register infer-ok obligations properly

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

cc #32730

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))