sql: use correct FuncExpr when encoding sequences

Previously, when encoding sequences by swapping sequence
names for IDs, we were always wrapping the sequence in
a nextval func. This is incorrect, and instead
we should wrap the sequence in whatever function
it came in before this encoding. This patch makes
this change.

Release justification: bug fix for new functionality
Release note (bug fix): use correct FuncExpr when encoding sequences.

pkg/sql/logictest/testdata/logic_test/sequences_regclass

@@ -29,7 +29,10 @@ statement ok
 ALTER TABLE foo ADD COLUMN l INT NOT NULL
 
 statement ok
-ALTER TABLE FOO ALTER COLUMN l SET DEFAULT nextval('test_seq2')
+ALTER TABLE FOO ALTER COLUMN l SET DEFAULT currval('test_seq2')
+
+statement ok
+SELECT nextval('test_seq2')
 
 query TT
 SHOW CREATE TABLE foo
@@ -38,7 +41,7 @@ foo  CREATE TABLE public.foo (
      i INT8 NOT NULL DEFAULT nextval('test.public.foo_i_seq':::STRING::REGCLASS),
      j INT8 NOT NULL DEFAULT nextval('test.public.test_seq':::STRING::REGCLASS),
      k INT8 NOT NULL DEFAULT nextval('test.public.foo_k_seq':::STRING::REGCLASS),
-     l INT8 NOT NULL DEFAULT nextval('test.public.test_seq2':::STRING::REGCLASS),
+     l INT8 NOT NULL DEFAULT currval('test.public.test_seq2':::STRING::REGCLASS),
      CONSTRAINT "primary" PRIMARY KEY (i ASC),
      FAMILY "primary" (i, j, k, l)
 )
@@ -103,10 +106,13 @@ CREATE SEQUENCE s2
 statement ok
 CREATE TABLE bar (
   i SERIAL PRIMARY KEY,
-  j INT NOT NULL DEFAULT nextval($s1_id::regclass),
+  j INT NOT NULL DEFAULT currval($s1_id::regclass),
   k INT NOT NULL DEFAULT nextval('s2'),
   FAMILY (i, j, k))
 
+statement ok
+SELECT nextval($s1_id::regclass)
+
 statement ok
 INSERT INTO bar VALUES (default, default, default)
 
@@ -125,7 +131,7 @@ SHOW CREATE TABLE bar
 ----
 bar  CREATE TABLE public.bar (
      i INT8 NOT NULL DEFAULT nextval('test.public.new_bar_i_seq':::STRING::REGCLASS),
-     j INT8 NOT NULL DEFAULT nextval('test.public.new_s1':::STRING::REGCLASS),
+     j INT8 NOT NULL DEFAULT currval('test.public.new_s1':::STRING::REGCLASS),
      k INT8 NOT NULL DEFAULT nextval('test.public.new_s2':::STRING::REGCLASS),
      CONSTRAINT "primary" PRIMARY KEY (i ASC),
      FAMILY fam_0_i_j_k (i, j, k)
@@ -139,7 +145,7 @@ query III
 SELECT i, j, k FROM bar ORDER BY i, j, k
 ----
 1  1  1
-2  2  2
+2  1  2
 
 
 # Test that databases with sequences can be renamed, even if they are
@@ -164,9 +170,12 @@ CREATE SEQUENCE other_db.s2
 statement ok
 CREATE TABLE other_db.t (
   i INT NOT NULL DEFAULT nextval($s_id::regclass),
-  j INT NOT NULL DEFAULT nextval('other_db.public.s2'),
+  j INT NOT NULL DEFAULT currval('other_db.public.s2'),
   FAMILY (i, j))
 
+statement ok
+SELECT nextval('other_db.public.s2')
+
 statement ok
 INSERT INTO other_db.t VALUES (default, default)
 
