Use &mut for CombineFields in inference relations

9 files changed, 58 insertions, 78 deletions

diff --git a/src/librustc/infer/bivariate.rs b/src/librustc/infer/bivariate.rs
index d790391cd4c..e54522b8433 100644
--- a/src/librustc/infer/bivariate.rs
+++ b/src/librustc/infer/bivariate.rs
@@ -32,18 +32,18 @@ use ty::{self, Ty, TyCtxt};
 use ty::TyVar;
 use ty::relate::{Relate, RelateResult, TypeRelation};
 
-pub struct Bivariate<'infcx, 'gcx: 'infcx+'tcx, 'tcx: 'infcx> {
-    fields: CombineFields<'infcx, 'gcx, 'tcx>,
+pub struct Bivariate<'combine, 'infcx: 'combine, 'gcx: 'infcx+'tcx, 'tcx: 'infcx> {
+    fields: &'combine mut CombineFields<'infcx, 'gcx, 'tcx>,
     a_is_expected: bool,
 }
 
-impl<'infcx, 'gcx, 'tcx> Bivariate<'infcx, 'gcx, 'tcx> {
-    pub fn new(fields: CombineFields<'infcx, 'gcx, 'tcx>, a_is_expected: bool) -> Bivariate<'infcx, 'gcx, 'tcx> {
+impl<'combine, 'infcx, 'gcx, 'tcx> Bivariate<'combine, 'infcx, 'gcx, 'tcx> {
+    pub fn new(fields: &'combine mut CombineFields<'infcx, 'gcx, 'tcx>, a_is_expected: bool) -> Bivariate<'combine, 'infcx, 'gcx, 'tcx> {
         Bivariate { fields: fields, a_is_expected: a_is_expected }
     }
 }
 
-impl<'infcx, 'gcx, 'tcx> TypeRelation<'infcx, 'gcx, 'tcx> for Bivariate<'infcx, 'gcx, 'tcx> {
+impl<'combine, 'infcx, 'gcx, 'tcx> TypeRelation<'infcx, 'gcx, 'tcx> for Bivariate<'combine, 'infcx, 'gcx, 'tcx> {
     fn tag(&self) -> &'static str { "Bivariate" }
 
     fn tcx(&self) -> TyCtxt<'infcx, 'gcx, 'tcx> { self.fields.tcx() }
diff --git a/src/librustc/infer/combine.rs b/src/librustc/infer/combine.rs
index 41369299e72..fc5b52ee30a 100644
--- a/src/librustc/infer/combine.rs
+++ b/src/librustc/infer/combine.rs
@@ -154,27 +154,27 @@ impl<'infcx, 'gcx, 'tcx> CombineFields<'infcx, 'gcx, 'tcx> {
         self.infcx.tcx
     }
 
-    pub fn equate(&self, a_is_expected: bool) -> Equate<'infcx, 'gcx, 'tcx> {
-        Equate::new(self.clone(), a_is_expected)
+    pub fn equate<'a>(&'a mut self, a_is_expected: bool) -> Equate<'a, 'infcx, 'gcx, 'tcx> {
+        Equate::new(self, a_is_expected)
     }
 
-    pub fn bivariate(&self, a_is_expected: bool) -> Bivariate<'infcx, 'gcx, 'tcx> {
-        Bivariate::new(self.clone(), a_is_expected)
+    pub fn bivariate<'a>(&'a mut self, a_is_expected: bool) -> Bivariate<'a, 'infcx, 'gcx, 'tcx> {
+        Bivariate::new(self, a_is_expected)
     }
 
-    pub fn sub(&self, a_is_expected: bool) -> Sub<'infcx, 'gcx, 'tcx> {
-        Sub::new(self.clone(), a_is_expected)
+    pub fn sub<'a>(&'a mut self, a_is_expected: bool) -> Sub<'a, 'infcx, 'gcx, 'tcx> {
+        Sub::new(self, a_is_expected)
     }
 
