Replace need for drop_types_in_const with lazy_static

Cargo.lock

@@ -10,6 +10,7 @@ dependencies = [
  "font 0.1.0",
  "gl_generator 0.5.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "glutin 0.6.1 (git+https://github.com/jwilm/glutin?rev=af7fe340bd4a2af53ea521defcb4f377cdc588cf)",
+ "lazy_static 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "libc 0.2.18 (registry+https://github.com/rust-lang/crates.io-index)",
  "mio 0.6.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "notify 2.6.3 (registry+https://github.com/rust-lang/crates.io-index)",

Cargo.toml

@@ -17,6 +17,7 @@ notify = "2.6"
 bitflags = "*"
 font = { path = "./font" }
 errno = "0.1.6"
+lazy_static = "0.2.2"
 parking_lot = { version = "0.3.1", features = ["nightly"] }
 serde = "0.8"
 serde_yaml = "0.5"

src/lib.rs

@@ -16,7 +16,6 @@
 #![feature(range_contains)]
 #![feature(inclusive_range_syntax)]
 #![feature(inclusive_range)]
-#![feature(drop_types_in_const)]
 #![cfg_attr(feature = "clippy", feature(plugin))]
 #![cfg_attr(feature = "clippy", plugin(clippy))]
 #![cfg_attr(feature = "clippy", deny(clippy))]
@@ -36,6 +35,8 @@ extern crate copypasta;
 extern crate errno;
 extern crate font;
 extern crate glutin;
+#[macro_use]
+extern crate lazy_static;
 extern crate libc;
 extern crate mio;
 extern crate notify;

src/window.rs

@@ -14,6 +14,7 @@
 use std::convert::From;
 use std::fmt::{self, Display};
 use std::ops::Deref;
+use std::sync::Mutex;
 
 use gl;
 use glutin;
@@ -26,13 +27,13 @@ use glutin;
 ///
 /// This will fail horribly if more than one window is created. Don't do that :)
 fn window_resize_handler(width: u32, height: u32) {
-    unsafe {
-        RESIZE_CALLBACK.as_ref().map(|func| func(width, height));
-    }
+        RESIZE_CALLBACK.lock().unwrap().as_ref().map(|func| (*func)(width, height));
 }
 
-/// The resize callback invoked by `window_resize_handler`
-static mut RESIZE_CALLBACK: Option<Box<Fn(u32, u32)>> = None;
+lazy_static! {
+    /// The resize callback invoked by `window_resize_handler`
+   static ref RESIZE_CALLBACK: Mutex<Option<Box<Fn(u32, u32) + 'static + Send>>> = Mutex::new(None); 
+}
 
 /// Window errors
 #[derive(Debug)]
@@ -238,10 +239,9 @@ impl Window {
     ///
     /// This method takes self mutably to ensure there's no race condition
     /// setting the callback.
-    pub fn set_resize_callback<F: Fn(u32, u32) + 'static>(&mut self, func: F) {
-        unsafe {
-            RESIZE_CALLBACK = Some(Box::new(func));
-        }
+    pub fn set_resize_callback<F: Fn(u32, u32) + 'static + Send>(&mut self, func: F) {
+        let mut guard = RESIZE_CALLBACK.lock().unwrap();
+        *guard = Some(Box::new(func));
     }
 
     pub fn inner_size_pixels(&self) -> Option<Size<Pixels<u32>>> {