diff --git a/compiler/rustc_macros/src/serialize.rs b/compiler/rustc_macros/src/serialize.rs
index 5fa11d22f0e75..7b5dd1601c1f6 100644
--- a/compiler/rustc_macros/src/serialize.rs
+++ b/compiler/rustc_macros/src/serialize.rs
@@ -13,7 +13,7 @@ pub fn type_decodable_derive(mut s: synstructure::Structure<'_>) -> proc_macro2:
         quote! {}
     };
 
-    s.add_impl_generic(parse_quote! {#decoder_ty: ::rustc_type_ir::codec::TyDecoder #bound });
+    s.add_impl_generic(parse_quote! { #decoder_ty: ::rustc_type_ir::codec::TyDecoder #bound });
     s.add_bounds(synstructure::AddBounds::Fields);
     s.underscore_const(true);
 
@@ -34,7 +34,7 @@ pub fn meta_decodable_derive(mut s: synstructure::Structure<'_>) -> proc_macro2:
 
 pub fn decodable_derive(mut s: synstructure::Structure<'_>) -> proc_macro2::TokenStream {
     let decoder_ty = quote! { __D };
-    s.add_impl_generic(parse_quote! {#decoder_ty: ::rustc_span::SpanDecoder});
+    s.add_impl_generic(parse_quote! { #decoder_ty: ::rustc_span::SpanDecoder });
     s.add_bounds(synstructure::AddBounds::Generics);
     s.underscore_const(true);
 
@@ -43,7 +43,7 @@ pub fn decodable_derive(mut s: synstructure::Structure<'_>) -> proc_macro2::Toke
 
 pub fn decodable_generic_derive(mut s: synstructure::Structure<'_>) -> proc_macro2::TokenStream {
     let decoder_ty = quote! { __D };
-    s.add_impl_generic(parse_quote! {#decoder_ty: ::rustc_serialize::Decoder});
+    s.add_impl_generic(parse_quote! { #decoder_ty: ::rustc_serialize::Decoder });
     s.add_bounds(synstructure::AddBounds::Generics);
     s.underscore_const(true);
 
@@ -120,7 +120,7 @@ fn decode_field(field: &syn::Field) -> proc_macro2::TokenStream {
     let __decoder = quote! { __decoder };
     // Use the span of the field for the method call, so
     // that backtraces will point to the field.
-    quote_spanned! {field_span=> #decode_inner_method(#__decoder) }
+    quote_spanned! { field_span=> #decode_inner_method(#__decoder) }
 }
 
 pub fn type_encodable_derive(mut s: synstructure::Structure<'_>) -> proc_macro2::TokenStream {
@@ -133,7 +133,7 @@ pub fn type_encodable_derive(mut s: synstructure::Structure<'_>) -> proc_macro2:
     };
 
     let encoder_ty = quote! { __E };
-    s.add_impl_generic(parse_quote! {#encoder_ty: ::rustc_type_ir::codec::TyEncoder #bound });
+    s.add_impl_generic(parse_quote! { #encoder_ty: ::rustc_type_ir::codec::TyEncoder #bound });
     s.add_bounds(synstructure::AddBounds::Fields);
     s.underscore_const(true);
 
@@ -142,7 +142,7 @@ pub fn type_encodable_derive(mut s: synstructure::Structure<'_>) -> proc_macro2:
 
 pub fn meta_encodable_derive(mut s: synstructure::Structure<'_>) -> proc_macro2::TokenStream {
     if !s.ast().generics.lifetimes().any(|lt| lt.lifetime.ident == "tcx") {
-        s.add_impl_generic(parse_quote! {'tcx});
+        s.add_impl_generic(parse_quote! { 'tcx });
     }
     s.add_impl_generic(parse_quote! { '__a });
     let encoder_ty = quote! { EncodeContext<'__a, 'tcx> };
@@ -154,7 +154,7 @@ pub fn meta_encodable_derive(mut s: synstructure::Structure<'_>) -> proc_macro2:
 
 pub fn encodable_derive(mut s: synstructure::Structure<'_>) -> proc_macro2::TokenStream {
     let encoder_ty = quote! { __E };
-    s.add_impl_generic(parse_quote! { #encoder_ty: ::rustc_span::SpanEncoder});
+    s.add_impl_generic(parse_quote! { #encoder_ty: ::rustc_span::SpanEncoder });
     s.add_bounds(synstructure::AddBounds::Generics);
     s.underscore_const(true);
 
@@ -163,7 +163,7 @@ pub fn encodable_derive(mut s: synstructure::Structure<'_>) -> proc_macro2::Toke
 
 pub fn encodable_generic_derive(mut s: synstructure::Structure<'_>) -> proc_macro2::TokenStream {
     let encoder_ty = quote! { __E };
-    s.add_impl_generic(parse_quote! { #encoder_ty: ::rustc_serialize::Encoder});
+    s.add_impl_generic(parse_quote! { #encoder_ty: ::rustc_serialize::Encoder });
     s.add_bounds(synstructure::AddBounds::Generics);
     s.underscore_const(true);
 
diff --git a/compiler/rustc_span/src/hygiene.rs b/compiler/rustc_span/src/hygiene.rs
index aa4bcefab9391..00ef17d630c5d 100644
--- a/compiler/rustc_span/src/hygiene.rs
+++ b/compiler/rustc_span/src/hygiene.rs
@@ -40,6 +40,7 @@ use std::cell::RefCell;
 use std::collections::hash_map::Entry;
 use std::fmt;
 use std::hash::Hash;
+use tracing::{debug, trace};
 
 /// A `SyntaxContext` represents a chain of pairs `(ExpnId, Transparency)` named "marks".
 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
diff --git a/compiler/rustc_span/src/lib.rs b/compiler/rustc_span/src/lib.rs
index f83bacdcebe77..b2ca01fe3b94c 100644
--- a/compiler/rustc_span/src/lib.rs
+++ b/compiler/rustc_span/src/lib.rs
@@ -33,15 +33,16 @@
 #![feature(rustdoc_internals)]
 // tidy-alphabetical-end
 
+// The code produced by the `Encodable`/`Decodable` derive macros refer to
+// `rustc_span::Span{Encoder,Decoder}`. That's fine outside this crate, but doesn't work inside
+// this crate without this line making `rustc_span` available.
 extern crate self as rustc_span;
 
-#[macro_use]
-extern crate tracing;
-
 use rustc_data_structures::{outline, AtomicRef};
 use rustc_macros::{Decodable, Encodable, HashStable_Generic};
 use rustc_serialize::opaque::{FileEncoder, MemDecoder};
 use rustc_serialize::{Decodable, Decoder, Encodable, Encoder};
+use tracing::debug;
 
 mod caching_source_map_view;
 pub mod source_map;
diff --git a/compiler/rustc_span/src/source_map.rs b/compiler/rustc_span/src/source_map.rs
index 2093dcf0e8315..fb212d67997a7 100644
--- a/compiler/rustc_span/src/source_map.rs
+++ b/compiler/rustc_span/src/source_map.rs
@@ -16,6 +16,7 @@ use rustc_macros::{Decodable, Encodable};
 use std::fs;
 use std::io::{self, BorrowedBuf, Read};
 use std::path;
+use tracing::{debug, instrument, trace};
 
 #[cfg(test)]
 mod tests;