-    pub fn lub(&self, a_is_expected: bool) -> Lub<'infcx, 'gcx, 'tcx> {
-        Lub::new(self.clone(), a_is_expected)
+    pub fn lub<'a>(&'a mut self, a_is_expected: bool) -> Lub<'a, 'infcx, 'gcx, 'tcx> {
+        Lub::new(self, a_is_expected)
     }
 
-    pub fn glb(&self, a_is_expected: bool) -> Glb<'infcx, 'gcx, 'tcx> {
-        Glb::new(self.clone(), a_is_expected)
+    pub fn glb<'a>(&'a mut self, a_is_expected: bool) -> Glb<'a, 'infcx, 'gcx, 'tcx> {
+        Glb::new(self, a_is_expected)
     }
 
-    pub fn instantiate(&self,
+    pub fn instantiate(&mut self,
                        a_ty: Ty<'tcx>,
                        dir: RelationDir,
                        b_vid: ty::TyVid,
diff --git a/src/librustc/infer/equate.rs b/src/librustc/infer/equate.rs
index 7980ba91c5e..09800412e0b 100644
--- a/src/librustc/infer/equate.rs
+++ b/src/librustc/infer/equate.rs
@@ -15,25 +15,20 @@ use super::type_variable::{EqTo};
 use ty::{self, Ty, TyCtxt};
 use ty::TyVar;
 use ty::relate::{Relate, RelateResult, TypeRelation};
-use traits::PredicateObligations;
 
 /// Ensures `a` is made equal to `b`. Returns `a` on success.
-pub struct Equate<'infcx, 'gcx: 'infcx+'tcx, 'tcx: 'infcx> {
-    fields: CombineFields<'infcx, 'gcx, 'tcx>,
+pub struct Equate<'combine, 'infcx: 'combine, 'gcx: 'infcx+'tcx, 'tcx: 'infcx> {
+    fields: &'combine mut CombineFields<'infcx, 'gcx, 'tcx>,
     a_is_expected: bool,
 }
 
-impl<'infcx, 'gcx, 'tcx> Equate<'infcx, 'gcx, 'tcx> {
-    pub fn new(fields: CombineFields<'infcx, 'gcx, 'tcx>, a_is_expected: bool) -> Equate<'infcx, 'gcx, 'tcx> {
+impl<'combine, 'infcx, 'gcx, 'tcx> Equate<'combine, 'infcx, 'gcx, 'tcx> {
+    pub fn new(fields: &'combine mut CombineFields<'infcx, 'gcx, 'tcx>, a_is_expected: bool) -> Equate<'combine, 'infcx, 'gcx, 'tcx> {
         Equate { fields: fields, a_is_expected: a_is_expected }
     }
-
-    pub fn obligations(self) -> PredicateObligations<'tcx> {
-        self.fields.obligations
-    }
 }
 
-impl<'infcx, 'gcx, 'tcx> TypeRelation<'infcx, 'gcx, 'tcx> for Equate<'infcx, 'gcx, 'tcx> {
+impl<'combine, 'infcx, 'gcx, 'tcx> TypeRelation<'infcx, 'gcx, 'tcx> for Equate<'combine, 'infcx, 'gcx, 'tcx> {
     fn tag(&self) -> &'static str { "Equate" }
 
     fn tcx(&self) -> TyCtxt<'infcx, 'gcx, 'tcx> { self.fields.tcx() }
diff --git a/src/librustc/infer/glb.rs b/src/librustc/infer/glb.rs
index 7893846b214..46d5991b7ad 100644
--- a/src/librustc/infer/glb.rs
+++ b/src/librustc/infer/glb.rs
@@ -15,25 +15,20 @@ use super::Subtype;
 
 use ty::{self, Ty, TyCtxt};
 use ty::relate::{Relate, RelateResult, TypeRelation};
-use traits::PredicateObligations;
 
