Rollup merge of #135104 - the8472:disable-in-place-iter-for-flatten, r=Mark-Simulacrum

do not in-place-iterate over flatmap/flatten

The implementation is unsound when a partially consumed iterator has some elements buffered in the front/back parts and cloning the Iterator removes the capacity from the backing vec::IntoIter.

This is a fix for #135103 that removes the specialization trait impls without removing some supporting parts. I've kept it small so it can be easily backported. I'll either remove the remaining parts or think of a way to recover the optimization in a separate PR.

0 files changed, 0 insertions, 0 deletions