rustc: make mk_substs_trait take &[Kind] instead of &[Ty].

16 files changed, 70 insertions, 98 deletions

diff --git a/src/librustc/traits/error_reporting.rs b/src/librustc/traits/error_reporting.rs
index 97ce730c59e..9ad98b45e96 100644
--- a/src/librustc/traits/error_reporting.rs
+++ b/src/librustc/traits/error_reporting.rs
@@ -652,14 +652,10 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
                             && fallback_has_occurred
                         {
                             let predicate = trait_predicate.map_bound(|mut trait_pred| {
-                                {
-                                    let trait_ref = &mut trait_pred.trait_ref;
-                                    let never_substs = trait_ref.substs;
-                                    let mut unit_substs = Vec::with_capacity(never_substs.len());
-                                    unit_substs.push(self.tcx.mk_nil().into());
-                                    unit_substs.extend(&never_substs[1..]);
-                                    trait_ref.substs = self.tcx.intern_substs(&unit_substs);
-                                }
+                                trait_pred.trait_ref.substs = self.tcx.mk_substs_trait(
+                                    self.tcx.mk_nil(),
+                                    &trait_pred.trait_ref.substs[1..],
+                                );
                                 trait_pred
                             });
                             let unit_obligation = Obligation {
diff --git a/src/librustc/traits/select.rs b/src/librustc/traits/select.rs
index bd7ec4a12b0..3ab51a0eb2f 100644
--- a/src/librustc/traits/select.rs
+++ b/src/librustc/traits/select.rs
@@ -3058,7 +3058,7 @@ impl<'cx, 'gcx, 'tcx> SelectionContext<'cx, 'gcx, 'tcx> {
                     obligation.predicate.def_id(),
                     obligation.recursion_depth + 1,
                     inner_source,
-                    &[inner_target]));
+                    &[inner_target.into()]));
             }
 
             // (.., T) -> (.., U).
@@ -3066,16 +3066,16 @@ impl<'cx, 'gcx, 'tcx> SelectionContext<'cx, 'gcx, 'tcx> {
                 assert_eq!(tys_a.len(), tys_b.len());
 
                 // The last field of the tuple has to exist.
-                let (a_last, a_mid) = if let Some(x) = tys_a.split_last() {
+                let (&a_last, a_mid) = if let Some(x) = tys_a.split_last() {
                     x
                 } else {
                     return Err(Unimplemented);
                 };
-                let b_last = tys_b.last().unwrap();
+                let &b_last = tys_b.last().unwrap();
 
                 // Check that the source tuple with the target's
                 // last element is equal to the target.
-                let new_tuple = tcx.mk_tup(a_mid.iter().chain(Some(b_last)));
+                let new_tuple = tcx.mk_tup(a_mid.iter().cloned().chain(iter::once(b_last)));
                 let InferOk { obligations, .. } =
                     self.infcx.at(&obligation.cause, obligation.param_env)
                               .eq(target, new_tuple)
@@ -3089,7 +3089,7 @@ impl<'cx, 'gcx, 'tcx> SelectionContext<'cx, 'gcx, 'tcx> {
                     obligation.predicate.def_id(),
                     obligation.recursion_depth + 1,
                     a_last,
-                    &[b_last]));
+                    &[b_last.into()]));
             }
 
             _ => bug!()
diff --git a/src/librustc/traits/util.rs b/src/librustc/traits/util.rs
index f5a9d2a7f00..684022f8e8a 100644
--- a/src/librustc/traits/util.rs
+++ b/src/librustc/traits/util.rs
@@ -9,7 +9,7 @@
 // except according to those terms.
 
