auto merge of #13050 : alexcrichton/rust/no-send-default, r=huonw

See #10296 for the rationale, and commits for the implementation.

src/doc/tutorial.md

@@ -2103,7 +2103,7 @@ a `&T` pointer. `MutexArc` is an example of a *sharable* type with internal muta
 These are types that do not contain any data whose lifetime is bound to
 a particular stack frame. These are types that do not contain any
 references, or types where the only contained references
-have the `'static` lifetime. (For more on named lifetimes and their uses, 
+have the `'static` lifetime. (For more on named lifetimes and their uses,
 see the [references and lifetimes guide][lifetimes].)
 
 > ***Note:*** These two traits were referred to as 'kinds' in earlier
@@ -2430,23 +2430,25 @@ select the method to call at runtime.
 
 This usage of traits is similar to Java interfaces.
 
-By default, each of the three storage classes for traits enforce a
-particular set of built-in kinds that their contents must fulfill in
-order to be packaged up in a trait object of that storage class.
+There are some built-in bounds, such as `Send` and `Share`, which are properties
+of the components of types. By design, trait objects don't know the exact type
+of their contents and so the compiler cannot reason about those properties.
 
-* The contents of owned traits (`~Trait`) must fulfill the `Send` bound.
-* The contents of reference traits (`&Trait`) are not constrained by any bound.
+You can instruct the compiler, however, that the contents of a trait object must
+acribe to a particular bound with a trailing colon (`:`). These are examples of
+valid types:
 
-Consequently, the trait objects themselves automatically fulfill their
-respective kind bounds. However, this default behavior can be overridden by
-specifying a list of bounds on the trait type, for example, by writing `~Trait:`
-(which indicates that the contents of the owned trait need not fulfill any
-bounds), or by writing `~Trait:Send+Share`, which indicates that in addition
-to fulfilling `Send`, contents must also fulfill `Share`, and as a consequence,
-the trait itself fulfills `Share`.
+~~~rust
+trait Foo {}
+trait Bar<T> {}
 
-* `~Trait:Send` is equivalent to `~Trait`.
-* `&Trait:` is equivalent to `&Trait`.
+fn sendable_foo(f: ~Foo:Send) { /* ... */ }
+fn shareable_bar<T: Share>(b: &Bar<T>: Share) { /* ... */ }
+~~~
+
+When no colon is specified (such as the type `~Foo`), it is inferred that the
+value ascribes to no bounds. They must be added manually if any bounds are
+necessary for usage.
 
 Builtin kind bounds can also be specified on closure types in the same way (for
 example, by writing `fn:Send()`), and the default behaviours are the same as

src/libgreen/basic.rs

@@ -22,14 +22,14 @@ use std::rt::rtio::{EventLoop, IoFactory, RemoteCallback, PausableIdleCallback,
 use std::unstable::sync::Exclusive;
 
 /// This is the only exported function from this module.
-pub fn event_loop() -> ~EventLoop {
-    ~BasicLoop::new() as ~EventLoop
+pub fn event_loop() -> ~EventLoop:Send {
+    ~BasicLoop::new() as ~EventLoop:Send
 }
 
 struct BasicLoop {
-    work: ~[proc()],                  // pending work
+    work: ~[proc:Send()],             // pending work
     idle: Option<*mut BasicPausable>, // only one is allowed
-    remotes: ~[(uint, ~Callback)],
+    remotes: ~[(uint, ~Callback:Send)],
     next_remote: uint,
     messages: Exclusive<~[Message]>,
 }
@@ -135,26 +135,28 @@ impl EventLoop for BasicLoop {
         }
     }
 
-    fn callback(&mut self, f: proc()) {
+    fn callback(&mut self, f: proc:Send()) {
         self.work.push(f);
     }
 