@@ -179,7 +188,7 @@ SHOW CREATE TABLE new_other_db.t
 ----
 new_other_db.public.t  CREATE TABLE public.t (
                        i INT8 NOT NULL DEFAULT nextval('new_other_db.public.s':::STRING::REGCLASS),
-                       j INT8 NOT NULL DEFAULT nextval('new_other_db.public.s2':::STRING::REGCLASS),
+                       j INT8 NOT NULL DEFAULT currval('new_other_db.public.s2':::STRING::REGCLASS),
                        rowid INT8 NOT VISIBLE NOT NULL DEFAULT unique_rowid(),
                        CONSTRAINT "primary" PRIMARY KEY (rowid ASC),
                        FAMILY fam_0_i_j_rowid (i, j, rowid)
@@ -193,7 +202,7 @@ query II
 SELECT i, j FROM new_other_db.t ORDER BY i, j
 ----
 1  1
-2  2
+2  1
 
 
 # Test that sequences can change schemas even if they're referenced
@@ -219,9 +228,12 @@ statement ok
 CREATE TABLE tb (
   i SERIAL PRIMARY KEY,
   j INT NOT NULL DEFAULT nextval($sc_s1_id::regclass),
-  k INT NOT NULL DEFAULT nextval('test.public.sc_s2'),
+  k INT NOT NULL DEFAULT currval('test.public.sc_s2'),
   FAMILY (i, j, k))
 
+statement ok
+SELECT nextval('test.public.sc_s2')
+
 statement ok
 INSERT INTO tb VALUES (default, default, default)
 
@@ -241,7 +253,7 @@ SHOW CREATE TABLE tb
 tb  CREATE TABLE public.tb (
     i INT8 NOT NULL DEFAULT nextval('test.test_schema.tb_i_seq':::STRING::REGCLASS),
     j INT8 NOT NULL DEFAULT nextval('test.test_schema.sc_s1':::STRING::REGCLASS),
-    k INT8 NOT NULL DEFAULT nextval('test.test_schema.sc_s2':::STRING::REGCLASS),
+    k INT8 NOT NULL DEFAULT currval('test.test_schema.sc_s2':::STRING::REGCLASS),
     CONSTRAINT "primary" PRIMARY KEY (i ASC),
     FAMILY fam_0_i_j_k (i, j, k)
 )
@@ -254,7 +266,7 @@ query III
 SELECT i, j, k FROM tb ORDER BY i, j, k
 ----
 1  1  1
-2  2  2
+2  2  1
 
 
 # Test that sequences can have their schemas renamed even if
@@ -277,9 +289,12 @@ statement ok
 CREATE TABLE foo (
   i SERIAL PRIMARY KEY,
   j INT NOT NULL DEFAULT nextval($s3_id::regclass),
-  k INT NOT NULL DEFAULT nextval('test.test_schema.s4'),
+  k INT NOT NULL DEFAULT currval('test.test_schema.s4'),
   FAMILY (i, j, k))
 
+statement ok
+SELECT nextval('test.test_schema.s4')
+
 statement ok
 INSERT INTO foo VALUES (default, default, default)
 
@@ -293,7 +308,7 @@ SHOW CREATE TABLE new_test_schema.foo
 new_test_schema.foo  CREATE TABLE new_test_schema.foo (
                      i INT8 NOT NULL DEFAULT nextval('test.new_test_schema.foo_i_seq':::STRING::REGCLASS),
                      j INT8 NOT NULL DEFAULT nextval('test.new_test_schema.s3':::STRING::REGCLASS),
-                     k INT8 NOT NULL DEFAULT nextval('test.new_test_schema.s4':::STRING::REGCLASS),
+                     k INT8 NOT NULL DEFAULT currval('test.new_test_schema.s4':::STRING::REGCLASS),
                      CONSTRAINT "primary" PRIMARY KEY (i ASC),
                      FAMILY fam_0_i_j_k (i, j, k)
 )
@@ -306,7 +321,7 @@ query III
 SELECT i, j, k FROM new_test_schema.foo ORDER BY i, j, k
 ----
 1  1  1
-2  2  2
+2  2  1
 
 statement ok
 SET SCHEMA public

pkg/util/sequence/sequence.go

@@ -143,7 +143,7 @@ func ReplaceSequenceNamesWithIDs(
 				return true, expr, nil
 			}
 			return false, &tree.FuncExpr{
-				Func: tree.WrapFunction("nextval"),
+				Func: t.Func,
 				Exprs: tree.Exprs{
 					&tree.AnnotateTypeExpr{
 						Type:       types.RegClass,