Auto merge of #89648 - nbdd0121:issue-89606, r=nikomatsakis

Ignore type of projections for upvar capturing

Fix #89606

Ignore type of projections for upvar capturing. Originally HashMap is used, and the hash/eq implementation of Place takes the type of projections into account. These types may differ by lifetime which causes #89606 to ICE.

I originally considered erasing regions but `place.ty()` is used when creating upvar tuple type, more than just serving as a key type, so I switched to a linear comparison with custom eq (`compare_place_ignore_ty`) instead.

r? `@wesleywiser`

`@rustbot` label +T-compiler

Author: bors

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;
 
@@ -2278,15 +2279,17 @@ 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 {
+        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

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);
+}