[clang] [Clang][CodeGen] Bail out on constexpr unknown values in ConstantEmitter (PR #127525)

[Eli Friedman via cfe-commits]

efriedma-quic wrote:

> Clang rejects the following case after modifying evaluateValue to treat constexpr-unknown value as invalid

I don't see the connection.  At least, there isn't any obvious connection: the testcase doesn't require constexpr-unknown.  Maybe you need to "reject" the value earlier?

https://github.com/llvm/llvm-project/pull/127525