Comment by thesz

There is tinycc, that makes it three compilers.

There is a C compiler implemented in Rust from scratch: https://github.com/PhilippRados/wrecc/commits/master/?after=... (the very beginning of commit history)

There are several C compilers written in Rust from scratch of comparable quality.

We do not know whether Anthropic has a closed source C compiler written in Rust in their training data. We also do not know whether Anthropic validated their models on their ability to implement C compiler from scratch before releasing this experiment.

That language J I proposed does not have any C compiler implemented in it at all. Idiomatic J expertise is scarce and expensive so that it would be a significant expense for Anthropic to have C compiler in J for their training data. Being Turing-complete, J can express all typical compiler tips and tricks from compiler books, albeit in an unusual way.