Refactor s.t. TypeRelation implementors in infer don't escape InferCtxt

src/librustc/infer/mod.rs

@@ -386,33 +386,6 @@ pub fn normalizing_infer_ctxt<'a, 'tcx>(tcx: &'a TyCtxt<'tcx>,
     infcx
 }
 
-/// Computes the least upper-bound of `a` and `b`. If this is not possible, reports an error and
-/// returns ty::err.
-pub fn common_supertype<'a, 'tcx>(cx: &InferCtxt<'a, 'tcx>,
-                                  origin: TypeOrigin,
-                                  a_is_expected: bool,
-                                  a: Ty<'tcx>,
-                                  b: Ty<'tcx>)
-                                  -> Ty<'tcx>
-{
-    debug!("common_supertype({:?}, {:?})",
-           a, b);
-
-    let trace = TypeTrace {
-        origin: origin,
-        values: Types(expected_found(a_is_expected, a, b))
-    };
-
-    let result = cx.commit_if_ok(|_| cx.lub(a_is_expected, trace.clone()).relate(&a, &b));
-    match result {
-        Ok(t) => t,
-        Err(ref err) => {
-            cx.report_and_explain_type_error(trace, err).emit();
-            cx.tcx.types.err
-        }
-    }
-}
-
 pub fn mk_subty<'a, 'tcx>(cx: &InferCtxt<'a, 'tcx>,
                           a_is_expected: bool,
                           origin: TypeOrigin,
@@ -434,7 +407,7 @@ pub fn can_mk_subty<'a, 'tcx>(cx: &InferCtxt<'a, 'tcx>,
             origin: TypeOrigin::Misc(codemap::DUMMY_SP),
             values: Types(expected_found(true, a, b))
         };
-        cx.sub(true, trace).relate(&a, &b).map(|_| ())
+        cx.sub(true, trace, &a, &b).map(|_| ())
     })
 }
 
@@ -695,32 +668,32 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
                        cause: None}
     }
 
-    // public so that it can be used from the rustc_driver unit tests
-    pub fn equate(&'a self, a_is_expected: bool, trace: TypeTrace<'tcx>)
-              -> equate::Equate<'a, 'tcx>
+    pub fn equate<T>(&'a self, a_is_expected: bool, trace: TypeTrace<'tcx>, a: &T, b: &T)
+        -> RelateResult<'tcx, T>
+        where T: Relate<'a, 'tcx>
     {
-        self.combine_fields(a_is_expected, trace).equate()
+        self.combine_fields(a_is_expected, trace).equate().relate(a, b)
     }
 
-    // public so that it can be used from the rustc_driver unit tests
-    pub fn sub(&'a self, a_is_expected: bool, trace: TypeTrace<'tcx>)
-               -> sub::Sub<'a, 'tcx>
+    pub fn sub<T>(&'a self, a_is_expected: bool, trace: TypeTrace<'tcx>, a: &T, b: &T)
+        -> RelateResult<'tcx, T>
+        where T: Relate<'a, 'tcx>
     {
-        self.combine_fields(a_is_expected, trace).sub()
+        self.combine_fields(a_is_expected, trace).sub().relate(a, b)
     }
 
-    // public so that it can be used from the rustc_driver unit tests
-    pub fn lub(&'a self, a_is_expected: bool, trace: TypeTrace<'tcx>)
-               -> lub::Lub<'a, 'tcx>
+    pub fn lub<T>(&'a self, a_is_expected: bool, trace: TypeTrace<'tcx>, a: &T, b: &T)
+        -> RelateResult<'tcx, T>
+        where T: Relate<'a, 'tcx>
     {
-        self.combine_fields(a_is_expected, trace).lub()
+        self.combine_fields(a_is_expected, trace).lub().relate(a, b)
     }
 
-    // public so that it can be used from the rustc_driver unit tests
-    pub fn glb(&'a self, a_is_expected: bool, trace: TypeTrace<'tcx>)
-               -> glb::Glb<'a, 'tcx>
+    pub fn glb<T>(&'a self, a_is_expected: bool, trace: TypeTrace<'tcx>, a: &T, b: &T)
+        -> RelateResult<'tcx, T>
+        where T: Relate<'a, 'tcx>
     {
-        self.combine_fields(a_is_expected, trace).glb()
+        self.combine_fields(a_is_expected, trace).glb().relate(a, b)
     }
 
     fn start_snapshot(&self) -> CombinedSnapshot {
@@ -861,7 +834,7 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
         debug!("sub_types({:?} <: {:?})", a, b);
         self.commit_if_ok(|_| {
             let trace = TypeTrace::types(origin, a_is_expected, a, b);
-            self.sub(a_is_expected, trace).relate(&a, &b).map(|_| ())
+            self.sub(a_is_expected, trace, &a, &b).map(|_| ())
         })
     }
 
@@ -874,7 +847,7 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
     {
         self.commit_if_ok(|_| {
             let trace = TypeTrace::types(origin, a_is_expected, a, b);
-            self.equate(a_is_expected, trace).relate(&a, &b).map(|_| ())
+            self.equate(a_is_expected, trace, &a, &b).map(|_| ())
         })
     }
 
