deduplicate erase_regions

there is no need for 3 versions of the function

src/librustc/middle/infer/mod.rs

@@ -503,7 +503,7 @@ pub fn normalize_associated_type<'tcx,T>(tcx: &ty::ctxt<'tcx>, value: &T) -> T
 {
     debug!("normalize_associated_type(t={:?})", value);
 
-    let value = erase_regions(tcx, value);
+    let value = tcx.erase_regions(value);
 
     if !value.has_projection_types() {
         return value;
@@ -525,17 +525,15 @@ pub fn normalize_associated_type<'tcx,T>(tcx: &ty::ctxt<'tcx>, value: &T) -> T
         fulfill_cx.register_predicate_obligation(&infcx, obligation);
     }
 
-    let result = drain_fulfillment_cx_or_panic(DUMMY_SP, &infcx, &mut fulfill_cx, &result);
-
-    result
+    drain_fulfillment_cx_or_panic(DUMMY_SP, &infcx, &mut fulfill_cx, &result)
 }
 
 pub fn drain_fulfillment_cx_or_panic<'a,'tcx,T>(span: Span,
                                                 infcx: &InferCtxt<'a,'tcx>,
                                                 fulfill_cx: &mut traits::FulfillmentContext<'tcx>,
                                                 result: &T)
                                                 -> T
-    where T : TypeFoldable<'tcx>
+    where T : TypeFoldable<'tcx> + HasTypeFlags
 {
     match drain_fulfillment_cx(infcx, fulfill_cx, result) {
         Ok(v) => v,
@@ -559,7 +557,7 @@ pub fn drain_fulfillment_cx<'a,'tcx,T>(infcx: &InferCtxt<'a,'tcx>,
                                        fulfill_cx: &mut traits::FulfillmentContext<'tcx>,
                                        result: &T)
                                        -> Result<T,Vec<traits::FulfillmentError<'tcx>>>
-    where T : TypeFoldable<'tcx>
+    where T : TypeFoldable<'tcx> + HasTypeFlags
 {
     debug!("drain_fulfillment_cx(result={:?})",
            result);
@@ -574,71 +572,8 @@ pub fn drain_fulfillment_cx<'a,'tcx,T>(infcx: &InferCtxt<'a,'tcx>,
         }
     }
 
-    // Use freshen to simultaneously replace all type variables with
-    // their bindings and replace all regions with 'static.  This is
-    // sort of overkill because we do not expect there to be any
-    // unbound type variables, hence no `TyFresh` types should ever be
-    // inserted.
-    Ok(result.fold_with(&mut infcx.freshener()))
-}
-
-/// Returns an equivalent value with all free regions removed (note
-/// that late-bound regions remain, because they are important for
-/// subtyping, but they are anonymized and normalized as well). This
-/// is a stronger, caching version of `ty::fold::erase_regions`.
-pub fn erase_regions<'tcx,T>(cx: &ty::ctxt<'tcx>, value: &T) -> T
-    where T : TypeFoldable<'tcx>
-{
-    let value1 = value.fold_with(&mut RegionEraser(cx));
-    debug!("erase_regions({:?}) = {:?}",
-           value, value1);
-    return value1;
-
-    struct RegionEraser<'a, 'tcx: 'a>(&'a ty::ctxt<'tcx>);
-
-    impl<'a, 'tcx> TypeFolder<'tcx> for RegionEraser<'a, 'tcx> {
-        fn tcx(&self) -> &ty::ctxt<'tcx> { self.0 }
-
-        fn fold_ty(&mut self, ty: Ty<'tcx>) -> Ty<'tcx> {
-            match self.tcx().normalized_cache.borrow().get(&ty).cloned() {
-                None => {}
-                Some(u) => return u
-            }
-
-            let t_norm = ty::fold::super_fold_ty(self, ty);
-            self.tcx().normalized_cache.borrow_mut().insert(ty, t_norm);
-            return t_norm;
-        }
-
-        fn fold_binder<T>(&mut self, t: &ty::Binder<T>) -> ty::Binder<T>
-            where T : TypeFoldable<'tcx>
-        {
-            let u = self.tcx().anonymize_late_bound_regions(t);
-            ty::fold::super_fold_binder(self, &u)
-        }
-
-        fn fold_region(&mut self, r: ty::Region) -> ty::Region {
-            // because late-bound regions affect subtyping, we can't
-            // erase the bound/free distinction, but we can replace
-            // all free regions with 'static.
-            //
-            // Note that we *CAN* replace early-bound regions -- the
-            // type system never "sees" those, they get substituted
-            // away. In trans, they will always be erased to 'static
-            // whenever a substitution occurs.
-            match r {
-                ty::ReLateBound(..) => r,
-                _ => ty::ReStatic
-            }
-        }
-
-        fn fold_substs(&mut self,
-                       substs: &subst::Substs<'tcx>)
-                       -> subst::Substs<'tcx> {
-            subst::Substs { regions: subst::ErasedRegions,
-                            types: substs.types.fold_with(self) }
-        }
-    }
+    let result = infcx.resolve_type_vars_if_possible(result);
+    Ok(infcx.tcx.erase_regions(&result))
 }
 
