Re: Prickliness of the "invalid byte code" stuff

[Eli Zaretskii <eliz@gnu.org>]

> From: Stefan Monnier <monnier@iro.umontreal.ca>
> Cc: eggert@cs.ucla.edu,  rms@gnu.org,  emacs-devel@gnu.org
> Date: Tue, 18 Jun 2019 14:11:01 -0400
> 
> byte-compile-dynamic is a compilation option which makes the .elc file
> have the actual bytes of the bytecoded functions lazy-loaded (in the
> same way as the docstrings are lazy-loaded: the byte-code-function-p
> objects contain in their bytecode field a "pointer" to the
> file-and-position so the bytecodes are fecthed on-demand when the
> function is called, via `fetch-bytecode`).
> 
> This was introduced at the same time as the lazy loading of docstrings.
> 
> The files using this option are expected to be faster to load (because
> we load a bit less into heap).

There's also the effect on Emacs memory footprint, right?

> The downsides are:
> - it doesn't work when the .elc files are compressed.
> - it doesn't work when the .elc files are loaded via Tramp.
> - If the .elc files is re-generated after the .elc file was loaded,
>   calling functions from that file typically signal an error (such as
>   "invalid byte code").

The same problems happen with lazily loading doc strings, right?  Or
is that different in some way?

> A `grep byte-compile-dynamic: **/*.el` seems to indicate it's currently
> used in 12 files bundled with Emacs.

Any idea why those 12 use it?

Thanks.