Promote row expressions to full-fledged citizens of the expression syntax,

rather than allowing them only in a few special cases as before.  In
particular you can now pass a ROW() construct to a function that accepts
a rowtype parameter.  Internal generation of RowExprs fixes a number of
corner cases that used to not work very well, such as referencing the
whole-row result of a JOIN or subquery.  This represents a further step in
the work I started a month or so back to make rowtype values into
first-class citizens.

src/test/regress/input/misc.source

@@ -218,6 +218,17 @@ SELECT hobbies_by_name('basketball');
 
 SELECT name, overpaid(emp.*) FROM emp;
 
+--
+-- Try a few cases with SQL-spec row constructor expressions
+--
+SELECT * FROM equipment(ROW('skywalking', 'mer'));
+
+SELECT name(equipment(ROW('skywalking', 'mer')));
+
+SELECT *, name(equipment(h.*)) FROM hobbies_r h;
+
+SELECT *, (equipment(CAST((h.*) AS hobbies_r))).name FROM hobbies_r h;
+
 --
 -- check that old-style C functions work properly with TOASTed values
 --

src/test/regress/output/constraints.source

@@ -45,9 +45,9 @@ SELECT '' AS four, * FROM DEFAULTEXPR_TBL;
 -- syntax errors
 --  test for extraneous comma
 CREATE TABLE error_tbl (i int DEFAULT (100, ));
-ERROR:  syntax error at or near "," at character 43
+ERROR:  syntax error at or near ")" at character 45
 LINE 1: CREATE TABLE error_tbl (i int DEFAULT (100, ));
-                                                  ^
+                                                    ^
 --  this will fail because gram.y uses b_expr not a_expr for defaults,
 --  to avoid a shift/reduce conflict that arises from NOT NULL being
 --  part of the column definition syntax:

src/test/regress/output/misc.source

@@ -686,6 +686,45 @@ SELECT name, overpaid(emp.*) FROM emp;
  linda  | f
 (6 rows)
 
+--
+-- Try a few cases with SQL-spec row constructor expressions
+--
+SELECT * FROM equipment(ROW('skywalking', 'mer'));
+ name |   hobby    
+------+------------
+ guts | skywalking
+(1 row)
+
+SELECT name(equipment(ROW('skywalking', 'mer')));
+ name 
+------
+ guts
+(1 row)
+
+SELECT *, name(equipment(h.*)) FROM hobbies_r h;
+    name     | person |     name      
+-------------+--------+---------------
+ posthacking | mike   | advil
+ posthacking | mike   | peet's coffee
+ posthacking | jeff   | advil
+ posthacking | jeff   | peet's coffee
+ basketball  | joe    | hightops
+ basketball  | sally  | hightops
+ skywalking  |        | guts
+(7 rows)
+
+SELECT *, (equipment(CAST((h.*) AS hobbies_r))).name FROM hobbies_r h;
+    name     | person |     name      
+-------------+--------+---------------
+ posthacking | mike   | advil
+ posthacking | mike   | peet's coffee
+ posthacking | jeff   | advil
+ posthacking | jeff   | peet's coffee
+ basketball  | joe    | hightops
+ basketball  | sally  | hightops
+ skywalking  |        | guts
+(7 rows)
+
 --
 -- check that old-style C functions work properly with TOASTed values
 --