AS SELECT * FROM foo OFFSET 0;
+UPDATE foo SET f2 = foo_v.f2 FROM foo_v WHERE foo_v.f1 = foo.f1
+  RETURNING foo_v;
+SELECT * FROM foo;
+
+-- Check use of a whole-row variable for an inlined set-returning function
+CREATE FUNCTION foo_f() RETURNS SETOF foo AS
+  $$ SELECT * FROM foo OFFSET 0 $$ LANGUAGE sql STABLE;
+UPDATE foo SET f2 = foo_f.f2 FROM foo_f() WHERE foo_f.f1 = foo.f1
+  RETURNING foo_f;
+SELECT * FROM foo;
+DROP FUNCTION foo_f();
+
+-- As above, but SRF is defined to return a composite type
+CREATE TYPE foo_t AS (f1 int, f2 text, f3 int, f4 int8);
+CREATE FUNCTION foo_f() RETURNS SETOF foo_t AS
+  $$ SELECT * FROM foo OFFSET 0 $$ LANGUAGE sql STABLE;
+UPDATE foo SET f2 = foo_f.f2 FROM foo_f() WHERE foo_f.f1 = foo.f1
+  RETURNING foo_f;
+SELECT * FROM foo;
+DROP FUNCTION foo_f();
+DROP TYPE foo_t;
+
 -- Try a join case
 
 CREATE TEMP TABLE joinme (f2j text, other int);