gh-108765: Python.h no longer includes <unistd.h>

[vstinner]

• Issue: C API: Cleanup header files #108765

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📚 Documentation preview 📚: https://cpython-previews--108783.org.readthedocs.build/

[vstinner]

I merged my PR.

If it causes too many trouble in 3rd party C extensions (require to update too many C extensions before Python 3.13 beta1), I can make this change conditional only in the limited C API version 3.13, as I did for other headers in Python.h:

// errno.h, stdio.h, stdlib.h and string.h headers are no longer used by Python
// headers, but kept for backward compatibility (no introduce new compiler
// warnings). They are not included by the limited C API version 3.11 and
// above.
#if !defined(Py_LIMITED_API) || Py_LIMITED_API+0 < 0x030b0000
#  include <errno.h>              // errno
#  include <stdio.h>              // FILE*
#  include <stdlib.h>             // getenv()
#  include <string.h>             // memcpy()
#endif

I consider that <unistd.h> is less commonly used by than the very common <errno.h>, <stdio.h>, <stdlib.h> and <string.h>. Again, if it causes too much burden, I can make the change conditional.

[jibal]

breaks signalmodule.c

[vstinner]

breaks signalmodule.c

Would you mind to elaborate your comment "a little bit"? What is broken? Is it a build issue? On which Python version? On which OS (name, version) and compiler (name, version)?

[jibal]

signalmodule.c calls pause() and alarm() (under #ifdef HAVE_{PAUSE,ALARM} guards), which are defined in unistd.h

On the Python version where you deleted unistd.h from Python.h, of course.

[vstinner]

signalmodule.c calls pause() and alarm() (under #ifdef HAVE_{PAUSE,ALARM} guards), which are defined in unistd.h

Hum, in fact, <unistd.h> is included indirectly by pycore_pythread.h. But well, I wrote PR #111402 to make it extra clear.

[jibal]

Hum, in fact, <unistd.h> is included indirectly by pycore_pythread.h.

Which is not necessarily included when signalmodule.c is compiled ... it wasn't in my build. (Which I've abandoned ... I never actually intended to build the top of tree.)

But well, I wrote PR #111402 to make it extra clear.

Seems like the right thing to do.

[vstinner]

Which is not necessarily included when signalmodule.c is compiled ... it wasn't in my build. (Which I've abandoned ... I never actually intended to build the top of tree.)

You didn't reply to my question about OS and compiler... Also, pycore_pythread.h was modified recently.