Allow CREATE TABLE (LIKE ...) from composite type

The only reason this didn't work before was that parserOpenTable()
rejects composite types.  So use relation_openrv() directly and
manually do the errposition() setup that parserOpenTable() does.

doc/src/sgml/ref/create_table.sgml

@@ -370,7 +370,7 @@ CREATE [ [ GLOBAL | LOCAL ] { TEMPORARY | TEMP } | UNLOGGED ] TABLE [ IF NOT EXI
      </para>
      <para>
       The <literal>LIKE</literal> clause can also be used to copy columns from
-      views or foreign tables.  Inapplicable options (e.g., <literal>INCLUDING
+      views, foreign tables, or composite types.  Inapplicable options (e.g., <literal>INCLUDING
       INDEXES</literal> from a view) are ignored.
      </para>
     </listitem>

src/backend/parser/parse_utilcmd.c

@@ -636,26 +636,42 @@ transformTableLikeClause(CreateStmtContext *cxt, TableLikeClause *table_like_cla
 	TupleConstr *constr;
 	AclResult	aclresult;
 	char	   *comment;
+	ParseCallbackState pcbstate;
 
-	relation = parserOpenTable(cxt->pstate, table_like_clause->relation,
-							   AccessShareLock);
+	setup_parser_errposition_callback(&pcbstate, cxt->pstate, table_like_clause->relation->location);
+
+	relation = relation_openrv(table_like_clause->relation, AccessShareLock);
 
 	if (relation->rd_rel->relkind != RELKIND_RELATION
 		&& relation->rd_rel->relkind != RELKIND_VIEW
-		&& relation->rd_rel->relkind != RELKIND_FOREIGN_TABLE)
+		&& relation->rd_rel->relkind != RELKIND_FOREIGN_TABLE
+		&& relation->rd_rel->relkind != RELKIND_COMPOSITE_TYPE)
 		ereport(ERROR,
 				(errcode(ERRCODE_WRONG_OBJECT_TYPE),
-				 errmsg("LIKE source relation \"%s\" is not a table, view, or foreign table",
+				 errmsg("\"%s\" is not a table, view, composite type, or foreign table",
 						table_like_clause->relation->relname)));
 
+	cancel_parser_errposition_callback(&pcbstate);
+
 	/*
-	 * Check for SELECT privileges
+	 * Check for privileges
 	 */
-	aclresult = pg_class_aclcheck(RelationGetRelid(relation), GetUserId(),
+	if (relation->rd_rel->relkind == RELKIND_COMPOSITE_TYPE)
+	{
+		aclresult = pg_type_aclcheck(relation->rd_rel->reltype, GetUserId(),
+									 ACL_USAGE);
+		if (aclresult != ACLCHECK_OK)
+			aclcheck_error(aclresult, ACL_KIND_TYPE,
+						   RelationGetRelationName(relation));
+	}
+	else
+	{
+		aclresult = pg_class_aclcheck(RelationGetRelid(relation), GetUserId(),
 								  ACL_SELECT);
-	if (aclresult != ACLCHECK_OK)
-		aclcheck_error(aclresult, ACL_KIND_CLASS,
-					   RelationGetRelationName(relation));
+		if (aclresult != ACLCHECK_OK)
+			aclcheck_error(aclresult, ACL_KIND_CLASS,
+						   RelationGetRelationName(relation));
+	}
 
 	tupleDesc = RelationGetDescr(relation);
 	constr = tupleDesc->constr;

src/test/regress/expected/create_table_like.out

@@ -8,6 +8,10 @@ CREATE TABLE inhx (xx text DEFAULT 'text');
  */
 CREATE TABLE ctla (aa TEXT);
 CREATE TABLE ctlb (bb TEXT) INHERITS (ctla);
+CREATE TABLE foo (LIKE nonexistent);
+ERROR:  relation "nonexistent" does not exist
+LINE 1: CREATE TABLE foo (LIKE nonexistent);
+                               ^
 CREATE TABLE inhe (ee text, LIKE inhx) inherits (ctlb);
 INSERT INTO inhe VALUES ('ee-col1', 'ee-col2', DEFAULT, 'ee-col4');
 SELECT * FROM inhe; /* Columns aa, bb, xx value NULL, ee */
@@ -224,18 +228,16 @@ NOTICE:  drop cascades to table inhe
 CREATE TABLE ctlt4 (a int, b text);
 CREATE SEQUENCE ctlseq1;
 CREATE TABLE ctlt10 (LIKE ctlseq1);  -- fail
-ERROR:  LIKE source relation "ctlseq1" is not a table, view, or foreign table
+ERROR:  "ctlseq1" is not a table, view, composite type, or foreign table
+LINE 1: CREATE TABLE ctlt10 (LIKE ctlseq1);
+                                  ^
 CREATE VIEW ctlv1 AS SELECT * FROM ctlt4;
 CREATE TABLE ctlt11 (LIKE ctlv1);
 CREATE TABLE ctlt11a (LIKE ctlv1 INCLUDING ALL);
 CREATE TYPE ctlty1 AS (a int, b text);
-CREATE TABLE ctlt12 (LIKE ctlty1);  -- currently fails
-ERROR:  "ctlty1" is a composite type
-LINE 1: CREATE TABLE ctlt12 (LIKE ctlty1);
-                                  ^
+CREATE TABLE ctlt12 (LIKE ctlty1);
 DROP SEQUENCE ctlseq1;
 DROP TYPE ctlty1;
 DROP VIEW ctlv1;
 DROP TABLE IF EXISTS ctlt4, ctlt10, ctlt11, ctlt11a, ctlt12;
 NOTICE:  table "ctlt10" does not exist, skipping
-NOTICE:  table "ctlt12" does not exist, skipping

src/test/regress/sql/create_table_like.sql

@@ -10,6 +10,8 @@ CREATE TABLE inhx (xx text DEFAULT 'text');
 CREATE TABLE ctla (aa TEXT);
 CREATE TABLE ctlb (bb TEXT) INHERITS (ctla);
 
+CREATE TABLE foo (LIKE nonexistent);
+
 CREATE TABLE inhe (ee text, LIKE inhx) inherits (ctlb);
 INSERT INTO inhe VALUES ('ee-col1', 'ee-col2', DEFAULT, 'ee-col4');
 SELECT * FROM inhe; /* Columns aa, bb, xx value NULL, ee */
@@ -111,7 +113,7 @@ CREATE TABLE ctlt11 (LIKE ctlv1);
 CREATE TABLE ctlt11a (LIKE ctlv1 INCLUDING ALL);
 
 CREATE TYPE ctlty1 AS (a int, b text);
-CREATE TABLE ctlt12 (LIKE ctlty1);  -- currently fails
+CREATE TABLE ctlt12 (LIKE ctlty1);
 
 DROP SEQUENCE ctlseq1;
 DROP TYPE ctlty1;