@blenderdumbass The average fediverse user can just ask what those are and they'll get their answer.

GCC was GNU C Compiler, a 100% free software compiler in the time where all usable compilers were proprietary, which eventually turned into GNU Compiler Collection, when more languages were added and upgraded to the GPLv3-or-later, when that license was released - ensuring it's 100% free software for *all* of it users.

LLVM (Low Level Virtual Machine, but they don't use that name anymore) was previously a GCC backend (I made an error in the previous comment and called it a frontend) to investigate dynamic compilation techniques, under a weak license and apple a few years later hired some of the developers to develop it further (as they wanted a functional compiler for their use without having to continue to license proprietary compilers) and paid those developers to turn it into a standalone backend and later add the clang frontend to make it a standalone compiler.

Apple also didn't really want to hire and pay for more programmers to improve LLVM, so they agreed that LLVM and clang etc (less their private modifications) could be released under a weak license, so other people could do gratis labor for them without apple having to pay.

Other companies like nvidia and AMD and many other companies saw the weak license and went "great, lets make this proprietary" and the result is a compiler that is under a free license, but is proprietary software for many, or possibly most of its users.