Add a session field to ty_ctxt and change an err to span_err

I changed instantiate to print out a more helpful error message,
which required passing it a session argument. To avoid
threading extra arguments through a lot of functions,
I added a session field to ty_ctxt.

src/comp/driver/rustc.rs

@@ -80,8 +80,8 @@ fn compile_input(session.session sess,
     crate = resolve.resolve_crate(sess, crate);
     capture.check_for_captures(sess, crate);
 
-    auto ty_cx = ty.mk_ctxt();
+    auto ty_cx = ty.mk_ctxt(sess);
-    auto typeck_result = typeck.check_crate(sess, ty_cx, crate);
+    auto typeck_result = typeck.check_crate(ty_cx, crate);
     crate = typeck_result._0;
     auto type_cache = typeck_result._1;
     // FIXME: uncomment once typestate_check works

src/comp/middle/ty.rs

@@ -46,7 +46,7 @@ type mt = rec(t ty, ast.mutability mut);
 
 // Contains information needed to resolve types and (in the future) look up
 // the types of AST nodes.
-type ctxt = rec(@type_store ts);
+type ctxt = rec(@type_store ts, session.session sess);
 type ty_ctxt = ctxt;    // Needed for disambiguation from Unify.ctxt.
 
 // Convert from method type to function type.  Pretty easy; we just drop
@@ -200,7 +200,7 @@ fn mk_type_store() -> @type_store {
              others=map.mk_hashmap[t,t](hasher, eqer));
 }
 
-fn mk_ctxt() -> ctxt { ret rec(ts=mk_type_store()); }
+fn mk_ctxt(session.session s) -> ctxt { ret rec(ts=mk_type_store(), sess=s); }
 
 // Type constructors
 

src/comp/middle/typeck.rs

@@ -106,7 +106,7 @@ fn substitute_ty_params(&@crate_ctxt ccx,
 
 
 // Returns the type parameter count and the type for the given definition.
-fn ty_param_count_and_ty_for_def(@fn_ctxt fcx, &ast.def defn)
+fn ty_param_count_and_ty_for_def(@fn_ctxt fcx, &ast.span sp, &ast.def defn)
         -> ty_param_count_and_ty {
     alt (defn) {
         case (ast.def_arg(?id)) {
@@ -157,7 +157,7 @@ fn ty_param_count_and_ty_for_def(@fn_ctxt fcx, &ast.def defn)
         }
 
         case (ast.def_ty(_)) {
-            fcx.ccx.sess.err("expected value but found type");
+            fcx.ccx.sess.span_err(sp, "expected value but found type");
             fail;
         }
 
@@ -308,7 +308,10 @@ fn ast_ty_to_ty(ty.ctxt tcx, ty_getter getter, &@ast.ty ast_ty) -> ty.t {
                     typ = instantiate(tcx, getter, id, path.node.types);
                 }
                 case (ast.def_ty_arg(?id)) { typ = ty.mk_param(tcx, id); }
-                case (_)                   { fail; }
+                case (_)                   { 
+                    tcx.sess.span_err(ast_ty.span,
+                       "found type name used as a variable");
+                    fail; }
             }
 
             cname = some(path_to_str(path));
@@ -1839,7 +1842,7 @@ fn check_expr(&@fn_ctxt fcx, @ast.expr expr) -> @ast.expr {
             check (defopt != none[ast.def]);
             auto defn = option.get[ast.def](defopt);
 
-            auto tpt = ty_param_count_and_ty_for_def(fcx, defn);
+            auto tpt = ty_param_count_and_ty_for_def(fcx, expr.span, defn);
 
             if (ty.def_has_ty_params(defn)) {
                 auto ann = instantiate_path(fcx, pth, tpt, expr.span);
@@ -2623,13 +2626,15 @@ fn check_stmt(&@fn_ctxt fcx, &@ast.stmt stmt) -> @ast.stmt {
                 case (ast.decl_local(_)) {
                     auto decl_1 = check_decl_local(fcx, decl);
                     ret @fold.respan[ast.stmt_](stmt.span,
-                           ast.stmt_decl(decl_1, plain_ann(fcx.ccx.tystore)));
+                           ast.stmt_decl(decl_1,
+                             plain_ann(fcx.ccx.tcx)));
                 }
 
                 case (ast.decl_item(_)) {
                     // Ignore for now. We'll return later.
                     ret @fold.respan[ast.stmt_](stmt.span,
-                           ast.stmt_decl(decl, plain_ann(fcx.ccx.tystore)));
+                           ast.stmt_decl(decl,
+                             plain_ann(fcx.ccx.tcx)));
                 }
             }
 
@@ -2641,7 +2646,7 @@ fn check_stmt(&@fn_ctxt fcx, &@ast.stmt stmt) -> @ast.stmt {
             expr_t = Pushdown.pushdown_expr(fcx, expr_ty(fcx.ccx.tcx, expr_t),
                                             expr_t);
             ret @fold.respan[ast.stmt_](stmt.span,
-                   ast.stmt_expr(expr_t, plain_ann(fcx.ccx.tystore)));
+                   ast.stmt_expr(expr_t, plain_ann(fcx.ccx.tcx)));
         }
     }
 
@@ -2790,8 +2795,9 @@ fn eq_unify_cache_entry(&unify_cache_entry a, &unify_cache_entry b) -> bool {
 
 type typecheck_result = tup(@ast.crate, ty.type_cache);
 
-fn check_crate(session.session sess, ty.ctxt tcx, @ast.crate crate)
+fn check_crate(ty.ctxt tcx, @ast.crate crate)
         -> typecheck_result {
+    auto sess = tcx.sess;
     auto result = Collect.collect_item_types(sess, tcx, crate);
 
     let vec[ast.obj_field] fields = vec();