[Sphinx] Support older recommonmark versions.

The "new way" of enabling recommonmark is only supported in recommonmark
0.5 and later. Use the deprecated approach with versions of Sphinx that
still support it.

If I understand correctly there's no way to use older versions of
recommonmark (<0.5) with newer versions of Sphinx (>3.0) because the old
approach got removed.

Differential revision: https://reviews.llvm.org/D75284

diff --git a/llvm/docs/conf.py b/llvm/docs/conf.py
index 13bbc82..948c61c 100644 (file)
--- a/llvm/docs/conf.py
+++ b/llvm/docs/conf.py
@@ -26,7 +26,14 @@ from datetime import date
 
 # Add any Sphinx extension module names here, as strings. They can be extensions
 # coming with Sphinx (named 'sphinx.ext.*') or your custom ones.
-extensions = ['sphinx.ext.intersphinx', 'sphinx.ext.todo', 'recommonmark']
+extensions = ['sphinx.ext.intersphinx', 'sphinx.ext.todo']
+
+import sphinx
+if sphinx.version_info >= (3, 0):
+  # This requires 0.5 or later.
+  extensions.append('recommonmark')
+else:
+  source_parsers = {'.md': 'recommonmark.parser.CommonMarkParser'}
 
 # Add any paths that contain templates here, relative to this directory.
 templates_path = ['_templates']