register infer-ok obligations properly

Or at least, more properly. I think I left one or two FIXMEs still in
there.

cc #32730

Author: nikomatsakis

src/librustc/infer/sub.rs

@@ -8,8 +8,8 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use super::combine::CombineFields;
 use super::SubregionOrigin;
+use super::combine::CombineFields;
 use super::type_variable::{SubtypeOf, SupertypeOf};
 
 use ty::{self, Ty, TyCtxt};
@@ -117,6 +117,7 @@ impl<'combine, 'infcx, 'gcx, 'tcx> TypeRelation<'infcx, 'gcx, 'tcx>
         // error messages.
         let origin = SubregionOrigin::Subtype(self.fields.trace.clone());
         self.fields.infcx.region_vars.make_subregion(origin, a, b);
+
         Ok(a)
     }
 

src/librustc/traits/fulfill.rs

@@ -520,10 +520,8 @@ fn process_predicate<'a, 'gcx, 'tcx>(
 
         ty::Predicate::Equate(ref binder) => {
             match selcx.infcx().equality_predicate(&obligation.cause, binder) {
-                Ok(InferOk { obligations, .. }) => {
-                    // FIXME(#32730) propagate obligations
-                    assert!(obligations.is_empty());
-                    Ok(Some(Vec::new()))
+                Ok(InferOk { obligations, value: () }) => {
+                    Ok(Some(obligations))
                 },
                 Err(_) => Err(CodeSelectionError(Unimplemented)),
             }

src/librustc/traits/project.rs

@@ -210,9 +210,7 @@ fn project_and_unify_type<'cx, 'gcx, 'tcx>(
 
     let infcx = selcx.infcx();
     match infcx.eq_types(true, &obligation.cause, normalized_ty, obligation.predicate.ty) {
-        Ok(InferOk { obligations: inferred_obligations, .. }) => {
-            // FIXME(#32730) once obligations are generated in inference, drop this assertion
-            assert!(inferred_obligations.is_empty());
+        Ok(InferOk { obligations: inferred_obligations, value: () }) => {
             obligations.extend(inferred_obligations);
             Ok(Some(obligations))
         },
@@ -847,9 +845,10 @@ fn assemble_candidates_from_predicates<'cx, 'gcx, 'tcx, I>(
                                               obligation.cause.clone(),
                                               data_poly_trait_ref,
                                               obligation_poly_trait_ref)
-                        // FIXME(#32730) once obligations are propagated from unification in
-                        // inference, drop this assertion
-                        .map(|InferOk { obligations, .. }| assert!(obligations.is_empty()))
+                        .map(|InferOk { obligations: _, value: () }| {
+                            // FIXME(#32730) -- do we need to take obligations
+                            // into account in any way? At the moment, no.
+                        })
                         .is_ok()
                 });
 
@@ -1184,12 +1183,10 @@ fn confirm_fn_pointer_candidate<'cx, 'gcx, 'tcx>(
     fn_pointer_vtable: VtableFnPointerData<'tcx, PredicateObligation<'tcx>>)
     -> Progress<'tcx>
 {
-    // FIXME(#32730) drop this assertion once obligations are propagated from inference (fn pointer
-    // vtable nested obligations ONLY come from unification in inference)
-    assert!(fn_pointer_vtable.nested.is_empty());
     let fn_type = selcx.infcx().shallow_resolve(fn_pointer_vtable.fn_ty);
     let sig = fn_type.fn_sig();
     confirm_callable_candidate(selcx, obligation, sig, util::TupleArgumentsFlag::Yes)
+        .with_addl_obligations(fn_pointer_vtable.nested)
 }
 
 fn confirm_closure_candidate<'cx, 'gcx, 'tcx>(
@@ -1266,8 +1263,6 @@ fn confirm_param_env_candidate<'cx, 'gcx, 'tcx>(
     let trait_ref = obligation.predicate.trait_ref;
     match infcx.match_poly_projection_predicate(cause, poly_projection, trait_ref) {
         Ok(InferOk { value: ty_match, obligations }) => {
-            // FIXME(#32730) once obligations are generated in inference, drop this assertion
-            assert!(obligations.is_empty());
             Progress {
                 ty: ty_match.value,
                 obligations: obligations,