 impl<'a, 'tcx> InferCtxt<'a, 'tcx> {

src/librustc/middle/traits/structural_impls.rs

@@ -150,6 +150,52 @@ impl<'tcx, T: HasTypeFlags> HasTypeFlags for Normalized<'tcx, T> {
     }
 }
 
+impl<'tcx, N: HasTypeFlags> HasTypeFlags for traits::VtableImplData<'tcx, N> {
+    fn has_type_flags(&self, flags: TypeFlags) -> bool {
+        self.substs.has_type_flags(flags) ||
+            self.nested.has_type_flags(flags)
+    }
+}
+
+impl<'tcx, N: HasTypeFlags> HasTypeFlags for traits::VtableClosureData<'tcx, N> {
+    fn has_type_flags(&self, flags: TypeFlags) -> bool {
+        self.substs.has_type_flags(flags) ||
+            self.nested.has_type_flags(flags)
+    }
+}
+
+impl<'tcx, N: HasTypeFlags> HasTypeFlags for traits::VtableDefaultImplData<N> {
+    fn has_type_flags(&self, flags: TypeFlags) -> bool {
+        self.nested.has_type_flags(flags)
+    }
+}
+
+impl<'tcx, N: HasTypeFlags> HasTypeFlags for traits::VtableBuiltinData<N> {
+    fn has_type_flags(&self, flags: TypeFlags) -> bool {
+        self.nested.has_type_flags(flags)
+    }
+}
+
+impl<'tcx> HasTypeFlags for traits::VtableObjectData<'tcx> {
+    fn has_type_flags(&self, flags: TypeFlags) -> bool {
+        self.upcast_trait_ref.has_type_flags(flags)
+    }
+}
+
+impl<'tcx, N: HasTypeFlags> HasTypeFlags for traits::Vtable<'tcx, N> {
+    fn has_type_flags(&self, flags: TypeFlags) -> bool {
+        match *self {
+            traits::VtableImpl(ref v) => v.has_type_flags(flags),
+            traits::VtableDefaultImpl(ref t) => t.has_type_flags(flags),
+            traits::VtableClosure(ref d) => d.has_type_flags(flags),
+            traits::VtableFnPointer(ref d) => d.has_type_flags(flags),
+            traits::VtableParam(ref n) => n.has_type_flags(flags),
+            traits::VtableBuiltin(ref d) => d.has_type_flags(flags),
+            traits::VtableObject(ref d) => d.has_type_flags(flags)
+        }
+    }
+}
+
 impl<'tcx, O: TypeFoldable<'tcx>> TypeFoldable<'tcx> for traits::Obligation<'tcx, O>
 {
     fn fold_with<F:TypeFolder<'tcx>>(&self, folder: &mut F) -> traits::Obligation<'tcx, O> {
@@ -198,6 +244,15 @@ impl<'tcx, N: TypeFoldable<'tcx>> TypeFoldable<'tcx> for traits::VtableBuiltinDa
     }
 }
 
