1 files changed, 26 insertions, 25 deletions

diff --git a/compiler/rustc_hir_typeck/src/closure.rs b/compiler/rustc_hir_typeck/src/closure.rs
index d84fabb78..8c2495e1d 100644
--- a/compiler/rustc_hir_typeck/src/closure.rs
+++ b/compiler/rustc_hir_typeck/src/closure.rs
@@ -2,13 +2,12 @@
 
 use super::{check_fn, Expectation, FnCtxt, GeneratorTypes};
 
-use hir::def::DefKind;
 use rustc_errors::ErrorGuaranteed;
 use rustc_hir as hir;
 use rustc_hir::lang_items::LangItem;
 use rustc_hir_analysis::astconv::AstConv;
 use rustc_infer::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind};
-use rustc_infer::infer::LateBoundRegionConversionTime;
+use rustc_infer::infer::{DefineOpaqueTypes, LateBoundRegionConversionTime};
 use rustc_infer::infer::{InferOk, InferResult};
 use rustc_macros::{TypeFoldable, TypeVisitable};
 use rustc_middle::ty::subst::InternalSubsts;
@@ -205,15 +204,18 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         let mut expected_sig = None;
         let mut expected_kind = None;
 
-        for obligation in traits::elaborate_predicates_with_span(
+        for (pred, span) in traits::elaborate(
             self.tcx,
             // Reverse the obligations here, since `elaborate_*` uses a stack,
             // and we want to keep inference generally in the same order of
             // the registered obligations.
             predicates.rev(),
-        ) {
-            debug!(?obligation.predicate);
-            let bound_predicate = obligation.predicate.kind();
+        )
+        // We only care about self bounds
+        .filter_only_self()
+        {
+            debug!(?pred);
+            let bound_predicate = pred.kind();
 
             // Given a Projection predicate, we can potentially infer
             // the complete signature.
@@ -221,9 +223,9 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 && let ty::PredicateKind::Clause(ty::Clause::Projection(proj_predicate)) = bound_predicate.skip_binder()
             {
                 let inferred_sig = self.normalize(
-                    obligation.cause.span,
+                    span,
                     self.deduce_sig_from_projection(
-                    Some(obligation.cause.span),
+                    Some(span),
                         bound_predicate.rebind(proj_predicate),
                     ),
                 );
@@ -398,7 +400,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
     ///
     /// Here:
     /// - E would be `fn(&u32) -> &u32`.
-    /// - S would be `fn(&u32) ->
+    /// - S would be `fn(&u32) -> ?T`
     /// - E' is `&'!0 u32 -> &'!0 u32`
     /// - S' is `&'?0 u32 -> ?T`
     ///
@@ -563,10 +565,11 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             ) {
                 // Check that E' = S'.
                 let cause = self.misc(hir_ty.span);
-                let InferOk { value: (), obligations } = self
-                    .at(&cause, self.param_env)
-                    .define_opaque_types(true)
-                    .eq(*expected_ty, supplied_ty)?;
+                let InferOk { value: (), obligations } = self.at(&cause, self.param_env).eq(
+                    DefineOpaqueTypes::Yes,
+                    *expected_ty,
+                    supplied_ty,
+                )?;
                 all_obligations.extend(obligations);
             }
 
@@ -576,10 +579,11 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 supplied_sig.output(),
             );
             let cause = &self.misc(decl.output.span());
-            let InferOk { value: (), obligations } = self
-                .at(cause, self.param_env)
-                .define_opaque_types(true)
-                .eq(expected_sigs.liberated_sig.output(), supplied_output_ty)?;
+            let InferOk { value: (), obligations } = self.at(cause, self.param_env).eq(
+                DefineOpaqueTypes::Yes,
+                expected_sigs.liberated_sig.output(),
+                supplied_output_ty,
+            )?;
             all_obligations.extend(obligations);
 
             let inputs = inputs.into_iter().map(|ty| self.resolve_vars_if_possible(ty));
@@ -713,14 +717,11 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 .subst_iter_copied(self.tcx, substs)
                 .find_map(|(p, s)| get_future_output(p, s))?,
             ty::Error(_) => return None,
-            ty::Alias(ty::Projection, proj)
-                if self.tcx.def_kind(proj.def_id) == DefKind::ImplTraitPlaceholder =>
-            {
-                self.tcx
-                    .bound_explicit_item_bounds(proj.def_id)
-                    .subst_iter_copied(self.tcx, proj.substs)
-                    .find_map(|(p, s)| get_future_output(p, s))?
-            }
+            ty::Alias(ty::Projection, proj) if self.tcx.is_impl_trait_in_trait(proj.def_id) => self
+                .tcx
+                .bound_explicit_item_bounds(proj.def_id)
+                .subst_iter_copied(self.tcx, proj.substs)
+                .find_map(|(p, s)| get_future_output(p, s))?,
             _ => span_bug!(
                 self.tcx.def_span(expr_def_id),
                 "async fn generator return type not an inference variable: {ret_ty}"