Provide more context for rustc +nightly -Zunstable-options on stable

Author: jieyouxu

src/driver.rs

@@ -16,6 +16,8 @@ extern crate rustc_session;
 extern crate rustc_span;
 
 use rustc_interface::interface;
+use rustc_session::EarlyErrorHandler;
+use rustc_session::config::ErrorOutputType;
 use rustc_session::parse::ParseSess;
 use rustc_span::symbol::Symbol;
 
@@ -187,7 +189,9 @@ const BUG_REPORT_URL: &str = "https://github.com/rust-lang/rust-clippy/issues/ne
 
 #[allow(clippy::too_many_lines)]
 pub fn main() {
-    rustc_driver::init_rustc_env_logger();
+    let handler = EarlyErrorHandler::new(ErrorOutputType::default());
+
+    rustc_driver::init_rustc_env_logger(&handler);
 
     rustc_driver::install_ice_hook(BUG_REPORT_URL, |handler| {
         // FIXME: this macro calls unwrap internally but is called in a panicking context!  It's not