bug#49426: 28.0.50; Byte-compilation can fail with large fill-column

[Basil L. Contovounesios]

"Basil L. Contovounesios" <contovob@tcd.ie> writes:

> The same error occurs post-installation with 'M-x byte-compile-file' on
> dash.el.  Either way, the error confusingly only shows up when Dash is
> installed from MELPA:
>
>   package-archives = '(("melpa" . "https://melpa.org/packages/";))
>
> and not from GNU-devel ELPA:
>
>   package-archives = '(("gnu" . "https://elpa.gnu.org/devel/";))
>
> even though both contain identical versions of the file dash.el.  So I
> guess it's some other part of the package .tar that gives rise to the
> discrepancy.

Duh, the GNU ELPA .tar includes a .dir-locals.el with a custom
fill-column, whereas the MELPA package installs only dash.el and its
Texinfo manual, so there is nothing to override the pathological default
value of fill-column.

In which case the recipe becomes much simpler:

0. emacs -Q
1. M-: (setq-default fill-column 9999999) RET
2. (defalias 'foo #'ignore "Foo.")
3. C-x C-s foo.el RET
4. M-x byte-compile-file RET foo.el RET

This gives:

Compiling file /home/blc/foo.el at Tue Jul  6 09:05:44 2021
foo.el:4:1: Error: Invalid regexp: "Invalid content of \\{\\}"

-- 
Basil