Use trans_expr_save_in instead of trans_expr when appropriate

This guards against passing a save_in destination to nil or bot-typed things.

Author: marijnh

src/comp/middle/trans.rs

@@ -4272,7 +4272,7 @@ fn trans_temp_lval(bcx: @block_ctxt, e: @ast::expr) -> lval_result {
             ret {bcx: bcx, val: *cell, kind: temporary};
         } else {
             let {bcx, val: scratch} = alloc_ty(bcx, ty);
-            bcx = trans_expr(bcx, e, save_in(scratch));
+            bcx = trans_expr_save_in(bcx, e, scratch);
             add_clean_temp(bcx, scratch, ty);
             ret {bcx: bcx, val: scratch, kind: temporary};
         }

src/comp/middle/trans_objects.rs

@@ -370,7 +370,7 @@ fn trans_anon_obj(bcx: @block_ctxt, sp: span, anon_obj: ast::anon_obj,
             check type_is_tup_like(bcx, body_ty);
             let {bcx: cx, val: body_inner_obj} = GEP_tup_like
                 (bcx, body_ty, body, [0, abi::obj_body_elt_inner_obj]);
-            bcx = trans_expr(cx, e, save_in(body_inner_obj));
+            bcx = trans_expr_save_in(cx, e, body_inner_obj);
           }
         }
         revoke_clean(bcx, box);