[clang] Clang/Preprocessor: Support short circuit in directive (PR #123912)

[Fabian Ritter via cfe-commits]

ritter-x2a wrote:

I think it would be more useful in practice if the deprecation warnings respected lazy evaluation, as the PR suggests, but it's worth noting that this deviates from the C Standard, which specifies that macros are replaced first, before short-circuit evaluation takes place.

https://github.com/llvm/llvm-project/pull/123912