Clang 6.0.[01]: UNREACHABLE executed

[Jonathan Anderson]

Hi all,

I recently ran into an unreachable statement execution in Clang 6, both
with v6.0.0 from the llvm60 package and v6.0.1 from HEAD (FreeBSD
r335799 / LLVM r335540). I don't see this issue in Clang 5 or in the
version that ships with macOS High Sierra (which they're calling 9.1.0,
but that's apparently more of a "marketing version" than a true version
number).

creduce managed to shrink my 2.8 MiB preprocessed sources down to a 604
B test case:

https://gist.github.com/trombonehero/2da555bd1292be973f9d14c843c56ae5

This isn't a valid C++ file (e.g., it cuts off after `return o` on line
23), but I would expect it to cause compiler errors rather than a
compiler crash. You can see the output from the crash at:

https://gist.github.com/trombonehero/8fce4a8f39ae121a2f9f14b45b0b65a1

Any thoughts?


Jonathan Anderson
--
jonathan at FreeBSD.org