Allow logging to be disabled

This is a somewhat nontraditioonal use of features, but I don't want to
make logging opt in.

Closes rust-postgres#215

Author: sfackler

Cargo.toml

@@ -31,6 +31,8 @@ with-serde_json = ["serde_json"]
 with-time = ["time"]
 with-uuid = ["uuid"]
 
+no-logging = []
+
 [dependencies]
 bufstream = "0.1"
 fallible-iterator = "0.1.3"

src/lib.rs

@@ -73,6 +73,7 @@
 extern crate bufstream;
 extern crate fallible_iterator;
 extern crate hex;
+#[cfg(not(feature = "no-logging"))]
 #[macro_use]
 extern crate log;
 extern crate phf;

src/macros.rs

@@ -25,3 +25,13 @@ macro_rules! bad_response {
         return Err(::error::Error::Io(::bad_response()));
     })
 }
+
+#[cfg(feature = "no-logging")]
+macro_rules! debug {
+    ($($t:tt)*) => {}
+}
+
+#[cfg(feature = "no-logging")]
+macro_rules! info {
+    ($($t:tt)*) => {}
+}