From 193a664b380089bcb3e86414d9a62bd958c7c526 Mon Sep 17 00:00:00 2001
From: Aaron Carlisle <carlisle.b3d@gmail.com>
Date: Mon, 15 Mar 2021 16:57:48 -0400
Subject: [PATCH] Require Sphinx 1.6 deprecate html4

Sphinx 1.6 is required for de76c03824cc7396fa882cca2d35f4a2f2a3ede2 we also do not test against versions lower than 1.6 so we should safely drop it.

This is similar to #1076 and #1075 but less strict
---
 docs/installing.rst          |  8 ++++++++
 setup.py                     |  2 +-
 sphinx_rtd_theme/__init__.py | 20 +++++++++++---------
 3 files changed, 20 insertions(+), 10 deletions(-)

diff --git a/docs/installing.rst b/docs/installing.rst
index 9e38bebdd..759e73a9c 100644
--- a/docs/installing.rst
+++ b/docs/installing.rst
@@ -45,3 +45,11 @@ Symlink or subtree the ``sphinx_rtd_theme/sphinx_rtd_theme`` repository into you
 
     html_theme = "sphinx_rtd_theme"
     html_theme_path = ["_themes", ]
+
+Compatibility
+=============
+
+``sphinx_rtd_theme`` depends on at least Sphinx 1.6 although,
+we recommend at least Sphinx 2 to take advantage of the html5 writer.
+The html4 writer is still supported however,
+it is deprecated and support will be removed in the near future.
diff --git a/setup.py b/setup.py
index c121a1e3b..362c81398 100644
--- a/setup.py
+++ b/setup.py
@@ -117,7 +117,7 @@ def run(self):
         ]
     },
     install_requires=[
-        'sphinx'
+        'sphinx>=1.6'
     ],
     tests_require=[
         'pytest',
diff --git a/sphinx_rtd_theme/__init__.py b/sphinx_rtd_theme/__init__.py
index b4d72c99b..87a2342ea 100644
--- a/sphinx_rtd_theme/__init__.py
+++ b/sphinx_rtd_theme/__init__.py
@@ -8,12 +8,7 @@
 
 from sphinx import version_info
 from sphinx.locale import _
-
-try:
-    # Avaliable from Sphinx 1.6
-    from sphinx.util.logging import getLogger
-except ImportError:
-    from logging import getLogger
+from sphinx.util.logging import getLogger
 
 
 __version__ = '0.5.1'
@@ -38,9 +33,16 @@ def config_initiated(app, config):
 
 # See http://www.sphinx-doc.org/en/stable/theming.html#distribute-your-theme-as-a-python-package
 def setup(app):
-    if version_info >= (1, 6, 0):
-        # Register the theme that can be referenced without adding a theme path
-        app.add_html_theme('sphinx_rtd_theme', path.abspath(path.dirname(__file__)))
+    app.require_sphinx('1.6')
+    if version_info <= (2, 0, 0):
+        if not app.config.html_experimental_html5_writer:
+            logger.warning("'html4_writer' is deprecated with sphinx_rtd_theme")
+    else:
+        if app.config.html4_writer:
+            logger.warning("'html4_writer' is deprecated with sphinx_rtd_theme")
+
+    # Register the theme that can be referenced without adding a theme path
+    app.add_html_theme('sphinx_rtd_theme', path.abspath(path.dirname(__file__)))
 
     if version_info >= (1, 8, 0):
         # Add Sphinx message catalog for newer versions of Sphinx