[plsql] DEFAULT for Argument - fixups from #5088

pmd-plsql/etc/grammar/PLSQL.jjt

@@ -3872,10 +3872,13 @@ ASTArgument Argument() :
 {
 	//[LOOKAHEAD(2) UnqualifiedID() "=>"] Expression()
 	[LOOKAHEAD(2) (simpleNode = UnqualifiedID())  ("=>" | <AS> )  ]
-        (Expression() [ <_DEFAULT> Expression() <ON> <CONVERSION> "ERROR" ] )
+        Expression()
+        // e.g. TO_NUMBER allows a DEFAULT clause within an argument
+        // https://docs.oracle.com/en/database/oracle/oracle-database/23/sqlrf/TO_NUMBER.html#GUID-D4807212-AFD7-48A7-9AED-BEC3E8809866
+        [ <_DEFAULT> Expression() <ON> KEYWORD("CONVERSION") "ERROR" ]
 	//Allow Using CharacterSet suffix clause
 	[
-	   ( <USING>  )
+	   <USING>
 	   ( <CHAR_CS> | <NCHAR_CS>  )
 	]
  {
@@ -5022,7 +5025,6 @@ TOKEN [IGNORE_CASE]:
 <CONSTRAINT: "CONSTRAINT"> |
 <CONSTRUCTOR: "CONSTRUCTOR"> |
 <CONTINUE: "CONTINUE"> |
-<CONVERSION: "CONVERSION"> |
 <CONVERT: "CONVERT"> |
 <CROSS: "CROSS"> |
 <CUBE: "CUBE"> |

pmd-plsql/src/test/java/net/sourceforge/pmd/lang/plsql/ast/PlsqlTreeDumpTest.java

@@ -66,4 +66,9 @@ class PlsqlTreeDumpTest extends BaseTreeDumpTest {
     void sqlMacroClause() {
         doTest("SqlMacroClause");
     }
+
+    @Test
+    void parseSelectExpression() {
+        doTest("SelectExpressions");
+    }
 }

pmd-plsql/src/test/java/net/sourceforge/pmd/lang/plsql/ast/SelectExpressionsTest.java

@@ -15,11 +15,6 @@ import net.sourceforge.pmd.lang.plsql.AbstractPLSQLParserTst;
 
 class SelectExpressionsTest extends AbstractPLSQLParserTst {
 
-    @Test
-    void parseSelectExpression() {
-        plsql.parseResource("SelectExpressions.pls");
-    }
-
     @Test
     void parseSelectSimpleExpression() {
         ASTInput input = plsql.parseResource("SelectSimpleExpression.pls");