From 79189ce212aa86456b12e3ed52918c63cf55a878 Mon Sep 17 00:00:00 2001
From: Tim Hoffmann <2836374+timhoffm@users.noreply.github.com>
Date: Thu, 31 Mar 2022 23:59:31 +0200
Subject: [PATCH] Mark artist property aliases explicitly

---
 lib/matplotlib/_api/__init__.py | 14 +++++++++++++-
 lib/matplotlib/artist.py        |  7 ++++++-
 lib/matplotlib/text.py          |  1 +
 3 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/lib/matplotlib/_api/__init__.py b/lib/matplotlib/_api/__init__.py
index 483b810e5d7d..1aec5be218ea 100644
--- a/lib/matplotlib/_api/__init__.py
+++ b/lib/matplotlib/_api/__init__.py
@@ -9,7 +9,7 @@
     in your own code.  We may change the API at any time with no warning.
 
 """
-
+from collections import namedtuple
 import functools
 import itertools
 import re
@@ -58,6 +58,16 @@ def fget(self):
         return self._fget
 
 
+ArtistPropertyInfo = namedtuple('ArtistPropertyInfo', 'kwdoc, is_alias')
+
+
+def artist_property(kwdoc=None, is_alias=False):
+    def decorator(func):
+        func._artist_property = ArtistPropertyInfo(kwdoc, is_alias)
+        return func
+    return decorator
+
+
 # In the following check_foo() functions, the first parameter starts with an
 # underscore because it is intended to be positional-only (e.g., so that
 # `_api.check_isinstance([...], types=foo)` doesn't fail.
@@ -261,6 +271,8 @@ def method(self, *args, **kwargs):
                     method = make_alias(prefix + prop)
                     method.__name__ = prefix + alias
                     method.__doc__ = "Alias for `{}`.".format(prefix + prop)
+                    method._artist_property = \
+                        ArtistPropertyInfo(kwdoc=None, is_alias=True)
                     setattr(cls, prefix + alias, method)
         if not exists:
             raise ValueError(
diff --git a/lib/matplotlib/artist.py b/lib/matplotlib/artist.py
index 1f33b9d3ec11..b66b862854e2 100644
--- a/lib/matplotlib/artist.py
+++ b/lib/matplotlib/artist.py
@@ -1490,7 +1490,12 @@ def is_alias(self, o):
         ds = inspect.getdoc(o)
         if ds is None:
             return False
-        return ds.startswith('Alias for ')
+        result = ds.startswith('Alias for ')
+        alt_result = (o._artist_property.is_alias
+                      if hasattr(o, '_artist_property')
+                      else False)
+        assert result == alt_result
+        return result
 
     def aliased_name(self, s):
         """
diff --git a/lib/matplotlib/text.py b/lib/matplotlib/text.py
index 4aac1f055db7..efc1f05c2713 100644
--- a/lib/matplotlib/text.py
+++ b/lib/matplotlib/text.py
@@ -1304,6 +1304,7 @@ def get_parse_math(self):
         """Return whether mathtext parsing is considered for this `Text`."""
         return self._parse_math
 
+    @_api.artist_property(is_alias=True)
     def set_fontname(self, fontname):
         """
         Alias for `set_family`.