Fix #7832 - Crash on "... RETURNING *" without INTO in PSQL.

Author: asfernandes

src/dsql/StmtNodes.cpp

@@ -10971,7 +10971,7 @@ static ReturningClause* dsqlProcessReturning(DsqlCompilerScratch* dsqlScratch, d
 
 	auto inputFirst = input->first;
 
-	if (!inputFirst)
+	if (inputFirst->items.isEmpty())
 	{
 		// Process RETURNING *
 		inputFirst = FB_NEW_POOL(pool) ValueListNode(pool, 0u);

src/dsql/parse.y

@@ -6042,7 +6042,7 @@ query_spec
 			rse->dsqlFirst = $2 ? $2->items[1] : NULL;
 			rse->dsqlSkip = $2 ? $2->items[0] : NULL;
 			rse->dsqlDistinct = $3;
-			rse->dsqlSelectList = $4;
+			rse->dsqlSelectList = $4->items.hasData() ? $4 : nullptr;
 			rse->dsqlFrom = $5;
 			rse->dsqlWhere = $6;
 			rse->dsqlGroup = $7;
@@ -6077,14 +6077,14 @@ skip_clause
 
 %type <valueListNode> distinct_clause
 distinct_clause
-	: DISTINCT		{ $$ = newNode<ValueListNode>(0); }
+	: DISTINCT		{ $$ = newNode<ValueListNode>(0u); }
 	| all_noise		{ $$ = NULL; }
 	;
 
 %type <valueListNode> select_list
 select_list
 	: select_items	{ $$ = $1; }
-	| '*'			{ $$ = NULL; }
+	| '*'			{ $$ = newNode<ValueListNode>(0u); }
 	;
 
 %type <valueListNode> select_items