Switch uses of __import__ to importlib.get_module()

The Python docs for __import__ recommend using importlib.get_module().

https://docs.python.org/3/library/functions.html#__import__

> Note: This is an advanced function that is not needed in everyday
> Python programming, unlike importlib.import_module().

As importlib.get_module() uses the Python module cache and returns the
module, this also allows simplifying many module cache checks of use of
sys.modules.

importlib.get_module() has been available since Python 3.3.

1 files changed, 2 insertions, 1 deletions

diff --git a/sphinx/highlighting.py b/sphinx/highlighting.py
index b4e63209f..977b71f28 100644
--- a/sphinx/highlighting.py
+++ b/sphinx/highlighting.py
@@ -11,6 +11,7 @@
 import html
 import warnings
 from functools import partial
+from importlib import import_module
 
 from pygments import highlight
 from pygments.filters import ErrorToken
@@ -92,7 +93,7 @@ class PygmentsBridge:
             return NoneStyle
         elif '.' in stylename:
             module, stylename = stylename.rsplit('.', 1)
-            return getattr(__import__(module, None, None, ['__name__']), stylename)
+            return getattr(import_module(module), stylename)
         else:
             return get_style_by_name(stylename)