I would hazard that that main reason that many (by no means all) FOSS projects are migrating to LLVM is that clang is dramatically easier to work on, and at or over parity in efficiency of output.

They changed to Apache 2.0 recently, actually.

Not everyone is replacing GCC with LLVM, and it’s being relicensed under Apache anyways.

First, why should they contribute? You make it sound like a problem for the FOSS guys being exploited, but the choice of license is usually made explicitly to allow third parties to profit from their project without the burden of contribution.

Second, despite not having to contribute, license while, LLVM has still seen so much contribution from big companies (Apple for one) that the whole argument is moot.

Third, I meant companies like RedHat, or projects like Mongo, MySQL and others -- far more successful money-wise than most niche commercial compilers the kind that you appear to be a fan of while deriding FOSS for not making money...