[PATCH 1/2] Python: bump minimum sphinx version to 3.4.3

[John Snow <jsnow@redhat.com>]

With RHEL 8 support retired (It's been two years today since RHEL 9
came out), our very oldest build platform version of Sphinx is now
3.4.3; and keeping backwards compatibility for versions as old as v1.6
when using domain extensions is a lot of work we don't need to do.

This patch is motivated by my work creating a new QAPI domain, which
unlike the dbus documentation, cannot be allowed to regress by creating
a "dummy" doc. Easier is to improve our minimum version as far as we can
push it forwards, reducing my burden in creating cross-compatibility
hacks and patches.

A sampling of sphinx versions from various distributions, courtesy
https://repology.org/project/python:sphinx/versions

Alpine 3.16: v4.3.0 (QEMU support ended 2024-05-23)
Alpine 3.17: v5.3.0
Alpine 3.18: v6.1.3
Alpine 3.19: v6.2.1
Ubuntu 20.04 LTS: EOL
Ubuntu 22.04 LTS: v4.3.2
Ubuntu 22.10: EOL
Ubuntu 23.04: EOL
Ubuntu 23.10: v5.3.0
Ubuntu 24.04 LTS: v7.2.6
Debian 11: v3.4.3 (QEMU support ends 2024-07-xx)
Debian 12: v5.3.0
Fedora 38: EOL
Fedora 39: v6.2.1
Fedora 40: v7.2.6
CentOS Stream 8: v1.7.6 (QEMU support ended 2024-05-17)
CentOS Stream 9: v3.4.3
OpenSUSE Leap 15.4: EOL
OpenSUSE Leap 15.5: 2.3.1, 4.2.0 and 7.2.6

Signed-off-by: John Snow <jsnow@redhat.com>
---
 docs/conf.py           |  7 +++----
 docs/sphinx/qapidoc.py | 29 +++--------------------------
 pythondeps.toml        |  2 +-
 3 files changed, 7 insertions(+), 31 deletions(-)

diff --git a/docs/conf.py b/docs/conf.py
index aae0304ac6e..876f6768815 100644
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -53,10 +53,9 @@
 
 # If your documentation needs a minimal Sphinx version, state it here.
 #
-# Sphinx 1.5 and earlier can't build our docs because they are too
-# picky about the syntax of the argument to the option:: directive
-# (see Sphinx bugs #646, #3366).
-needs_sphinx = '1.6'
+# 3.4.3 is the oldest version of Sphinx that ships on a platform we
+# pledge build support for.
+needs_sphinx = '3.4.3'
 
 # Add any Sphinx extension module names here, as strings. They can be
 # extensions coming with Sphinx (named 'sphinx.ext.*') or your custom
diff --git a/docs/sphinx/qapidoc.py b/docs/sphinx/qapidoc.py
index f270b494f01..9a0cfcbce75 100644
--- a/docs/sphinx/qapidoc.py
+++ b/docs/sphinx/qapidoc.py
@@ -31,6 +31,7 @@
 from docutils.statemachine import ViewList
 from docutils.parsers.rst import directives, Directive
 from sphinx.errors import ExtensionError
+from sphinx.util.docutils import switch_source_input
 from sphinx.util.nodes import nested_parse_with_titles
 import sphinx
 from qapi.gen import QAPISchemaVisitor
@@ -38,15 +39,6 @@
 from qapi.schema import QAPISchema
 
 
-# Sphinx up to 1.6 uses AutodocReporter; 1.7 and later
-# use switch_source_input. Check borrowed from kerneldoc.py.
-Use_SSI = sphinx.__version__[:3] >= '1.7'
-if Use_SSI:
-    from sphinx.util.docutils import switch_source_input
-else:
-    from sphinx.ext.autodoc import AutodocReporter
-
-
 __version__ = '1.0'
 
 
@@ -517,23 +509,8 @@ def do_parse(self, rstlist, node):
         subheadings (titles) without confusing the rendering of
         anything else.
         """
-        # This is from kerneldoc.py -- it works around an API change in
-        # Sphinx between 1.6 and 1.7. Unlike kerneldoc.py, we use
-        # sphinx.util.nodes.nested_parse_with_titles() rather than the
-        # plain self.state.nested_parse(), and so we can drop the saving
-        # of title_styles and section_level that kerneldoc.py does,
-        # because nested_parse_with_titles() does that for us.
-        if Use_SSI:
-            with switch_source_input(self.state, rstlist):
-                nested_parse_with_titles(self.state, rstlist, node)
-        else:
-            save = self.state.memo.reporter
-            self.state.memo.reporter = AutodocReporter(
-                rstlist, self.state.memo.reporter)
-            try:
-                nested_parse_with_titles(self.state, rstlist, node)
-            finally:
-                self.state.memo.reporter = save
+        with switch_source_input(self.state, rstlist):
+            nested_parse_with_titles(self.state, rstlist, node)
 
 
 def setup(app):
diff --git a/pythondeps.toml b/pythondeps.toml
index 9c16602d303..bc656376caa 100644
--- a/pythondeps.toml
+++ b/pythondeps.toml
@@ -23,7 +23,7 @@ meson = { accepted = ">=0.63.0", installed = "1.2.3", canary = "meson" }
 
 [docs]
 # Please keep the installed versions in sync with docs/requirements.txt
-sphinx = { accepted = ">=1.6", installed = "5.3.0", canary = "sphinx-build" }
+sphinx = { accepted = ">=3.4.3", installed = "5.3.0", canary = "sphinx-build" }
 sphinx_rtd_theme = { accepted = ">=0.5", installed = "1.1.1" }
 
 [avocado]
-- 
2.45.0