+impl<'tcx> TypeFoldable<'tcx> for traits::VtableObjectData<'tcx> {
+    fn fold_with<F:TypeFolder<'tcx>>(&self, folder: &mut F) -> traits::VtableObjectData<'tcx> {
+        traits::VtableObjectData {
+            upcast_trait_ref: self.upcast_trait_ref.fold_with(folder),
+            vtable_base: self.vtable_base
+        }
+    }
+}
+
 impl<'tcx, N: TypeFoldable<'tcx>> TypeFoldable<'tcx> for traits::Vtable<'tcx, N> {
     fn fold_with<F:TypeFolder<'tcx>>(&self, folder: &mut F) -> traits::Vtable<'tcx, N> {
         match *self {
@@ -216,15 +271,6 @@ impl<'tcx, N: TypeFoldable<'tcx>> TypeFoldable<'tcx> for traits::Vtable<'tcx, N>
     }
 }
 
-impl<'tcx> TypeFoldable<'tcx> for traits::VtableObjectData<'tcx> {
-    fn fold_with<F:TypeFolder<'tcx>>(&self, folder: &mut F) -> traits::VtableObjectData<'tcx> {
-        traits::VtableObjectData {
-            upcast_trait_ref: self.upcast_trait_ref.fold_with(folder),
-            vtable_base: self.vtable_base
-        }
-    }
-}
-
 impl<'tcx, T: TypeFoldable<'tcx>> TypeFoldable<'tcx> for Normalized<'tcx, T> {
     fn fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Normalized<'tcx, T> {
         Normalized {

src/librustc/middle/ty/fold.rs

@@ -37,7 +37,7 @@
 use middle::region;
 use middle::subst;
 use middle::ty::adjustment;
-use middle::ty::{self, Binder, Ty, HasTypeFlags, RegionEscape};
+use middle::ty::{self, Binder, Ty, RegionEscape};
 
 use std::fmt;
 use util::nodemap::{FnvHashMap, FnvHashSet};
@@ -588,39 +588,63 @@ impl<'a, 'tcx> TypeFolder<'tcx> for RegionReplacer<'a, 'tcx>
 
 ///////////////////////////////////////////////////////////////////////////
 // Region eraser
-//
-// Replaces all free regions with 'static. Useful in contexts, such as
-// method probing, where precise region relationships are not
-// important. Note that in trans you should use
-// `common::erase_regions` instead.
 
-pub struct RegionEraser<'a, 'tcx: 'a> {
-    tcx: &'a ty::ctxt<'tcx>,
-}
+impl<'tcx> ty::ctxt<'tcx> {
+    /// Returns an equivalent value with all free regions removed (note
+    /// that late-bound regions remain, because they are important for
+    /// subtyping, but they are anonymized and normalized as well)..
+    pub fn erase_regions<T>(&self, value: &T) -> T
+        where T : TypeFoldable<'tcx>
+    {
+        let value1 = value.fold_with(&mut RegionEraser(self));
+        debug!("erase_regions({:?}) = {:?}",
+               value, value1);
+        return value1;
 
-pub fn erase_regions<'tcx, T: TypeFoldable<'tcx>>(tcx: &ty::ctxt<'tcx>, t: T) -> T {
-    let mut eraser = RegionEraser { tcx: tcx };
-    t.fold_with(&mut eraser)
-}
+        struct RegionEraser<'a, 'tcx: 'a>(&'a ty::ctxt<'tcx>);
 
-impl<'a, 'tcx> TypeFolder<'tcx> for RegionEraser<'a, 'tcx> {
-    fn tcx(&self) -> &ty::ctxt<'tcx> { self.tcx }
+        impl<'a, 'tcx> TypeFolder<'tcx> for RegionEraser<'a, 'tcx> {
+            fn tcx(&self) -> &ty::ctxt<'tcx> { self.0 }
 
-    fn fold_ty(&mut self, t: Ty<'tcx>) -> Ty<'tcx> {
-        if !t.has_erasable_regions() {
-            return t;
-        }
+            fn fold_ty(&mut self, ty: Ty<'tcx>) -> Ty<'tcx> {
+                match self.tcx().normalized_cache.borrow().get(&ty).cloned() {
+                    None => {}
+                    Some(u) => return u
+                }
 
