Fix warnings (#929)

* Fix warnings

* Bring back derivatives crate for Windows

src/lib.rs

@@ -86,6 +86,7 @@ extern crate log;
 #[macro_use]
 extern crate serde;
 #[macro_use]
+#[cfg(target_os = "windows")]
 extern crate derivative;
 #[macro_use]
 #[cfg(target_os = "windows")]

src/platform_impl/macos/app_state.rs

@@ -1,5 +1,5 @@
 use std::{
-    collections::VecDeque, fmt::{self, Debug, Formatter},
+    collections::VecDeque, fmt::{self, Debug},
     hint::unreachable_unchecked, mem,
     sync::{atomic::{AtomicBool, Ordering}, Mutex, MutexGuard}, time::Instant,
 };

src/platform_impl/macos/observer.rs

@@ -54,6 +54,7 @@ extern {
         source: CFRunLoopSourceRef,
         mode: CFRunLoopMode,
     );
+    #[allow(dead_code)]
     pub fn CFRunLoopSourceInvalidate(source: CFRunLoopSourceRef);
     pub fn CFRunLoopSourceSignal(source: CFRunLoopSourceRef);
 
@@ -62,6 +63,7 @@ extern {
 }
 
 pub type Boolean = u8;
+#[allow(dead_code)]
 const FALSE: Boolean = 0;
 const TRUE: Boolean = 1;
 
@@ -87,9 +89,13 @@ pub type CFRunLoopActivity = CFOptionFlags;
 pub type CFAbsoluteTime = CFTimeInterval;
 pub type CFTimeInterval = f64;
 
+#[allow(non_upper_case_globals)]
 pub const kCFRunLoopEntry: CFRunLoopActivity = 0;
+#[allow(non_upper_case_globals)]
 pub const kCFRunLoopBeforeWaiting: CFRunLoopActivity = 1 << 5;
+#[allow(non_upper_case_globals)]
 pub const kCFRunLoopAfterWaiting: CFRunLoopActivity = 1 << 6;
+#[allow(non_upper_case_globals)]
 pub const kCFRunLoopExit: CFRunLoopActivity = 1 << 7;
 
 pub type CFRunLoopObserverCallBack = extern "C" fn(
@@ -105,6 +111,7 @@ pub type CFRunLoopTimerCallBack = extern "C" fn(
 pub enum CFRunLoopObserverContext {}
 pub enum CFRunLoopTimerContext {}
 
+#[allow(non_snake_case)]
 #[repr(C)]
 pub struct CFRunLoopSourceContext {
     pub version: CFIndex,

tests/send_objects.rs

@@ -4,6 +4,7 @@ fn needs_send<T:Send>() {}
 
 #[test]
 fn event_loop_proxy_send() {
+    #[allow(dead_code)]
     fn is_send<T: 'static + Send>() {
         // ensures that `winit::EventLoopProxy` implements `Send`
         needs_send::<winit::event_loop::EventLoopProxy<T>>();