Replace use of deprecated Python module distutils.sysconfig, take 2.

With Python 3.10, configure spits out warnings about the module
distutils.sysconfig being deprecated and scheduled for removal in
Python 3.12.  Change the uses in configure to use the module sysconfig
instead.  The logic stays largely the same, although we have to
rely on INCLUDEPY instead of the deprecated get_python_inc function.

Note that sysconfig exists since Python 2.7, so this moves the
minimum required version up from Python 2.6 (or 2.4, before v13).
Also, sysconfig didn't exist in Python 3.1, so the minimum 3.x
version is now 3.2.

Back-patch of commit bd233bdd8 into all supported branches.

In v10, this also includes back-patching v11's beff4bb9c, primarily
because this opinion is clearly out-of-date:

    While at it, get rid of the code's assumption that both the major and
    minor numbers contain exactly one digit.  That will foreseeably be
    broken by Python 3.10 in perhaps four or five years.  That's far enough
    out that we probably don't need to back-patch this.

Peter Eisentraut, Tom Lane, Andres Freund

Discussion: https://postgr.es/m/c74add3c-09c4-a9dd-1a03-a846e5b2fc52@enterprisedb.com

1 files changed, 23 insertions, 26 deletions

diff --git a/config/python.m4 b/config/python.m4
index 0fa1e3e80d5..2fd1473b747 100644
--- a/config/python.m4
+++ b/config/python.m4
@@ -29,35 +29,32 @@ fi
 # as well as the Python version.
 AC_DEFUN([_PGAC_CHECK_PYTHON_DIRS],
 [AC_REQUIRE([PGAC_PATH_PYTHON])
-AC_MSG_CHECKING([for Python distutils module])
-if "${PYTHON}" -c 'import distutils' 2>&AS_MESSAGE_LOG_FD
+python_fullversion=`${PYTHON} -c "import sys; print(sys.version)" | sed q`
+AC_MSG_NOTICE([using python $python_fullversion])
+# python_fullversion is typically n.n.n plus some trailing junk
+python_majorversion=`echo "$python_fullversion" | sed '[s/^\([0-9]*\).*/\1/]'`
+python_minorversion=`echo "$python_fullversion" | sed '[s/^[0-9]*\.\([0-9]*\).*/\1/]'`
+python_version=`echo "$python_fullversion" | sed '[s/^\([0-9]*\.[0-9]*\).*/\1/]'`
+# Reject unsupported Python versions as soon as practical.
+if test "$python_majorversion" -lt 3 -a "$python_minorversion" -lt 7; then
+  AC_MSG_ERROR([Python version $python_version is too old (version 2.7 or later is required)])
+fi
+
+AC_MSG_CHECKING([for Python sysconfig module])
+if "${PYTHON}" -c 'import sysconfig' 2>&AS_MESSAGE_LOG_FD
 then
     AC_MSG_RESULT(yes)
 else
     AC_MSG_RESULT(no)
-    AC_MSG_ERROR([distutils module not found])
+    AC_MSG_ERROR([sysconfig module not found])
 fi
+
 AC_MSG_CHECKING([Python configuration directory])
-python_majorversion=`${PYTHON} -c "import sys; print(sys.version[[0]])"`
-python_minorversion=`${PYTHON} -c "import sys; print(sys.version[[2]])"`
-python_version=`${PYTHON} -c "import sys; print(sys.version[[:3]])"`
-python_configdir=`${PYTHON} -c "import distutils.sysconfig; print(' '.join(filter(None,distutils.sysconfig.get_config_vars('LIBPL'))))"`
+python_configdir=`${PYTHON} -c "import sysconfig; print(' '.join(filter(None,sysconfig.get_config_vars('LIBPL'))))"`
 AC_MSG_RESULT([$python_configdir])
 
