From 0837a6ba04bd3cf8330901678dc38b6f2c953f20 Mon Sep 17 00:00:00 2001
From: Patrick Walton <pcwalton@mimiga.net>
Date: Tue, 13 Mar 2012 14:12:44 -0700
Subject: [PATCH] rustc: Don't cache ast_ty_to_ty results for types that have
 references

---
 src/rustc/middle/ty.rs     | 10 +++++++++-
 src/rustc/middle/typeck.rs | 18 ++++++++++++------
 2 files changed, 21 insertions(+), 7 deletions(-)

diff --git a/src/rustc/middle/ty.rs b/src/rustc/middle/ty.rs
index 7e0e94ef494f..ea5347a60745 100644
--- a/src/rustc/middle/ty.rs
+++ b/src/rustc/middle/ty.rs
@@ -135,6 +135,8 @@ export param_bounds_to_kind;
 export default_arg_mode_for_ty;
 export item_path;
 export item_path_str;
+export ast_ty_to_ty_cache_entry;
+export atttce_unresolved, atttce_resolved, atttce_has_regions;
 
 // Data types
 
@@ -162,6 +164,12 @@ type creader_cache = hashmap<{cnum: int, pos: uint, len: uint}, t>;
 
 type intern_key = {struct: sty, o_def_id: option<ast::def_id>};
 
+enum ast_ty_to_ty_cache_entry {
+    atttce_unresolved,  /* not resolved yet */
+    atttce_resolved(t), /* resolved to a type, irrespective of region */
+    atttce_has_regions  /* has regions; cannot be cached */
+}
+
 type ctxt =
     @{interner: hashmap<intern_key, t_box>,
       mutable next_id: uint,
@@ -177,7 +185,7 @@ type ctxt =
       short_names_cache: hashmap<t, @str>,
       needs_drop_cache: hashmap<t, bool>,
       kind_cache: hashmap<t, kind>,
-      ast_ty_to_ty_cache: hashmap<@ast::ty, option<t>>,
+      ast_ty_to_ty_cache: hashmap<@ast::ty, ast_ty_to_ty_cache_entry>,
       enum_var_cache: hashmap<def_id, @[variant_info]>,
       iface_method_cache: hashmap<def_id, @[method]>,
       ty_param_bounds: hashmap<ast::node_id, param_bounds>,
diff --git a/src/rustc/middle/typeck.rs b/src/rustc/middle/typeck.rs
index ba27c84a017b..337b22663856 100644
--- a/src/rustc/middle/typeck.rs
+++ b/src/rustc/middle/typeck.rs
@@ -270,16 +270,16 @@ fn ast_ty_to_ty(tcx: ty::ctxt, mode: mode, &&ast_ty: @ast::ty) -> ty::t {
         }
     }
     alt tcx.ast_ty_to_ty_cache.find(ast_ty) {
-      some(some(ty)) { ret ty; }
-      some(none) {
+      some(ty::atttce_resolved(ty)) { ret ty; }
+      some(ty::atttce_unresolved) {
         tcx.sess.span_fatal(ast_ty.span, "illegal recursive type. \
                                           insert a enum in the cycle, \
                                           if this is desired)");
       }
-      none { }
-    } /* go on */
+      some(ty::atttce_has_regions) | none { /* go on */ }
+    }
 
-    tcx.ast_ty_to_ty_cache.insert(ast_ty, none::<ty::t>);
+    tcx.ast_ty_to_ty_cache.insert(ast_ty, ty::atttce_unresolved);
     fn ast_mt_to_mt(tcx: ty::ctxt, mode: mode, mt: ast::mt) -> ty::mt {
         ret {ty: ast_ty_to_ty(tcx, mode, mt.ty), mutbl: mt.mutbl};
     }
@@ -425,7 +425,13 @@ fn ast_ty_to_ty(tcx: ty::ctxt, mode: mode, &&ast_ty: @ast::ty) -> ty::t {
                                 "found `ty_mac` in unexpected place");
       }
     };
-    tcx.ast_ty_to_ty_cache.insert(ast_ty, some(typ));
+
+    if ty::type_has_rptrs(typ) {
+        tcx.ast_ty_to_ty_cache.insert(ast_ty, ty::atttce_has_regions);
+    } else {
+        tcx.ast_ty_to_ty_cache.insert(ast_ty, ty::atttce_resolved(typ));
+    }
+
     ret typ;
 }