From c7f7ca4ed1ae03d89510324ee4f845efebf64c6f Mon Sep 17 00:00:00 2001
From: Stephen Toub <stoub@microsoft.com>
Date: Mon, 2 Feb 2026 12:44:27 -0500
Subject: [PATCH] Use Contains in FileSystemName.MatchPattern

---
 .../src/System/IO/Enumeration/FileSystemName.cs | 17 +++++------------
 1 file changed, 5 insertions(+), 12 deletions(-)

diff --git a/src/libraries/System.Private.CoreLib/src/System/IO/Enumeration/FileSystemName.cs b/src/libraries/System.Private.CoreLib/src/System/IO/Enumeration/FileSystemName.cs
index cc742422ab458c..c6641d75fbeb18 100644
--- a/src/libraries/System.Private.CoreLib/src/System/IO/Enumeration/FileSystemName.cs
+++ b/src/libraries/System.Private.CoreLib/src/System/IO/Enumeration/FileSystemName.cs
@@ -274,18 +274,11 @@ private static bool MatchPattern(ReadOnlySpan<char> expression, ReadOnlySpan<cha
                             // If we are at a period, determine if we are allowed to
                             // consume it, i.e. make sure it is not the last one.
 
-                            bool notLastPeriod = false;
-                            if (!nameFinished && nameChar == '.')
-                            {
-                                for (int offset = nameOffset; offset < name.Length; offset++)
-                                {
-                                    if (name[offset] == '.')
-                                    {
-                                        notLastPeriod = true;
-                                        break;
-                                    }
-                                }
-                            }
+                            // Check if there's another period after this one (not the last period)
+                            bool notLastPeriod =
+                                !nameFinished &&
+                                nameChar == '.' &&
+                                name.Slice(nameOffset).Contains('.');
 
                             if (nameFinished || nameChar != '.' || notLastPeriod)
                             {