Remove `extern crate tracing`.

`use` is a nicer way of doing things.

1 files changed, 1 insertions, 1 deletions

diff --git a/compiler/rustc_data_structures/src/obligation_forest/mod.rs b/compiler/rustc_data_structures/src/obligation_forest/mod.rs
index a47908648ba..d477b86da74 100644
--- a/compiler/rustc_data_structures/src/obligation_forest/mod.rs
+++ b/compiler/rustc_data_structures/src/obligation_forest/mod.rs
@@ -70,12 +70,12 @@
 //! aren't needed anymore.
 
 use crate::fx::{FxHashMap, FxHashSet};
-
 use std::cell::Cell;
 use std::collections::hash_map::Entry;
 use std::fmt::Debug;
 use std::hash;
 use std::marker::PhantomData;
+use tracing::debug;
 
 mod graphviz;