fix: allow ROWNUM/ROWID as PL/iSQL variable names

In PL/iSQL's pre-columnref hook, check if ROWNUM or ROWID identifiers
resolve to declared variables. This prevents the SQL parser from
converting them to pseudocolumn references, matching Oracle behavior
where these can be used as variable/parameter names in PL/SQL.

The fix adds special handling in plisql_pre_column_ref() to check
ROWNUM/ROWID names even when resolve_option is not PLISQL_RESOLVE_VARIABLE,
since the SQL parser would otherwise intercept them first.

Author: rophy

src/oracle_test/regress/expected/ora_plisql.out

@@ -1830,12 +1830,8 @@ drop function ff_test;
 -- Oracle allows ROWNUM as parameter/variable name in PL/SQL.
 -- https://github.com/IvorySQL/IvorySQL/pull/1000#issuecomment-3717690863
 --
--- Current IvorySQL behavior: Fails because ROWNUM is treated as keyword
--- TODO: These should work to match Oracle behavior
---
 -- Test 1: Function with 'rownum' as parameter name
 -- Oracle: Creates successfully
--- IvorySQL: Currently fails with syntax error
 CREATE OR REPLACE FUNCTION test_rownum_param(rownum IN VARCHAR2) RETURN INTEGER IS
 BEGIN
     RAISE NOTICE 'Parameter value: %', rownum;
@@ -1844,7 +1840,6 @@ END;
 /
 -- Test 2: Call the function with variable named 'rownum'
 -- Oracle: Runs successfully
--- IvorySQL: Currently fails
 DECLARE
     rownum VARCHAR2(256) := 'hello';
     ret INTEGER;
@@ -1853,19 +1848,18 @@ BEGIN
     RAISE NOTICE 'Return value: %', ret;
 END;
 /
-NOTICE:  Parameter value: 1
+NOTICE:  Parameter value: hello
 NOTICE:  Return value: 23
 -- Test 3: Named parameter call using 'rownum =>'
 -- Oracle: Runs successfully
--- IvorySQL: Currently fails
 DECLARE
     ret INTEGER;
 BEGIN
     ret := test_rownum_param(rownum => 'world');
     RAISE NOTICE 'Named param return: %', ret;
 END;
 /
-NOTICE:  Parameter value: 1
+NOTICE:  Parameter value: world
 NOTICE:  Named param return: 23
 -- Cleanup (may fail if function wasn't created)
 DROP FUNCTION IF EXISTS test_rownum_param;

src/oracle_test/regress/sql/ora_plisql.sql

@@ -1462,13 +1462,9 @@ drop function ff_test;
 -- Oracle allows ROWNUM as parameter/variable name in PL/SQL.
 -- https://github.com/IvorySQL/IvorySQL/pull/1000#issuecomment-3717690863
 --
--- Current IvorySQL behavior: Fails because ROWNUM is treated as keyword
--- TODO: These should work to match Oracle behavior
---
 
 -- Test 1: Function with 'rownum' as parameter name
 -- Oracle: Creates successfully
--- IvorySQL: Currently fails with syntax error
 CREATE OR REPLACE FUNCTION test_rownum_param(rownum IN VARCHAR2) RETURN INTEGER IS
 BEGIN
     RAISE NOTICE 'Parameter value: %', rownum;
@@ -1478,7 +1474,6 @@ END;
 
 -- Test 2: Call the function with variable named 'rownum'
 -- Oracle: Runs successfully
--- IvorySQL: Currently fails
 DECLARE
     rownum VARCHAR2(256) := 'hello';
     ret INTEGER;
@@ -1490,7 +1485,6 @@ END;
 
 -- Test 3: Named parameter call using 'rownum =>'
 -- Oracle: Runs successfully
--- IvorySQL: Currently fails
 DECLARE
     ret INTEGER;
 BEGIN

src/pl/plisql/src/pl_comp.c

@@ -34,6 +34,7 @@
 #include "utils/fmgroids.h"
 #include "utils/guc.h"
 #include "utils/lsyscache.h"
+#include "utils/ora_compatible.h"
 #include "utils/memutils.h"
 #include "utils/regproc.h"
 #include "utils/syscache.h"
@@ -1610,8 +1611,34 @@ plisql_pre_column_ref(ParseState *pstate, ColumnRef *cref)
 
 	if (expr->func->resolve_option == PLISQL_RESOLVE_VARIABLE)
 		return resolve_column_ref(pstate, expr, cref, false);
-	else
-		return NULL;
+
+	/*
+	 * Even when resolve_option is not PLISQL_RESOLVE_VARIABLE, we need to
+	 * check if the identifier is ROWNUM or ROWID and exists as a PL/iSQL
+	 * variable. This is necessary because the SQL parser would otherwise
+	 * convert these to pseudocolumn references before the post-columnref
+	 * hook has a chance to resolve them as variables.
+	 *
+	 * This matches Oracle behavior where ROWNUM/ROWID can be used as
+	 * variable names in PL/SQL.
+	 */
+	if (compatible_db == ORA_PARSER && list_length(cref->fields) == 1)
+	{
+		Node	   *field1 = (Node *) linitial(cref->fields);
+		const char *name1 = strVal(field1);
+
+		if (pg_strcasecmp(name1, "rownum") == 0 ||
+			pg_strcasecmp(name1, "rowid") == 0)
+		{
+			Node	   *result;
+
+			result = resolve_column_ref(pstate, expr, cref, false);
+			if (result != NULL)
+				return result;
+		}
+	}
+
+	return NULL;
 }
 
 /*