Always import all tracing macros for the entire crate instead of piecemeal by module

compiler/rustc_span/src/hygiene.rs

@@ -41,7 +41,6 @@ use rustc_macros::HashStable_Generic;
 use rustc_serialize::{Decodable, Decoder, Encodable, Encoder};
 use std::fmt;
 use std::hash::Hash;
-use tracing::*;
 
 /// A `SyntaxContext` represents a chain of pairs `(ExpnId, Transparency)` named "marks".
 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]

compiler/rustc_span/src/lib.rs

@@ -76,8 +76,6 @@ use md5::Md5;
 use sha1::Sha1;
 use sha2::Sha256;
 
-use tracing::debug;
-
 #[cfg(test)]
 mod tests;
 

compiler/rustc_span/src/source_map.rs

@@ -23,7 +23,6 @@ use std::{convert::TryFrom, unreachable};
 
 use std::fs;
 use std::io;
-use tracing::debug;
 
 #[cfg(test)]
 mod tests;