#[macro_use]
extern crate lazy_static;
+#[macro_use]
+extern crate tracing;
+
+// N.B. these need `extern crate` even in 2018 edition
+// because they're loaded implicitly from the sysroot.
+// Dependencies listed in Cargo.toml do not need extern crate.
extern crate rustc_ast;
extern crate rustc_ast_pretty;
extern crate rustc_attr;
extern crate rustc_trait_selection;
extern crate rustc_typeck;
extern crate test as testing;
-#[macro_use]
-extern crate tracing;
use std::default::Default;
use std::env;