---

yaml
---
r: 20727
b: refs/heads/snap-stage3
c: 5d32d03
h: refs/heads/master
i:
  20725: c335e5b
  20723: ea7776a
  20719: 53d1509
v: v3

Author: nikomatsakis

[refs]

@@ -1,7 +1,7 @@
 ---
 refs/heads/master: e430a699f2c60890d9b86069fd0c68a70ece7120
 refs/heads/snap-stage1: e33de59e47c5076a89eadeb38f4934f58a3618a6
-refs/heads/snap-stage3: 6ef13e76e95ea67103a2bc4f4becc91dc290aafc
+refs/heads/snap-stage3: 5d32d03b892d67f2cc0574966b50b3eab4b8bd94
 refs/heads/try: ffbe0e0e00374358b789b0037bcb3a577cd218be
 refs/tags/release-0.1: 1f5c5126e96c79d22cb7862f75304136e204f105
 refs/heads/ndm: f3868061cd7988080c30d6d5bf352a5a5fe2460b

branches/snap-stage3/src/rustc/middle/astencode.rs

@@ -436,21 +436,6 @@ impl of tr for method_origin {
     }
 }
 
-// ______________________________________________________________________
-// Encoding and decoding of borrow
-
-trait read_borrow_helper {
-    fn read_borrow(xcx: extended_decode_ctxt) -> ty::borrow;
-}
-
-impl helper of read_borrow_helper for ebml::ebml_deserializer {
-    fn read_borrow(xcx: extended_decode_ctxt) -> ty::borrow {
-        let borrow = ty::deserialize_borrow(self);
-        {scope_id: xcx.tr_id(borrow.scope_id),
-         mutbl: borrow.mutbl}
-    }
-}
-
 // ______________________________________________________________________
 // Encoding and decoding vtable_res
 
@@ -766,11 +751,13 @@ fn encode_side_tables_for_id(ecx: @e::encode_ctxt,
         }
     }
 
-    do option::iter(tcx.borrowings.find(id)) |borrow| {
+    do option::iter(tcx.borrowings.find(id)) |_borrow| {
         do ebml_w.tag(c::tag_table_borrowings) {
             ebml_w.id(id);
             do ebml_w.tag(c::tag_table_val) {
-                ty::serialize_borrow(ebml_w, borrow)
+                // N.B. We don't actually serialize borrows as, in
+                // trans, we only care whether a value is borrowed or
+                // not.
             }
         }
     }
@@ -890,7 +877,10 @@ fn decode_side_tables(xcx: extended_decode_ctxt,
                 dcx.maps.vtable_map.insert(id,
                                            val_dsr.read_vtable_res(xcx));
             } else if tag == (c::tag_table_borrowings as uint) {
-                let borrow = val_dsr.read_borrow(xcx);
+                // N.B.: we don't actually *serialize* borrows because, in
+                // trans, the only thing we care about is whether a value was
+                // borrowed or not.
+                let borrow = {region: ty::re_static, mutbl: ast::m_imm};
                 dcx.tcx.borrowings.insert(id, borrow);
             } else {
                 xcx.dcx.tcx.sess.bug(

branches/snap-stage3/src/rustc/middle/borrowck.rs

@@ -321,9 +321,10 @@ type binding_map = std::map::hashmap<ast::node_id, ast::mutability>;
 enum bckerr_code {
     err_mut_uniq,
     err_mut_variant,
-    err_preserve_gc,
-    err_mutbl(ast::mutability,
-              ast::mutability)
+    err_root_not_permitted,
+    err_mutbl(ast::mutability, ast::mutability),
+    err_out_of_root_scope(ty::region, ty::region), // superscope, subscope
+    err_out_of_scope(ty::region, ty::region) // superscope, subscope
 }
 
 // Combination of an error code and the categorization of the expression
@@ -346,7 +347,7 @@ enum categorization {
 }
 
 // different kinds of pointers:
-enum ptr_kind {uniq_ptr, gc_ptr, region_ptr, unsafe_ptr}
+enum ptr_kind {uniq_ptr, gc_ptr, region_ptr(ty::region), unsafe_ptr}
 
 // I am coining the term "components" to mean "pieces of a data
 // structure accessible without a dereference":
@@ -391,10 +392,15 @@ enum loan_path {
     lp_comp(@loan_path, comp_kind)
 }
 
-// a complete record of a loan that was granted
+/// a complete record of a loan that was granted
 type loan = {lp: @loan_path, cmt: cmt, mutbl: ast::mutability};
 