     // FIXME: Seems like a really weird requirement to have an event loop provide.
-    fn pausable_idle_callback(&mut self, cb: ~Callback) -> ~PausableIdleCallback {
+    fn pausable_idle_callback(&mut self, cb: ~Callback:Send)
+        -> ~PausableIdleCallback:Send
+    {
         let callback = ~BasicPausable::new(self, cb);
         rtassert!(self.idle.is_none());
         unsafe {
             let cb_ptr: &*mut BasicPausable = cast::transmute(&callback);
             self.idle = Some(*cb_ptr);
         }
-        return callback as ~PausableIdleCallback;
+        callback as ~PausableIdleCallback:Send
     }
 
-    fn remote_callback(&mut self, f: ~Callback) -> ~RemoteCallback {
+    fn remote_callback(&mut self, f: ~Callback:Send) -> ~RemoteCallback:Send {
         let id = self.next_remote;
         self.next_remote += 1;
         self.remotes.push((id, f));
-        ~BasicRemote::new(self.messages.clone(), id) as ~RemoteCallback
+        ~BasicRemote::new(self.messages.clone(), id) as ~RemoteCallback:Send
     }
 
     fn io<'a>(&'a mut self) -> Option<&'a mut IoFactory> { None }
@@ -195,12 +197,12 @@ impl Drop for BasicRemote {
 
 struct BasicPausable {
     eloop: *mut BasicLoop,
-    work: ~Callback,
+    work: ~Callback:Send,
     active: bool,
 }
 
 impl BasicPausable {
-    fn new(eloop: &mut BasicLoop, cb: ~Callback) -> BasicPausable {
+    fn new(eloop: &mut BasicLoop, cb: ~Callback:Send) -> BasicPausable {
         BasicPausable {
             active: false,
             work: cb,

src/libgreen/lib.rs

@@ -247,7 +247,7 @@ pub mod task;
 /// The return value is used as the process return code. 0 on success, 101 on
 /// error.
 pub fn start(argc: int, argv: **u8,
-             event_loop_factory: fn() -> ~rtio::EventLoop,
+             event_loop_factory: fn() -> ~rtio::EventLoop:Send,
              main: proc()) -> int {
     rt::init(argc, argv);
     let mut main = Some(main);
@@ -268,7 +268,8 @@ pub fn start(argc: int, argv: **u8,
 ///
 /// This function will not return until all schedulers in the associated pool
 /// have returned.
-pub fn run(event_loop_factory: fn() -> ~rtio::EventLoop, main: proc()) -> int {
+pub fn run(event_loop_factory: fn() -> ~rtio::EventLoop:Send,
+           main: proc()) -> int {
     // Create a scheduler pool and spawn the main task into this pool. We will
     // get notified over a channel when the main task exits.
     let mut cfg = PoolConfig::new();
@@ -298,7 +299,7 @@ pub struct PoolConfig {
     threads: uint,
     /// A factory function used to create new event loops. If this is not
     /// specified then the default event loop factory is used.
-    event_loop_factory: fn() -> ~rtio::EventLoop,
+    event_loop_factory: fn() -> ~rtio::EventLoop:Send,
 }
 
 impl PoolConfig {
@@ -323,7 +324,7 @@ pub struct SchedPool {
     priv stack_pool: StackPool,
     priv deque_pool: deque::BufferPool<~task::GreenTask>,
     priv sleepers: SleeperList,
-    priv factory: fn() -> ~rtio::EventLoop,
+    priv factory: fn() -> ~rtio::EventLoop:Send,
     priv task_state: TaskState,
     priv tasks_done: Receiver<()>,
 }

src/libgreen/sched.rs

@@ -79,7 +79,7 @@ pub struct Scheduler {
     /// A fast XorShift rng for scheduler use
     rng: XorShiftRng,
     /// A togglable idle callback
-    idle_callback: Option<~PausableIdleCallback>,
+    idle_callback: Option<~PausableIdleCallback:Send>,
     /// A countdown that starts at a random value and is decremented
     /// every time a yield check is performed. When it hits 0 a task
     /// will yield.
@@ -99,7 +99,7 @@ pub struct Scheduler {
     //      destroyed before it's actually destroyed.
 