 /// "Greatest lower bound" (common subtype)
-pub struct Glb<'infcx, 'gcx: 'infcx+'tcx, 'tcx: 'infcx> {
-    fields: CombineFields<'infcx, 'gcx, 'tcx>,
+pub struct Glb<'combine, 'infcx: 'combine, 'gcx: 'infcx+'tcx, 'tcx: 'infcx> {
+    fields: &'combine mut CombineFields<'infcx, 'gcx, 'tcx>,
     a_is_expected: bool,
 }
 
-impl<'infcx, 'gcx, 'tcx> Glb<'infcx, 'gcx, 'tcx> {
-    pub fn new(fields: CombineFields<'infcx, 'gcx, 'tcx>, a_is_expected: bool) -> Glb<'infcx, 'gcx, 'tcx> {
+impl<'combine, 'infcx, 'gcx, 'tcx> Glb<'combine, 'infcx, 'gcx, 'tcx> {
+    pub fn new(fields: &'combine mut CombineFields<'infcx, 'gcx, 'tcx>, a_is_expected: bool) -> Glb<'combine, 'infcx, 'gcx, 'tcx> {
         Glb { fields: fields, a_is_expected: a_is_expected }
     }
-
-    pub fn obligations(self) -> PredicateObligations<'tcx> {
-        self.fields.obligations
-    }
 }
 
-impl<'infcx, 'gcx, 'tcx> TypeRelation<'infcx, 'gcx, 'tcx> for Glb<'infcx, 'gcx, 'tcx> {
+impl<'combine, 'infcx, 'gcx, 'tcx> TypeRelation<'infcx, 'gcx, 'tcx> for Glb<'combine, 'infcx, 'gcx, 'tcx> {
     fn tag(&self) -> &'static str { "Glb" }
 
     fn tcx(&self) -> TyCtxt<'infcx, 'gcx, 'tcx> { self.fields.tcx() }
@@ -76,12 +71,12 @@ impl<'infcx, 'gcx, 'tcx> TypeRelation<'infcx, 'gcx, 'tcx> for Glb<'infcx, 'gcx,
     }
 }
 
-impl<'infcx, 'gcx, 'tcx> LatticeDir<'infcx, 'gcx, 'tcx> for Glb<'infcx, 'gcx, 'tcx> {
+impl<'combine, 'infcx, 'gcx, 'tcx> LatticeDir<'infcx, 'gcx, 'tcx> for Glb<'combine, 'infcx, 'gcx, 'tcx> {
     fn infcx(&self) -> &'infcx InferCtxt<'infcx, 'gcx, 'tcx> {
         self.fields.infcx
     }
 
-    fn relate_bound(&self, v: Ty<'tcx>, a: Ty<'tcx>, b: Ty<'tcx>) -> RelateResult<'tcx, ()> {
+    fn relate_bound(&mut self, v: Ty<'tcx>, a: Ty<'tcx>, b: Ty<'tcx>) -> RelateResult<'tcx, ()> {
         let mut sub = self.fields.sub(self.a_is_expected);
         sub.relate(&v, &a)?;
         sub.relate(&v, &b)?;
diff --git a/src/librustc/infer/higher_ranked/mod.rs b/src/librustc/infer/higher_ranked/mod.rs
index 386c1ba272f..743d6135fbb 100644
--- a/src/librustc/infer/higher_ranked/mod.rs
+++ b/src/librustc/infer/higher_ranked/mod.rs
@@ -40,7 +40,7 @@ pub struct HrMatchResult<U> {
 }
 
 impl<'a, 'gcx, 'tcx> CombineFields<'a, 'gcx, 'tcx> {
-    pub fn higher_ranked_sub<T>(&self, a: &Binder<T>, b: &Binder<T>, a_is_expected: bool)
+    pub fn higher_ranked_sub<T>(&mut self, a: &Binder<T>, b: &Binder<T>, a_is_expected: bool)
                                 -> RelateResult<'tcx, Binder<T>>
         where T: Relate<'tcx>
     {
@@ -106,7 +106,7 @@ impl<'a, 'gcx, 'tcx> CombineFields<'a, 'gcx, 'tcx> {
     /// NB. It should not happen that there are LBR appearing in `U`
     /// that do not appear in `T`. If that happens, those regions are
     /// unconstrained, and this routine replaces them with `'static`.
-    pub fn higher_ranked_match<T, U>(&self,
+    pub fn higher_ranked_match<T, U>(&mut self,
                                      span: Span,
                                      a_pair: &Binder<(T, U)>,
                                      b_match: &T,
@@ -222,7 +222,7 @@ impl<'a, 'gcx, 'tcx> CombineFields<'a, 'gcx, 'tcx> {
         });
     }
 
