It couldn't run "hello, world" on systems where the include files were not located in the directory that it expected -- producing instead diagnostics saying, quite clearly, that the header files were not found. On systems where they were, it built versions of postgresql, redis, and several other things which passed their test suites completely.

If you've heard this problem described as a fundamental limitation of the compiler, and not the kind of packaging glitch that's routine to find in pre-alpha software of all descriptions, whoever described it to you that way is not serving their readers well.

I'm not saying CCC was production-ready, or close -- the total lack of an optimizer would be a killer in any real use, and I assume that there were problems with the diagnostics at least as bad as problems with performance and the include files, for similar reasons -- the LLMs hadn't been asked to optimize for that stuff yet, just test suite correctness. But it did achieve that, and the amount of cope I've seen on social media claiming otherwise is more than a bit disturbing.