From f9ee681181798d5183e78d5ffff813cba40b44a7 Mon Sep 17 00:00:00 2001
From: Ellen <supbscripter@gmail.com>
Date: Fri, 12 Nov 2021 20:50:25 +0000
Subject: [PATCH] variant of PR 90840 with limited scope for backport.

---
 compiler/rustc_typeck/src/check/dropck.rs       |  3 ---
 .../generic_const_exprs/drop_impl.rs            | 16 ----------------
 .../dropck/relate_lt_in_type_outlives_bound.rs  | 13 +++++++++++++
 .../relate_lt_in_type_outlives_bound.stderr     | 17 +++++++++++++++++
 4 files changed, 30 insertions(+), 19 deletions(-)
 delete mode 100644 src/test/ui/const-generics/generic_const_exprs/drop_impl.rs
 create mode 100644 src/test/ui/dropck/relate_lt_in_type_outlives_bound.rs
 create mode 100644 src/test/ui/dropck/relate_lt_in_type_outlives_bound.stderr

diff --git a/compiler/rustc_typeck/src/check/dropck.rs b/compiler/rustc_typeck/src/check/dropck.rs
index fd150978f0074..8eeb8c315ec40 100644
--- a/compiler/rustc_typeck/src/check/dropck.rs
+++ b/compiler/rustc_typeck/src/check/dropck.rs
@@ -239,9 +239,6 @@ fn ensure_drop_predicates_are_implied_by_item_defn<'tcx>(
                     ty::PredicateKind::ConstEvaluatable(a),
                     ty::PredicateKind::ConstEvaluatable(b),
                 ) => tcx.try_unify_abstract_consts((a, b)),
-                (ty::PredicateKind::TypeOutlives(a), ty::PredicateKind::TypeOutlives(b)) => {
-                    relator.relate(predicate.rebind(a.0), p.rebind(b.0)).is_ok()
-                }
                 _ => predicate == p,
             }
         };
diff --git a/src/test/ui/const-generics/generic_const_exprs/drop_impl.rs b/src/test/ui/const-generics/generic_const_exprs/drop_impl.rs
deleted file mode 100644
index 077f77aa0f404..0000000000000
--- a/src/test/ui/const-generics/generic_const_exprs/drop_impl.rs
+++ /dev/null
@@ -1,16 +0,0 @@
-//check-pass
-#![feature(generic_const_exprs)]
-#![allow(incomplete_features)]
-
-struct Foo<const N: usize>
-where
-    [(); N + 1]: ;
-
-impl<const N: usize> Drop for Foo<N>
-where
-    [(); N + 1]: ,
-{
-    fn drop(&mut self) {}
-}
-
-fn main() {}
diff --git a/src/test/ui/dropck/relate_lt_in_type_outlives_bound.rs b/src/test/ui/dropck/relate_lt_in_type_outlives_bound.rs
new file mode 100644
index 0000000000000..42530d317308a
--- /dev/null
+++ b/src/test/ui/dropck/relate_lt_in_type_outlives_bound.rs
@@ -0,0 +1,13 @@
+struct Wrapper<'a, T>(&'a T)
+where
+    T: 'a;
+
+impl<'a, T> Drop for Wrapper<'a, T>
+where
+    T: 'static,
+    //~^ error: `Drop` impl requires `T: 'static` but the struct it is implemented for does not
+{
+    fn drop(&mut self) {}
+}
+
+fn main() {}
diff --git a/src/test/ui/dropck/relate_lt_in_type_outlives_bound.stderr b/src/test/ui/dropck/relate_lt_in_type_outlives_bound.stderr
new file mode 100644
index 0000000000000..5176684e15340
--- /dev/null
+++ b/src/test/ui/dropck/relate_lt_in_type_outlives_bound.stderr
@@ -0,0 +1,17 @@
+error[E0367]: `Drop` impl requires `T: 'static` but the struct it is implemented for does not
+  --> $DIR/relate_lt_in_type_outlives_bound.rs:7:8
+   |
+LL |     T: 'static,
+   |        ^^^^^^^
+   |
+note: the implementor must specify the same requirement
+  --> $DIR/relate_lt_in_type_outlives_bound.rs:1:1
+   |
+LL | / struct Wrapper<'a, T>(&'a T)
+LL | | where
+LL | |     T: 'a;
+   | |__________^
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0367`.