-    pub fn higher_ranked_lub<T>(&self, a: &Binder<T>, b: &Binder<T>, a_is_expected: bool)
+    pub fn higher_ranked_lub<T>(&mut self, a: &Binder<T>, b: &Binder<T>, a_is_expected: bool)
                                 -> RelateResult<'tcx, Binder<T>>
         where T: Relate<'tcx>
     {
@@ -312,7 +312,7 @@ impl<'a, 'gcx, 'tcx> CombineFields<'a, 'gcx, 'tcx> {
         }
     }
 
-    pub fn higher_ranked_glb<T>(&self, a: &Binder<T>, b: &Binder<T>, a_is_expected: bool)
+    pub fn higher_ranked_glb<T>(&mut self, a: &Binder<T>, b: &Binder<T>, a_is_expected: bool)
                                 -> RelateResult<'tcx, Binder<T>>
         where T: Relate<'tcx>
     {
diff --git a/src/librustc/infer/lattice.rs b/src/librustc/infer/lattice.rs
index 1a2bc4b5cf2..eda78428e61 100644
--- a/src/librustc/infer/lattice.rs
+++ b/src/librustc/infer/lattice.rs
@@ -40,7 +40,7 @@ pub trait LatticeDir<'f, 'gcx: 'f+'tcx, 'tcx: 'f> : TypeRelation<'f, 'gcx, 'tcx>
 
     // Relates the type `v` to `a` and `b` such that `v` represents
     // the LUB/GLB of `a` and `b` as appropriate.
-    fn relate_bound(&self, v: Ty<'tcx>, a: Ty<'tcx>, b: Ty<'tcx>) -> RelateResult<'tcx, ()>;
+    fn relate_bound(&mut self, v: Ty<'tcx>, a: Ty<'tcx>, b: Ty<'tcx>) -> RelateResult<'tcx, ()>;
 }
 
 pub fn super_lattice_tys<'a, 'gcx, 'tcx, L>(this: &mut L,
diff --git a/src/librustc/infer/lub.rs b/src/librustc/infer/lub.rs
index 6f3bd004f1f..2639e06f2e5 100644
--- a/src/librustc/infer/lub.rs
+++ b/src/librustc/infer/lub.rs
@@ -15,25 +15,20 @@ use super::Subtype;
 
 use ty::{self, Ty, TyCtxt};
 use ty::relate::{Relate, RelateResult, TypeRelation};
-use traits::PredicateObligations;
 
 /// "Least upper bound" (common supertype)
-pub struct Lub<'infcx, 'gcx: 'infcx+'tcx, 'tcx: 'infcx> {
-    fields: CombineFields<'infcx, 'gcx, 'tcx>,
+pub struct Lub<'combine, 'infcx: 'combine, 'gcx: 'infcx+'tcx, 'tcx: 'infcx> {
+    fields: &'combine mut CombineFields<'infcx, 'gcx, 'tcx>,
     a_is_expected: bool,
 }
 
-impl<'infcx, 'gcx, 'tcx> Lub<'infcx, 'gcx, 'tcx> {
-    pub fn new(fields: CombineFields<'infcx, 'gcx, 'tcx>, a_is_expected: bool) -> Lub<'infcx, 'gcx, 'tcx> {
+impl<'combine, 'infcx, 'gcx, 'tcx> Lub<'combine, 'infcx, 'gcx, 'tcx> {
+    pub fn new(fields: &'combine mut CombineFields<'infcx, 'gcx, 'tcx>, a_is_expected: bool) -> Lub<'combine, 'infcx, 'gcx, 'tcx> {
         Lub { fields: fields, a_is_expected: a_is_expected }
     }
-
-    pub fn obligations(self) -> PredicateObligations<'tcx> {
-        self.fields.obligations
-    }
 }
 
