start cleaning up subst mess

fix an ICE

fix method name

6 files changed, 38 insertions, 58 deletions

diff --git a/src/librustc_mir/interpret/cast.rs b/src/librustc_mir/interpret/cast.rs
index 26cfbfe53a3..d570b754c87 100644
--- a/src/librustc_mir/interpret/cast.rs
+++ b/src/librustc_mir/interpret/cast.rs
@@ -67,7 +67,7 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                 // The src operand does not matter, just its type
                 match src.layout.ty.sty {
                     ty::Closure(def_id, substs) => {
-                        let substs = self.subst_and_normalize_erasing_regions(substs)?;
+                        let substs = self.subst_from_frame_and_normalize_erasing_regions(substs)?;
                         let instance = ty::Instance::resolve_closure(
                             *self.tcx,
                             def_id,
diff --git a/src/librustc_mir/interpret/eval_context.rs b/src/librustc_mir/interpret/eval_context.rs
index 6f4227ed34c..d00411548e9 100644
--- a/src/librustc_mir/interpret/eval_context.rs
+++ b/src/librustc_mir/interpret/eval_context.rs
@@ -9,7 +9,7 @@ use rustc::mir;
 use rustc::ty::layout::{
     self, Size, Align, HasDataLayout, LayoutOf, TyLayout
 };
-use rustc::ty::subst::{Subst, SubstsRef};
+use rustc::ty::subst::SubstsRef;
 use rustc::ty::{self, Ty, TyCtxt, TypeFoldable};
 use rustc::ty::query::TyCtxtAt;
 use rustc_data_structures::indexed_vec::IndexVec;
@@ -291,41 +291,6 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
         ty.is_freeze(*self.tcx, self.param_env, DUMMY_SP)
     }
 
-    pub(super) fn subst_and_normalize_erasing_regions<T: TypeFoldable<'tcx>>(
-        &self,
-        substs: T,
-    ) -> InterpResult<'tcx, T> {
-        match self.stack.last() {
-            Some(frame) => Ok(self.tcx.subst_and_normalize_erasing_regions(
-                frame.instance.substs,
-                self.param_env,
-                &substs,
-            )),
-            None => if substs.needs_subst() {
-                throw_inval!(TooGeneric)
-            } else {
-                Ok(substs)
-            },
-        }
-    }
-
-    pub(super) fn resolve(
-        &self,
-        def_id: DefId,
-        substs: SubstsRef<'tcx>
-    ) -> InterpResult<'tcx, ty::Instance<'tcx>> {
-        trace!("resolve: {:?}, {:#?}", def_id, substs);
-        trace!("param_env: {:#?}", self.param_env);
-        let substs = self.subst_and_normalize_erasing_regions(substs)?;
-        trace!("substs: {:#?}", substs);
-        ty::Instance::resolve(
-            *self.tcx,
-            self.param_env,
-            def_id,
-            substs,
-        ).ok_or_else(|| err_inval!(TooGeneric).into())
-    }
-
     pub fn load_mir(
         &self,
         instance: ty::InstanceDef<'tcx>,
@@ -349,12 +314,18 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
         }
     }
 
-    pub(super) fn monomorphize<T: TypeFoldable<'tcx> + Subst<'tcx>>(
+    /// Call this on things you got out of the MIR (so it is as generic as the current
+    /// stack rameframe), to bring it into the proper environment for this interpreter.
+    pub(super) fn subst_from_frame_and_normalize_erasing_regions<T: TypeFoldable<'tcx>>(
         &self,
         t: T,
     ) -> InterpResult<'tcx, T> {
         match self.stack.last() {
-            Some(frame) => Ok(self.monomorphize_with_substs(t, frame.instance.substs)?),
+            Some(frame) => Ok(self.tcx.subst_and_normalize_erasing_regions(
+                frame.instance.substs,
+                self.param_env,
+                &t,
+            )),
             None => if t.needs_subst() {
                 throw_inval!(TooGeneric)
             } else {
@@ -363,20 +334,21 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
         }
     }
 
