Build fails with Clang 16 on Mac OS

[kostyaorkostya]

Hi,

Building with default flags fails on Mac OS 14.6 (23G80) with Clang 16:

$ pip install MacFSEvents

Collecting MacFSEvents
  Using cached MacFSEvents-0.8.4.tar.gz (11 kB)
  Installing build dependencies ... done
  Getting requirements to build wheel ... done
  Preparing metadata (pyproject.toml) ... done
Building wheels for collected packages: MacFSEvents
  Building wheel for MacFSEvents (pyproject.toml) ... error
  error: subprocess-exited-with-error
  
  × Building wheel for MacFSEvents (pyproject.toml) did not run successfully.
  │ exit code: 1
  ╰─> [31 lines of output]
      /private/var/folders/81/1h30ll5x0s3dpfzh3chmyny80000gn/T/pip-build-env-uxfzyrxi/overlay/lib/python3.13/site-packages/setuptools/_distutils/dist.py:261: UserWarning: Unknown distribution option: 'test_suite'
        warnings.warn(msg)
      running bdist_wheel
      running build
      running build_py
      creating build/lib.macosx-14.6-arm64-cpython-313
      copying fsevents.py -> build/lib.macosx-14.6-arm64-cpython-313
      running build_ext
      building '_fsevents' extension
      creating build/temp.macosx-14.6-arm64-cpython-313
      clang -fno-strict-overflow -Wsign-compare -Wunreachable-code -DNDEBUG -g -O3 -Wall -I/Users/kostya/.pyenv/versions/3.13.0/envs/py3nvim/include -I/Users/kostya/.pyenv/versions/3.13.0/include/python3.13 -c _fsevents.c -o build/temp.macosx-14.6-arm64-cpython-313/_fsevents.o
      _fsevents.c:97:11: error: call to undeclared function 'PyEval_ThreadsInitialized'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
         97 |     if (! PyEval_ThreadsInitialized()) {
            |           ^
      _fsevents.c:98:9: warning: 'PyEval_InitThreads' is deprecated [-Wdeprecated-declarations]
         98 |         PyEval_InitThreads();
            |         ^
      /Users/kostya/.pyenv/versions/3.13.0/include/python3.13/ceval.h:114:1: note: 'PyEval_InitThreads' has been explicitly marked deprecated here
        114 | Py_DEPRECATED(3.9) PyAPI_FUNC(void) PyEval_InitThreads(void);
            | ^
      /Users/kostya/.pyenv/versions/3.13.0/include/python3.13/pyport.h:251:54: note: expanded from macro 'Py_DEPRECATED'
        251 | #define Py_DEPRECATED(VERSION_UNUSED) __attribute__((__deprecated__))
            |                                                      ^
      _fsevents.c:194:5: warning: 'FSEventStreamScheduleWithRunLoop' is deprecated: first deprecated in macOS 13.0 - Use FSEventStreamSetDispatchQueue instead. [-Wdeprecated-declarations]
        194 |     FSEventStreamScheduleWithRunLoop(fsstream, loop, kCFRunLoopDefaultMode);
            |     ^
      /Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/System/Library/Frameworks/CoreServices.framework/Frameworks/FSEvents.framework/Headers/FSEvents.h:1154:1: note: 'FSEventStreamScheduleWithRunLoop' has been explicitly marked deprecated here
       1154 | FSEventStreamScheduleWithRunLoop(
            | ^
      2 warnings and 1 error generated.
      error: command '/usr/bin/clang' failed with exit code 1
      [end of output]
  
  note: This error originates from a subprocess, and is likely not a problem with pip.
  ERROR: Failed building wheel for MacFSEvents
Failed to build MacFSEvents
ERROR: ERROR: Failed to build installable wheels for some pyproject.toml based projects (MacFSEvents)
$ /usr/bin/clang --version
Apple clang version 16.0.0 (clang-1600.0.26.4)
Target: arm64-apple-darwin23.6.0
Thread model: posix
InstalledDir: /Library/Developer/CommandLineTools/usr/bin
$ python -V
Python 3.13.0
$ pip -V      
pip 24.3.1 from ... (python 3.13)

Passing -Wno-implicit-function-declaration solves the issue:

$ CFLAGS='-Wno-implicit-function-declaration' pip install MacFSEvents
Collecting MacFSEvents
  Using cached MacFSEvents-0.8.4.tar.gz (11 kB)
  Installing build dependencies ... done
  Getting requirements to build wheel ... done
  Preparing metadata (pyproject.toml) ... done
Building wheels for collected packages: MacFSEvents
  Building wheel for MacFSEvents (pyproject.toml) ... done
  Created wheel for MacFSEvents: filename=MacFSEvents-0.8.4-cp313-cp313-macosx_14_0_arm64.whl size=15804 sha256=dbca236412e6fd327734e827f8f75f15735f39c680f8ffc7bf0c06f8983db5db
  Stored in directory: /Users/kostya/Library/Caches/pip/wheels/f3/73/2a/f42bcc31a3f5b8c1e5abaf129886ab1844bc88249fc37cb68c
Successfully built MacFSEvents
Installing collected packages: MacFSEvents
Successfully installed MacFSEvents-0.8.4

I suspect that it's because of a breaking change in Clang 16:
https://releases.llvm.org/16.0.0/tools/clang/docs/ReleaseNotes.html#potentially-breaking-changes