-impl<'infcx, 'gcx, 'tcx> TypeRelation<'infcx, 'gcx, 'tcx> for Lub<'infcx, 'gcx, 'tcx> {
+impl<'combine, 'infcx, 'gcx, 'tcx> TypeRelation<'infcx, 'gcx, 'tcx> for Lub<'combine, 'infcx, 'gcx, 'tcx> {
     fn tag(&self) -> &'static str { "Lub" }
 
     fn tcx(&self) -> TyCtxt<'infcx, 'gcx, 'tcx> { self.fields.tcx() }
@@ -76,12 +71,12 @@ impl<'infcx, 'gcx, 'tcx> TypeRelation<'infcx, 'gcx, 'tcx> for Lub<'infcx, 'gcx,
     }
 }
 
-impl<'infcx, 'gcx, 'tcx> LatticeDir<'infcx, 'gcx, 'tcx> for Lub<'infcx, 'gcx, 'tcx> {
+impl<'combine, 'infcx, 'gcx, 'tcx> LatticeDir<'infcx, 'gcx, 'tcx> for Lub<'combine, 'infcx, 'gcx, 'tcx> {
     fn infcx(&self) -> &'infcx InferCtxt<'infcx, 'gcx, 'tcx> {
         self.fields.infcx
     }
 
-    fn relate_bound(&self, v: Ty<'tcx>, a: Ty<'tcx>, b: Ty<'tcx>) -> RelateResult<'tcx, ()> {
+    fn relate_bound(&mut self, v: Ty<'tcx>, a: Ty<'tcx>, b: Ty<'tcx>) -> RelateResult<'tcx, ()> {
         let mut sub = self.fields.sub(self.a_is_expected);
         sub.relate(&a, &v)?;
         sub.relate(&b, &v)?;
diff --git a/src/librustc/infer/mod.rs b/src/librustc/infer/mod.rs
index 9ee0da4d0ed..58d2b963bbf 100644
--- a/src/librustc/infer/mod.rs
+++ b/src/librustc/infer/mod.rs
@@ -813,36 +813,36 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
         -> InferResult<'tcx, T>
         where T: Relate<'tcx>
     {
-        let mut equate = self.combine_fields(trace).equate(a_is_expected);
-        let result = equate.relate(a, b);
-        result.map(|t| InferOk { value: t, obligations: equate.obligations() })
+        let mut fields = self.combine_fields(trace);
+        let result = fields.equate(a_is_expected).relate(a, b);
+        result.map(move |t| InferOk { value: t, obligations: fields.obligations })
     }
 
     pub fn sub<T>(&'a self, a_is_expected: bool, trace: TypeTrace<'tcx>, a: &T, b: &T)
         -> InferResult<'tcx, T>
         where T: Relate<'tcx>
     {
-        let mut sub = self.combine_fields(trace).sub(a_is_expected);
-        let result = sub.relate(a, b);
-        result.map(|t| InferOk { value: t, obligations: sub.obligations() })
+        let mut fields = self.combine_fields(trace);
+        let result = fields.sub(a_is_expected).relate(a, b);
+        result.map(move |t| InferOk { value: t, obligations: fields.obligations })
     }
 
     pub fn lub<T>(&'a self, a_is_expected: bool, trace: TypeTrace<'tcx>, a: &T, b: &T)
         -> InferResult<'tcx, T>
         where T: Relate<'tcx>
     {
-        let mut lub = self.combine_fields(trace).lub(a_is_expected);
-        let result = lub.relate(a, b);
-        result.map(|t| InferOk { value: t, obligations: lub.obligations() })
+        let mut fields = self.combine_fields(trace);
+        let result = fields.lub(a_is_expected).relate(a, b);
+        result.map(move |t| InferOk { value: t, obligations: fields.obligations })
     }
 