 use hir::def_id::DefId;
-use ty::subst::{Subst, Substs};
+use ty::subst::{Kind, Subst, Substs};
 use ty::{self, Ty, TyCtxt, ToPredicate, ToPolyTraitRef};
 use ty::outlives::Component;
 use util::nodemap::FxHashSet;
@@ -430,13 +430,13 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
                                    cause: ObligationCause<'tcx>,
                                    trait_def_id: DefId,
                                    recursion_depth: usize,
-                                   param_ty: Ty<'tcx>,
-                                   ty_params: &[Ty<'tcx>])
+                                   self_ty: Ty<'tcx>,
+                                   params: &[Kind<'tcx>])
         -> PredicateObligation<'tcx>
     {
         let trait_ref = ty::TraitRef {
             def_id: trait_def_id,
-            substs: self.mk_substs_trait(param_ty, ty_params)
+            substs: self.mk_substs_trait(self_ty, params)
         };
         predicate_for_trait_ref(cause, param_env, trait_ref, recursion_depth)
     }
@@ -512,7 +512,7 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
         };
         let trait_ref = ty::TraitRef {
             def_id: fn_trait_def_id,
-            substs: self.mk_substs_trait(self_ty, &[arguments_tuple]),
+            substs: self.mk_substs_trait(self_ty, &[arguments_tuple.into()]),
         };
         ty::Binder::bind((trait_ref, sig.skip_binder().output()))
     }
diff --git a/src/librustc/ty/context.rs b/src/librustc/ty/context.rs
index ee55b8dd767..b1e9aab6872 100644
--- a/src/librustc/ty/context.rs
+++ b/src/librustc/ty/context.rs
@@ -2584,11 +2584,11 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
     }
 
     pub fn mk_substs_trait(self,
-                     s: Ty<'tcx>,
-                     t: &[Ty<'tcx>])
+                     self_ty: Ty<'tcx>,
+                     rest: &[Kind<'tcx>])
                     -> &'tcx Substs<'tcx>
     {
-        self.mk_substs(iter::once(s).chain(t.into_iter().cloned()).map(Kind::from))
+        self.mk_substs(iter::once(self_ty.into()).chain(rest.iter().cloned()))
     }
 
     pub fn mk_clauses<I: InternAs<[Clause<'tcx>], Clauses<'tcx>>>(self, iter: I) -> I::Output {
diff --git a/src/librustc/ty/instance.rs b/src/librustc/ty/instance.rs
index e97f782fccf..66edbeff749 100644
--- a/src/librustc/ty/instance.rs
+++ b/src/librustc/ty/instance.rs
@@ -10,7 +10,6 @@
 
 use hir::def_id::DefId;
 use ty::{self, Ty, TypeFoldable, Substs, TyCtxt};
-use ty::subst::Kind;
 use traits;
 use rustc_target::spec::abi::Abi;
 use util::ppaux;
@@ -361,7 +360,7 @@ fn fn_once_adapter_instance<'a, 'tcx>(
     let sig = substs.closure_sig(closure_did, tcx);
     let sig = tcx.normalize_erasing_late_bound_regions(ty::ParamEnv::reveal_all(), &sig);
     assert_eq!(sig.inputs().len(), 1);
-    let substs = tcx.mk_substs([Kind::from(self_ty), sig.inputs()[0].into()].iter().cloned());
+    let substs = tcx.mk_substs_trait(self_ty, &[sig.inputs()[0].into()]);
 
     debug!("fn_once_adapter_shim: self_ty={:?} sig={:?}", self_ty, sig);
     Instance { def, substs }
diff --git a/src/librustc/ty/sty.rs b/src/librustc/ty/sty.rs
index 0b8f10d311d..6bc0cb51a92 100644
--- a/src/librustc/ty/sty.rs
+++ b/src/librustc/ty/sty.rs
@@ -622,6 +622,18 @@ impl<'tcx> TraitRef<'tcx> {
         // associated types.
         self.substs.types()
     }
+
+    pub fn from_method(tcx: TyCtxt<'_, '_, 'tcx>,
+                       trait_id: DefId,
+                       substs: &Substs<'tcx>)
+                       -> ty::TraitRef<'tcx> {
+        let defs = tcx.generics_of(trait_id);
+
+        ty::TraitRef {
+            def_id: trait_id,
+            substs: tcx.intern_substs(&substs[..defs.params.len()])
+        }
+    }
 }
 
 pub type PolyTraitRef<'tcx> = Binder<TraitRef<'tcx>>;
@@ -663,6 +675,18 @@ impl<'a, 'gcx, 'tcx> ExistentialTraitRef<'tcx> {
         self.substs.types()
     }
 
