This is similar to bug#48497, but appears to still happen even after
commit 3f207753a0.

The basic problem is that the installed lisp path does not match either
of the search expressions in comp-el-to-eln-rel-filename, meaning that
native lisp needs to be recompiled needlessly.

The problem seems to come from PATH_REL_LOADSEARCH being set for me (on
macOS) to Contents/Resources/lisp, but the lisp files actually being
installed to
/nix/store/...-emacs-gcc-20210612.0/share/emacs/28.0.50/lisp (path
generated by Nix). As a result, comp-el-to-eln-rel-filename used the
filename comp-034d3699-516ce4bf.eln for comp.el.gz where 516ce4bf is the
md5sum of the contents of comp.el and 034d3699 is the md5sum of the full
path of comp.el, not of //emacs-lisp/comp.el (7672a6ed), which is what
Emacs installs.

To fix this, I propose using PATH_LOADSEARCH in addition to
PATH_REL_LOADSEARCH so that we can catch both types of macOS installs
(.app and unix). I’ve attached a patch which implements this, adding
relative and absolute loadsearch resolution.

- Matthew