From 52a5dfdf7dc9dec580c015543e330253d44f1baf Mon Sep 17 00:00:00 2001
From: jsjeelshah <jeel16@somaiya.edu>
Date: Fri, 22 Sep 2023 17:13:11 -0400
Subject: [PATCH] Remove deprecated code from _fontconfig_patterns

---
 doc/api/next_api_changes/removals/26884-JS.rst  |  5 +++++
 lib/matplotlib/_fontconfig_pattern.py           | 13 ++-----------
 lib/matplotlib/tests/test_fontconfig_pattern.py |  2 +-
 3 files changed, 8 insertions(+), 12 deletions(-)
 create mode 100644 doc/api/next_api_changes/removals/26884-JS.rst

diff --git a/doc/api/next_api_changes/removals/26884-JS.rst b/doc/api/next_api_changes/removals/26884-JS.rst
new file mode 100644
index 000000000000..71608b8d94be
--- /dev/null
+++ b/doc/api/next_api_changes/removals/26884-JS.rst
@@ -0,0 +1,5 @@
+``parse_fontconfig_pattern`` raises on unknown constant names
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Previously, in a fontconfig pattern like ``DejaVu Sans:foo``, the unknown
+``foo`` constant name would be silently ignored.  This now raises an error.
diff --git a/lib/matplotlib/_fontconfig_pattern.py b/lib/matplotlib/_fontconfig_pattern.py
index d3933b9f396d..6802c6ae24d7 100644
--- a/lib/matplotlib/_fontconfig_pattern.py
+++ b/lib/matplotlib/_fontconfig_pattern.py
@@ -13,9 +13,7 @@
 import re
 
 from pyparsing import (
-    Group, Optional, ParseException, Regex, StringEnd, Suppress, ZeroOrMore)
-
-from matplotlib import _api
+    Optional, ParseException, Regex, StringEnd, Suppress, ZeroOrMore, oneOf)
 
 
 _family_punc = r'\\\-:,'
@@ -63,8 +61,7 @@ def comma_separated(elem):
     size = Regex(r"([0-9]+\.?[0-9]*|\.[0-9]+)")
     name = Regex(r"[a-z]+")
     value = Regex(fr"([^{_value_punc}]|(\\[{_value_punc}]))*")
-    # replace trailing `| name` by oneOf(_CONSTANTS) in mpl 3.9.
-    prop = Group((name + Suppress("=") + comma_separated(value)) | name)
+    prop = (name + Suppress("=") + comma_separated(value)) | oneOf(_CONSTANTS)
     return (
         Optional(comma_separated(family)("families"))
         + Optional("-" + comma_separated(size)("sizes"))
@@ -97,12 +94,6 @@ def parse_fontconfig_pattern(pattern):
         props["size"] = [*parse["sizes"]]
     for prop in parse.get("properties", []):
         if len(prop) == 1:
-            if prop[0] not in _CONSTANTS:
-                _api.warn_deprecated(
-                    "3.7", message=f"Support for unknown constants "
-                    f"({prop[0]!r}) is deprecated since %(since)s and "
-                    f"will be removed %(removal)s.")
-                continue
             prop = _CONSTANTS[prop[0]]
         k, *v = prop
         props.setdefault(k, []).extend(map(_value_unescape, v))
diff --git a/lib/matplotlib/tests/test_fontconfig_pattern.py b/lib/matplotlib/tests/test_fontconfig_pattern.py
index 792a8ed517c2..496a35b95cf2 100644
--- a/lib/matplotlib/tests/test_fontconfig_pattern.py
+++ b/lib/matplotlib/tests/test_fontconfig_pattern.py
@@ -73,5 +73,5 @@ def test_fontconfig_str():
 
 
 def test_fontconfig_unknown_constant():
-    with pytest.warns(DeprecationWarning):
+    with pytest.raises(ValueError, match="ParseException"):
         FontProperties(":unknown")