From 54812011600a2c19f7076c438e6eabe6a8063774 Mon Sep 17 00:00:00 2001
From: Gary Guo <gary@garyguo.net>
Date: Fri, 8 Oct 2021 03:59:56 +0100
Subject: [PATCH 1/3] Ignore projection type when determining upvar ancestory

---
 compiler/rustc_typeck/src/check/upvar.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/compiler/rustc_typeck/src/check/upvar.rs b/compiler/rustc_typeck/src/check/upvar.rs
index b7c042a08cf1c..9b94fda515363 100644
--- a/compiler/rustc_typeck/src/check/upvar.rs
+++ b/compiler/rustc_typeck/src/check/upvar.rs
@@ -2278,7 +2278,7 @@ fn determine_place_ancestry_relation(
     let projections_b = &place_b.projections;
 
     let same_initial_projections =
-        iter::zip(projections_a, projections_b).all(|(proj_a, proj_b)| proj_a == proj_b);
+        iter::zip(projections_a, projections_b).all(|(proj_a, proj_b)| proj_a.kind == proj_b.kind);
 
     if same_initial_projections {
         // First min(n, m) projections are the same

From d7f8a0678012f8a0fa24609345b777af4a6a4c04 Mon Sep 17 00:00:00 2001
From: Gary Guo <gary@garyguo.net>
Date: Thu, 7 Oct 2021 22:04:13 +0100
Subject: [PATCH 2/3] Add regression test

---
 .../2229_closure_analysis/issue-89606.rs      | 40 +++++++++++++++++++
 1 file changed, 40 insertions(+)
 create mode 100644 src/test/ui/closures/2229_closure_analysis/issue-89606.rs

diff --git a/src/test/ui/closures/2229_closure_analysis/issue-89606.rs b/src/test/ui/closures/2229_closure_analysis/issue-89606.rs
new file mode 100644
index 0000000000000..1bb6aa40f06fa
--- /dev/null
+++ b/src/test/ui/closures/2229_closure_analysis/issue-89606.rs
@@ -0,0 +1,40 @@
+// Regression test for #89606. Used to ICE.
+//
+// check-pass
+// revisions: twenty_eighteen twenty_twentyone
+// [twenty_eighteen]compile-flags: --edition 2018
+// [twenty_twentyone]compile-flags: --edition 2021
+
+struct S<'a>(Option<&'a mut i32>);
+
+fn by_ref(s: &mut S<'_>) {
+    (|| {
+        let S(_o) = s;
+        s.0 = None;
+    })();
+}
+
+fn by_value(s: S<'_>) {
+    (|| {
+        let S(ref _o) = s;
+        let _g = s.0;
+    })();
+}
+
+struct V<'a>((Option<&'a mut i32>,));
+
+fn nested(v: &mut V<'_>) {
+    (|| {
+        let V((_o,)) = v;
+        v.0 = (None, );
+    })();
+}
+
+fn main() {
+    let mut s = S(None);
+    by_ref(&mut s);
+    by_value(s);
+
+    let mut v = V((None, ));
+    nested(&mut v);
+}

From 7275cfa47cf3fdbf41c2ad859ac937bffe5923a4 Mon Sep 17 00:00:00 2001
From: Gary Guo <gary@garyguo.net>
Date: Sat, 9 Oct 2021 06:41:05 +0100
Subject: [PATCH 3/3] Explicit `PlaceAncestryRelation::SamePlace` and handle
 like `Descendant`

---
 compiler/rustc_typeck/src/check/upvar.rs | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/compiler/rustc_typeck/src/check/upvar.rs b/compiler/rustc_typeck/src/check/upvar.rs
index 9b94fda515363..3a10988bba0b9 100644
--- a/compiler/rustc_typeck/src/check/upvar.rs
+++ b/compiler/rustc_typeck/src/check/upvar.rs
@@ -65,6 +65,7 @@ use std::iter;
 enum PlaceAncestryRelation {
     Ancestor,
     Descendant,
+    SamePlace,
     Divergent,
 }
 
@@ -564,7 +565,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 for possible_ancestor in min_cap_list.iter_mut() {
                     match determine_place_ancestry_relation(&place, &possible_ancestor.place) {
                         // current place is descendant of possible_ancestor
-                        PlaceAncestryRelation::Descendant => {
+                        PlaceAncestryRelation::Descendant | PlaceAncestryRelation::SamePlace => {
                             ancestor_found = true;
                             let backup_path_expr_id = possible_ancestor.info.path_expr_id;
 
@@ -2281,12 +2282,14 @@ fn determine_place_ancestry_relation(
         iter::zip(projections_a, projections_b).all(|(proj_a, proj_b)| proj_a.kind == proj_b.kind);
 
     if same_initial_projections {
+        use std::cmp::Ordering;
+
         // First min(n, m) projections are the same
         // Select Ancestor/Descendant
-        if projections_b.len() >= projections_a.len() {
-            PlaceAncestryRelation::Ancestor
-        } else {
-            PlaceAncestryRelation::Descendant
+        match projections_b.len().cmp(&projections_a.len()) {
+            Ordering::Greater => PlaceAncestryRelation::Ancestor,
+            Ordering::Equal => PlaceAncestryRelation::SamePlace,
+            Ordering::Less => PlaceAncestryRelation::Descendant,
         }
     } else {
         PlaceAncestryRelation::Divergent