From: Michael Fladischer <FladischerMichael@fladi.at>
Date: Fri, 7 Jul 2023 06:24:43 +0000
Subject: Use local objects.inv in intersphinx mapping.

---
 docs/source/conf.py | 61 ++++++++++++++++++++++++++++++++++++++++++++++-------
 1 file changed, 53 insertions(+), 8 deletions(-)

diff --git a/docs/source/conf.py b/docs/source/conf.py
index ab0d1e5..7ab42de 100755
--- a/docs/source/conf.py
+++ b/docs/source/conf.py
@@ -32,6 +32,8 @@ if TYPE_CHECKING:
     from sphinx.application import Sphinx
     from sphinx.util.typing import Inventory
 
+import OpenSSL
+
 # For our local_customization module
 sys.path.insert(0, os.path.abspath("."))
 
@@ -239,14 +241,57 @@ extensions = [
     "typevars",
 ]
 
-intersphinx_mapping = {
-    "python": ("https://docs.python.org/3", None),
-    "outcome": ("https://outcome.readthedocs.io/en/latest/", None),
-    "pyopenssl": ("https://www.pyopenssl.org/en/stable/", None),
-    "sniffio": ("https://sniffio.readthedocs.io/en/latest/", None),
-    "trio-util": ("https://trio-util.readthedocs.io/en/latest/", None),
-    "flake8-async": ("https://flake8-async.readthedocs.io/en/latest/", None),
-}
+def check_object_path(
+    key: str, url: str, path: str
+) -> dict[str, tuple[str, str]]:
+    if os.path.isfile(path):
+        return {key: (url, path)}
+    return {}
+
+
+intersphinx_mapping = {}
+intersphinx_mapping.update(
+    check_object_path(
+        "python",
+        "https://docs.python.org/",
+        "/usr/share/doc/python" + ".".join((str(x) for x in sys.version_info[:2])) + "/html/objects.inv"
+    )
+)
+intersphinx_mapping.update(
+    check_object_path(
+        "pyopenssl",
+        "https://www.pyopenssl.org/en/{v}".format(v=OpenSSL.__version__),
+        "/usr/share/doc/python-openssl-doc/html/objects.inv"
+    )
+)
+intersphinx_mapping.update(
+    check_object_path(
+        "outcome",
+        "https://outcome.readthedocs.io/en/latest/",
+        "/usr/share/doc/python-outcome-doc/html/objects.inv"
+    )
+)
+intersphinx_mapping.update(
+    check_object_path(
+        "sniffio",
+        "https://sniffio.readthedocs.io/en/latest/",
+        "/usr/share/doc/python-sniffio-doc/html/objects.inv"
+    )
+)
+intersphinx_mapping.update(
+    check_object_path(
+        "trio-util",
+        "https://trio-util.readthedocs.io/en/latest/",
+        "/usr/share/doc/python-trio-util-doc/html/objects.inv"
+    )
+)
+intersphinx_mapping.update(
+    check_object_path(
+        "flake8-async",
+        "https://flake8-async.readthedocs.io/en/latest/",
+        "/usr/share/doc/python-flake8-async-doc/html/objects.inv"
+    )
+)
 
 # See https://sphinx-codeautolink.readthedocs.io/en/latest/reference.html#configuration
 codeautolink_autodoc_inject = False