It's definitely a problem that LLVM has features which are in practice not really exercised by C++ (because the ISO C++ standard says something is Undefined Behaviour) and so clang doesn't need to use those features yet LLVM developers too often act as though only C++ matters. Rust spent a while with trivial crashes if you have an infinite loop. Here's how that happened as I understand it:

From Rust's point of view infinite loops are well formed. Sure, your program never exits but that's what you told it to do, so it's your problem not Rust's.

However in C++ that isn't a thing. In C++ an infinite loop is Undefined Behaviour. And so LLVM just didn't have working infinite loop code. If your C++ program has an infinite loop, too bad the ISO Standard says your program is wrong, clang is behaving as intended. Sure that's crazy but C++ programmers have a sort of Stockholm Syndrome.

So LLVM had a bug, but because the most important customer of LLVM is clang, and clang didn't care about this hideous bug while its users had just become numbed to the consequences, the bug lived on for ages.