From d98384595f105179fef37960f37a636e562d6425 Mon Sep 17 00:00:00 2001
From: Santiago Pastorino <spastorino@gmail.com>
Date: Wed, 14 Jul 2021 17:12:34 -0300
Subject: [PATCH] Removing unhandled region constraint error that is only for
 impl_trait_in_bindings

---
 .../src/borrow_check/member_constraints.rs    |  5 ---
 .../src/borrow_check/region_infer/mod.rs      | 34 +++----------------
 2 files changed, 5 insertions(+), 34 deletions(-)

diff --git a/compiler/rustc_mir/src/borrow_check/member_constraints.rs b/compiler/rustc_mir/src/borrow_check/member_constraints.rs
index baaf6f27ee8..2e2578df011 100644
--- a/compiler/rustc_mir/src/borrow_check/member_constraints.rs
+++ b/compiler/rustc_mir/src/borrow_check/member_constraints.rs
@@ -1,5 +1,4 @@
 use rustc_data_structures::fx::FxHashMap;
-use rustc_hir::def_id::DefId;
 use rustc_index::vec::IndexVec;
 use rustc_middle::infer::MemberConstraint;
 use rustc_middle::ty::{self, Ty};
@@ -32,9 +31,6 @@ where
 crate struct NllMemberConstraint<'tcx> {
     next_constraint: Option<NllMemberConstraintIndex>,
 
-    /// The opaque type whose hidden type is being inferred. (Used in error reporting.)
-    crate opaque_type_def_id: DefId,
-
     /// The span where the hidden type was instantiated.
     crate definition_span: Span,
 
@@ -91,7 +87,6 @@ impl<'tcx> MemberConstraintSet<'tcx, ty::RegionVid> {
         let constraint_index = self.constraints.push(NllMemberConstraint {
             next_constraint,
             member_region_vid,
-            opaque_type_def_id: m_c.opaque_type_def_id,
             definition_span: m_c.definition_span,
             hidden_ty: m_c.hidden_ty,
             start_index,
diff --git a/compiler/rustc_mir/src/borrow_check/region_infer/mod.rs b/compiler/rustc_mir/src/borrow_check/region_infer/mod.rs
index 0306782bfe4..c40e6bf1ec3 100644
--- a/compiler/rustc_mir/src/borrow_check/region_infer/mod.rs
+++ b/compiler/rustc_mir/src/borrow_check/region_infer/mod.rs
@@ -551,7 +551,7 @@ impl<'tcx> RegionInferenceContext<'tcx> {
         polonius_output: Option<Rc<PoloniusOutput>>,
     ) -> (Option<ClosureRegionRequirements<'tcx>>, RegionErrors<'tcx>) {
         let mir_def_id = body.source.def_id();
-        self.propagate_constraints(body, infcx.tcx);
+        self.propagate_constraints(body);
 
         let mut errors_buffer = RegionErrors::new();
 
@@ -599,7 +599,7 @@ impl<'tcx> RegionInferenceContext<'tcx> {
     /// for each region variable until all the constraints are
     /// satisfied. Note that some values may grow **too** large to be
     /// feasible, but we check this later.
-    fn propagate_constraints(&mut self, _body: &Body<'tcx>, tcx: TyCtxt<'tcx>) {
+    fn propagate_constraints(&mut self, _body: &Body<'tcx>) {
         debug!("propagate_constraints()");
 
         debug!("propagate_constraints: constraints={:#?}", {
@@ -617,7 +617,7 @@ impl<'tcx> RegionInferenceContext<'tcx> {
         // own.
         let constraint_sccs = self.constraint_sccs.clone();
         for scc in constraint_sccs.all_sccs() {
-            self.compute_value_for_scc(scc, tcx);
+            self.compute_value_for_scc(scc);
         }
 
         // Sort the applied member constraints so we can binary search
@@ -629,7 +629,7 @@ impl<'tcx> RegionInferenceContext<'tcx> {
     /// computed, by unioning the values of its successors.
     /// Assumes that all successors have been computed already
     /// (which is assured by iterating over SCCs in dependency order).
-    fn compute_value_for_scc(&mut self, scc_a: ConstraintSccIndex, tcx: TyCtxt<'tcx>) {
+    fn compute_value_for_scc(&mut self, scc_a: ConstraintSccIndex) {
         let constraint_sccs = self.constraint_sccs.clone();
 
         // Walk each SCC `B` such that `A: B`...
@@ -652,12 +652,7 @@ impl<'tcx> RegionInferenceContext<'tcx> {
         // Now take member constraints into account.
         let member_constraints = self.member_constraints.clone();
         for m_c_i in member_constraints.indices(scc_a) {
-            self.apply_member_constraint(
-                tcx,
-                scc_a,
-                m_c_i,
-                member_constraints.choice_regions(m_c_i),
-            );
+            self.apply_member_constraint(scc_a, m_c_i, member_constraints.choice_regions(m_c_i));
         }
 
         debug!(
@@ -680,31 +675,12 @@ impl<'tcx> RegionInferenceContext<'tcx> {
     /// If we make any changes, returns true, else false.
     fn apply_member_constraint(
         &mut self,
-        tcx: TyCtxt<'tcx>,
         scc: ConstraintSccIndex,
         member_constraint_index: NllMemberConstraintIndex,
         choice_regions: &[ty::RegionVid],
     ) -> bool {
         debug!("apply_member_constraint(scc={:?}, choice_regions={:#?})", scc, choice_regions,);
 
-        if let Some(uh_oh) =
-            choice_regions.iter().find(|&&r| !self.universal_regions.is_universal_region(r))
-        {
-            // FIXME(#61773): This case can only occur with
-            // `impl_trait_in_bindings`, I believe, and we are just
-            // opting not to handle it for now. See #61773 for
-            // details.
-            tcx.sess.delay_span_bug(
-                self.member_constraints[member_constraint_index].definition_span,
-                &format!(
-                    "member constraint for `{:?}` has an option region `{:?}` \
-                     that is not a universal region",
-                    self.member_constraints[member_constraint_index].opaque_type_def_id, uh_oh,
-                ),
-            );
-            return false;
-        }
-
         // Create a mutable vector of the options. We'll try to winnow
         // them down.
         let mut choice_regions: Vec<ty::RegionVid> = choice_regions.to_vec();