Filter out stmts made for the redundant_semicolon lint when pretty-printing

Author: nathanwhit

src/libsyntax/print/pprust.rs

@@ -1657,9 +1657,18 @@ impl<'a> State<'a> {
                 }
             }
             ast::StmtKind::Semi(ref expr) => {
-                self.space_if_not_bol();
-                self.print_expr_outer_attr_style(expr, false);
-                self.s.word(";");
+                match expr.node {
+                    // Filter out empty `Tup` exprs created for the `redundant_semicolon`
+                    // lint, as they shouldn't be visible and interact poorly
+                    // with proc macros.
+                    ast::ExprKind::Tup(ref exprs) if exprs.is_empty()
+                      && expr.attrs.is_empty() => (),
+                    _ => {
+                        self.space_if_not_bol();
+                        self.print_expr_outer_attr_style(expr, false);
+                        self.s.word(";");
+                    }
+                }
             }
             ast::StmtKind::Mac(ref mac) => {
                 let (ref mac, style, ref attrs) = **mac;