+    pub fn erase_self_ty(tcx: TyCtxt<'a, 'gcx, 'tcx>,
+                         trait_ref: ty::TraitRef<'tcx>)
+                         -> ty::ExistentialTraitRef<'tcx> {
+        // Assert there is a Self.
+        trait_ref.substs.type_at(0);
+
+        ty::ExistentialTraitRef {
+            def_id: trait_ref.def_id,
+            substs: tcx.intern_substs(&trait_ref.substs[1..])
+        }
+    }
+
     /// Object types don't have a self-type specified. Therefore, when
     /// we convert the principal trait-ref into a normal trait-ref,
     /// you must give *some* self-type. A common choice is `mk_err()`
@@ -674,8 +698,7 @@ impl<'a, 'gcx, 'tcx> ExistentialTraitRef<'tcx> {
 
         ty::TraitRef {
             def_id: self.def_id,
-            substs: tcx.mk_substs(
-                iter::once(self_ty.into()).chain(self.substs.iter().cloned()))
+            substs: tcx.mk_substs_trait(self_ty, self.substs)
         }
     }
 }
@@ -686,6 +709,16 @@ impl<'tcx> PolyExistentialTraitRef<'tcx> {
     pub fn def_id(&self) -> DefId {
         self.skip_binder().def_id
     }
+
+    /// Object types don't have a self-type specified. Therefore, when
+    /// we convert the principal trait-ref into a normal trait-ref,
+    /// you must give *some* self-type. A common choice is `mk_err()`
+    /// or some skolemized type.
+    pub fn with_self_ty(&self, tcx: TyCtxt<'_, '_, 'tcx>,
+                        self_ty: Ty<'tcx>)
+                        -> ty::PolyTraitRef<'tcx>  {
+        self.map_bound(|trait_ref| trait_ref.with_self_ty(tcx, self_ty))
+    }
 }
 
 /// Binder is a binder for higher-ranked lifetimes. It is part of the
@@ -1188,8 +1221,7 @@ impl<'a, 'tcx, 'gcx> ExistentialProjection<'tcx> {
         ty::ProjectionPredicate {
             projection_ty: ty::ProjectionTy {
                 item_def_id: self.item_def_id,
-                substs: tcx.mk_substs(
-                iter::once(self_ty.into()).chain(self.substs.iter().cloned())),
+                substs: tcx.mk_substs_trait(self_ty, self.substs),
             },
             ty: self.ty,
         }
diff --git a/src/librustc/ty/subst.rs b/src/librustc/ty/subst.rs
index b94b3e17f86..67dde685f8d 100644
--- a/src/librustc/ty/subst.rs
+++ b/src/librustc/ty/subst.rs
@@ -20,7 +20,6 @@ use rustc_data_structures::accumulate_vec::AccumulateVec;
 
