[clang] Diagnose noreturn calls from a const or pure function (PR #206134)

[Nikita Popov via cfe-commits]

nikic wrote:

Yes, passing a null pointer to that would be UB. But you don't know whether null will be passed or not, so it can be well-defined. (Esp. if you consider an argument-independent assert. Like an assert that all switch cases were covered, which is actually unreachable.)

https://github.com/llvm/llvm-project/pull/206134