Subject: bug#70108: 29.1.90; `defalias' and `current-load-list'

From: Mickey Petersen <[email-masked]>
Date: Sun, 31 Mar 2024 16:34:37 +0100

Here's a curious one. This is not so much a bug, I think, as a gotcha
and perhaps something that I wouldn't mind understanding a bit better.

My package creates a number of dynamic commands (think:
tempo/skeletons) to expand text.

It does so using the common (defalias NAME (lambda () ...)) pattern.

This obviously goes into the C core where a bunch of stuff takes
place. One of variables that gets updated (somehow) is
`current-load-list'. Curiously, it ends up with duplicate entries. I'm
presuming there is a good reason for this.

This variable can easily get overrun with identical entries if the
inattentive programmer does not check if it is already bound.

Due to a screwup on my part, I did not `fboundp' check first, which had the
odd effect of causing incredible slowdowns when I ran my 600+ ERT test
suite.

I have not narrowed down exactly *why* my ERT suite, when beset by 600
tests to run in one go, causes the slowdown. What I'm guessing from
how each successive tests slows down, that there is some sort of
non-linear searching going on here, and either `load' (and friends) or
the mere fact that putting more defaliases into the system causes this
slowdown to occur.

Anyway. Not sure it's a bug; but it caught me out, and as
`current-load-list' is rather obscure, I figured I'd at least ask.

Thanks!

Mickey.