Be a little more clever about calculating sizes for class types

We could try to calculate the size of a partially-converted class type,
and run into an LLVM error because we were trying to calculate the size
of a named struct whose fields hadn't yet be filled in. The issue can be
dodged by extending simplify_type to convert classes to isomorphic
structural records, just for the purposes of size calculations.

(for real this time) Closes #2718

src/rustc/middle/trans/shape.rs

@@ -18,6 +18,7 @@ import syntax::codemap::span;
 import dvec::{dvec, extensions};
 
 import std::map::hashmap;
+import option::is_some;
 
 import ty_ctxt = middle::ty::ctxt;
 
@@ -732,19 +733,24 @@ fn simplify_type(tcx: ty::ctxt, typ: ty::t) -> ty::t {
           ty::ty_estr(ty::vstore_slice(_)) {
             ty::mk_tup(tcx, [nilptr(tcx), ty::mk_int(tcx)]/~)
           }
+          // Reduce a class type to a record type in which all the fields are
+          // simplified
+          ty::ty_class(did, substs) {
+            let simpl_fields = (if is_some(ty::ty_dtor(tcx, did)) {
+                // remember the drop flag
+                  [{ident: @"drop", mt: {ty:
+                                        ty::mk_u8(tcx),
+                                        mutbl: ast::m_mutbl}}]/~ }
+                else { []/~ }) +
+              ty::lookup_class_fields(tcx, did).map {|f|
+                 let t = ty::lookup_field_type(tcx, did, f.id, substs);
+                 {ident: f.ident,
+                  mt: {ty: simplify_type(tcx, t), mutbl: ast::m_const}}
+            };
+            ty::mk_rec(tcx, simpl_fields)
+          }
           _ { typ }
         }
     }
     ty::fold_ty(tcx, typ) {|t| simplifier(tcx, t) }
 }
-
-// Given a tag type `ty`, returns the offset of the payload.
-//fn tag_payload_offs(bcx: block, tag_id: ast::def_id, tps: [ty::t]/~)
-//    -> ValueRef {
-//    alt tag_kind(tag_id) {
-//      tk_unit | tk_enum | tk_newtype { C_int(bcx.ccx(), 0) }
-//      tk_complex {
-//        compute_tag_metrics(tag_id, tps)
-//      }
-//    }
-//}

src/test/run-pass/issue-2718.rs

@@ -1,7 +1,141 @@
-fn sender_terminate<T:send>(p: *packet<T>) {
-}
+mod pipes {
+    import unsafe::{forget, reinterpret_cast};
+
+    enum state {
+        empty,
+        full,
+        blocked,
+        terminated
+    }
+
+    type packet<T: send> = {
+        mut state: state,
+        mut blocked_task: option<task::task>,
+        mut payload: option<T>
+    };
+
+    fn packet<T: send>() -> *packet<T> unsafe {
+        let p: *packet<T> = unsafe::transmute(~{
+            mut state: empty,
+            mut blocked_task: none::<task::task>,
+            mut payload: none::<T>
+        });
+        p
+    }
+
+    #[abi = "rust-intrinsic"]
+    mod rusti {
+      fn atomic_xchng(&dst: int, src: int) -> int { fail; }
+      fn atomic_xchng_acq(&dst: int, src: int) -> int { fail; }
+      fn atomic_xchng_rel(&dst: int, src: int) -> int { fail; }
+    }
+
+    // We should consider moving this to core::unsafe, although I
+    // suspect graydon would want us to use void pointers instead.
+    unsafe fn uniquify<T>(x: *T) -> ~T {
+        unsafe { unsafe::reinterpret_cast(x) }
+    }
+
+    fn swap_state_acq(&dst: state, src: state) -> state {
+        unsafe {
+            reinterpret_cast(rusti::atomic_xchng_acq(
+                *(ptr::mut_addr_of(dst) as *mut int),
+                src as int))
+        }
+    }
+
+    fn swap_state_rel(&dst: state, src: state) -> state {
+        unsafe {
+            reinterpret_cast(rusti::atomic_xchng_rel(
+                *(ptr::mut_addr_of(dst) as *mut int),
+                src as int))
+        }
+    }
+
+    fn send<T: send>(-p: send_packet<T>, -payload: T) {
+        let p = p.unwrap();
+        let p = unsafe { uniquify(p) };
+        assert (*p).payload == none;
+        (*p).payload <- some(payload);
+        let old_state = swap_state_rel((*p).state, full);
+        alt old_state {
+          empty {
+            // Yay, fastpath.
 