-# Reject unsupported Python versions as soon as practical.
-if test "$python_majorversion" -lt 3 -a "$python_minorversion" -lt 4; then
-  AC_MSG_ERROR([Python version $python_version is too old (version 2.4 or later is required)])
-fi
-
-AC_MSG_CHECKING([Python include directories])
-python_includespec=`${PYTHON} -c "
-import distutils.sysconfig
-a = '-I' + distutils.sysconfig.get_python_inc(False)
-b = '-I' + distutils.sysconfig.get_python_inc(True)
-if a == b:
-    print(a)
-else:
-    print(a + ' ' + b)"`
+AC_MSG_CHECKING([Python include directory])
+python_includespec=`${PYTHON} -c "import sysconfig; print('-I' + sysconfig.get_config_var('INCLUDEPY'))"`
 if test "$PORTNAME" = win32 ; then
     python_includespec=`echo $python_includespec | sed 's,[[\]],/,g'`
 fi
@@ -91,8 +88,8 @@ AC_DEFUN([PGAC_CHECK_PYTHON_EMBED_SETUP],
 [AC_REQUIRE([_PGAC_CHECK_PYTHON_DIRS])
 AC_MSG_CHECKING([how to link an embedded Python application])
 
-python_libdir=`${PYTHON} -c "import distutils.sysconfig; print(' '.join(filter(None,distutils.sysconfig.get_config_vars('LIBDIR'))))"`
-python_ldlibrary=`${PYTHON} -c "import distutils.sysconfig; print(' '.join(filter(None,distutils.sysconfig.get_config_vars('LDLIBRARY'))))"`
+python_libdir=`${PYTHON} -c "import sysconfig; print(' '.join(filter(None,sysconfig.get_config_vars('LIBDIR'))))"`
+python_ldlibrary=`${PYTHON} -c "import sysconfig; print(' '.join(filter(None,sysconfig.get_config_vars('LDLIBRARY'))))"`
 
 # If LDLIBRARY exists and has a shlib extension, use it verbatim.
 ldlibrary=`echo "${python_ldlibrary}" | sed -e 's/\.so$//' -e 's/\.dll$//' -e 's/\.dylib$//' -e 's/\.sl$//'`
@@ -104,11 +101,11 @@ else
 	# Otherwise, guess the base name of the shlib.
 	# LDVERSION was added in Python 3.2, before that use VERSION,
 	# or failing that, $python_version from _PGAC_CHECK_PYTHON_DIRS.
-	python_ldversion=`${PYTHON} -c "import distutils.sysconfig; print(' '.join(filter(None,distutils.sysconfig.get_config_vars('LDVERSION'))))"`
+	python_ldversion=`${PYTHON} -c "import sysconfig; print(' '.join(filter(None,sysconfig.get_config_vars('LDVERSION'))))"`
 	if test x"${python_ldversion}" != x""; then
 		ldlibrary="python${python_ldversion}"
 	else
-		python_version_var=`${PYTHON} -c "import distutils.sysconfig; print(' '.join(filter(None,distutils.sysconfig.get_config_vars('VERSION'))))"`
+		python_version_var=`${PYTHON} -c "import sysconfig; print(' '.join(filter(None,sysconfig.get_config_vars('VERSION'))))"`
 		if test x"${python_version_var}" != x""; then
 			ldlibrary="python${python_version_var}"
 		else
@@ -168,7 +165,7 @@ PL/Python.])
 fi
 python_libspec="-L${python_libdir} -l${ldlibrary}"
 
-python_additional_libs=`${PYTHON} -c "import distutils.sysconfig; print(' '.join(filter(None,distutils.sysconfig.get_config_vars('LIBS','LIBC','LIBM','BASEMODLIBS'))))"`
+python_additional_libs=`${PYTHON} -c "import sysconfig; print(' '.join(filter(None,sysconfig.get_config_vars('LIBS','LIBC','LIBM','BASEMODLIBS'))))"`
 
 AC_MSG_RESULT([${python_libspec} ${python_additional_libs}])