GeezerVison

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.

breaks signalmodule.c

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)?

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.

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.

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.

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.