Auto merge of #561 - pornel:logging, r=fitzgen

Run without logging feature

The build was broken without default features

Author: bors-servo

src/log_stubs.rs

@@ -1,12 +1,12 @@
 macro_rules! log {
-    (target: $target:expr, $lvl:expr, $($arg)+) => {
+    (target: $target:expr, $lvl:expr, $($arg:tt)+) => {
         let _ = $target;
         let _ = log!($lvl, $($arg)+);
     };
-    ($lvl:expr, $($arg:tt)+) => {
+    ($lvl:expr, $($arg:tt)+) => {{
         let _ = $lvl;
         let _ = format_args!($($arg)+);
-    };
+    }};
 }
 macro_rules! error {
     (target: $target:expr, $($arg:tt)*) => { log!($target, $($arg)*); };

src/main.rs

@@ -1,6 +1,8 @@
 extern crate bindgen;
+#[cfg(feature="logging")]
 extern crate env_logger;
 #[macro_use]
+#[cfg(feature="logging")]
 extern crate log;
 extern crate clang_sys;
 extern crate clap;
@@ -10,10 +12,15 @@ use bindgen::clang_version;
 use std::env;
 use std::panic;
 
+#[macro_use]
+#[cfg(not(feature="logging"))]
+mod log_stubs;
+
 mod options;
 use options::builder_from_flags;
 
 pub fn main() {
+    #[cfg(feature="logging")]
     log::set_logger(|max_log_level| {
             use env_logger::Logger;
             let env_logger = Logger::new();