codec: make tracing feature optional for codecs (#6434)

Signed-off-by: Jens Reidel <[email protected]>

tokio-util/Cargo.toml

@@ -25,7 +25,7 @@ full = ["codec", "compat", "io-util", "time", "net", "rt"]
 
 net = ["tokio/net"]
 compat = ["futures-io",]
-codec = ["tracing"]
+codec = []
 time = ["tokio/time","slab"]
 io = []
 io-util = ["io", "tokio/rt", "tokio/io-util"]

tokio-util/src/codec/framed_impl.rs

@@ -12,7 +12,6 @@ use std::borrow::{Borrow, BorrowMut};
 use std::io;
 use std::pin::Pin;
 use std::task::{Context, Poll};
-use tracing::trace;
 
 pin_project! {
     #[derive(Debug)]

tokio-util/src/lib.rs

@@ -25,6 +25,9 @@ mod cfg;
 mod loom;
 
 cfg_codec! {
+    #[macro_use]
+    mod tracing;
+
     pub mod codec;
 }
 

tokio-util/src/tracing.rs

@@ -0,0 +1,6 @@
+macro_rules! trace {
+    ($($arg:tt)*) => {
+        #[cfg(feature = "tracing")]
+        tracing::trace!($($arg)*);
+    };
+}