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

Doc/whatsnew/3.13.rst

@@ -915,6 +915,10 @@ New Features
 Porting to Python 3.13
 ----------------------
 
+* ``Python.h`` no longer includes the ``<unistd.h>`` standard header file. If
+  needed, it should now be included explicitly.
+  (Contributed by Victor Stinner in :gh:`108765`.)
+
 Deprecated
 ----------
 

Include/Python.h

@@ -25,14 +25,13 @@
 #ifdef HAVE_STDDEF_H
 #  include <stddef.h>             // size_t
 #endif
-#ifndef MS_WINDOWS
-#  include <unistd.h>             // sysconf()
+#ifdef HAVE_SYS_TYPES_H
+#  include <sys/types.h>          // ssize_t
 #endif
 
-// 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.
+// errno.h, stdio.h, stdlib.h and string.h headers are no longer used by
+// Python, but kept for backward compatibility (avoid compiler warnings).
+// They are no longer included by limited C API version 3.11 and newer.
 #if !defined(Py_LIMITED_API) || Py_LIMITED_API+0 < 0x030b0000
 #  include <errno.h>              // errno
 #  include <stdio.h>              // FILE*

Misc/NEWS.d/next/C API/2023-09-01-21-10-29.gh-issue-108765.eeXtYF.rst

@@ -0,0 +1,2 @@
+``Python.h`` no longer includes the ``<unistd.h>`` standard header file. If
+needed, it should now be included explicitly. Patch by Victor Stinner.

Modules/grpmodule.c

@@ -4,7 +4,8 @@
 #include "Python.h"
 #include "posixmodule.h"
 
-#include <grp.h>
+#include <grp.h>                  // getgrgid_r()
+#include <unistd.h>               // sysconf()
 
 #include "clinic/grpmodule.c.h"
 /*[clinic input]

Modules/mmapmodule.c

@@ -28,6 +28,7 @@
 #include "pycore_fileutils.h"     // _Py_stat_struct
 
 #include <stddef.h>               // offsetof()
+#include <unistd.h>               // close()
 
 // to support MS_WINDOWS_SYSTEM OpenFileMappingA / CreateFileMappingA
 // need to be replaced with OpenFileMappingW / CreateFileMappingW

Modules/pwdmodule.c

@@ -4,7 +4,9 @@
 #include "Python.h"
 #include "posixmodule.h"
 
-#include <pwd.h>
+#include <pwd.h>                  // getpwuid()
+#include <unistd.h>               // sysconf()
+
 
 #include "clinic/pwdmodule.c.h"
 /*[clinic input]

Modules/selectmodule.c

@@ -17,6 +17,7 @@
 #include "pycore_time.h"          // _PyTime_t
 
 #include <stddef.h>               // offsetof()
+#include <unistd.h>               // close()
 
 #ifdef HAVE_SYS_DEVPOLL_H
 #include <sys/resource.h>