Add macos_brew_install_llvm to ci.yml

[rwgk]

Description

Previously tested under PRs #4324, #4319

Primary motivation: inform #4319

Note that test_cross_module_exception_translator fails for the new job (1569415). See also #4319 (comment).

Note that #4324 — but not this PR — includes this change:

--- a/include/pybind11/detail/common.h
+++ b/include/pybind11/detail/common.h
@@ -96,7 +96,7 @@
 #endif

 #if !defined(PYBIND11_EXPORT_EXCEPTION)
-#    if defined(__apple_build_version__)
+#    if defined(_LIBCPP_VERSION)
 #        define PYBIND11_EXPORT_EXCEPTION PYBIND11_EXPORT
 #    else
 #        define PYBIND11_EXPORT_EXCEPTION

That diff is not included here because it does not make a difference for the new job (test_cross_module_exception_translator fails with and without it). It is probably a good change to make in general, but left for a separate PR.

Suggested changelog entry:

[rwgk]

The 1 CI failure is another test_iostream flake (very common). Ignoring.

[rwgk]

This is the pytest summary. I'll try to add pip install numpy, although I don't think it adds a lot of value.

=========================== short test summary info ============================
SKIPPED [1] test_buffers.py:11: could not import 'numpy': No module named 'numpy'
SKIPPED [1] test_eigen_matrix.py:5: could not import 'numpy': No module named 'numpy'
SKIPPED [1] test_eigen_tensor.py:5: could not import 'numpy': No module named 'numpy'
SKIPPED [1] test_numpy_array.py:6: could not import 'numpy': No module named 'numpy'
SKIPPED [1] test_numpy_dtypes.py:8: could not import 'numpy': No module named 'numpy'
SKIPPED [1] test_numpy_vectorize.py:5: could not import 'numpy': No module named 'numpy'
SKIPPED [1] test_builtin_casters.py:320: could not import 'numpy': No module named 'numpy'
SKIPPED [1] test_builtin_casters.py:486: could not import 'numpy': No module named 'numpy'
SKIPPED [1] test_callbacks.py:203: Current PYBIND11_INTERNALS_VERSION too low
SKIPPED [1] test_pytypes.py:397: Not defined: PYBIND11_HANDLE_REF_DEBUG
SKIPPED [1] test_stl.py:[143](https://github.com/pybind/pybind11/actions/runs/3438766122/jobs/5735262857#step:13:144): no <experimental/optional>
SKIPPED [1] test_stl.py:175: no <boost/optional>
SKIPPED [1] test_stl_binders.py:89: could not import 'numpy': No module named 'numpy'
XFAIL test_exceptions.py::test_cross_module_exception_translator
  See Issue #2847, PR #2999, PR #4324
================= 554 passed, 13 skipped, 1 xfailed in 33.63s ==================

[rwgk]

This is why numpy isn't installed via tests/requirements.txt:

2022-11-10T16:55:39.8160260Z Ignoring numpy: markers 'platform_python_implementation == "PyPy" and sys_platform == "linux" and python_version == "3.7"' don't match your environment
2022-11-10T16:55:39.8164270Z Ignoring numpy: markers 'platform_python_implementation != "PyPy" and python_version == "3.6"' don't match your environment
2022-11-10T16:55:39.8168100Z Ignoring numpy: markers 'platform_python_implementation != "PyPy" and python_version >= "3.7" and python_version < "3.10"' don't match your environment
2022-11-10T16:55:39.8172280Z Ignoring numpy: markers 'platform_python_implementation != "PyPy" and python_version >= "3.10" and python_version < "3.11"' don't match your environment
2022-11-10T16:55:39.8175720Z Ignoring scipy: markers 'platform_python_implementation != "PyPy" and python_version < "3.10"' don't match your environment
2022-11-10T16:55:39.8179450Z Ignoring scipy: markers 'platform_python_implementation != "PyPy" and python_version == "3.10"' don't match your environment

[rwgk]

This is the reduced pytest summary (copied from PR #4324 results):

• https://github.com/pybind/pybind11/actions/runs/3439301148/jobs/5736431691

=========================== short test summary info ============================
SKIPPED [1] test_callbacks.py:203: Current PYBIND11_INTERNALS_VERSION too low
SKIPPED [1] test_pytypes.py:397: Not defined: PYBIND11_HANDLE_REF_DEBUG
SKIPPED [1] test_stl.py:143: no <experimental/optional>
SKIPPED [1] test_stl.py:175: no <boost/optional>
XFAIL test_exceptions.py::test_cross_module_exception_translator
  See Issue #2847, PR #2999, PR #4324
================== 785 passed, 4 skipped, 1 xfailed in 57.60s ==================

In theory we could install boost, somehow, but I really don't think that's worth the trouble.

[rwgk]

Thanks @Skylion007!