fix clippy warnings (apache#367)

Author: jimexist

src/ast/mod.rs

@@ -433,15 +433,14 @@ impl fmt::Display for WindowSpec {
             write!(f, "ORDER BY {}", display_comma_separated(&self.order_by))?;
         }
         if let Some(window_frame) = &self.window_frame {
+            f.write_str(delim)?;
             if let Some(end_bound) = &window_frame.end_bound {
-                f.write_str(delim)?;
                 write!(
                     f,
                     "{} BETWEEN {} AND {}",
                     window_frame.units, window_frame.start_bound, end_bound
                 )?;
             } else {
-                f.write_str(delim)?;
                 write!(f, "{} {}", window_frame.units, window_frame.start_bound)?;
             }
         }

src/parser.rs

@@ -2772,6 +2772,7 @@ impl<'a> Parser<'a> {
             // followed by some joins or (B) another level of nesting.
             let mut table_and_joins = self.parse_table_and_joins()?;
 
+            #[allow(clippy::if_same_then_else)]
             if !table_and_joins.joins.is_empty() {
                 self.expect_token(&Token::RParen)?;
                 Ok(TableFactor::NestedJoin(Box::new(table_and_joins))) // (A)