Rust and GCC, two different ways

Apple *appears* to ship LLVM source code, and maintain a public repository. Their patches aren't upstream, but it doesn't look like they're proprietary, unless they're adding further patches atop the public sources before shipping the version in the xcode SDK.

The issue with Apple appears to be more that their build-and-sign toolchain and requirements are based on their "bitcode" format which uses a specific version of LLVM, and using a newer toolchain produces things Apple's infrastructure won't accept.

> I personally think the best strategy for maintaining a world of free compilers is to ensure we focus on GCC whenever possible, though not excluding LLVM as the competition is healthy.

LLVM exists. You can't prevent people from building proprietary compilers atop it; the existence of GCC doesn't prevent that, only the non-existence of competing permissively licensed compilers would prevent that, and that isn't going to happen.

We can't prevent the existence of proprietary compilers; all we can do is reject them when they arise, and ensure that everything upstream is Open Source.