Use the `misc.highlighting_failure warning sub-type for PygmentsBridge.get_lexer()` (#13335)

Co-authored-by: Adam Turner <9087854+aa-turner@users.noreply.github.com>

AUTHORS.rst

@@ -28,6 +28,7 @@ Contributors
 * Antonio Valentino -- qthelp builder, docstring inheritance
 * Antti Kaihola -- doctest extension (skipif option)
 * Barry Warsaw -- setup command improvements
+* Bart Kamphorst -- warning improvements
 * Ben Egan -- Napoleon improvements & viewcode improvements
 * Benjamin Peterson -- unittests
 * Blaise Laflamme -- pyramid theme

CHANGES.rst

@@ -111,6 +111,8 @@ Features added
 * #13326: Remove hardcoding from handling :class:`~sphinx.addnodes.productionlist`
   nodes in all writers, to improve flexibility.
   Patch by Adam Turner.
+* #13335: Use ``misc.highlighting_failure`` subtype for Pygments unknown lexers.
+  Patch by Bart Kamphorst.
 
 Bugs fixed
 ----------

sphinx/highlighting.py

@@ -167,7 +167,11 @@ class PygmentsBridge:
                     lexer = get_lexer_by_name(lang, **opts)
             except ClassNotFound:
                 logger.warning(
-                    __('Pygments lexer name %r is not known'), lang, location=location
+                    __('Pygments lexer name %r is not known'),
+                    lang,
+                    location=location,
+                    type='misc',
+                    subtype='higlighting_failure',
                 )
                 lexer = lexer_classes['none'](**opts)