prevent regions from escaping in ifaces; remove &r.T syntax

src/libcore/task.rs

@@ -832,10 +832,10 @@ fn spawn_raw(opts: task_opts, +f: fn~()) {
  * types; arbitrary type coercion is possible this way. The interface is safe
  * as long as all key functions are monomorphic.
  */
-type local_data_key<T> = fn@(+@T);
+type local_data_key<T: owned> = fn@(+@T);
 
 iface local_data { }
-impl<T> of local_data for @T { }
+impl<T: owned> of local_data for @T { }
 
 // We use dvec because it's the best data structure in core. If TLS is used
 // heavily in future, this could be made more efficient with a proper map.
@@ -852,6 +852,7 @@ extern fn cleanup_task_local_map(map_ptr: *libc::c_void) unsafe {
 
 // Gets the map from the runtime. Lazily initialises if not done so already.
 unsafe fn get_task_local_map(task: *rust_task) -> task_local_map {
+
     // Relies on the runtime initialising the pointer to null.
     // NOTE: The map's box lives in TLS invisibly referenced once. Each time
     // we retrieve it for get/set, we make another reference, which get/set
@@ -872,16 +873,20 @@ unsafe fn get_task_local_map(task: *rust_task) -> task_local_map {
     }
 }
 
-unsafe fn key_to_key_value<T>(key: local_data_key<T>) -> *libc::c_void {
+unsafe fn key_to_key_value<T: owned>(
+    key: local_data_key<T>) -> *libc::c_void {
+
     // Keys are closures, which are (fnptr,envptr) pairs. Use fnptr.
     // Use reintepret_cast -- transmute would leak (forget) the closure.
     let pair: (*libc::c_void, *libc::c_void) = unsafe::reinterpret_cast(key);
     pair.first()
 }
 
 // If returning some(..), returns with @T with the map's reference. Careful!
-unsafe fn local_data_lookup<T>(map: task_local_map, key: local_data_key<T>)
-        -> option<(uint, *libc::c_void)> {
+unsafe fn local_data_lookup<T: owned>(
+    map: task_local_map, key: local_data_key<T>)
+    -> option<(uint, *libc::c_void)> {
+
     let key_value = key_to_key_value(key);
     let map_pos = (*map).position(|entry|
         alt entry { some((k,_,_)) { k == key_value } none { false } }
@@ -893,8 +898,10 @@ unsafe fn local_data_lookup<T>(map: task_local_map, key: local_data_key<T>)
     }
 }
 
-unsafe fn local_get_helper<T>(task: *rust_task, key: local_data_key<T>,
-                              do_pop: bool) -> option<@T> {
+unsafe fn local_get_helper<T: owned>(
+    task: *rust_task, key: local_data_key<T>,
+    do_pop: bool) -> option<@T> {
+
     let map = get_task_local_map(task);
     // Interpret our findings from the map
     do local_data_lookup(map, key).map |result| {
@@ -912,17 +919,23 @@ unsafe fn local_get_helper<T>(task: *rust_task, key: local_data_key<T>,
     }
 }
 
-unsafe fn local_pop<T>(task: *rust_task,
-                       key: local_data_key<T>) -> option<@T> {
+unsafe fn local_pop<T: owned>(
+    task: *rust_task,
+    key: local_data_key<T>) -> option<@T> {
+
     local_get_helper(task, key, true)
 }
 
-unsafe fn local_get<T>(task: *rust_task,
-                       key: local_data_key<T>) -> option<@T> {
+unsafe fn local_get<T: owned>(
+    task: *rust_task,
+    key: local_data_key<T>) -> option<@T> {
+
     local_get_helper(task, key, false)
 }
 
-unsafe fn local_set<T>(task: *rust_task, key: local_data_key<T>, +data: @T) {
+unsafe fn local_set<T: owned>(
+    task: *rust_task, key: local_data_key<T>, +data: @T) {
+
     let map = get_task_local_map(task);
     // Store key+data as *voids. Data is invisibly referenced once; key isn't.
     let keyval = key_to_key_value(key);
@@ -956,8 +969,10 @@ unsafe fn local_set<T>(task: *rust_task, key: local_data_key<T>, +data: @T) {
     }
 }
 
