From b23358fcfab57a5e68f88fe79c5a8abdfb3643e4 Mon Sep 17 00:00:00 2001
From: "Aryan Singh K." <70511529+aryansk@users.noreply.github.com>
Date: Sun, 9 Aug 2026 02:09:34 +0530
Subject: [PATCH] Fix lexical normalization assertion for parent traversal

---
 Sources/System/FilePath/FilePathParsing.swift            | 2 +-
 Tests/SystemTests/FilePathTests/FilePathSyntaxTest.swift | 7 +++++++
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/Sources/System/FilePath/FilePathParsing.swift b/Sources/System/FilePath/FilePathParsing.swift
index f372dd67e..efff34922 100644
--- a/Sources/System/FilePath/FilePathParsing.swift
+++ b/Sources/System/FilePath/FilePathParsing.swift
@@ -168,7 +168,7 @@ extension FilePath {
             readIdx = nextStart
             continue
           }
-          assert(self.root == nil && self.components.first!.kind == .parentDirectory)
+          assert(!hasRoot && _isParentDirectory(priorComponent))
         }
       }
 
diff --git a/Tests/SystemTests/FilePathTests/FilePathSyntaxTest.swift b/Tests/SystemTests/FilePathTests/FilePathSyntaxTest.swift
index 0fdfbc279..9df2019ec 100644
--- a/Tests/SystemTests/FilePathTests/FilePathSyntaxTest.swift
+++ b/Tests/SystemTests/FilePathTests/FilePathSyntaxTest.swift
@@ -436,6 +436,13 @@ final class FilePathSyntaxTest: XCTestCase {
         lexicallyNormalized: ".."
       ),
 
+      .unix(
+        "foo/../../../bar",
+        dirname: "foo/../../..", basename: "bar",
+        components: ["foo", "..", "..", "..", "bar"],
+        lexicallyNormalized: "../../bar"
+      ),
+
       .unix(
         "a/.././.././../b",
         dirname: "a/.././.././..", basename: "b",