Bug with lexical-binding and package-install?

Bug with lexical-binding and package-install?

[Magnar Sveen]

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I got a bug report yesterday in which my package was broken because lexical
scoping was suddenly in effect.

After some init-file-bisecting, this is the conclusion:

> It appears as though your first instinct about lexical-binding is
correct. I had a ;;; -*- lexical-binding: t -*- directive in my
init-packages.el file, which is responsible for downloading the installing
missing packages (of which multiple-cursors.el is one).
>
> It seems that if the file which calls package-install has that flag
turned on, it applies the lexical binding to the compiler, which results in
the following compiler warning:
>
> In mc/region-strings:
> mc-mark-more.el:78:20:Warning: assignment to free variable `strings'
>
> This warning doesn't appear in the compiler messages if lexical-binding
is nil.

This is on Emacs 24.2.1 on OS X. Full compiler warnings and code excerpts
can be found here:

https://github.com/magnars/multiple-cursors.el/issues/39

- Magnar Sveen

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Re: Bug with lexical-binding and package-install?

[Stefan Monnier]

> It appears as though your first instinct about lexical-binding is
> correct. I had a ;;; -*- lexical-binding: t -*- directive in my
> init-packages.el file, which is responsible for downloading the installing
> missing packages (of which multiple-cursors.el is one).

What is "init-packages.el"?
"grep init-package **/*.el" doesn't find anything in Emacs's trunk.

I'm trying to understand how this could happen, which I find difficult
to imagine: lexical-binding is made buffer-local in every file that is
byte-compiled, so for an external lexical-binding setting to affect
byte-compilation, you'd have to call `byte-compile' directly rather than
via byte-compile-file.
At least that's the way the code should behave.

Oh, and please make it an actual bug-report rather than sending it here
on emacs-devel.


        Stefan

Re: Bug with lexical-binding and package-install?

[Magnar Sveen]

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Sorry about that, I have sent a proper bug report with reproducible steps.



On Mon, Nov 19, 2012 at 9:31 PM, Stefan Monnier <monnier@iro.umontreal.ca>wrote:

> > It appears as though your first instinct about lexical-binding is
> > correct. I had a ;;; -*- lexical-binding: t -*- directive in my
> > init-packages.el file, which is responsible for downloading the
> installing
> > missing packages (of which multiple-cursors.el is one).
>
> What is "init-packages.el"?
> "grep init-package **/*.el" doesn't find anything in Emacs's trunk.
>
> I'm trying to understand how this could happen, which I find difficult
> to imagine: lexical-binding is made buffer-local in every file that is
> byte-compiled, so for an external lexical-binding setting to affect
> byte-compilation, you'd have to call `byte-compile' directly rather than
> via byte-compile-file.
> At least that's the way the code should behave.
>
> Oh, and please make it an actual bug-report rather than sending it here
> on emacs-devel.
>
>
>         Stefan
>

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