src/librustc/traits/select.rs

@@ -418,9 +418,6 @@ impl<'cx, 'gcx, 'tcx> SelectionContext<'cx, 'gcx, 'tcx> {
             None => Ok(None),
             Some(candidate) => {
                 let mut candidate = self.confirm_candidate(obligation, candidate)?;
-                // FIXME(#32730) remove this assertion once inferred obligations are propagated
-                // from inference
-                assert!(self.inferred_obligations.len() == 0);
                 let inferred_obligations = (*self.inferred_obligations).into_iter().cloned();
                 candidate.nested_obligations_mut().extend(inferred_obligations);
                 Ok(Some(candidate))

src/librustc_mir/transform/type_check.rs

@@ -324,20 +324,25 @@ impl<'a, 'gcx, 'tcx> TypeChecker<'a, 'gcx, 'tcx> {
         traits::ObligationCause::misc(span, self.body_id)
     }
 
-    fn sub_types(&self, span: Span, sup: Ty<'tcx>, sub: Ty<'tcx>)
+    pub fn register_infer_ok_obligations<T>(&mut self, infer_ok: InferOk<'tcx, T>) -> T {
+        for obligation in infer_ok.obligations {
+            self.fulfillment_cx.register_predicate_obligation(self.infcx, obligation);
+        }
+        infer_ok.value
+    }
+
+    fn sub_types(&mut self, sup: Ty<'tcx>, sub: Ty<'tcx>)
                  -> infer::UnitResult<'tcx>
     {
-        self.infcx.sub_types(false, &self.misc(span), sup, sub)
-            // FIXME(#32730) propagate obligations
-            .map(|InferOk { obligations, .. }| assert!(obligations.is_empty()))
+        self.infcx.sub_types(false, &self.misc(self.last_span), sup, sub)
+            .map(|ok| self.register_infer_ok_obligations(ok))
     }
 
-    fn eq_types(&self, span: Span, a: Ty<'tcx>, b: Ty<'tcx>)
+    fn eq_types(&mut self, span: Span, a: Ty<'tcx>, b: Ty<'tcx>)
                 -> infer::UnitResult<'tcx>
     {
         self.infcx.eq_types(false, &self.misc(span), a, b)
-            // FIXME(#32730) propagate obligations
-            .map(|InferOk { obligations, .. }| assert!(obligations.is_empty()))
+            .map(|ok| self.register_infer_ok_obligations(ok))
     }
 
     fn tcx(&self) -> TyCtxt<'a, 'gcx, 'tcx> {
@@ -352,7 +357,7 @@ impl<'a, 'gcx, 'tcx> TypeChecker<'a, 'gcx, 'tcx> {
                 let lv_ty = lv.ty(mir, tcx).to_ty(tcx);
                 let rv_ty = rv.ty(mir, tcx);
                 if let Some(rv_ty) = rv_ty {
-                    if let Err(terr) = self.sub_types(self.last_span, rv_ty, lv_ty) {
+                    if let Err(terr) = self.sub_types(rv_ty, lv_ty) {
                         span_mirbug!(self, stmt, "bad assignment ({:?} = {:?}): {:?}",
                                      lv_ty, rv_ty, terr);
                     }
@@ -413,7 +418,7 @@ impl<'a, 'gcx, 'tcx> TypeChecker<'a, 'gcx, 'tcx> {
             } => {
                 let lv_ty = location.ty(mir, tcx).to_ty(tcx);
                 let rv_ty = value.ty(mir, tcx);
-                if let Err(terr) = self.sub_types(self.last_span, rv_ty, lv_ty) {
+                if let Err(terr) = self.sub_types(rv_ty, lv_ty) {
                     span_mirbug!(self, term, "bad DropAndReplace ({:?} = {:?}): {:?}",
                                  lv_ty, rv_ty, terr);
                 }
@@ -430,7 +435,7 @@ impl<'a, 'gcx, 'tcx> TypeChecker<'a, 'gcx, 'tcx> {
             }
             TerminatorKind::SwitchInt { ref discr, switch_ty, .. } => {
                 let discr_ty = discr.ty(mir, tcx).to_ty(tcx);
-                if let Err(terr) = self.sub_types(self.last_span, discr_ty, switch_ty) {
+                if let Err(terr) = self.sub_types(discr_ty, switch_ty) {
                     span_mirbug!(self, term, "bad SwitchInt ({:?} on {:?}): {:?}",
                                  switch_ty, discr_ty, terr);
                 }
@@ -492,7 +497,7 @@ impl<'a, 'gcx, 'tcx> TypeChecker<'a, 'gcx, 'tcx> {
         }
     }
 
