The stash has its own reflog

git gc only prunes nodes unreachable from branches AND the reflog, which I think by default is 30 days long

I explicitly said "committed data" would not be lost, because data only staged in the index certianly can be lost, and I think stashed data is also semi-suceptable to loss as well.

git stash drop does print the sha1 of the stash, and as long as you know that sha1, and it's not been gc'd, you can get a dropped stash back. (git fsck will also show the sha1s of dangling commits left from dropped stashes.) But while a separate reflog records existing stashes, that information is not retained when they're dropped. It's perhaps best to think of git stash as a more convenient form of git diff > patch, and you wouldn't expect that to keep a log of the patch file either.

Yes but the original author in this very thread has said that the data loss was through MQ(Mercurial patch Queue) delete. mercurial queues are an optionally controlled patch queue, so he had some code stashed it in an uncontrolled queue, deleted it and was surprised that it was really gone. This is rather analogous to what I posted for git. It was a bit of bad luck on his part but switching to git doesn't close that hole his code is still vulnerable to the same set of actions.

So his whole reason for switching is I shot myself in the foot. And instead of learning more about his weapon of choice to avoid doing that in the future, he traded in his gun for one that is slightly more complicated.