1 files changed, 44 insertions, 0 deletions
diff --git a/dev-lang/rust/files/rustc-1.51.0-backport-pr81741.patch b/dev-lang/rust/files/rustc-1.51.0-backport-pr81741.patch
new file mode 100644
index 000000000000..8ef22eea56fd
--- /dev/null
+++ b/dev-lang/rust/files/rustc-1.51.0-backport-pr81741.patch
@@ -0,0 +1,44 @@
+From 40d3f2d7ef5835317fe9df9ecc01f4c363def4fd Mon Sep 17 00:00:00 2001
+From: =?UTF-8?q?Sebastian=20Dr=C3=B6ge?= <sebastian@centricular.com>
+Date: Thu, 4 Feb 2021 10:23:01 +0200
+Subject: [PATCH] Increment `self.index` before calling
+ `Iterator::self.a.__iterator_get_unchecked` in `Zip` `TrustedRandomAccess`
+ specialization
+
+Otherwise if `Iterator::self.a.__iterator_get_unchecked` panics the
+index would not have been incremented yet and another call to
+`Iterator::next` would read from the same index again, which is not
+allowed according to the API contract of `TrustedRandomAccess` for
+`!Clone`.
+
+Fixes https://github.com/rust-lang/rust/issues/81740
+
+(cherry picked from commit 86a4b27475aab52b998c15f5758540697cc9cff0)
+---
+ library/core/src/iter/adapters/zip.rs | 7 ++++---
+ 1 file changed, 4 insertions(+), 3 deletions(-)
+
+diff --git a/library/core/src/iter/adapters/zip.rs b/library/core/src/iter/adapters/zip.rs
+index 98b8dca96140..9f9835345200 100644
+--- a/library/core/src/iter/adapters/zip.rs
++++ b/library/core/src/iter/adapters/zip.rs
+@@ -198,12 +198,13 @@ fn next(&mut self) -> Option<(A::Item, B::Item)> {
+                 Some((self.a.__iterator_get_unchecked(i), self.b.__iterator_get_unchecked(i)))
+             }
+         } else if A::may_have_side_effect() && self.index < self.a.size() {
++            let i = self.index;
++            self.index += 1;
+             // match the base implementation's potential side effects
+-            // SAFETY: we just checked that `self.index` < `self.a.len()`
++            // SAFETY: we just checked that `i` < `self.a.len()`
+             unsafe {
+-                self.a.__iterator_get_unchecked(self.index);
++                self.a.__iterator_get_unchecked(i);
+             }
+-            self.index += 1;
+             None
+         } else {
+             None
+-- 
+2.31.1
+