clang-scan-deps fails on ut.hpp

[tambry]

Expected Behavior

/usr/bin/clang-scan-deps -format=p1689 -- /usr/bin/clang++ -x c++ include/boost/ut.hpp works.

Actual Behavior

raul@dev1:~/vehicle/common/build$ /usr/bin/clang-scan-deps -format=p1689 -- /usr/bin/clang++ -x c++ /usr/include/boost/ut.hpp
Error while scanning dependencies for /usr/include/boost/ut.hpp:
/usr/include/boost/ut.hpp:19:2: error: unterminated conditional directive
{
  "revision": 0,
  "rules": [],
  "version": 1
}

Steps to Reproduce the Problem

1. /usr/bin/clang-scan-deps -format=p1689 -- /usr/bin/clang++ -x c++ include/boost/ut.hpp

Specifications

• Version: LLVM tip-of-tree from 2024-01-02
• Platform: Debian
• Subsystem: x86_64

Additional information

After CMP0155 CMake runs clang-scan-deps for Clang to support modules. However it fails to run on boost-ut's main include file causing build failures when using this library.

I can't see a direct fault with μt, but I'm unsure. Might there be an issue with the library and has this problem come up before, or should I open a bug report in LLVM upstream?