     /// The event loop used to drive the scheduler and perform I/O
-    event_loop: ~EventLoop,
+    event_loop: ~EventLoop:Send,
 }
 
 /// An indication of how hard to work on a given operation, the difference
@@ -122,7 +122,7 @@ impl Scheduler {
     // * Initialization Functions
 
     pub fn new(pool_id: uint,
-               event_loop: ~EventLoop,
+               event_loop: ~EventLoop:Send,
                work_queue: deque::Worker<~GreenTask>,
                work_queues: ~[deque::Stealer<~GreenTask>],
                sleeper_list: SleeperList,
@@ -135,7 +135,7 @@ impl Scheduler {
     }
 
     pub fn new_special(pool_id: uint,
-                       event_loop: ~EventLoop,
+                       event_loop: ~EventLoop:Send,
                        work_queue: deque::Worker<~GreenTask>,
                        work_queues: ~[deque::Stealer<~GreenTask>],
                        sleeper_list: SleeperList,
@@ -182,7 +182,7 @@ impl Scheduler {
     pub fn bootstrap(mut ~self) {
 
         // Build an Idle callback.
-        let cb = ~SchedRunner as ~Callback;
+        let cb = ~SchedRunner as ~Callback:Send;
         self.idle_callback = Some(self.event_loop.pausable_idle_callback(cb));
 
         // Create a task for the scheduler with an empty context.
@@ -230,7 +230,7 @@ impl Scheduler {
         // mutable reference to the event_loop to give it the "run"
         // command.
         unsafe {
-            let event_loop: *mut ~EventLoop = &mut self.event_loop;
+            let event_loop: *mut ~EventLoop:Send = &mut self.event_loop;
             // Our scheduler must be in the task before the event loop
             // is started.
             stask.put_with_sched(self);
@@ -868,7 +868,7 @@ impl Scheduler {
     }
 
     pub fn make_handle(&mut self) -> SchedHandle {
-        let remote = self.event_loop.remote_callback(~SchedRunner as ~Callback);
+        let remote = self.event_loop.remote_callback(~SchedRunner);
 
         return SchedHandle {
             remote: remote,
@@ -893,7 +893,7 @@ pub enum SchedMessage {
 }
 
 pub struct SchedHandle {
-    priv remote: ~RemoteCallback,
+    priv remote: ~RemoteCallback:Send,
     priv queue: msgq::Producer<SchedMessage>,
     sched_id: uint
 }
@@ -1007,7 +1007,6 @@ mod test {
 
     use std::comm;
     use std::task::TaskOpts;
-    use std::rt::Runtime;
     use std::rt::task::Task;
     use std::rt::local::Local;
 
@@ -1034,7 +1033,7 @@ mod test {
         match task.get().maybe_take_runtime::<GreenTask>() {
             Some(green) => {
                 let ret = green.sched.get_ref().sched_id();
-                task.get().put_runtime(green as ~Runtime);
+                task.get().put_runtime(green);
                 return ret;
             }
             None => fail!()

src/libgreen/simple.rs

@@ -34,7 +34,7 @@ impl Runtime for SimpleTask {
 
         let me = &mut *self as *mut SimpleTask;
         let cur_dupe = &*cur_task as *Task;
-        cur_task.put_runtime(self as ~Runtime);
+        cur_task.put_runtime(self);
         let task = BlockedTask::block(cur_task);
 