-// maps computed by `gather_loans` that are then used by `check_loans`
+/// maps computed by `gather_loans` that are then used by `check_loans`
+///
+/// - `req_loan_map`: map from each block/expr to the required loans needed
+///   for the duration of that block/expr
+/// - `pure_map`: map from block/expr that must be pure to the error message
+///   that should be reported if they are not pure
 type req_maps = {
     req_loan_map: hashmap<ast::node_id, @dvec<@dvec<loan>>>,
     pure_map: hashmap<ast::node_id, bckerr>
@@ -519,7 +525,7 @@ impl to_str_methods for borrowck_ctxt {
         alt ptr {
           uniq_ptr { ~"~" }
           gc_ptr { ~"@" }
-          region_ptr { ~"&" }
+          region_ptr(_) { ~"&" }
           unsafe_ptr { ~"*" }
         }
     }
@@ -561,15 +567,6 @@ impl to_str_methods for borrowck_ctxt {
              ty_to_str(self.tcx, cmt.ty)]
     }
 
-    fn pk_to_sigil(pk: ptr_kind) -> ~str {
-        alt pk {
-          uniq_ptr {~"~"}
-          gc_ptr {~"@"}
-          region_ptr {~"&"}
-          unsafe_ptr {~"*"}
-        }
-    }
-
     fn cmt_to_str(cmt: cmt) -> ~str {
         let mut_str = self.mut_to_str(cmt.mutbl);
         alt cmt.cat {
@@ -584,7 +581,7 @@ impl to_str_methods for borrowck_ctxt {
           cat_binding(_) { ~"pattern binding" }
           cat_arg(_) { ~"argument" }
           cat_deref(_, _, pk) { #fmt["dereference of %s %s pointer",
-                                     mut_str, self.pk_to_sigil(pk)] }
+                                     mut_str, self.ptr_sigil(pk)] }
           cat_stack_upvar(_) {
             ~"captured outer " + mut_str + ~" variable in a stack closure"
           }
@@ -622,12 +619,30 @@ impl to_str_methods for borrowck_ctxt {
           err_mut_variant {
             ~"enum variant in aliasable, mutable location"
           }
-          err_preserve_gc {
-            ~"GC'd value would have to be preserved for longer \
-                 than the scope of the function"
+          err_root_not_permitted {
+            // note: I don't expect users to ever see this error
+            // message, reasons are discussed in attempt_root() in
+            // preserve.rs.
+            ~"rooting is not permitted"
+          }
+          err_out_of_root_scope(super_scope, sub_scope) {
+            #fmt["managed value would have to be rooted for lifetime %s, \
+                  but can only be rooted for lifetime %s",
+                 self.region_to_str(sub_scope),
+                 self.region_to_str(super_scope)]
+          }
+          err_out_of_scope(super_scope, sub_scope) {
+            #fmt["borrowed pointer has lifetime %s, \
+                  but the borrowed value only has lifetime %s",
+                 self.region_to_str(sub_scope),
+                 self.region_to_str(super_scope)]
           }
         }
     }
+
+    fn region_to_str(r: ty::region) -> ~str {
+        region_to_str(self.tcx, r)
+    }
 }
 
 // The inherent mutability of a component is its default mutability

branches/snap-stage3/src/rustc/middle/borrowck/categorization.rs

@@ -50,10 +50,10 @@ fn opt_deref_kind(t: ty::t) -> option<deref_kind> {
         some(deref_ptr(uniq_ptr))
       }
 
-      ty::ty_rptr(*) |
-      ty::ty_evec(_, ty::vstore_slice(_)) |
-      ty::ty_estr(ty::vstore_slice(_)) {
-        some(deref_ptr(region_ptr))
+      ty::ty_rptr(r, _) |
+      ty::ty_evec(_, ty::vstore_slice(r)) |
+      ty::ty_estr(ty::vstore_slice(r)) {
+        some(deref_ptr(region_ptr(r)))
       }
 
       ty::ty_box(*) |
@@ -343,7 +343,7 @@ impl public_methods for borrowck_ctxt {
                     // not loanable.
                     alt ptr {
                       uniq_ptr => {some(@lp_deref(l, ptr))}
-                      gc_ptr | region_ptr | unsafe_ptr => {none}
+                      gc_ptr | region_ptr(_) | unsafe_ptr => {none}
                     }
                 };
 
@@ -353,7 +353,7 @@ impl public_methods for borrowck_ctxt {
                   uniq_ptr => {
                     self.inherited_mutability(base_cmt.mutbl, mt.mutbl)
                   }
-                  gc_ptr | region_ptr | unsafe_ptr => {
+                  gc_ptr | region_ptr(_) | unsafe_ptr => {
                     mt.mutbl
                   }
                 };
@@ -402,7 +402,7 @@ impl public_methods for borrowck_ctxt {
               uniq_ptr => {
                 self.inherited_mutability(base_cmt.mutbl, mt.mutbl)
               }
-              gc_ptr | region_ptr | unsafe_ptr => {
+              gc_ptr | region_ptr(_) | unsafe_ptr => {
                 mt.mutbl
               }
             };