-class send_packet<T: send> {
+            // The receiver will eventually clean this up.
+            unsafe { forget(p); }
+          }
+          full { fail "duplicate send" }
+          blocked {
+            // FIXME: once the target will actually block, tell the
+            // scheduler to wake it up.
+
+            // The receiver will eventually clean this up.
+            unsafe { forget(p); }
+          }
+          terminated {
+            // The receiver will never receive this. Rely on drop_glue
+            // to clean everything up.
+          }
+        }
+    }
+
+    fn recv<T: send>(-p: recv_packet<T>) -> option<T> {
+        let p = p.unwrap();
+        let p = unsafe { uniquify(p) };
+        loop {
+            let old_state = swap_state_acq((*p).state,
+                                           blocked);
+            alt old_state {
+              empty | blocked { task::yield(); }
+              full {
+                let mut payload = none;
+                payload <-> (*p).payload;
+                ret some(option::unwrap(payload))
+              }
+              terminated {
+                assert old_state == terminated;
+                ret none;
+              }
+            }
+        }
+    }
+
+    fn sender_terminate<T: send>(p: *packet<T>) {
+        let p = unsafe { uniquify(p) };
+        alt swap_state_rel((*p).state, terminated) {
+          empty | blocked {
+            // The receiver will eventually clean up.
+            unsafe { forget(p) }
+          }
+          full {
+            // This is impossible
+            fail "you dun goofed"
+          }
+          terminated {
+            // I have to clean up, use drop_glue
+          }
+        }
+    }
+
+    fn receiver_terminate<T: send>(p: *packet<T>) {
+        let p = unsafe { uniquify(p) };
+        alt swap_state_rel((*p).state, terminated) {
+          empty {
+            // the sender will clean up
+            unsafe { forget(p) }
+          }
+          blocked {
+            // this shouldn't happen.
+            fail "terminating a blocked packet"
+          }
+          terminated | full {
+            // I have to clean up, use drop_glue
+          }
+        }
+    }
+
+    class send_packet<T: send> {
         let mut p: option<*packet<T>>;
         new(p: *packet<T>) { self.p = some(p); }
         drop {
@@ -16,23 +150,128 @@ class send_packet<T: send> {
             p <-> self.p;
             option::unwrap(p)
         }
+    }
+
+    class recv_packet<T: send> {
+        let mut p: option<*packet<T>>;
+        new(p: *packet<T>) { self.p = some(p); }
+        drop {
+            if self.p != none {
+                let mut p = none;
+                p <-> self.p;
+                receiver_terminate(option::unwrap(p))
+            }
+        }
+        fn unwrap() -> *packet<T> {
+            let mut p = none;
+            p <-> self.p;
+            option::unwrap(p)
+        }
+    }
+
+    fn entangle<T: send>() -> (send_packet<T>, recv_packet<T>) {
+        let p = packet();
+        (send_packet(p), recv_packet(p))
+    }
 }
 
-enum state {
-        empty,
-        full,
-        blocked,
-        terminated
+mod pingpong {
+    enum ping = pipes::send_packet<pong>;
+    enum pong = pipes::send_packet<ping>;
+
+    fn liberate_ping(-p: ping) -> pipes::send_packet<pong> unsafe {
+        let addr : *pipes::send_packet<pong> = alt p {
+          ping(x) { unsafe::reinterpret_cast(ptr::addr_of(x)) }
+        };
+        let liberated_value <- *addr;
+        unsafe::forget(p);
+        liberated_value
+    }
+
+    fn liberate_pong(-p: pong) -> pipes::send_packet<ping> unsafe {
+        let addr : *pipes::send_packet<ping> = alt p {
+          pong(x) { unsafe::reinterpret_cast(ptr::addr_of(x)) }
+        };
+        let liberated_value <- *addr;
+        unsafe::forget(p);
+        liberated_value
+    }
+
+    fn init() -> (client::ping, server::ping) {
+        pipes::entangle()
+    }
+
+    mod client {
+        type ping = pipes::send_packet<pingpong::ping>;
+        type pong = pipes::recv_packet<pingpong::pong>;
+
+        fn do_ping(-c: ping) -> pong {
+            let (sp, rp) = pipes::entangle();
+
+            pipes::send(c, ping(sp));
+            rp
+        }
+
+        fn do_pong(-c: pong) -> (ping, ()) {
+            let packet = pipes::recv(c);
+            if packet == none {
+                fail "sender closed the connection"
+            }
+            (liberate_pong(option::unwrap(packet)), ())
+        }
+    }
+
+    mod server {
+        type ping = pipes::recv_packet<pingpong::ping>;
+        type pong = pipes::send_packet<pingpong::pong>;
+
+        fn do_ping(-c: ping) -> (pong, ()) {
+            let packet = pipes::recv(c);
+            if packet == none {
+                fail "sender closed the connection"
+            }
+            (liberate_ping(option::unwrap(packet)), ())
+        }
+
+        fn do_pong(-c: pong) -> ping {
+            let (sp, rp) = pipes::entangle();
+            pipes::send(c, pong(sp));
+            rp
+        }
+    }
 }
 
-type packet<T: send> = {
-        mut state: state,
-        mut blocked_task: option<task::task>,
-        mut payload: option<T>
-};
+fn client(-chan: pingpong::client::ping) {
+    let chan = pingpong::client::do_ping(chan);
+    log(error, "Sent ping");
+    let (chan, _data) = pingpong::client::do_pong(chan);
+    log(error, "Received pong");
+}
+
+fn server(-chan: pingpong::server::ping) {
+    let (chan, _data) = pingpong::server::do_ping(chan);
+    log(error, "Received ping");
+    let chan = pingpong::server::do_pong(chan);
+    log(error, "Sent pong");
+}
 
 fn main() {
-  let _s: send_packet<int> = send_packet(ptr::addr_of({mut state: empty,
-        mut blocked_task: none,
-        mut payload: some(42)}));
+  /*
+//    Commented out because of option::get error
+
+    let (client_, server_) = pingpong::init();
+    let client_ = ~mut some(client_);
+    let server_ = ~mut some(server_);
+
+    task::spawn {|move client_|
+        let mut client__ = none;
+        *client_ <-> client__;
+        client(option::unwrap(client__));
+    };
+    task::spawn {|move server_|
+        let mut server_ˊ = none;
+        *server_ <-> server_ˊ;
+        server(option::unwrap(server_ˊ));
+    };
+  */
 }