-unsafe fn local_modify<T>(task: *rust_task, key: local_data_key<T>,
-                          modify_fn: fn(option<@T>) -> option<@T>) {
+unsafe fn local_modify<T: owned>(
+    task: *rust_task, key: local_data_key<T>,
+    modify_fn: fn(option<@T>) -> option<@T>) {
+
     // Could be more efficient by doing the lookup work, but this is easy.
     let newdata = modify_fn(local_pop(task, key));
     if newdata.is_some() {
@@ -970,29 +985,37 @@ unsafe fn local_modify<T>(task: *rust_task, key: local_data_key<T>,
  * Remove a task-local data value from the table, returning the
  * reference that was originally created to insert it.
  */
-unsafe fn local_data_pop<T>(key: local_data_key<T>) -> option<@T> {
+unsafe fn local_data_pop<T: owned>(
+    key: local_data_key<T>) -> option<@T> {
+
     local_pop(rustrt::rust_get_task(), key)
 }
 /**
  * Retrieve a task-local data value. It will also be kept alive in the
  * table until explicitly removed.
  */
-unsafe fn local_data_get<T>(key: local_data_key<T>) -> option<@T> {
+unsafe fn local_data_get<T: owned>(
+    key: local_data_key<T>) -> option<@T> {
+
     local_get(rustrt::rust_get_task(), key)
 }
 /**
  * Store a value in task-local data. If this key already has a value,
  * that value is overwritten (and its destructor is run).
  */
-unsafe fn local_data_set<T>(key: local_data_key<T>, +data: @T) {
+unsafe fn local_data_set<T: owned>(
+    key: local_data_key<T>, +data: @T) {
+
     local_set(rustrt::rust_get_task(), key, data)
 }
 /**
  * Modify a task-local data value. If the function returns 'none', the
  * data is removed (and its reference dropped).
  */
-unsafe fn local_data_modify<T>(key: local_data_key<T>,
-                               modify_fn: fn(option<@T>) -> option<@T>) {
+unsafe fn local_data_modify<T: owned>(
+    key: local_data_key<T>,
+    modify_fn: fn(option<@T>) -> option<@T>) {
+
     local_modify(rustrt::rust_get_task(), key, modify_fn)
 }
 

src/libstd/deque.rs

@@ -193,7 +193,9 @@ mod tests {
 
     type eqfn<T> = fn@(T, T) -> bool;
 
-    fn test_parameterized<T: copy>(e: eqfn<T>, a: T, b: T, c: T, d: T) {
+    fn test_parameterized<T: copy owned>(
+        e: eqfn<T>, a: T, b: T, c: T, d: T) {
+
         let deq: deque::t<T> = deque::create::<T>();
         assert (deq.size() == 0u);
         deq.add_front(a);

src/libsyntax/parse/parser.rs

@@ -383,8 +383,7 @@ class parser {
         let name =
             alt copy self.token {
               token::IDENT(sid, _) => {
-                if self.look_ahead(1u) == token::DOT || // backwards compat
-                    self.look_ahead(1u) == token::BINOP(token::SLASH) {
+                if self.look_ahead(1u) == token::BINOP(token::SLASH) {
                     self.bump(); self.bump();
                     some(self.get_str(sid))
                 } else {

src/libsyntax/print/pprust.rs

@@ -345,7 +345,7 @@ fn print_type_ex(s: ps, &&ty: @ast::ty, print_colons: bool) {
       ast::ty_rptr(region, mt) {
         alt region.node {
           ast::re_anon { word(s.s, ~"&"); }
-          _ { print_region(s, region); word(s.s, ~"."); }
+          _ { print_region(s, region); word(s.s, ~"/"); }
         }
         print_mt(s, mt);
       }

src/rustc/metadata/tyencode.rs

@@ -272,7 +272,7 @@ fn enc_sty(w: io::writer, cx: @ctxt, st: ty::sty) {
         w.write_char('I');
         w.write_uint(id.to_uint());
       }
-      ty::ty_param(id, did) {
+      ty::ty_param({idx: id, def_id: did}) {
         w.write_char('p');
         w.write_str(cx.ds(did));
         w.write_char('|');

src/rustc/middle/kind.rs

@@ -115,7 +115,7 @@ fn with_appropriate_checker(cx: ctx, id: node_id, b: fn(check_fn)) {
     fn check_for_box(cx: ctx, id: node_id, fv: option<@freevar_entry>,
                      is_move: bool, var_t: ty::t, sp: span) {
         // all captured data must be owned
-        if !check_owned(cx, var_t, sp) { ret; }
+        if !check_owned(cx.tcx, var_t, sp) { ret; }
 
         // copied in data must be copyable, but moved in data can be anything
         let is_implicit = fv.is_some();
@@ -217,7 +217,13 @@ fn check_expr(e: @expr, cx: ctx, v: visit::vt<ctx>) {
     alt e.node {
       expr_assign(_, ex) |
       expr_unary(box(_), ex) | expr_unary(uniq(_), ex) |
-      expr_ret(some(ex)) | expr_cast(ex, _) { maybe_copy(cx, ex); }
+      expr_ret(some(ex)) {
+        maybe_copy(cx, ex);
+      }
+      expr_cast(source, _) {
+        maybe_copy(cx, source);
+        check_cast_for_escaping_regions(cx, source, e);
+      }
       expr_copy(expr) { check_copy_ex(cx, expr, false); }
       // Vector add copies, but not "implicitly"
       expr_assign_op(_, _, ex) { check_copy_ex(cx, ex, false) }
@@ -440,15 +446,92 @@ fn check_send(cx: ctx, ty: ty::t, sp: span) -> bool {
     }
 }
 