@@ -893,7 +866,7 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
                 origin: origin,
                 values: TraitRefs(expected_found(a_is_expected, a.clone(), b.clone()))
             };
-            self.equate(a_is_expected, trace).relate(&a, &b).map(|_| ())
+            self.equate(a_is_expected, trace, &a, &b).map(|_| ())
         })
     }
 
@@ -912,7 +885,7 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
                 origin: origin,
                 values: PolyTraitRefs(expected_found(a_is_expected, a.clone(), b.clone()))
             };
-            self.sub(a_is_expected, trace).relate(&a, &b).map(|_| ())
+            self.sub(a_is_expected, trace, &a, &b).map(|_| ())
         })
     }
 
@@ -1461,7 +1434,7 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
                 origin: TypeOrigin::Misc(codemap::DUMMY_SP),
                 values: Types(expected_found(true, e, e))
             };
-            self.equate(true, trace).relate(a, b)
+            self.equate(true, trace, a, b)
         }).map(|_| ())
     }
 

src/librustc/ty/relate.rs

@@ -602,6 +602,17 @@ impl<'a,'tcx:'a> Relate<'a,'tcx> for ty::ClosureSubsts<'tcx> {
     }
 }
 
+impl<'a,'tcx:'a> Relate<'a,'tcx> for Substs<'tcx> {
+    fn relate<R>(relation: &mut R,
+                 a: &Substs<'tcx>,
+                 b: &Substs<'tcx>)
+                 -> RelateResult<'tcx, Substs<'tcx>>
+        where R: TypeRelation<'a,'tcx>
+    {
+        relate_substs(relation, None, a, b)
+    }
+}
+
 impl<'a,'tcx:'a> Relate<'a,'tcx> for ty::Region {
     fn relate<R>(relation: &mut R,
                  a: &ty::Region,

src/librustc_driver/test.rs

@@ -24,11 +24,8 @@ use rustc::ty::subst;
 use rustc::ty::subst::Subst;
 use rustc::traits::ProjectionMode;
 use rustc::ty::{self, Ty, TyCtxt, TypeFoldable};
-use rustc::ty::relate::TypeRelation;
+use rustc::ty::relate::{TypeRelation, RelateResult};
 use rustc::infer::{self, TypeOrigin};
-use rustc::infer::lub::Lub;
-use rustc::infer::glb::Glb;
-use rustc::infer::sub::Sub;
 use rustc_metadata::cstore::CStore;
 use rustc::front::map as hir_map;
 use rustc::session::{self, config};
@@ -358,25 +355,25 @@ impl<'a, 'tcx> Env<'a, 'tcx> {
         infer::TypeTrace::dummy(self.tcx())
     }
 
-    pub fn sub(&self) -> Sub<'a, 'tcx> {
+    pub fn sub(&self, t1: &Ty<'tcx>, t2: &Ty<'tcx>) -> RelateResult<'tcx, Ty<'tcx>> {
         let trace = self.dummy_type_trace();
-        self.infcx.sub(true, trace)
+        self.infcx.sub(true, trace, t1, t2)
     }
 
-    pub fn lub(&self) -> Lub<'a, 'tcx> {
+    pub fn lub(&self, t1: &Ty<'tcx>, t2: &Ty<'tcx>) -> RelateResult<'tcx, Ty<'tcx>> {
         let trace = self.dummy_type_trace();
-        self.infcx.lub(true, trace)
+        self.infcx.lub(true, trace, t1, t2)
     }
 
-    pub fn glb(&self) -> Glb<'a, 'tcx> {
+    pub fn glb(&self, t1: &Ty<'tcx>, t2: &Ty<'tcx>) -> RelateResult<'tcx, Ty<'tcx>> {
         let trace = self.dummy_type_trace();
-        self.infcx.glb(true, trace)
+        self.infcx.glb(true, trace, t1, t2)
     }
 
     /// Checks that `t1 <: t2` is true (this may register additional
     /// region checks).
     pub fn check_sub(&self, t1: Ty<'tcx>, t2: Ty<'tcx>) {
-        match self.sub().relate(&t1, &t2) {
+        match self.sub(&t1, &t2) {
             Ok(_) => {}
             Err(ref e) => {
                 panic!("unexpected error computing sub({:?},{:?}): {}", t1, t2, e);
@@ -387,7 +384,7 @@ impl<'a, 'tcx> Env<'a, 'tcx> {
     /// Checks that `t1 <: t2` is false (this may register additional
     /// region checks).
     pub fn check_not_sub(&self, t1: Ty<'tcx>, t2: Ty<'tcx>) {
-        match self.sub().relate(&t1, &t2) {
+        match self.sub(&t1, &t2) {
             Err(_) => {}
             Ok(_) => {
                 panic!("unexpected success computing sub({:?},{:?})", t1, t2);
@@ -397,7 +394,7 @@ impl<'a, 'tcx> Env<'a, 'tcx> {
 
