Remove extern crate tracing from numerous crates.

compiler/rustc_ast_lowering/src/index.rs

@@ -7,6 +7,7 @@ use rustc_index::IndexVec;
 use rustc_middle::span_bug;
 use rustc_middle::ty::TyCtxt;
 use rustc_span::{Span, DUMMY_SP};
+use tracing::{debug, instrument};
 
 /// A visitor that walks over the HIR and collects `Node`s into a HIR map.
 struct NodeCollector<'a, 'hir> {

compiler/rustc_ast_lowering/src/item.rs

@@ -20,6 +20,7 @@ use rustc_span::{DesugaringKind, Span, Symbol};
 use rustc_target::spec::abi;
 use smallvec::{smallvec, SmallVec};
 use thin_vec::ThinVec;
+use tracing::instrument;
 
 pub(super) struct ItemLowerer<'a, 'hir> {
     pub(super) tcx: TyCtxt<'hir>,

compiler/rustc_ast_lowering/src/lib.rs

@@ -37,11 +37,7 @@
 #![feature(box_patterns)]
 #![feature(let_chains)]
 
-#[macro_use]
-extern crate tracing;
-
 use crate::errors::{AssocTyParentheses, AssocTyParenthesesSub, MisplacedImplTrait};
-
 use rustc_ast::node_id::NodeMap;
 use rustc_ast::ptr::P;
 use rustc_ast::{self as ast, *};
@@ -69,6 +65,7 @@ use rustc_span::{DesugaringKind, Span, DUMMY_SP};
 use smallvec::{smallvec, SmallVec};
 use std::collections::hash_map::Entry;
 use thin_vec::ThinVec;
+use tracing::{debug, instrument, trace};
 
 macro_rules! arena_vec {
     ($this:expr; $($x:expr),*) => (

compiler/rustc_ast_lowering/src/path.rs

@@ -18,6 +18,7 @@ use rustc_span::symbol::{kw, sym, Ident};
 use rustc_span::{BytePos, DesugaringKind, Span, Symbol, DUMMY_SP};
 
 use smallvec::{smallvec, SmallVec};
+use tracing::{debug, instrument};
 
 impl<'a, 'hir> LoweringContext<'a, 'hir> {
     #[instrument(level = "trace", skip(self))]