 use core::intrinsics;
 use std::fmt;
-use std::iter;
 use std::marker::PhantomData;
 use std::mem;
 use std::num::NonZeroUsize;
@@ -543,54 +542,3 @@ impl<'a, 'gcx, 'tcx> SubstFolder<'a, 'gcx, 'tcx> {
         self.tcx().mk_region(ty::fold::shift_region(*region, self.region_binders_passed))
     }
 }
-
-// Helper methods that modify substitutions.
-
-impl<'a, 'gcx, 'tcx> ty::TraitRef<'tcx> {
-    pub fn from_method(tcx: TyCtxt<'a, 'gcx, 'tcx>,
-                       trait_id: DefId,
-                       substs: &Substs<'tcx>)
-                       -> ty::TraitRef<'tcx> {
-        let defs = tcx.generics_of(trait_id);
-
-        ty::TraitRef {
-            def_id: trait_id,
-            substs: tcx.intern_substs(&substs[..defs.params.len()])
-        }
-    }
-}
-
-impl<'a, 'gcx, 'tcx> ty::ExistentialTraitRef<'tcx> {
-    pub fn erase_self_ty(tcx: TyCtxt<'a, 'gcx, 'tcx>,
-                         trait_ref: ty::TraitRef<'tcx>)
-                         -> ty::ExistentialTraitRef<'tcx> {
-        // Assert there is a Self.
-        trait_ref.substs.type_at(0);
-
-        ty::ExistentialTraitRef {
-            def_id: trait_ref.def_id,
-            substs: tcx.intern_substs(&trait_ref.substs[1..])
-        }
-    }
-}
-
-impl<'a, 'gcx, 'tcx> ty::PolyExistentialTraitRef<'tcx> {
-    /// Object types don't have a self-type specified. Therefore, when
-    /// we convert the principal trait-ref into a normal trait-ref,
-    /// you must give *some* self-type. A common choice is `mk_err()`
-    /// or some skolemized type.
-    pub fn with_self_ty(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>,
-                        self_ty: Ty<'tcx>)
-                        -> ty::PolyTraitRef<'tcx>  {
-        // otherwise the escaping regions would be captured by the binder
-        assert!(!self_ty.has_escaping_regions());
-
-        self.map_bound(|trait_ref| {
-            ty::TraitRef {
-                def_id: trait_ref.def_id,
-                substs: tcx.mk_substs(
-                    iter::once(self_ty.into()).chain(trait_ref.substs.iter().cloned()))
-            }
-        })
-    }
-}
diff --git a/src/librustc_mir/borrow_check/nll/type_check/mod.rs b/src/librustc_mir/borrow_check/nll/type_check/mod.rs
index 1014299c708..456aa1aa66f 100644
--- a/src/librustc_mir/borrow_check/nll/type_check/mod.rs
+++ b/src/librustc_mir/borrow_check/nll/type_check/mod.rs
@@ -1375,9 +1375,10 @@ impl<'a, 'gcx, 'tcx> TypeChecker<'a, 'gcx, 'tcx> {
                 }
 
                 CastKind::Unsize => {
+                    let &ty = ty;
                     let trait_ref = ty::TraitRef {
                         def_id: tcx.lang_items().coerce_unsized_trait().unwrap(),
-                        substs: tcx.mk_substs_trait(op.ty(mir, tcx), &[ty]),
+                        substs: tcx.mk_substs_trait(op.ty(mir, tcx), &[ty.into()]),
                     };
 
                     self.prove_trait_ref(trait_ref, location);
diff --git a/src/librustc_mir/build/matches/test.rs b/src/librustc_mir/build/matches/test.rs
index 913cb944835..5dbe8d850bd 100644
--- a/src/librustc_mir/build/matches/test.rs
+++ b/src/librustc_mir/build/matches/test.rs
@@ -312,7 +312,7 @@ impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
                         },
                     }
                     let eq_def_id = self.hir.tcx().lang_items().eq_trait().unwrap();
-                    let (mty, method) = self.hir.trait_method(eq_def_id, "eq", ty, &[ty]);
+                    let (mty, method) = self.hir.trait_method(eq_def_id, "eq", ty, &[ty.into()]);
 
