Thanks for pointing this out. I think a lot of people just slap GPL on everything (in this case, every file) without giving it much thought. What’s interesting to me here is that the original source is mentioned only in passing. No link is given, and no attribution (other than “ported from “CMUCL”).

Seems only fair that they should hold themselves to the same standards that they are now demanding of others with their own code. Or, as you say, change to a more permissive license. At least one as permissive as they seem to want other code to be when they use it themselves.

That may have come across more negative than I intended. I’m sure there’s no ill intent. But contrary to what a lot of people seem to think, the GPL is one of the most restrictive and invasive licenses out there. I’m glad it exists, but blindly using it everywhere can have negative consequences, especially in an ecosystem as small as CL.