Remove BasicEmitter

src/libsyntax/parse/lexer/mod.rs

@@ -1686,7 +1686,7 @@ mod tests {
         // FIXME (#22405): Replace `Box::new` with `box` here when/if possible.
         let emitter = errors::emitter::EmitterWriter::new(Box::new(io::sink()),
                                                 None,
-                                                cm,
+                                                Some(cm),
                                                 errors::snippet::FormatMode::EnvironmentSelected);
         errors::Handler::with_emitter(true, false, Box::new(emitter))
     }