Avoid an unnecessary clone in `macro_parser::parse`.

This avoids ~800,000 allocations in html5ever.

diff --git a/src/libsyntax/ext/tt/macro_parser.rs b/src/libsyntax/ext/tt/macro_parser.rs
index ef2e466a04398ae6f47751738f7d9a5b97940394..a664e115ce4b45a254a38c4bcd06cf0d68becad1 100644 (file)
--- a/src/libsyntax/ext/tt/macro_parser.rs
+++ b/src/libsyntax/ext/tt/macro_parser.rs
@@ -425,8 +425,8 @@ pub fn parse(sess: &ParseSess,
                         cur_eis.push(ei);
                     }
                     TokenTree::Token(_, ref t) => {
-                        let mut ei_t = ei.clone();
                         if token_name_eq(t,&tok) {
+                            let mut ei_t = ei.clone();
                             ei_t.idx += 1;
                             next_eis.push(ei_t);
                         }