Add some diagnostics about which clang we find and which flags we derive from it.

Author: emilio

src/lib.rs

@@ -1734,11 +1734,15 @@ impl Bindings {
             }).cloned().collect::<Vec<_>>()
         };
 
+        debug!("Trying to find clang with flags: {:?}", clang_args_for_clang_sys);
+
         // TODO: Make this path fixup configurable?
         if let Some(clang) = clang_sys::support::Clang::find(
             None,
             &clang_args_for_clang_sys,
         ) {
+            debug!("Found clang: {:?}", clang);
+
             // If --target is specified, assume caller knows what they're doing
             // and don't mess with include paths for them
             let has_target_arg = options
@@ -1798,6 +1802,8 @@ impl Bindings {
             options.clang_args.push(f.name.to_str().unwrap().to_owned())
         }
 
+        debug!("Fixed-up options: {:?}", options);
+
         let time_phases = options.time_phases;
         let mut context = BindgenContext::new(options);