-    fn monomorphize_with_substs<T: TypeFoldable<'tcx> + Subst<'tcx>>(
+    /// The `substs` are assumed to already be in our interpreter "universe" (param_env).
+    pub(super) fn resolve(
         &self,
-        t: T,
+        def_id: DefId,
         substs: SubstsRef<'tcx>
-    ) -> InterpResult<'tcx, T> {
-        // miri doesn't care about lifetimes, and will choke on some crazy ones
-        // let's simply get rid of them
-        let substituted = t.subst(*self.tcx, substs);
-
-        if substituted.needs_subst() {
-            throw_inval!(TooGeneric)
-        }
-
-        Ok(self.tcx.normalize_erasing_regions(ty::ParamEnv::reveal_all(), substituted))
+    ) -> InterpResult<'tcx, ty::Instance<'tcx>> {
+        trace!("resolve: {:?}, {:#?}", def_id, substs);
+        trace!("param_env: {:#?}", self.param_env);
+        trace!("substs: {:#?}", substs);
+        ty::Instance::resolve(
+            *self.tcx,
+            self.param_env,
+            def_id,
+            substs,
+        ).ok_or_else(|| err_inval!(TooGeneric).into())
     }
 
     pub fn layout_of_local(
@@ -391,7 +363,11 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
             None => {
                 let layout = crate::interpret::operand::from_known_layout(layout, || {
                     let local_ty = frame.body.local_decls[local].ty;
-                    let local_ty = self.monomorphize_with_substs(local_ty, frame.instance.substs)?;
+                    let local_ty = self.tcx.subst_and_normalize_erasing_regions(
+                        frame.instance.substs,
+                        self.param_env,
+                        &local_ty,
+                    );
                     self.layout_of(local_ty)
                 })?;
                 if let Some(state) = frame.locals.get(local) {
diff --git a/src/librustc_mir/interpret/operand.rs b/src/librustc_mir/interpret/operand.rs
index 726ae6fab10..f0559b13c33 100644
--- a/src/librustc_mir/interpret/operand.rs
+++ b/src/librustc_mir/interpret/operand.rs
@@ -540,6 +540,8 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
 
     // Used when the miri-engine runs into a constant and for extracting information from constants
     // in patterns via the `const_eval` module
+    /// The `val` and `layout` are assumed to already be in our interpreter
+    /// "universe" (param_env).
     crate fn eval_const_to_op(
         &self,
         val: &'tcx ty::Const<'tcx>,
@@ -552,7 +554,6 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
         // Early-return cases.
         match val.val {
             ConstValue::Param(_) =>
-                // FIXME(oli-obk): try to monomorphize
                 throw_inval!(TooGeneric),
             ConstValue::Unevaluated(def_id, substs) => {
                 let instance = self.resolve(def_id, substs)?;
@@ -565,7 +566,7 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
         }
         // Other cases need layout.
         let layout = from_known_layout(layout, || {
-            self.layout_of(self.monomorphize(val.ty)?)
+            self.layout_of(val.ty)
         })?;
         let op = match val.val {
             ConstValue::ByRef { alloc, offset } => {
diff --git a/src/librustc_mir/interpret/place.rs b/src/librustc_mir/interpret/place.rs
index ef9f20d5c97..71b9c83d615 100644
--- a/src/librustc_mir/interpret/place.rs
+++ b/src/librustc_mir/interpret/place.rs
@@ -640,8 +640,11 @@ where
                         // their layout on return.
                         PlaceTy {
                             place: *return_place,
-                            layout: self
-                                .layout_of(self.monomorphize(self.frame().body.return_ty())?)?,
+                            layout: self.layout_of(
+                                self.subst_from_frame_and_normalize_erasing_regions(
+                                    self.frame().body.return_ty()
+                                )?
+                            )?,
                         }
                     }
                     None => throw_unsup!(InvalidNullPointerUsage),
diff --git a/src/librustc_mir/interpret/step.rs b/src/librustc_mir/interpret/step.rs
index b010bf049dd..5a9cf888c93 100644
--- a/src/librustc_mir/interpret/step.rs
+++ b/src/librustc_mir/interpret/step.rs
@@ -254,7 +254,7 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
             }
 
             NullaryOp(mir::NullOp::SizeOf, ty) => {
-                let ty = self.monomorphize(ty)?;
+                let ty = self.subst_from_frame_and_normalize_erasing_regions(ty)?;
                 let layout = self.layout_of(ty)?;
                 assert!(!layout.is_unsized(),
                         "SizeOf nullary MIR operator called for unsized type");
diff --git a/src/librustc_mir/interpret/traits.rs b/src/librustc_mir/interpret/traits.rs
index e55b0d0fb1f..940a7bbdcce 100644
--- a/src/librustc_mir/interpret/traits.rs
+++ b/src/librustc_mir/interpret/traits.rs
@@ -77,7 +77,7 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
         for (i, method) in methods.iter().enumerate() {
             if let Some((def_id, substs)) = *method {
                 // resolve for vtable: insert shims where needed
-                let substs = self.subst_and_normalize_erasing_regions(substs)?;
+                let substs = self.subst_from_frame_and_normalize_erasing_regions(substs)?;
                 let instance = ty::Instance::resolve_for_vtable(
                     *self.tcx,
                     self.param_env,