                     // take the argument by reference
                     let region_scope = self.topmost_scope();
diff --git a/src/librustc_mir/hair/cx/mod.rs b/src/librustc_mir/hair/cx/mod.rs
index 4739c0e92ed..71dd35c010d 100644
--- a/src/librustc_mir/hair/cx/mod.rs
+++ b/src/librustc_mir/hair/cx/mod.rs
@@ -24,7 +24,7 @@ use rustc::infer::InferCtxt;
 use rustc::ty::layout::{IntegerExt, Size};
 use rustc::ty::subst::Subst;
 use rustc::ty::{self, Ty, TyCtxt, layout};
-use rustc::ty::subst::Substs;
+use rustc::ty::subst::{Kind, Substs};
 use syntax::ast::{self, LitKind};
 use syntax::attr;
 use syntax::symbol::Symbol;
@@ -235,7 +235,7 @@ impl<'a, 'gcx, 'tcx> Cx<'a, 'gcx, 'tcx> {
                         trait_def_id: DefId,
                         method_name: &str,
                         self_ty: Ty<'tcx>,
-                        params: &[Ty<'tcx>])
+                        params: &[Kind<'tcx>])
                         -> (Ty<'tcx>, Literal<'tcx>) {
         let method_name = Symbol::intern(method_name);
         let substs = self.tcx.mk_substs_trait(self_ty, params);
diff --git a/src/librustc_mir/monomorphize/mod.rs b/src/librustc_mir/monomorphize/mod.rs
index 51793305513..bf544e5120c 100644
--- a/src/librustc_mir/monomorphize/mod.rs
+++ b/src/librustc_mir/monomorphize/mod.rs
@@ -12,7 +12,6 @@ use rustc::hir::def_id::DefId;
 use rustc::middle::lang_items::DropInPlaceFnLangItem;
 use rustc::traits;
 use rustc::ty::adjustment::CustomCoerceUnsized;
-use rustc::ty::subst::Kind;
 use rustc::ty::{self, Ty, TyCtxt};
 
 pub use rustc::ty::Instance;
@@ -89,10 +88,7 @@ fn fn_once_adapter_instance<'a, 'tcx>(
     let sig = substs.closure_sig(closure_did, tcx);
     let sig = tcx.normalize_erasing_late_bound_regions(ty::ParamEnv::reveal_all(), &sig);
     assert_eq!(sig.inputs().len(), 1);
-    let substs = tcx.mk_substs([
-        Kind::from(self_ty),
-        sig.inputs()[0].into(),
-    ].iter().cloned());
+    let substs = tcx.mk_substs_trait(self_ty, &[sig.inputs()[0].into()]);
 
     debug!("fn_once_adapter_shim: self_ty={:?} sig={:?}", self_ty, sig);
     Instance { def, substs }
@@ -164,7 +160,7 @@ pub fn custom_coerce_unsize_info<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
 
     let trait_ref = ty::Binder::bind(ty::TraitRef {
         def_id: def_id,
-        substs: tcx.mk_substs_trait(source_ty, &[target_ty])
+        substs: tcx.mk_substs_trait(source_ty, &[target_ty.into()])
     });
 
     match tcx.codegen_fulfill_obligation( (ty::ParamEnv::reveal_all(), trait_ref)) {
diff --git a/src/librustc_mir/util/elaborate_drops.rs b/src/librustc_mir/util/elaborate_drops.rs
index 9fc04dc7d24..f70a5ef57fe 100644
--- a/src/librustc_mir/util/elaborate_drops.rs
+++ b/src/librustc_mir/util/elaborate_drops.rs
@@ -14,12 +14,12 @@ use rustc::mir::*;
 use rustc::middle::lang_items;
 use rustc::traits::Reveal;
 use rustc::ty::{self, Ty, TyCtxt};
-use rustc::ty::subst::{Kind, Substs};
+use rustc::ty::subst::Substs;
 use rustc::ty::util::IntTypeExt;
 use rustc_data_structures::indexed_vec::Idx;
 use util::patch::MirPatch;
 
-use std::{iter, u32};
+use std::u32;
 
