Auto merge of #29615 - steveklabnik:lol_strings, r=alexcrichton

&format!("...") is the same as "" if we're not doing any interpolation,
and doesn't allocate an intermediate String.

1 files changed, 1 insertions, 3 deletions

diff --git a/src/libsyntax/ext/expand.rs b/src/libsyntax/ext/expand.rs
index b1b4605d5ec..512f71fd4c1 100644
--- a/src/libsyntax/ext/expand.rs
+++ b/src/libsyntax/ext/expand.rs
@@ -400,9 +400,7 @@ pub fn expand_item_mac(it: P<ast::Item>,
                 }
                 MacroRulesTT => {
                     if ident.name == parse::token::special_idents::invalid.name {
-                        fld.cx.span_err(path_span,
-                                        &format!("macro_rules! expects an ident argument")
-                                        );
+                        fld.cx.span_err(path_span, "macro_rules! expects an ident argument");
                         return SmallVector::zero();
                     }