-    fn check_call_dest(&self,
+    fn check_call_dest(&mut self,
                        mir: &Mir<'tcx>,
                        term: &Terminator<'tcx>,
                        sig: &ty::FnSig<'tcx>,
@@ -501,7 +506,7 @@ impl<'a, 'gcx, 'tcx> TypeChecker<'a, 'gcx, 'tcx> {
         match *destination {
             Some((ref dest, _)) => {
                 let dest_ty = dest.ty(mir, tcx).to_ty(tcx);
-                if let Err(terr) = self.sub_types(self.last_span, sig.output, dest_ty) {
+                if let Err(terr) = self.sub_types(sig.output, dest_ty) {
                     span_mirbug!(self, term,
                                  "call dest mismatch ({:?} <- {:?}): {:?}",
                                  dest_ty, sig.output, terr);
@@ -516,7 +521,7 @@ impl<'a, 'gcx, 'tcx> TypeChecker<'a, 'gcx, 'tcx> {
         }
     }
 
-    fn check_call_inputs(&self,
+    fn check_call_inputs(&mut self,
                          mir: &Mir<'tcx>,
                          term: &Terminator<'tcx>,
                          sig: &ty::FnSig<'tcx>,
@@ -529,7 +534,7 @@ impl<'a, 'gcx, 'tcx> TypeChecker<'a, 'gcx, 'tcx> {
         }
         for (n, (fn_arg, op_arg)) in sig.inputs.iter().zip(args).enumerate() {
             let op_arg_ty = op_arg.ty(mir, self.tcx());
-            if let Err(terr) = self.sub_types(self.last_span, op_arg_ty, fn_arg) {
+            if let Err(terr) = self.sub_types(op_arg_ty, fn_arg) {
                 span_mirbug!(self, term, "bad arg #{:?} ({:?} <- {:?}): {:?}",
                              n, fn_arg, op_arg_ty, terr);
             }
@@ -547,7 +552,7 @@ impl<'a, 'gcx, 'tcx> TypeChecker<'a, 'gcx, 'tcx> {
         }
     }
 
-    fn check_box_free_inputs(&self,
+    fn check_box_free_inputs(&mut self,
                              mir: &Mir<'tcx>,
                              term: &Terminator<'tcx>,
                              sig: &ty::FnSig<'tcx>,
@@ -584,7 +589,7 @@ impl<'a, 'gcx, 'tcx> TypeChecker<'a, 'gcx, 'tcx> {
             }
         };
 
-        if let Err(terr) = self.sub_types(self.last_span, arg_ty, pointee_ty) {
+        if let Err(terr) = self.sub_types(arg_ty, pointee_ty) {
             span_mirbug!(self, term, "bad box_free arg ({:?} <- {:?}): {:?}",
                          pointee_ty, arg_ty, terr);
         }

src/librustc_typeck/check/_match.rs

@@ -11,7 +11,7 @@
 use rustc::hir::{self, PatKind};
 use rustc::hir::def::{Def, CtorKind};
 use rustc::hir::pat_util::EnumerateAndAdjustIterator;
-use rustc::infer::{self, InferOk};
+use rustc::infer;
 use rustc::traits::ObligationCauseCode;
 use rustc::ty::{self, Ty, TypeFoldable, LvaluePreference};
 use check::{FnCtxt, Expectation, Diverges};
@@ -462,9 +462,8 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
 
             let result = if is_if_let_fallback {
                 self.eq_types(true, &cause, arm_ty, result_ty)
-                    .map(|InferOk { obligations, .. }| {
-                        // FIXME(#32730) propagate obligations
-                        assert!(obligations.is_empty());
+                    .map(|infer_ok| {
+                        self.register_infer_ok_obligations(infer_ok);
                         arm_ty
                     })
             } else if i == 0 {

src/librustc_typeck/check/coercion.rs

@@ -118,16 +118,11 @@ impl<'f, 'gcx, 'tcx> Coerce<'f, 'gcx, 'tcx> {
             let trace = TypeTrace::types(&self.cause, false, a, b);
             if self.use_lub {
                 self.lub(false, trace, &a, &b)
-                    .map(|InferOk { value, obligations }| {
-                        // FIXME(#32730) propagate obligations
-                        assert!(obligations.is_empty());
-                        value
-                    })
+                    .map(|ok| self.register_infer_ok_obligations(ok))
             } else {
                 self.sub(false, trace, &a, &b)
                     .map(|InferOk { value, obligations }| {
-                        // FIXME(#32730) propagate obligations
-                        assert!(obligations.is_empty());
+                        self.fcx.register_predicates(obligations);
                         value
                     })
             }
@@ -678,21 +673,13 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
             (&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 = self.lub(true, trace.clone(), &a_fty, &b_fty)
-                    .map(|InferOk { value, obligations }| {
-                        // FIXME(#32730) propagate obligations
-                        assert!(obligations.is_empty());
-                        value
-                    })?;
+                              .map(|ok| self.register_infer_ok_obligations(ok))?;
 