         // See libnative/task.rs for what's going on here with the `awoken`
@@ -57,7 +57,7 @@ impl Runtime for SimpleTask {
     }
     fn reawaken(mut ~self, mut to_wake: ~Task) {
         let me = &mut *self as *mut SimpleTask;
-        to_wake.put_runtime(self as ~Runtime);
+        to_wake.put_runtime(self);
         unsafe {
             cast::forget(to_wake);
             let guard = (*me).lock.lock();
@@ -86,6 +86,6 @@ pub fn task() -> ~Task {
     task.put_runtime(~SimpleTask {
         lock: unsafe {NativeMutex::new()},
         awoken: false,
-    } as ~Runtime);
+    });
     return task;
 }

src/libgreen/task.rs

@@ -287,7 +287,7 @@ impl GreenTask {
 
     pub fn swap(mut ~self) -> ~Task {
         let mut task = self.task.take_unwrap();
-        task.put_runtime(self as ~Runtime);
+        task.put_runtime(self);
         return task;
     }
 
@@ -482,7 +482,6 @@ impl Runtime for GreenTask {
 
 #[cfg(test)]
 mod tests {
-    use std::rt::Runtime;
     use std::rt::local::Local;
     use std::rt::task::Task;
     use std::task;
@@ -576,7 +575,7 @@ mod tests {
                 let mut task: ~Task = Local::take();
                 match task.maybe_take_runtime::<GreenTask>() {
                     Some(ops) => {
-                        task.put_runtime(ops as ~Runtime);
+                        task.put_runtime(ops);
                     }
                     None => fail!(),
                 }

src/liblog/lib.rs

@@ -156,7 +156,7 @@ pub static WARN: u32 = 2;
 /// Error log level
 pub static ERROR: u32 = 1;
 
-local_data_key!(local_logger: ~Logger)
+local_data_key!(local_logger: ~Logger:Send)
 
 /// A trait used to represent an interface to a task-local logger. Each task
 /// can have its own custom logger which can respond to logging messages
@@ -203,7 +203,7 @@ pub fn log(level: u32, args: &fmt::Arguments) {
     // frob the slot while we're doing the logging. This will destroy any logger
     // set during logging.
     let mut logger = local_data::pop(local_logger).unwrap_or_else(|| {
-        ~DefaultLogger { handle: io::stderr() } as ~Logger
+        ~DefaultLogger { handle: io::stderr() } as ~Logger:Send
     });
     logger.log(level, args);
     local_data::set(local_logger, logger);
@@ -217,7 +217,7 @@ pub fn log_level() -> u32 { unsafe { LOG_LEVEL } }
 
 /// Replaces the task-local logger with the specified logger, returning the old
 /// logger.
-pub fn set_logger(logger: ~Logger) -> Option<~Logger> {
+pub fn set_logger(logger: ~Logger:Send) -> Option<~Logger:Send> {
     let prev = local_data::pop(local_logger);
     local_data::set(local_logger, logger);
     return prev;

src/libnative/io/file_unix.rs

@@ -176,8 +176,8 @@ impl rtio::RtioPipe for FileDesc {
     fn write(&mut self, buf: &[u8]) -> Result<(), IoError> {
         self.inner_write(buf)
     }
-    fn clone(&self) -> ~rtio::RtioPipe {
-        ~FileDesc { inner: self.inner.clone() } as ~rtio::RtioPipe
+    fn clone(&self) -> ~rtio::RtioPipe:Send {
+        ~FileDesc { inner: self.inner.clone() } as ~rtio::RtioPipe:Send
     }
 }
 

src/libnative/io/file_win32.rs

@@ -206,8 +206,8 @@ impl rtio::RtioPipe for FileDesc {
     fn write(&mut self, buf: &[u8]) -> Result<(), IoError> {
         self.inner_write(buf)
     }
-    fn clone(&self) -> ~rtio::RtioPipe {
-        ~FileDesc { inner: self.inner.clone() } as ~rtio::RtioPipe
+    fn clone(&self) -> ~rtio::RtioPipe:Send {
+        ~FileDesc { inner: self.inner.clone() } as ~rtio::RtioPipe:Send
     }
 }