implement evec/estr subtyping/lub/glb/etc

Author: nikomatsakis

src/rustc/middle/infer.rs

@@ -896,6 +896,8 @@ iface combine {
     fn ret_styles(r1: ret_style, r2: ret_style) -> cres<ret_style>;
     fn contraregions(a: ty::region, b: ty::region) -> cres<ty::region>;
     fn regions(a: ty::region, b: ty::region) -> cres<ty::region>;
+    fn vstores(vk: ty::terr_vstore_kind,
+               a: ty::vstore, b: ty::vstore) -> cres<ty::vstore>;
 }
 
 enum sub = infer_ctxt;  // "subtype", "subregion" etc
@@ -951,6 +953,27 @@ fn super_args<C:combine>(
     }
 }
 
+fn super_vstores<C:combine>(
+    self: C, vk: ty::terr_vstore_kind,
+    a: ty::vstore, b: ty::vstore) -> cres<ty::vstore> {
+
+    alt (a, b) {
+      (ty::vstore_slice(a_r), ty::vstore_slice(b_r)) {
+        self.contraregions(a_r, b_r).chain {|r|
+            ok(ty::vstore_slice(r))
+        }
+      }
+
+      _ if a == b {
+        ok(a)
+      }
+
+      _ {
+        err(ty::terr_vstores_differ(vk, b, a))
+      }
+    }
+}
+
 fn super_fns<C:combine>(
     self: C, a_f: ty::fn_ty, b_f: ty::fn_ty) -> cres<ty::fn_ty> {
 
@@ -1070,15 +1093,20 @@ fn super_tys<C:combine>(
         }
       }
 
-      (ty::ty_evec(a_mt, ty::vstore_slice(a_r)),
-       ty::ty_evec(b_mt, ty::vstore_slice(b_r))) {
-        self.contraregions(a_r, b_r).chain {|r|
-            self.mts(a_mt, b_mt).chain {|mt|
-                ok(ty::mk_evec(tcx, mt, ty::vstore_slice(r)))
+      (ty::ty_evec(a_mt, vs_a), ty::ty_evec(b_mt, vs_b)) {
+        self.mts(a_mt, b_mt).chain {|mt|
+            self.vstores(ty::terr_vec, vs_a, vs_b).chain {|vs|
+                ok(ty::mk_evec(tcx, mt, vs))
             }
         }
       }
 
+      (ty::ty_estr(vs_a), ty::ty_estr(vs_b)) {
+        self.vstores(ty::terr_str, vs_a, vs_b).chain {|vs|
+            ok(ty::mk_estr(tcx,vs))
+        }
+      }
+
       (ty::ty_res(a_id, a_t, a_tps), ty::ty_res(b_id, b_t, b_tps))
       if a_id == b_id {
         self.tys(a_t, b_t).chain {|t|
@@ -1234,6 +1262,11 @@ impl of combine for sub {
         super_flds(self, a, b)
     }
 
+    fn vstores(vk: ty::terr_vstore_kind,
+               a: ty::vstore, b: ty::vstore) -> cres<ty::vstore> {
+        super_vstores(self, vk, a, b)
+    }
+
     fn modes(a: ast::mode, b: ast::mode) -> cres<ast::mode> {
         super_modes(self, a, b)
     }
@@ -1402,6 +1435,11 @@ impl of combine for lub {
         super_flds(self, a, b)
     }
 
+    fn vstores(vk: ty::terr_vstore_kind,
+               a: ty::vstore, b: ty::vstore) -> cres<ty::vstore> {
+        super_vstores(self, vk, a, b)
+    }
+
     fn modes(a: ast::mode, b: ast::mode) -> cres<ast::mode> {
         super_modes(self, a, b)
     }
@@ -1587,6 +1625,11 @@ impl of combine for glb {
         super_flds(self, a, b)
     }
 
+    fn vstores(vk: ty::terr_vstore_kind,
+               a: ty::vstore, b: ty::vstore) -> cres<ty::vstore> {
+        super_vstores(self, vk, a, b)
+    }
+
     fn modes(a: ast::mode, b: ast::mode) -> cres<ast::mode> {
         super_modes(self, a, b)
     }

src/rustc/middle/trans/base.rs

@@ -2616,7 +2616,7 @@ fn trans_arg_expr(cx: block, arg: ty::arg, lldestty: TypeRef, e: @ast::expr,
     ret rslt(bcx, val);
 }
 
