Remove extern crate tracing from numerous crates.

compiler/rustc_traits/src/codegen.rs

@@ -13,6 +13,7 @@ use rustc_trait_selection::traits::{
     ImplSource, Obligation, ObligationCause, SelectionContext, TraitEngine, TraitEngineExt,
     Unimplemented,
 };
+use tracing::debug;
 
 /// Attempts to resolve an obligation to an `ImplSource`. The result is
 /// a shallow `ImplSource` resolution, meaning that we do not

compiler/rustc_traits/src/dropck_outlives.rs

@@ -12,6 +12,7 @@ use rustc_trait_selection::traits::query::dropck_outlives::{
     compute_dropck_outlives_inner, dtorck_constraint_for_ty_inner,
 };
 use rustc_trait_selection::traits::query::{CanonicalTyGoal, NoSolution};
+use tracing::debug;
 
 pub(crate) fn provide(p: &mut Providers) {
     *p = Providers { dropck_outlives, adt_dtorck_constraint, ..*p };

compiler/rustc_traits/src/evaluate_obligation.rs

@@ -6,6 +6,7 @@ use rustc_trait_selection::traits::query::CanonicalPredicateGoal;
 use rustc_trait_selection::traits::{
     EvaluationResult, Obligation, ObligationCause, OverflowError, SelectionContext, TraitQueryMode,
 };
+use tracing::debug;
 
 pub(crate) fn provide(p: &mut Providers) {
     *p = Providers { evaluate_obligation, ..*p };

compiler/rustc_traits/src/lib.rs

@@ -2,9 +2,6 @@
 
 #![recursion_limit = "256"]
 
-#[macro_use]
-extern crate tracing;
-
 mod codegen;
 mod dropck_outlives;
 mod evaluate_obligation;

compiler/rustc_traits/src/normalize_erasing_regions.rs

@@ -4,6 +4,7 @@ use rustc_middle::traits::query::NoSolution;
 use rustc_middle::ty::{self, ParamEnvAnd, TyCtxt, TypeFoldable, TypeVisitableExt};
 use rustc_trait_selection::traits::query::normalize::QueryNormalizeExt;
 use rustc_trait_selection::traits::{Normalized, ObligationCause};
+use tracing::debug;
 
 pub(crate) fn provide(p: &mut Providers) {
     *p = Providers {

compiler/rustc_traits/src/normalize_projection_ty.rs

@@ -10,6 +10,7 @@ use rustc_trait_selection::traits::query::{
 use rustc_trait_selection::traits::{
     self, FulfillmentErrorCode, ObligationCause, SelectionContext,
 };
+use tracing::debug;
 
 pub(crate) fn provide(p: &mut Providers) {
     *p = Providers {