From 5222e2ba2d97cd716a379b4ae6bc62c5f7c2dd36 Mon Sep 17 00:00:00 2001 From: Giacomo Stevanato Date: Fri, 19 Feb 2021 12:15:37 +0100 Subject: [PATCH 1/3] Increment self.len in specialized ZipImpl to avoid underflow in size_hint (cherry picked from commit 66a260617a88ed1ad55a46f03c5a90d5ad3004d3) --- library/core/src/iter/adapters/zip.rs | 1 + 1 file changed, 1 insertion(+) diff --git a/library/core/src/iter/adapters/zip.rs b/library/core/src/iter/adapters/zip.rs index 9f9835345200..f08bfac837fe 100644 --- a/library/core/src/iter/adapters/zip.rs +++ b/library/core/src/iter/adapters/zip.rs @@ -200,6 +200,7 @@ fn next(&mut self) -> Option<(A::Item, B::Item)> { } else if A::may_have_side_effect() && self.index < self.a.size() { let i = self.index; self.index += 1; + self.len += 1; // match the base implementation's potential side effects // SAFETY: we just checked that `i` < `self.a.len()` unsafe { -- 2.31.1 From d39669fc8282830a374d19d204f7b4ee8eb1e381 Mon Sep 17 00:00:00 2001 From: Giacomo Stevanato Date: Fri, 19 Feb 2021 12:16:12 +0100 Subject: [PATCH 2/3] Add test for underflow in specialized Zip's size_hint (cherry picked from commit 8b9ac4d4155c74db5b317046033ab9c05a09e351) --- library/core/tests/iter/adapters/zip.rs | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+) diff --git a/library/core/tests/iter/adapters/zip.rs b/library/core/tests/iter/adapters/zip.rs index 1fce0951e365..a59771039295 100644 --- a/library/core/tests/iter/adapters/zip.rs +++ b/library/core/tests/iter/adapters/zip.rs @@ -245,3 +245,23 @@ fn test_double_ended_zip() { assert_eq!(it.next_back(), Some((3, 3))); assert_eq!(it.next(), None); } + +#[test] +fn test_issue_82282() { + fn overflowed_zip(arr: &[i32]) -> impl Iterator { + static UNIT_EMPTY_ARR: [(); 0] = []; + + let mapped = arr.into_iter().map(|i| *i); + let mut zipped = mapped.zip(UNIT_EMPTY_ARR.iter()); + zipped.next(); + zipped + } + + let arr = [1, 2, 3]; + let zip = overflowed_zip(&arr).zip(overflowed_zip(&arr)); + + assert_eq!(zip.size_hint(), (0, Some(0))); + for _ in zip { + panic!(); + } +} -- 2.31.1 From 4b382167dd5ed5a6eac0cf314bfb86e3704b6e76 Mon Sep 17 00:00:00 2001 From: Giacomo Stevanato Date: Fri, 19 Feb 2021 12:17:48 +0100 Subject: [PATCH 3/3] Remove useless comparison since now self.index <= self.len is an invariant (cherry picked from commit aeb4ea739efb70e0002a4a9c4c7b8027dd0620b3) --- library/core/src/iter/adapters/zip.rs | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/library/core/src/iter/adapters/zip.rs b/library/core/src/iter/adapters/zip.rs index f08bfac837fe..dcbcb1ce7200 100644 --- a/library/core/src/iter/adapters/zip.rs +++ b/library/core/src/iter/adapters/zip.rs @@ -261,7 +261,7 @@ fn next_back(&mut self) -> Option<(A::Item, B::Item)> if sz_a != sz_b { let sz_a = self.a.size(); if a_side_effect && sz_a > self.len { - for _ in 0..sz_a - cmp::max(self.len, self.index) { + for _ in 0..sz_a - self.len { self.a.next_back(); } } -- 2.31.1