On 2/28/2022 5:18 AM, Stefan Monnier via Bug reports for GNU Emacs, the 
Swiss army knife of text editors wrote:
> Lars Ingebrigtsen [2022-02-28 10:38:31] wrote:
>> Jim Porter <jporterbugs@gmail.com> writes:
>>> Ok, the breaking commit is b03f74e0f2a578b1580e8b1c368665850ee7f808
>>> ("Don't quote lambdas in several places").
[snip]> Looks like a bug somewhere in the `eshell-do-eval` machinery, yes.
> Until we find the problem (or rewrite `eshell-do-eval` on top of the CPS
> converter of `generator.el`), I think reverting this change (and adding
> a comment pointing to this bug) sounds like a great plan.

Here's a patch to fix this, with a test so it doesn't regress again. I 
also re-attached the doc fix for simplicity. Both should apply to the 28 
branch with no issues.

I'll try to figure out why `eshell-do-eval' expects quoted lambdas, but 
unless that's a really trivial problem, the method here is probably 
safer for the 28 branch. Besides, I'm now 4 or 5 steps removed from the 
patch I was *trying* to work on, so a quick fix here will help me get 
back on track.

Longer term, I agree that rewriting `eshell-do-eval' in terms of 
generator.el would be good. I think there are some bugs with how local 
variable state is managed by `eshell-do-eval', but I haven't had a 
chance to investigate it in any detail yet.