Don't process alternative text in deprecation

to convert rst to plain text for warnings. This reverts the rst text
processing of commmit "Include alternatives to deprecations in the
documentation" as it was considered to be too complex to maintain
or potentially error prone.

Author: StefRe

doc/devel/contributing.rst

@@ -326,9 +326,7 @@ Introducing
    All these helpers take a first parameter *since*, which should be set to
    the next point release, e.g. "3.x".
 
-   You can use standard rst cross references in the alternative. The string
-   will be processed to remove back ticks and only include the link caption
-   in the runtime warning.
+   You can use standard rst cross references in *alternative*.
 
 Expiring
 ~~~~~~~~

lib/matplotlib/_api/deprecation.py

@@ -14,7 +14,6 @@
 import functools
 import inspect
 import math
-import re
 import warnings
 
 
@@ -48,10 +47,6 @@ def _generate_deprecation_warning(
             + (" %(addendum)s" if addendum else ""))
     warning_cls = (PendingDeprecationWarning if pending
                    else MatplotlibDeprecationWarning)
-    # remove backticks, optional leading dot and replace reference by caption
-    if alternative:
-        alternative = re.sub(r"`([^`]*?) *<.*?>`|`\.?(.+?)`", r"\1\2",
-                             alternative)
     return warning_cls(message % dict(
         func=name, name=name, obj_type=obj_type, since=since, removal=removal,
         alternative=alternative, addendum=addendum))

lib/matplotlib/tests/test_api.py

@@ -93,6 +93,3 @@ def test_deprecation_alternative():
     def f():
         pass
     assert alternative in f.__doc__
-    with pytest.warns(_api.MatplotlibDeprecationWarning,
-                      match=r".* f1, f2, f3\(x\) or f4\(x\)"):
-        f()