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because this opinion is clearly out-of-date: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

3 files changed, 31 insertions, 45 deletions

diff --git a/config/python.m4 b/config/python.m4
index c51aa4e332..c7310ee37d 100644
--- a/config/python.m4
+++ b/config/python.m4
@@ -37,32 +37,25 @@ 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 4; then
-  AC_MSG_ERROR([Python version $python_version is too old (version 2.4 or later is required)])
+if test "$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 distutils module])
-if "${PYTHON}" -c 'import distutils' 2>&AS_MESSAGE_LOG_FD
+AC_MSG_CHECKING([for Python sysconfig module])
+if "${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_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])
 
-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
@@ -96,8 +89,8 @@ 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$//'`
@@ -109,11 +102,11 @@ 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${python_version_var}"
 		else
@@ -173,7 +166,7 @@ PL/Python.])
 fi
 python_libspec="-L${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}])
 
diff --git a/configure b/configure
index 0cadf7aebb..504f8c0479 100755
--- a/configure
+++ b/configure
@@ -10098,38 +10098,31 @@ 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 4; then
-  as_fn_error $? "Python version $python_version is too old (version 2.4 or later is required)" "$LINENO" 5
+if test "$python_majorversion" -lt 3 -a "$python_minorversion" -lt 7; then
+  as_fn_error $? "Python version $python_version is too old (version 2.7 or later is required)" "$LINENO" 5
 fi
 
-{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for Python distutils module" >&5
-$as_echo_n "checking for Python distutils module... " >&6; }
-if "${PYTHON}" -c 'import distutils' 2>&5
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for Python sysconfig module" >&5
+$as_echo_n "checking for Python sysconfig module... " >&6; }
+if "${PYTHON}" -c 'import sysconfig' 2>&5
 then
     { $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
 $as_echo "yes" >&6; }
 else
     { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
 $as_echo "no" >&6; }
-    as_fn_error $? "distutils module not found" "$LINENO" 5
+    as_fn_error $? "sysconfig module not found" "$LINENO" 5
 fi
 
 { $as_echo "$as_me:${as_lineno-$LINENO}: checking Python configuration directory" >&5
 $as_echo_n "checking Python configuration directory... " >&6; }
-python_configdir=`${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'))))"`
 { $as_echo "$as_me:${as_lineno-$LINENO}: result: $python_configdir" >&5
 $as_echo "$python_configdir" >&6; }
 
-{ $as_echo "$as_me:${as_lineno-$LINENO}: checking Python include directories" >&5
-$as_echo_n "checking Python include directories... " >&6; }
-python_includespec=`${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)"`
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking Python include directory" >&5
+$as_echo_n "checking Python include directory... " >&6; }
+python_includespec=`${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
@@ -10141,8 +10134,8 @@ $as_echo "$python_includespec" >&6; }
 { $as_echo "$as_me:${as_lineno-$LINENO}: checking how to link an embedded Python application" >&5
 $as_echo_n "checking how to link an embedded Python application... " >&6; }
 
-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$//'`
@@ -10154,11 +10147,11 @@ 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${python_version_var}"
 		else
@@ -10218,7 +10211,7 @@ PL/Python." "$LINENO" 5
 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'))))"`
 
 { $as_echo "$as_me:${as_lineno-$LINENO}: result: ${python_libspec} ${python_additional_libs}" >&5
 $as_echo "${python_libspec} ${python_additional_libs}" >&6; }
diff --git a/doc/src/sgml/installation.sgml b/doc/src/sgml/installation.sgml
index 70f9e7b5e7..809db168cf 100644
--- a/doc/src/sgml/installation.sgml
+++ b/doc/src/sgml/installation.sgml
@@ -195,10 +195,10 @@ su - postgres
       To build the <application>PL/Python</application> server programming
       language, you need a <productname>Python</productname>
       installation with the header files and
-      the <application>distutils</application> module.  The minimum
-      required version is <productname>Python</productname> 2.4.
+      the <application>sysconfig</application> module.  The minimum
+      required version is <productname>Python</productname> 2.7.
       <productname>Python 3</productname> is supported if it's
-      version 3.1 or later; but see
+      version 3.2 or later; but see
       <xref linkend="plpython-python23"/>
       when using Python 3.
      </para>