bug#31052: 26.0.91; Improve documentation of inline-letevals

[Eli Zaretskii <eliz@gnu.org>]

> From: Gemini Lasswell <gazally@runbox.com>
> Cc: 31052@debbugs.gnu.org
> Date: Wed, 04 Apr 2018 10:10:39 -0700
> 
> > How about if you first tell informally what information is missing
> > from the original text, and then we see how to augment that by adding
> > the missing bits?
> 
> The main question the existing documentation doesn't answer is what the
> purpose of inline-letevals is and why it should be used instead of 'let'.

OK, but in that case we need only add a single sentence:

  This provides a convenient way to ensure that the arguments to an
  inlined function are evaluated exactly once, as well as to create
  local variables.

> The misleading part of the existing documentation is that it describes
> inline-letevals as similar to 'let' without mentioning that it does a
> completely different thing to symbols in the binding list.

The only part of your change that I perceive as related to this is the
following sentence:

  When an element of @var{bindings} is just a symbol @var{var}, the
  result of evaluating @var{var} is re-bound to @var{var}.

Is this what caused you to say it "does a completely different thing
to symbols in the binding list"?  Or did I misunderstand?

Thanks.