I’m away from my desk, so can’t check, but If I recall correctly there are name canonicalization functions that downcase.  I don’t know if these are only applied when a system designator is a symbol or to strings as well. 

The underscores would be an issue if the system name was merged with a logical pathname, if a logical pathname was part of the ASDF configuration. In that case, some lisp implementations would reject the resulting pathname as illegal. Some might be more permissive. I have had experiences with path names that work on allegro and not on SBCL. 

CL-JSON replaces underscores with 2 hyphens, perhaps you could do something similar and double letters to indicate caps. You could provide some translation of system names to file names like that if you wanted to permit non standard system names. 

Of course, you would have to ensure that anyone using one of these systems would also have loaded the extension that found it properly. Honestly, this seems a lot more trouble than it’s worth: the name restrictions aren’t that onerous. 

> If you're using logical pathnames, you're asking for trouble

> (especially on SBCL). I wasted weeks of my life on logical pathnames,

> and STRONGLY recommend that no one should ever use them anymore under

> any circumstances.

Just to be clear, I don't *want* to use logical pathnames, but I will

if it provides a solution to the problem.

> If you're not, there should be no problem having a system called

> Foo_Bar, is there?

>

> Just make sure you use a (defsystem |Foo_Bar| ...) with the same case, no?

I dunno, that doesn't seem to work ... I tried this in SBCL which has

ASDF 3.3.something bundled.

(asdf:load-system "Foo_Bar")

provokes a warning: "WARNING: System definition file

#P"/home/dodier/tmp/Foo_Bar.asd" contains definition for system

"foo_bar". Please only define "Foo_Bar" and secondary systems with a

name starting with "Foo_Bar/" (e.g. "Foo_Bar/test") in that file.

and an error: Component "Foo_Bar" not found

Anyway, the documentation says

(https://asdf.common-lisp.dev/asdf.html#rule_002dsystem_002ddesignator)

that "Foo_Bar" is an unacceptable name since it has both an underscore

and uppercase letters.

I find that (defsystem baz_quux ...) in a file named "baz_quux.asd" is

loaded successfully without complaint -- I'm surprised that works; I

guess the no underscores rule is not actually enforced?

I guess the stated rules about simple component names are not actually

enforced by the DEFSYSTEM macro itself ... the do-nothing system

* (asdf:defsystem "Blurf_Mumble")

* (asdf:operate 'asdf:load-op *)

succeeds. I guess the stuff about string case only comes into play

when the file system gets involved?

FWIW & all the best.

Robert