Formalize thread-safety guarantees (#322)

src/lib.rs

@@ -167,8 +167,14 @@ pub struct DeviceId(platform::DeviceId);
 /// an events loop opens a connection to the X or Wayland server.
 ///
 /// To wake up an `EventsLoop` from a another thread, see the `EventsLoopProxy` docs.
+///
+/// Note that the `EventsLoop` cannot be shared accross threads (due to platform-dependant logic
+/// forbiding it), as such it is neither `Send` nor `Sync`. If you need cross-thread access, the
+/// `Window` created from this `EventsLoop` _can_ be sent to an other thread, and the
+/// `EventsLoopProxy` allows you to wakeup an `EventsLoop` from an other thread.
 pub struct EventsLoop {
     events_loop: platform::EventsLoop,
+    _marker: ::std::marker::PhantomData<*mut ()> // Not Send nor Sync
 }
 
 /// Returned by the user callback given to the `EventsLoop::run_forever` method.
@@ -192,6 +198,7 @@ impl EventsLoop {
     pub fn new() -> EventsLoop {
         EventsLoop {
             events_loop: platform::EventsLoop::new(),
+            _marker: ::std::marker::PhantomData,
         }
     }
 

src/os/unix.rs

@@ -41,7 +41,12 @@ pub trait EventsLoopExt {
 impl EventsLoopExt for EventsLoop {
     #[inline]
     fn new_x11() -> Result<Self, XNotSupported> {
-        LinuxEventsLoop::new_x11().map(|ev| EventsLoop { events_loop: ev })
+        LinuxEventsLoop::new_x11().map(|ev|
+            EventsLoop {
+                events_loop: ev,
+                _marker: ::std::marker::PhantomData,
+            }
+        )
     }
 
     #[inline]
@@ -50,7 +55,8 @@ impl EventsLoopExt for EventsLoop {
             events_loop: match LinuxEventsLoop::new_wayland() {
                 Ok(e) => e,
                 Err(_) => panic!()      // TODO: propagate
-            }
+            },
+            _marker: ::std::marker::PhantomData,
         }
     }