bug#66636: Move lexical-binding warning from checkdoc to byte-compiler

[Po Lu]

Mattias Engdegård <mattias.engdegard@gmail.com> writes:

> The warning about a missing lexical-binding cookie rather belongs in
> the compiler than checkdoc, because it's not about documentation or
> style but code generation and ability to detect errors, both which are
> hindered by a missing cookie.
>
> Moving the warning to the compiler also makes it more widely seen.

So long as this warning is only displayed within code part of Emacs
itself, there are no valid objections to such a change.

But you have instead elected to generate warnings whenever such files
are byte-compiled.  There exist many packages which do not enable
lexical binding, whose authors have studiously elected not to: most of
Drew Adams' for example.  So this is tantamount to punitive action
against their users, in the form of an unsightly warning each time such
packages are installed.