DOC: skip generating c/c++ doc from comment blocks when Doxygen or Breathe isn't available.

1 files changed, 11 insertions, 1 deletions

diff --git a/doc/source/conf.py b/doc/source/conf.py
index 835ad9064..d08f29e59 100644
--- a/doc/source/conf.py
+++ b/doc/source/conf.py
@@ -2,6 +2,7 @@
 import os
 import re
 import sys
+import importlib
 
 # Minimum version, enforced by sphinx
 needs_sphinx = '3.2.0'
@@ -84,9 +85,18 @@ extensions = [
     'IPython.sphinxext.ipython_console_highlighting',
     'IPython.sphinxext.ipython_directive',
     'sphinx.ext.mathjax',
-    'breathe'
 ]
 
+skippable_extensions = [
+    ('breathe', 'skip generating C/C++ API from comment blocks.'),
+]
+for ext, warn in skippable_extensions:
+    ext_exist = importlib.util.find_spec(ext) is not None
+    if ext_exist:
+        extensions.append(ext)
+    else:
+        print(f"Unable to find Sphinx extension '{ext}', {warn}.")
+
 # Add any paths that contain templates here, relative to this directory.
 templates_path = ['_templates']