

I have never heard the licensing of Rust being raised as a concern for the Linux kernel.
As Charles Babbage would say, “I am not able rightly to apprehend the kind of confusion of ideas that could provoke such a question.”
The distro I use builds the entire Linux kernel with Clang which uses the same license as Rust. Linux is bound by the same modified GPL license regardless of what compiler I use to build it.
The compiler has no impact on the license applied to the code you build with that compiler. You can use closed source tools to build open source software and vice versa.
And, of course, the Rust license is totally open source as it is offered as both MIT and Apache. Apache 2.0 even provides patent guarantees which can matter for something like a compiler.
If you prefer to use GPL tools yourself, you may want to keep an eye on gccrs.
A legitimate concern about Rust may be that LLVM (Rust) supports a different list of hardware than GCC does. The gccrs project addresses that.

Ah thank you. You likely guessed the reason for the question.
Many popular projects written in Rust, including the UUtils core utils rewrite, are MIT licensed as Rust is. There have been people that purposely confuse things by saying that “the Rust community” is undermining the GPL. I can see how that may lead somebody to believe that there is some kind of inherent licence problem with code written in Rust.
Code written in Rust can of course be licensed however you want from AGPL to fully proprietary.
I personally perceive a shift in license popularity towards more permissive licenses at least with the “younger generation”. The fact that so many Rust projects are permissively licensed is just a consequence of those kinds of licenses being more popular with the kinds of “modern” programmers that would choose Rust as a language to begin with. Those programmers would choose the same licenses even they used the GCC toolchain. But the “modern” languages they have to choose from are things like Rust, Swift, Zig, Go, or Gleam (all permissively licensed ). Python and TypeScript are also still trendy (also permissively licensed).
Looking at that list, it is pretty silly to focus on Rust’s license. Most of the popular programming languages released over the past 20 years are permissively licensed.