-        super_fold_ty(self, t)
-    }
+                let t_norm = ty::fold::super_fold_ty(self, ty);
+                self.tcx().normalized_cache.borrow_mut().insert(ty, t_norm);
+                return t_norm;
+            }
 
-    fn fold_region(&mut self, r: ty::Region) -> ty::Region {
-        // because whether or not a region is bound affects subtyping,
-        // we can't erase the bound/free distinction, but we can
-        // replace all free regions with 'static
-        match r {
-            ty::ReLateBound(..) | ty::ReEarlyBound(..) => r,
-            _ => ty::ReStatic
+            fn fold_binder<T>(&mut self, t: &ty::Binder<T>) -> ty::Binder<T>
+                where T : TypeFoldable<'tcx>
+            {
+                let u = self.tcx().anonymize_late_bound_regions(t);
+                ty::fold::super_fold_binder(self, &u)
+            }
+
+            fn fold_region(&mut self, r: ty::Region) -> ty::Region {
+                // because late-bound regions affect subtyping, we can't
+                // erase the bound/free distinction, but we can replace
+                // all free regions with 'static.
+                //
+                // Note that we *CAN* replace early-bound regions -- the
+                // type system never "sees" those, they get substituted
+                // away. In trans, they will always be erased to 'static
+                // whenever a substitution occurs.
+                match r {
+                    ty::ReLateBound(..) => r,
+                    _ => ty::ReStatic
+                }
+            }
+
+            fn fold_substs(&mut self,
+                           substs: &subst::Substs<'tcx>)
+                           -> subst::Substs<'tcx> {
+                subst::Substs { regions: subst::ErasedRegions,
+                                types: substs.types.fold_with(self) }
+            }
         }
     }
 }

src/librustc/middle/ty/structural_impls.rs

@@ -185,6 +185,13 @@ impl<'tcx> RegionEscape for ty::ProjectionTy<'tcx> {
         self.trait_ref.has_regions_escaping_depth(depth)
     }
 }
+
+impl HasTypeFlags for () {
+    fn has_type_flags(&self, _flags: TypeFlags) -> bool {
+        false
+    }
+}
+
 impl<'tcx,T:HasTypeFlags> HasTypeFlags for Vec<T> {
     fn has_type_flags(&self, flags: TypeFlags) -> bool {
         self[..].has_type_flags(flags)

src/librustc_trans/trans/callee.rs

@@ -24,6 +24,7 @@ use session;
 use llvm::{self, ValueRef, get_params};
 use middle::def;
 use middle::def_id::{DefId, LOCAL_CRATE};
+use middle::infer::normalize_associated_type;
 use middle::subst;
 use middle::subst::{Subst, Substs};
 use rustc::front::map as hir_map;
@@ -260,7 +261,7 @@ pub fn trans_fn_pointer_shim<'a, 'tcx>(
     let tcx = ccx.tcx();
 
     // Normalize the type for better caching.
-    let bare_fn_ty = common::erase_regions(tcx, &bare_fn_ty);
+    let bare_fn_ty = tcx.erase_regions(&bare_fn_ty);
 
     // If this is an impl of `Fn` or `FnMut` trait, the receiver is `&self`.
     let is_by_ref = match closure_kind {
@@ -521,7 +522,7 @@ pub fn trans_fn_ref_with_substs<'a, 'tcx>(
 
     // Type scheme of the function item (may have type params)
     let fn_type_scheme = tcx.lookup_item_type(def_id);
-    let fn_type = monomorphize::normalize_associated_type(tcx, &fn_type_scheme.ty);
+    let fn_type = normalize_associated_type(tcx, &fn_type_scheme.ty);
 
     // Find the actual function pointer.
     let mut val = {

src/librustc_trans/trans/closure.rs

@@ -135,7 +135,7 @@ pub fn get_or_create_closure_declaration<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
                                                    -> ValueRef {
     // Normalize type so differences in regions and typedefs don't cause
     // duplicate declarations
-    let substs = erase_regions(ccx.tcx(), substs);
+    let substs = ccx.tcx().erase_regions(substs);
     let mono_id = MonoId {
         def: closure_id,
         params: &substs.func_substs.types