-fn check_owned(cx: ctx, ty: ty::t, sp: span) -> bool {
-    if !ty::kind_is_owned(ty::type_kind(cx.tcx, ty)) {
-        cx.tcx.sess.span_err(sp, ~"not an owned value");
+// note: also used from middle::typeck::regionck!
+fn check_owned(tcx: ty::ctxt, ty: ty::t, sp: span) -> bool {
+    if !ty::kind_is_owned(ty::type_kind(tcx, ty)) {
+        alt ty::get(ty).struct {
+          ty::ty_param(*) {
+            tcx.sess.span_err(sp, ~"value may contain borrowed \
+                                    pointers; use `owned` bound");
+          }
+          _ {
+            tcx.sess.span_err(sp, ~"value may contain borrowed \
+                                    pointers");
+          }
+        }
         false
     } else {
         true
     }
 }
 
+/// This is rather subtle.  When we are casting a value to a
+/// instantiated iface like `a as iface/&r`, regionck already ensures
+/// that any borrowed pointers that appear in the type of `a` are
+/// bounded by `&r`.  However, it is possible that there are *type
+/// parameters* in the type of `a`, and those *type parameters* may
+/// have borrowed pointers within them.  We have to guarantee that the
+/// regions which appear in those type parameters are not obscured.
+///
+/// Therefore, we ensure that one of three conditions holds:
+///
+/// (1) The iface instance cannot escape the current fn.  This is
+/// guaranteed if the region bound `&r` is some scope within the fn
+/// itself.  This case is safe because whatever borrowed pointers are
+/// found within the type parameter, they must enclose the fn body
+/// itself.
+///
+/// (2) The type parameter appears in the type of the iface.  For
+/// example, if the type parameter is `T` and the iface type is
+/// `deque<T>`, then whatever borrowed ptrs may appear in `T` also
+/// appear in `deque<T>`.
+///
+/// (3) The type parameter is owned (and therefore does not contain
+/// borrowed ptrs).
+fn check_cast_for_escaping_regions(
+    cx: ctx,
+    source: @expr,
+    target: @expr) {
+
+    // Determine what type we are casting to; if it is not an iface, then no
+    // worries.
+    let target_ty = ty::expr_ty(cx.tcx, target);
+    let target_substs = alt ty::get(target_ty).struct {
+      ty::ty_trait(_, substs) => {substs}
+      _ => { ret; /* not a cast to a trait */ }
+    };
+
+    // Check, based on the region associated with the iface, whether it can
+    // possibly escape the enclosing fn item (note that all type parameters
+    // must have been declared on the enclosing fn item):
+    alt target_substs.self_r {
+      some(ty::re_scope(*)) => { ret; /* case (1) */ }
+      none | some(ty::re_static) | some(ty::re_free(*)) => {}
+      some(ty::re_bound(*)) | some(ty::re_var(*)) => {
+        cx.tcx.sess.span_bug(
+            source.span,
+            #fmt["bad region found in kind: %?", target_substs.self_r]);
+      }
+    }
+
+    // Assuming the iface instance can escape, then ensure that each parameter
+    // either appears in the iface type or is owned:
+    let target_params = ty::param_tys_in_type(target_ty);
+    let source_ty = ty::expr_ty(cx.tcx, source);
+    do ty::walk_ty(source_ty) |ty| {
+        alt ty::get(ty).struct {
+          ty::ty_param(source_param) => {
+            if target_params.contains(source_param) {
+                /* case (2) */
+            } else {
+                check_owned(cx.tcx, ty, source.span); /* case (3) */
+            }
+          }
+          _ => {}
+        }
+    }
+}
+
 //
 // Local Variables:
 // mode: rust

src/rustc/middle/trans/base.rs

@@ -1317,7 +1317,7 @@ enum copy_action { INIT, DROP_EXISTING, }
 fn type_is_structural_or_param(t: ty::t) -> bool {
     if ty::type_is_structural(t) { ret true; }
     alt ty::get(t).struct {
-      ty::ty_param(_, _) { ret true; }
+      ty::ty_param(*) { ret true; }
       _ { ret false; }
     }
 }

src/rustc/middle/trans/reflect.rs

@@ -272,7 +272,7 @@ impl methods for reflector {
           ty::ty_trait(_, _) { self.leaf(~"trait") }
           ty::ty_var(_) { self.leaf(~"var") }
           ty::ty_var_integral(_) { self.leaf(~"var_integral") }
-          ty::ty_param(n, _) { self.visit(~"param", ~[self.c_uint(n)]) }
+          ty::ty_param(p) { self.visit(~"param", ~[self.c_uint(p.idx)]) }
           ty::ty_self { self.leaf(~"self") }
           ty::ty_type { self.leaf(~"type") }
           ty::ty_opaque_box { self.leaf(~"opaque_box") }

src/rustc/middle/trans/type_use.rs

@@ -137,8 +137,8 @@ fn type_needs_inner(cx: ctx, use: uint, ty: ty::t,
                 }
                 false
               }
-              ty::ty_param(n, _) {
-                cx.uses[n] |= use;
+              ty::ty_param(p) {
+                cx.uses[p.idx] |= use;
                 false
               }
               _ { true }