     pub fn glb<T>(&'a self, a_is_expected: bool, trace: TypeTrace<'tcx>, a: &T, b: &T)
         -> InferResult<'tcx, T>
         where T: Relate<'tcx>
     {
-        let mut glb = self.combine_fields(trace).glb(a_is_expected);
-        let result = glb.relate(a, b);
-        result.map(|t| InferOk { value: t, obligations: glb.obligations() })
+        let mut fields = self.combine_fields(trace);
+        let result = fields.glb(a_is_expected).relate(a, b);
+        result.map(move |t| InferOk { value: t, obligations: fields.obligations })
     }
 
     fn start_snapshot(&self) -> CombinedSnapshot {
@@ -1645,7 +1645,7 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
         };
 
         let match_pair = match_a.map_bound(|p| (p.projection_ty.trait_ref, p.ty));
-        let combine = self.combine_fields(trace);
+        let mut combine = self.combine_fields(trace);
         let result = combine.higher_ranked_match(span, &match_pair, &match_b, true)?;
         Ok(InferOk { value: result, obligations: combine.obligations })
     }
diff --git a/src/librustc/infer/sub.rs b/src/librustc/infer/sub.rs
index 7a25ea9f3c2..a3e50a23d3f 100644
--- a/src/librustc/infer/sub.rs
+++ b/src/librustc/infer/sub.rs
@@ -15,24 +15,19 @@ use super::type_variable::{SubtypeOf, SupertypeOf};
 use ty::{self, Ty, TyCtxt};
 use ty::TyVar;
 use ty::relate::{Cause, Relate, RelateResult, TypeRelation};
-use traits::PredicateObligations;
 use std::mem;
 
 /// Ensures `a` is made a subtype of `b`. Returns `a` on success.
-pub struct Sub<'infcx, 'gcx: 'infcx+'tcx, 'tcx: 'infcx> {
-    fields: CombineFields<'infcx, 'gcx, 'tcx>,
+pub struct Sub<'combine, 'infcx: 'combine, 'gcx: 'infcx+'tcx, 'tcx: 'infcx> {
+    fields: &'combine mut CombineFields<'infcx, 'gcx, 'tcx>,
     a_is_expected: bool,
 }
 
-impl<'infcx, 'gcx, 'tcx> Sub<'infcx, 'gcx, 'tcx> {
-    pub fn new(f: CombineFields<'infcx, 'gcx, 'tcx>, a_is_expected: bool) -> Sub<'infcx, 'gcx, 'tcx> {
+impl<'combine, 'infcx, 'gcx, 'tcx> Sub<'combine, 'infcx, 'gcx, 'tcx> {
+    pub fn new(f: &'combine mut CombineFields<'infcx, 'gcx, 'tcx>, a_is_expected: bool) -> Sub<'combine, 'infcx, 'gcx, 'tcx> {
         Sub { fields: f, a_is_expected: a_is_expected }
     }
 
-    pub fn obligations(self) -> PredicateObligations<'tcx> {
-        self.fields.obligations
-    }
-
     fn with_expected_switched<R, F: FnOnce(&mut Self) -> R>(&mut self, f: F) -> R {
         self.a_is_expected = !self.a_is_expected;
         let result = f(self);
@@ -41,7 +36,7 @@ impl<'infcx, 'gcx, 'tcx> Sub<'infcx, 'gcx, 'tcx> {
     }
 }
 
-impl<'infcx, 'gcx, 'tcx> TypeRelation<'infcx, 'gcx, 'tcx> for Sub<'infcx, 'gcx, 'tcx> {
+impl<'combine, 'infcx, 'gcx, 'tcx> TypeRelation<'infcx, 'gcx, 'tcx> for Sub<'combine, 'infcx, 'gcx, 'tcx> {
     fn tag(&self) -> &'static str { "Sub" }
     fn tcx(&self) -> TyCtxt<'infcx, 'gcx, 'tcx> { self.fields.infcx.tcx }
     fn a_is_expected(&self) -> bool { self.a_is_expected }