     /// Checks that `LUB(t1,t2) == t_lub`
     pub fn check_lub(&self, t1: Ty<'tcx>, t2: Ty<'tcx>, t_lub: Ty<'tcx>) {
-        match self.lub().relate(&t1, &t2) {
+        match self.lub(&t1, &t2) {
             Ok(t) => {
                 self.assert_eq(t, t_lub);
             }
@@ -410,7 +407,7 @@ impl<'a, 'tcx> Env<'a, 'tcx> {
     /// Checks that `GLB(t1,t2) == t_glb`
     pub fn check_glb(&self, t1: Ty<'tcx>, t2: Ty<'tcx>, t_glb: Ty<'tcx>) {
         debug!("check_glb(t1={}, t2={}, t_glb={})", t1, t2, t_glb);
-        match self.glb().relate(&t1, &t2) {
+        match self.glb(&t1, &t2) {
             Err(e) => {
                 panic!("unexpected error computing LUB: {:?}", e)
             }

src/librustc_typeck/check/coercion.rs

@@ -71,7 +71,7 @@ use rustc::ty::adjustment::{AdjustUnsafeFnPointer, AdjustMutToConstPointer};
 use rustc::ty::{self, LvaluePreference, TypeAndMut, Ty, TyCtxt};
 use rustc::ty::fold::TypeFoldable;
 use rustc::ty::error::TypeError;
-use rustc::ty::relate::{relate_substs, Relate, RelateResult, TypeRelation};
+use rustc::ty::relate::{RelateResult, TypeRelation};
 use util::common::indent;
 
 use std::cell::RefCell;
@@ -117,9 +117,9 @@ impl<'f, 'tcx> Coerce<'f, 'tcx> {
         infcx.commit_if_ok(|_| {
             let trace = TypeTrace::types(self.origin, false, a, b);
             if self.use_lub {
-                infcx.lub(false, trace).relate(&a, &b)
+                infcx.lub(false, trace, &a, &b)
             } else {
-                infcx.sub(false, trace).relate(&a, &b)
+                infcx.sub(false, trace, &a, &b)
             }
         })
     }
@@ -649,20 +649,19 @@ pub fn try_find_lub<'a, 'b, 'tcx, E, I>(fcx: &FnCtxt<'a, 'tcx>,
     debug!("coercion::try_find_lub({:?}, {:?})", prev_ty, new_ty);
 
     let trace = TypeTrace::types(origin, true, prev_ty, new_ty);
-    let mut lub = fcx.infcx().lub(true, trace);
 
     // Special-case that coercion alone cannot handle:
     // Two function item types of differing IDs or Substs.
     match (&prev_ty.sty, &new_ty.sty) {
         (&ty::TyFnDef(a_def_id, a_substs, a_fty),
          &ty::TyFnDef(b_def_id, b_substs, b_fty)) => {
             // The signature must always match.
-            let fty = lub.relate(a_fty, b_fty)?;
+            let fty = fcx.infcx().lub(true, trace.clone(), a_fty, b_fty)?;
 
             if a_def_id == b_def_id {
                 // Same function, maybe the parameters match.
                 let substs = fcx.infcx().commit_if_ok(|_| {
-                    relate_substs(&mut lub, None, a_substs, b_substs)
+                    fcx.infcx().lub(true, trace.clone(), a_substs, b_substs)
                 }).map(|s| fcx.tcx().mk_substs(s));
 
                 if let Ok(substs) = substs {
@@ -724,7 +723,9 @@ pub fn try_find_lub<'a, 'b, 'tcx, E, I>(fcx: &FnCtxt<'a, 'tcx>,
         };
 
         if !noop {
-            return fcx.infcx().commit_if_ok(|_| lub.relate(&prev_ty, &new_ty));
+            return fcx.infcx().commit_if_ok(|_| {
+                fcx.infcx().lub(true, trace.clone(), &prev_ty, &new_ty)
+            });
         }
     }
 
@@ -734,7 +735,9 @@ pub fn try_find_lub<'a, 'b, 'tcx, E, I>(fcx: &FnCtxt<'a, 'tcx>,
             if let Some(e) = first_error {
                 Err(e)
             } else {
-                fcx.infcx().commit_if_ok(|_| lub.relate(&prev_ty, &new_ty))
+                fcx.infcx().commit_if_ok(|_| {
+                    fcx.infcx().lub(true, trace, &prev_ty, &new_ty)
+                })
             }
         }
         Ok((ty, adjustment)) => {

src/librustc_typeck/check/mod.rs

@@ -2904,7 +2904,7 @@ fn check_expr_with_expectation_and_lvalue_pref<'a, 'tcx>(fcx: &FnCtxt<'a, 'tcx>,
             } else {
                 fcx.infcx().commit_if_ok(|_| {
                     let trace = TypeTrace::types(origin, true, then_ty, else_ty);
-                    fcx.infcx().lub(true, trace).relate(&then_ty, &else_ty)
+                    fcx.infcx().lub(true, trace, &then_ty, &else_ty)
                 })
             };
             (origin, then_ty, else_ty, result)