rustc: Introduce re_params into the typechecker

This is the first step of the region refactoring I need to do in order to handle named regions properly.

src/rustc/metadata/tyencode.rs

@@ -106,7 +106,9 @@ fn enc_region(w: io::writer, cx: @ctxt, r: ty::region) {
         ty::re_self(did) {
             w.write_char('s'); w.write_str(cx.ds(did)); w.write_char('|');
         }
-        ty::re_inferred { w.write_char('?'); }
+        ty::re_param(id) {
+            w.write_char('p'); w.write_uint(id); w.write_char('|');
+        }
     }
 }
 fn enc_sty(w: io::writer, cx: @ctxt, st: ty::sty) {

src/rustc/middle/region.rs

@@ -80,7 +80,7 @@ fn region_to_scope(region_map: @region_map, region: ty::region)
         ty::re_caller(def_id) | ty::re_self(def_id) { def_id.node }
         ty::re_named(def_id) { region_map.region_name_to_fn.get(def_id) }
         ty::re_block(node_id) { node_id }
-        ty::re_inferred { fail "unresolved region in region_to_scope" }
+        ty::re_param(_) { fail "unresolved region in region_to_scope" }
     };
 }
 
@@ -109,7 +109,7 @@ fn get_inferred_region(cx: ctxt, sp: syntax::codemap::span) -> ty::region {
             ty::re_caller({crate: ast::local_crate, node: item_id})
         }
         pa_block(block_id) { ty::re_block(block_id) }
-        pa_item(_) { ty::re_inferred }
+        pa_item(_) { ty::re_param(0u) }
         pa_crate { cx.sess.span_bug(sp, "inferred region at crate level?!"); }
     }
 }

src/rustc/middle/regionck.rs

@@ -51,7 +51,7 @@ fn check_expr(expr: @ast::expr, cx: ctxt, visitor: visit::vt<ctxt>) {
                                                      "escapes its block");
                             }
                         }
-                        ty::re_inferred {
+                        ty::re_param(_) {
                             cx.tcx.sess.span_bug(expr.span,
                                                  "unresolved region");
                         }

src/rustc/middle/ty.rs

@@ -89,7 +89,7 @@ export ty_uint, mk_uint, mk_mach_uint;
 export ty_uniq, mk_uniq, mk_imm_uniq, type_is_unique_box;
 export ty_var, mk_var;
 export ty_self, mk_self;
-export region, re_named, re_caller, re_block, re_inferred;
+export region, re_named, re_caller, re_block, re_param;
 export get, type_has_params, type_has_vars, type_has_rptrs, type_id;
 export same_type;
 export ty_var_id;
@@ -242,7 +242,10 @@ enum region {
     re_caller(def_id),
     re_self(def_id),
     re_block(node_id),
-    re_inferred         /* currently unresolved (for typedefs) */
+
+    // A region parameter. Currently used only for typedefs.
+    // TODO: Use this for caller and named regions as well.
+    re_param(uint)
 }
 
 // NB: If you change this, you'll probably want to change the corresponding
@@ -1163,7 +1166,7 @@ fn hash_type_structure(st: sty) -> uint {
           re_caller(_)  { 2u }
           re_self(_)    { 3u }
           re_block(_)   { 4u }
-          re_inferred   { 5u }
+          re_param(_)   { 5u }
         }
     }
     alt st {
@@ -1928,12 +1931,17 @@ mod unify {
             }
         }
 
-        if sub == ty::re_inferred || super == ty::re_inferred {
+        // FIXME: This is wrong. We should be keeping a set of region bindings
+        // around.
+        alt (sub, super) {
+            (ty::re_param(_), _) | (_, ty::re_param(_)) {
                 ret if sub == super {
                     nxt(super)
                 } else {
                     err(terr_regions_differ(true, super, sub))
-            };
+                }
+            }
+            _ { /* fall through */ }
         }
 
         // Outer regions are subtypes of inner regions. (This is somewhat

src/rustc/middle/typeck.rs

@@ -256,7 +256,8 @@ fn ast_ty_to_ty(tcx: ty::ctxt, mode: mode, &&ast_ty: @ast::ty) -> ty::t {
                               ty: ty::t) -> ty::t {
         ret ty::fold_ty(tcx, ty::fm_rptr({|r|
             alt r {
-                ty::re_inferred | ty::re_self(_) {
+                // FIXME: This is probably wrong for params.
+                ty::re_param(_) | ty::re_self(_) {
                     tcx.region_map.ast_type_to_inferred_region.get(use_site)
                 }
                 _ { r }
@@ -356,7 +357,11 @@ fn ast_ty_to_ty(tcx: ty::ctxt, mode: mode, &&ast_ty: @ast::ty) -> ty::t {
                     let attir = tcx.region_map.ast_type_to_inferred_region;
                     alt attir.find(ast_ty.id) {
                         some(resolved_region) { resolved_region }
-                        none { ty::re_inferred }
+                        none {
+                            // FIXME: Shouldn't be 0u and should instead be
+                            // a fresh variable.
+                            ty::re_param(0u)
+                        }
                     }
                 }
                 ast::re_named(_) | ast::re_self {
@@ -1488,7 +1493,8 @@ fn instantiate_self_regions(tcx: ty::ctxt, region: ty::region, &&ty: ty::t)
     if ty::type_has_rptrs(ty) {
         ty::fold_ty(tcx, ty::fm_rptr({|r|
             alt r {
-                ty::re_inferred | ty::re_caller(_) | ty::re_self(_) { region }
+                // FIXME: Should not happen for re_param.
+                ty::re_param(_) | ty::re_caller(_) | ty::re_self(_) { region }
                 _ { r }
             }
         }), ty)
@@ -1502,7 +1508,10 @@ fn instantiate_self_regions(tcx: ty::ctxt, region: ty::region, &&ty: ty::t)
 // refer to inferred regions.
 fn universally_quantify_regions(tcx: ty::ctxt, ty: ty::t) -> ty::t {
     if ty::type_has_rptrs(ty) {
-        ty::fold_ty(tcx, ty::fm_rptr({|_r| ty::re_inferred}), ty)
+        ty::fold_ty(tcx, ty::fm_rptr({|_r|
+            // FIXME: Very wrong. Shouldn't be 0u.
+            ty::re_param(0u)
+        }), ty)
     } else {
         ty
     }