-fn adapt_borrowed_value(lv: lval_result, arg: ty::arg,
+fn adapt_borrowed_value(lv: lval_result, _arg: ty::arg,
                         e: @ast::expr) -> lval_result {
     let bcx = lv.bcx;
     if !expr_is_borrowed(bcx, e) { ret lv; }

src/rustc/middle/ty.rs

@@ -11,6 +11,7 @@ import syntax::codemap::span;
 import metadata::csearch;
 import util::common::*;
 import util::ppaux::region_to_str;
+import util::ppaux::vstore_to_str;
 import util::ppaux::ty_to_str;
 import util::ppaux::ty_constr_to_str;
 import syntax::print::pprust::*;
@@ -105,7 +106,7 @@ export ty_fn_args;
 export type_constr;
 export kind, kind_sendable, kind_copyable, kind_noncopyable;
 export kind_can_be_copied, kind_can_be_sent, proto_kind, kind_lteq, type_kind;
-export type_err;
+export type_err, terr_vstore_kind;
 export type_err_to_str;
 export type_needs_drop;
 export type_allows_implicit_copy;
@@ -328,6 +329,10 @@ type constr_general<ARG> = spanned<constr_general_<ARG, def_id>>;
 type type_constr = constr_general<@path>;
 type constr = constr_general<uint>;
 
+enum terr_vstore_kind {
+    terr_vec, terr_str
+}
+
 // Data structures used in type unification
 enum type_err {
     terr_mismatch,
@@ -348,6 +353,7 @@ enum type_err {
     terr_constr_len(uint, uint),
     terr_constr_mismatch(@type_constr, @type_constr),
     terr_regions_differ(region, region),
+    terr_vstores_differ(terr_vstore_kind, vstore, vstore),
     terr_in_field(@type_err, str),
     terr_sorts(t, t)
 }
@@ -1976,6 +1982,10 @@ fn ty_sort_str(cx: ctxt, t: t) -> str {
 }
 
 fn type_err_to_str(cx: ctxt, err: type_err) -> str {
+    fn terr_vstore_kind_to_str(k: terr_vstore_kind) -> str {
+        alt k { terr_vec { "[]" } terr_str { "str" } }
+    }
+
     alt err {
       terr_mismatch { ret "types differ"; }
       terr_ret_style_mismatch(expect, actual) {
@@ -2038,6 +2048,12 @@ fn type_err_to_str(cx: ctxt, err: type_err) -> str {
                  region_to_str(cx, subregion),
                  region_to_str(cx, superregion));
       }
+      terr_vstores_differ(k, e_vs, a_vs) {
+        ret #fmt("%s storage differs: expected %s but found %s",
+                 terr_vstore_kind_to_str(k),
+                 vstore_to_str(cx, e_vs),
+                 vstore_to_str(cx, a_vs));
+      }
       terr_in_field(err, fname) {
         ret #fmt("in field `%s`, %s", fname, type_err_to_str(cx, *err));
       }

src/test/compile-fail/estr-subtyping.rs

@@ -0,0 +1,30 @@
+fn wants_box(x: str/@) { }
+fn wants_uniq(x: str/~) { }
+fn wants_three(x: str/3) { }
+
+fn has_box(x: str/@) {
+   wants_box(x);
+   wants_uniq(x); //! ERROR str storage differs: expected ~ but found @
+   wants_three(x); //! ERROR str storage differs: expected 3 but found @
+}
+
+fn has_uniq(x: str/~) {
+   wants_box(x); //! ERROR str storage differs: expected @ but found ~
+   wants_uniq(x);
+   wants_three(x); //! ERROR str storage differs: expected 3 but found ~
+}
+
+fn has_three(x: str/3) {
+   wants_box(x); //! ERROR str storage differs: expected @ but found 3
+   wants_uniq(x); //! ERROR str storage differs: expected ~ but found 3
+   wants_three(x);
+}
+
+fn has_four(x: str/4) {
+   wants_box(x); //! ERROR str storage differs: expected @ but found 4
+   wants_uniq(x); //! ERROR str storage differs: expected ~ but found 4
+   wants_three(x); //! ERROR str storage differs: expected 3 but found 4
+}
+
+fn main() {
+}

src/test/compile-fail/evec-subtyping.rs

@@ -0,0 +1,30 @@
+fn wants_box(x: [uint]/@) { }
+fn wants_uniq(x: [uint]/~) { }
+fn wants_three(x: [uint]/3) { }
+
+fn has_box(x: [uint]/@) {
+   wants_box(x);
+   wants_uniq(x); //! ERROR [] storage differs: expected ~ but found @
+   wants_three(x); //! ERROR [] storage differs: expected 3 but found @
+}
+
+fn has_uniq(x: [uint]/~) {
+   wants_box(x); //! ERROR [] storage differs: expected @ but found ~
+   wants_uniq(x);
+   wants_three(x); //! ERROR [] storage differs: expected 3 but found ~
+}
+
+fn has_three(x: [uint]/3) {
+   wants_box(x); //! ERROR [] storage differs: expected @ but found 3
+   wants_uniq(x); //! ERROR [] storage differs: expected ~ but found 3
+   wants_three(x);
+}
+
+fn has_four(x: [uint]/4) {
+   wants_box(x); //! ERROR [] storage differs: expected @ but found 4
+   wants_uniq(x); //! ERROR [] storage differs: expected ~ but found 4
+   wants_three(x); //! ERROR [] storage differs: expected 3 but found 4
+}
+
+fn main() {
+}