rustc: Add some simple region checking (no region vars yet)

Amazingly, this causes no test cases to fail!

Author: pcwalton

src/rustc/middle/infer.rs

@@ -294,9 +294,41 @@ impl unify_methods for infer_ctxt {
         iter2(as, bs) {|a,b| self.tys(a,b) }
     }
 
-    fn regions(_a: ty::region, _b: ty::region) -> ures {
-        // FIXME: pcwalton!
-        self.uok()
+    fn regions(a: ty::region, b: ty::region) -> ures {
+        alt (a, b) {
+          (ty::re_var(_), _) | (_, ty::re_var(_)) {
+            self.uok()  // FIXME: We need region variables!
+          }
+          (ty::re_inferred, _) | (_, ty::re_inferred) {
+            fail "tried to unify inferred regions"
+          }
+          (ty::re_param(_), ty::re_param(_)) |
+          (ty::re_self, ty::re_self) {
+            if a == b {
+                self.uok()
+            } else {
+                self.uerr(ty::terr_regions_differ(false, a, b))
+            }
+          }
+          (ty::re_param(_), ty::re_block(_)) |
+          (ty::re_self, ty::re_block(_)) {
+            self.uok()
+          }
+          (ty::re_block(_), ty::re_param(_)) |
+          (ty::re_block(_), ty::re_self) {
+            self.uerr(ty::terr_regions_differ(false, a, b))
+          }
+          (ty::re_block(superblock), ty::re_block(subblock)) {
+            // The region corresponding to an outer block is a subtype of the
+            // region corresponding to an inner block.
+            let rm = self.tcx.region_map;
+            if region::scope_contains(rm, subblock, superblock) {
+                self.uok()
+            } else {
+                self.uerr(ty::terr_regions_differ(false, a, b))
+            }
+          }
+        }
     }
 
     fn mts(a: ty::mt, b: ty::mt) -> ures {
@@ -650,4 +682,4 @@ impl resolve_methods for infer_ctxt {
           some(var_id) { ret self.rerr(var_id); }
         }
     }
-}
+}

src/rustc/middle/ty.rs

@@ -1682,59 +1682,9 @@ mod unify {
     }
 
     fn unify_regions<T:copy>(
-        cx: @uctxt, e_region: region, a_region: region,
-        nxt: fn(region) -> ures<T>) -> ures<T> {
-        let sub = a_region, super = e_region;
-
-        // FIXME: Should have a way of unifying regions that relies on bounds,
-        // not on unification.
-        alt (super, sub) {
-            (ty::re_var(superkey), ty::re_var(subkey)) {
-                ret union_region_sets(cx, subkey, superkey,
-                                      {|| nxt(sub) });
-            }
-            (ty::re_var(superkey), _) {
-                ret record_region_binding(cx, superkey, sub, nxt);
-            }
-            (_, ty::re_var(subkey)) {
-                ret record_region_binding(cx, subkey, super, nxt);
-            }
-            _ { /* fall through */ }
-        }
-
-        alt (super, sub) {
-            (ty::re_var(_), _) | (_, ty::re_var(_)) {
-                fail "should have been handled above";
-            }
-            (ty::re_inferred, _) | (_, ty::re_inferred) {
-                fail "tried to unify inferred regions";
-            }
-            (ty::re_param(_), ty::re_param(_)) |
-            (ty::re_self, ty::re_self) {
-                ret if super == sub {
-                    nxt(ty::re_self)
-                } else {
-                    err(terr_regions_differ(false, super, sub))
-                };
-            }
-            (ty::re_param(_), ty::re_block(_)) |
-            (ty::re_self, ty::re_block(_)) {
-                ret nxt(super);
-            }
-            (ty::re_block(_), ty::re_param(_)) |
-            (ty::re_block(_), ty::re_self) {
-                ret err(terr_regions_differ(false, super, sub));
-            }
-            (ty::re_block(superblock), ty::re_block(subblock)) {
-                // Outer regions are subtypes of inner regions. (This is
-                // somewhat surprising!)
-                let rm = cx.tcx.region_map;
-                if region::scope_contains(rm, subblock, superblock) {
-                    ret nxt(super);
-                }
-                ret err(terr_regions_differ(false, sub, super));
-            }
-        }
+            _cx: @uctxt, _e_region: region, _a_region: region,
+            _nxt: fn(region) -> ures<T>) -> ures<T> {
+        fail;   // unused
     }
 }