Merge tag 'docs-5.2-fixes2' of git://git.lwn.net/linux

Pull documentation fixes from Jonathan Corbet:
 "The Sphinx 2.0 release contained a few incompatible API changes that
  broke our extensions and, thus, the documentation build in general.
  Who knew that those deprecation warnings it was outputting actually
  meant we should change something? This set of fixes makes the build
  work again with Sphinx 2.0 and eliminates the warnings for 1.8. As
  part of that, we also need a few fixes to the docs for places where
  the new Sphinx is more strict.

  It is a bit late in the cycle for this kind of change, but it does fix
  problems that people are experiencing now.

  There has been some talk of raising the minimum version of Sphinx we
  support. I don't want to do that abruptly, though, so these changes
  add some glue to continue to support versions back to 1.3. We will be
  adding some infrastructure soon to nudge users of old versions
  forward, with the idea of maybe increasing our minimum version (and
  removing this glue) sometime in the future"

* tag 'docs-5.2-fixes2' of git://git.lwn.net/linux:
  drm/i915: Maintain consistent documentation subsection ordering
  scripts/sphinx-pre-install: make it handle Sphinx versions
  docs: Fix conf.py for Sphinx 2.0
  docs: fix multiple doc build warnings in enumeration.rst
  lib/list_sort: fix kerneldoc build error
  docs: fix numaperf.rst and add it to the doc tree
  doc: Cope with the deprecation of AutoReporter
  doc: Cope with Sphinx logging deprecations

scripts/sphinx-pre-install

@@ -13,7 +13,7 @@ use strict;
 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 # GNU General Public License for more details.
 
-my $virtenv_dir = "sphinx_1.4";
+my $conf = "Documentation/conf.py";
 my $requirement_file = "Documentation/sphinx/requirements.txt";
 
 #
@@ -26,7 +26,9 @@ my $need = 0;
 my $optional = 0;
 my $need_symlink = 0;
 my $need_sphinx = 0;
+my $rec_sphinx_upgrade = 0;
 my $install = "";
+my $virtenv_dir = "sphinx_";
 
 #
 # Command line arguments
@@ -201,13 +203,15 @@ sub check_missing_tex($)
 	}
 }
 
-sub check_sphinx()
+sub get_sphinx_fname()
 {
-	return if findprog("sphinx-build");
+	my $fname = "sphinx-build";
+	return $fname if findprog($fname);
 
-	if (findprog("sphinx-build-3")) {
+	$fname = "sphinx-build-3";
+	if (findprog($fname)) {
 		$need_symlink = 1;
-		return;
+		return $fname;
 	}
 
 	if ($virtualenv) {
@@ -219,6 +223,73 @@ sub check_sphinx()
 	} else {
 		add_package("python-sphinx", 0);
 	}
+
+	return "";
+}
+
+sub check_sphinx()
+{
+	my $min_version;
+	my $rec_version;
+	my $cur_version;
+
+	open IN, $conf or die "Can't open $conf";
+	while (<IN>) {
+		if (m/^\s*needs_sphinx\s*=\s*[\'\"]([\d\.]+)[\'\"]/) {
+			$min_version=$1;
+			last;
+		}
+	}
+	close IN;
+
+	die "Can't get needs_sphinx version from $conf" if (!$min_version);
+
+	open IN, $requirement_file or die "Can't open $requirement_file";
+	while (<IN>) {
+		if (m/^\s*Sphinx\s*==\s*([\d\.]+)$/) {
+			$rec_version=$1;
+			last;
+		}
+	}
+	close IN;
+
+	die "Can't get recommended sphinx version from $requirement_file" if (!$min_version);
+
+	$virtenv_dir .= $rec_version;
+
+	my $sphinx = get_sphinx_fname();
+	return if ($sphinx eq "");
+
+	open IN, "$sphinx --version 2>&1 |" or die "$sphinx returned an error";
+	while (<IN>) {
+		if (m/^\s*sphinx-build\s+([\d\.]+)$/) {
+			$cur_version=$1;
+			last;
+		}
+		# Sphinx 1.2.x uses a different format
+		if (m/^\s*Sphinx.*\s+([\d\.]+)$/) {
+			$cur_version=$1;
+			last;
+		}
+	}
+	close IN;
+
+	die "$sphinx didn't return its version" if (!$cur_version);
+
+	printf "Sphinx version %s (minimal: %s, recommended >= %s)\n",
+		$cur_version, $min_version, $rec_version;
+
+	if ($cur_version lt $min_version) {
+		print "Warning: Sphinx version should be >= $min_version\n\n";
+		$need_sphinx = 1;
+		return;
+	}
+
+	if ($cur_version lt $rec_version) {
+		print "Warning: It is recommended at least Sphinx version $rec_version.\n";
+		print "         To upgrade, use:\n\n";
+		$rec_sphinx_upgrade = 1;
+	}
 }
 
 #
@@ -540,7 +611,7 @@ sub check_needs()
 		printf "\tsudo ln -sf %s /usr/bin/sphinx-build\n\n",
 		       which("sphinx-build-3");
 	}
-	if ($need_sphinx) {
+	if ($need_sphinx || $rec_sphinx_upgrade) {
 		my $activate = "$virtenv_dir/bin/activate";
 		if (-e "$ENV{'PWD'}/$activate") {
 			printf "\nNeed to activate virtualenv with:\n";
@@ -554,7 +625,8 @@ sub check_needs()
 			printf "\t$virtualenv $virtenv_dir\n";
 			printf "\t. $activate\n";
 			printf "\tpip install -r $requirement_file\n";
-			$need++;
+
+			$need++ if (!$rec_sphinx_upgrade);
 		}
 	}
 	printf "\n";