Support bare RETURN without expression & add common test

Author: aharpervc

src/parser/mod.rs

@@ -15129,10 +15129,16 @@ impl<'a> Parser<'a> {
     }
     /// Parse [Statement::Return]
     fn parse_return(&mut self) -> Result<Statement, ParserError> {
-        let expr = self.parse_expr()?;
-        Ok(Statement::Return(ReturnStatement {
-            value: Some(ReturnStatementValue::Expr(expr)),
-        }))
+        let current_index = self.index;
+        match self.parse_expr() {
+            Ok(expr) => Ok(Statement::Return(ReturnStatement {
+                value: Some(ReturnStatementValue::Expr(expr)),
+            })),
+            Err(_) => {
+                self.index = current_index;
+                Ok(Statement::Return(ReturnStatement { value: None }))
+            }
+        }
     }
 
     /// Consume the parser and return its underlying token buffer

tests/sqlparser_common.rs

@@ -15029,3 +15029,8 @@ fn parse_set_time_zone_alias() {
         _ => unreachable!(),
     }
 }
+
+#[test]
+fn parse_return() {
+    all_dialects().verified_stmt("RETURN");
+}