@llvm/pr-subscribers-libcxx

Author: Ed Maste (emaste)

diff --git a/libcxx/utils/ci/buildkite-pipeline.yml b/libcxx/utils/ci/buildkite-pipeline.yml
index e42262620d5fb0..31e794e67d330d 100644
--- a/libcxx/utils/ci/buildkite-pipeline.yml
+++ b/libcxx/utils/ci/buildkite-pipeline.yml
@@ -209,8 +209,8 @@ steps:
   - label: FreeBSD 13 amd64
     command: libcxx/utils/ci/run-buildbot generic-cxx23
     env:
-      CC: clang16
-      CXX: clang++16
+      CC: clang17
+      CXX: clang++17
     agents:
       queue: libcxx-builders
       os: freebsd

Can we have C++26 mode enabled to be able to test the new features?

Can we have C++26 mode enabled to be able to test the new features?

Good point! Thanks! @emaste can you change that too?

Observed the following failures on the FreeBSD builder with this change:

********************
Failed Tests (5):
  llvm-libc++-shared.cfg.in :: libcxx/selftest/modules/std-and-std.compat-module.sh.cpp
  llvm-libc++-shared.cfg.in :: libcxx/selftest/modules/std-module.sh.cpp
  llvm-libc++-shared.cfg.in :: libcxx/selftest/modules/std.compat-module.sh.cpp
  llvm-libc++-shared.cfg.in :: std/modules/std.compat.pass.cpp
  llvm-libc++-shared.cfg.in :: std/modules/std.pass.cpp

Typical error:

# | In file included from /home/buildkite/.buildkite-agent/builds/freebsd-test-1/llvm-project/libcxx-ci/build/generic-cxx23/modules/c++/v1/std.cppm:227:
# | /home/buildkite/.buildkite-agent/builds/freebsd-test-1/llvm-project/libcxx-ci/build/generic-cxx23/modules/c++/v1/std/cfenv.inc:16:14: error: using declaration referring to 'feclearexcept' with internal linkage cannot be exported
# |    16 |   using std::feclearexcept;
# |       |              ^
# | /usr/include/fenv.h:267:1: note: target of using declaration
# |   267 | feclearexcept(int __excepts)
# |       | ^

It seems FreeBSD's libc is not standard compliant.
/usr/include/fenv.h:266

__fenv_static inline int
feclearexcept(int __excepts)

and __fenv_static is defined as static. This means feclearexcept has internal linkage. This is not allowed by the C standard and C++ modules can't export named declarations with internal linkage. So this is probably something to be fixed in FreeBSD.

For now you can disable the module tests by adding or "__FreeBSD__" in compilerMacros(cfg) in this test feature.
https://github.com/llvm/llvm-project/blob/main/libcxx/utils/libcxx/test/features.py#L279

Would extern inline work better here? Or is that also incompatible? (As far as I can see both the C and C++ standard just refer to this function as int feclearexcept(int excepts);.

That's indeed how they are written in the standard. But per C11 7.1.2 Standard headers/6
Any declaration of a library function shall have external linkage. I did not check older C standards.

Since it seems most (all?) declarations in this headers are definitions just inline should work. However I expect the developers of FreeBSD's libc know how to fix this and why they use something different at the moment.

For now you can disable the module tests

I'll give that a try now

✅ With the latest revision this PR passed the Python code formatter.

✅ With the latest revision this PR passed the C/C++ code formatter.

FreeBSD bug 277958 submitted for libc: https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=277958

FreeBSD is green now. https://buildkite.com/llvm-project/libcxx-ci/builds/34426#018e7715-1b52-43e2-849d-78cc8621f17d

Hrm, it's a bit unfortunate that the only option is "squash and merge" and any evidence of 490441c as a separate change is lost.

Can we have C++26 mode enabled to be able to test the new features?

Where do we enable it?

Can we have C++26 mode enabled to be able to test the new features?

OK, in #86658 I tested switching to generic-cxx26 and it's still green. However, I don't think there are any other C++26 builders yet and I don't want FreeBSD to be the only one - I worry that if FreeBSD fails it will be assumed to be a FreeBSD issue rather than a C++26 issue.

As mention in the other PR we already use C++26. However there used in GitHub actions and not on Buildkite.