                 if a_def_id == b_def_id {
                     // Same function, maybe the parameters match.
                     let substs = self.commit_if_ok(|_| {
                         self.lub(true, trace.clone(), &a_substs, &b_substs)
-                            .map(|InferOk { value, obligations }| {
-                                // FIXME(#32730) propagate obligations
-                                assert!(obligations.is_empty());
-                                value
-                            })
+                            .map(|ok| self.register_infer_ok_obligations(ok))
                     });
 
                     if let Ok(substs) = substs {
@@ -761,11 +748,7 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
             if !noop {
                 return self.commit_if_ok(|_| {
                     self.lub(true, trace.clone(), &prev_ty, &new_ty)
-                        .map(|InferOk { value, obligations }| {
-                            // FIXME(#32730) propagate obligations
-                            assert!(obligations.is_empty());
-                            value
-                        })
+                        .map(|ok| self.register_infer_ok_obligations(ok))
                 });
             }
         }
@@ -778,11 +761,7 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
                 } else {
                     self.commit_if_ok(|_| {
                         self.lub(true, trace, &prev_ty, &new_ty)
-                            .map(|InferOk { value, obligations }| {
-                                // FIXME(#32730) propagate obligations
-                                assert!(obligations.is_empty());
-                                value
-                            })
+                            .map(|ok| self.register_infer_ok_obligations(ok))
                     })
                 }
             }

src/librustc_typeck/check/compare_method.rs

@@ -810,10 +810,11 @@ pub fn compare_const_impl<'a, 'tcx>(ccx: &CrateCtxt<'a, 'tcx>,
             debug!("compare_const_impl: trait_ty={:?}", trait_ty);
 
             infcx.sub_types(false, &cause, impl_ty, trait_ty)
-                .map(|InferOk { obligations, .. }| {
-                    // FIXME(#32730) propagate obligations
-                    assert!(obligations.is_empty())
-                })
+                 .map(|InferOk { obligations, value: () }| {
+                     for obligation in obligations {
+                         fulfillment_cx.register_predicate_obligation(&infcx, obligation);
+                     }
+                 })
         });
 
         if let Err(terr) = err {

src/librustc_typeck/check/demand.rs

@@ -23,9 +23,8 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
     pub fn demand_suptype(&self, sp: Span, expected: Ty<'tcx>, actual: Ty<'tcx>) {
         let cause = self.misc(sp);
         match self.sub_types(false, &cause, actual, expected) {
-            Ok(InferOk { obligations, .. }) => {
-                // FIXME(#32730) propagate obligations
-                assert!(obligations.is_empty());
+            Ok(InferOk { obligations, value: () }) => {
+                self.register_predicates(obligations);
             },
             Err(e) => {
                 self.report_mismatched_types(&cause, expected, actual, e);
@@ -43,9 +42,8 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
                                      actual: Ty<'tcx>)
     {
         match self.eq_types(false, cause, actual, expected) {
-            Ok(InferOk { obligations, .. }) => {
-                // FIXME(#32730) propagate obligations
-                assert!(obligations.is_empty());
+            Ok(InferOk { obligations, value: () }) => {
+                self.register_predicates(obligations);
             },
             Err(e) => {
                 self.report_mismatched_types(cause, expected, actual, e);

src/librustc_typeck/check/method/confirm.rs

@@ -331,9 +331,8 @@ impl<'a, 'gcx, 'tcx> ConfirmContext<'a, 'gcx, 'tcx> {
 
     fn unify_receivers(&mut self, self_ty: Ty<'tcx>, method_self_ty: Ty<'tcx>) {
         match self.sub_types(false, &self.misc(self.span), self_ty, method_self_ty) {
-            Ok(InferOk { obligations, .. }) => {
-                // FIXME(#32730) propagate obligations
-                assert!(obligations.is_empty());
+            Ok(InferOk { obligations, value: () }) => {
+                self.register_predicates(obligations);
             }
             Err(_) => {
                 span_bug!(self.span,