 #[derive(Debug, PartialEq, Eq, Copy, Clone)]
 pub enum DropFlagState {
@@ -520,7 +520,7 @@ impl<'l, 'b, 'tcx, D> DropCtxt<'l, 'b, 'tcx, D>
         let drop_trait = tcx.lang_items().drop_trait().unwrap();
         let drop_fn = tcx.associated_items(drop_trait).next().unwrap();
         let ty = self.place_ty(self.place);
-        let substs = tcx.mk_substs(iter::once(Kind::from(ty)));
+        let substs = tcx.mk_substs_trait(ty, &[]);
 
         let ref_ty = tcx.mk_ref(tcx.types.re_erased, ty::TypeAndMut {
             ty,
diff --git a/src/librustc_typeck/check/coercion.rs b/src/librustc_typeck/check/coercion.rs
index 324af7b6270..5b3484dcccb 100644
--- a/src/librustc_typeck/check/coercion.rs
+++ b/src/librustc_typeck/check/coercion.rs
@@ -547,7 +547,7 @@ impl<'f, 'gcx, 'tcx> Coerce<'f, 'gcx, 'tcx> {
                                                          coerce_unsized_did,
                                                          0,
                                                          coerce_source,
-                                                         &[coerce_target]));
+                                                         &[coerce_target.into()]));
 
         let mut has_unsized_tuple_coercion = false;
 
diff --git a/src/librustc_typeck/check/method/suggest.rs b/src/librustc_typeck/check/method/suggest.rs
index 2dc7c7fe71a..8a575c14787 100644
--- a/src/librustc_typeck/check/method/suggest.rs
+++ b/src/librustc_typeck/check/method/suggest.rs
@@ -56,8 +56,9 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
 
                 self.autoderef(span, ty).any(|(ty, _)| {
                     self.probe(|_| {
-                        let fn_once_substs = tcx.mk_substs_trait(ty,
-                            &[self.next_ty_var(TypeVariableOrigin::MiscVariable(span))]);
+                        let fn_once_substs = tcx.mk_substs_trait(ty, &[
+                            self.next_ty_var(TypeVariableOrigin::MiscVariable(span)).into()
+                        ]);
                         let trait_ref = ty::TraitRef::new(fn_once, fn_once_substs);
                         let poly_trait_ref = trait_ref.to_poly_trait_ref();
                         let obligation =
diff --git a/src/librustc_typeck/check/mod.rs b/src/librustc_typeck/check/mod.rs
index 1088ec1b2ac..21197b4d85c 100644
--- a/src/librustc_typeck/check/mod.rs
+++ b/src/librustc_typeck/check/mod.rs
@@ -116,7 +116,6 @@ use std::collections::hash_map::Entry;
 use std::cmp;
 use std::fmt::Display;
 use std::mem::replace;
-use std::iter;
 use std::ops::{self, Deref};
 use rustc_target::spec::abi::Abi;
 use syntax::ast;
@@ -1114,7 +1113,7 @@ fn check_fn<'a, 'gcx, 'tcx>(inherited: &'a Inherited<'a, 'gcx, 'tcx>,
             if id == fn_id {
                 match entry_type {
                     config::EntryMain => {
-                        let substs = fcx.tcx.mk_substs(iter::once(Kind::from(declared_ret_ty)));
+                        let substs = fcx.tcx.mk_substs_trait(declared_ret_ty, &[]);
                         let trait_ref = ty::TraitRef::new(term_id, substs);
                         let return_ty_span = decl.output.span();
                         let cause = traits::ObligationCause::new(
diff --git a/src/librustc_typeck/coherence/builtin.rs b/src/librustc_typeck/coherence/builtin.rs
index 735ebbfcb3d..528f81a5612 100644
--- a/src/librustc_typeck/coherence/builtin.rs
+++ b/src/librustc_typeck/coherence/builtin.rs
@@ -387,7 +387,7 @@ pub fn coerce_unsized_info<'a, 'gcx>(gcx: TyCtxt<'a, 'gcx, 'gcx>,
                                                     trait_def_id,
                                                     0,
                                                     source,
-                                                    &[target]);
+                                                    &[target.into()]);
         fulfill_cx.register_predicate_obligation(&infcx, predicate);
 
         // Check that all transitive obligations are satisfied.