Remove box syntax from doctest.rs

Author: est31

src/librustdoc/doctest.rs

@@ -740,7 +740,7 @@ fn check_if_attr_is_complete(source: &str, edition: Edition) -> bool {
                 rustc_errors::fallback_fluent_bundle(rustc_errors::DEFAULT_LOCALE_RESOURCES, false);
 
             let emitter = EmitterWriter::new(
-                box io::sink(),
+                Box::new(io::sink()),
                 None,
                 None,
                 fallback_bundle,
@@ -751,7 +751,7 @@ fn check_if_attr_is_complete(source: &str, edition: Edition) -> bool {
                 false,
             );
 
-            let handler = Handler::with_emitter(false, None, box emitter);
+            let handler = Handler::with_emitter(false, None, Box::new(emitter));
             let sess = ParseSess::with_span_handler(handler, sm);
             let mut parser =
                 match maybe_new_parser_from_source_str(&sess, filename, source.to_owned()) {