Remove duplicate attr_to_string

attribute_to_string exists.

Author: Mark-Simulacrum

src/libsyntax/parse/token.rs

@@ -816,7 +816,7 @@ fn prepend_attrs(sess: &ParseSess,
         assert_eq!(attr.style, ast::AttrStyle::Outer,
                    "inner attributes should prevent cached tokens from existing");
 
-        let source = pprust::attr_to_string(attr);
+        let source = pprust::attribute_to_string(attr);
         let macro_filename = FileName::macro_expansion_source_code(&source);
         if attr.is_sugared_doc {
             let stream = parse_stream_from_source_str(macro_filename, source, sess, Some(span));

src/libsyntax/print/pprust.rs

@@ -350,10 +350,6 @@ pub fn stmt_to_string(stmt: &ast::Stmt) -> String {
     to_string(|s| s.print_stmt(stmt))
 }
 
-pub fn attr_to_string(attr: &ast::Attribute) -> String {
-    to_string(|s| s.print_attribute(attr))
-}
-
 pub fn item_to_string(i: &ast::Item) -> String {
     to_string(|s| s.print_item(i))
 }