> The patch looks fine, thank you.

Thanks!


> Just one detail about the tests: the change you made affects the
> evaluation of `let` in the case where the code is interpreted but it
> is not used when the code is byte-compiled.  So you might like your
> tests to use things like
> 
>     (eval '(let ...) t)
> 
> to avoid the compiler getting in the way.

Thanks, I didn't notice this point!  I fix testcases.


> Also, while this `let` is indeed invalid code, I don't think we
> guarantee that it will signal an error, and especially not at runtime
> (it's more likely to signal an error at macroexpansion or compile
> time).
> 
> I think the compiler (or `macroexpand-all`) should make an effort to
> detect and diagnose those problems, but I don't think it's important to
> catch those problems in the interpreter.

That testcase comes from this code (src/eval.c:L1014) which we already had.

      else if (! NILP (Fcdr (Fcdr (elt))))
	signal_error ("`let' bindings can have only one value-form", elt);

I tried to remove this, my temp Emacs works like this in *scratch* buffer.

    (let ((a 1 2))
       a)                       ; Type C-j
    1

This is very strange I think.  I still think it's important for
Emacs, even as an interpreter, to produce errors.