8191963: Path.equals() and File.equals() return true for two different files on Windows

src/java.base/windows/classes/java/io/WinNTFileSystem.java

@@ -635,7 +635,23 @@ public int getNameMax(String path) {
 
     @Override
     public int compare(File f1, File f2) {
-        return f1.getPath().compareToIgnoreCase(f2.getPath());
+        String s1 = f1.getPath();
+        String s2 = f2.getPath();
+        int n1 = s1.length();
+        int n2 = s2.length();
+        int min = Math.min(n1, n2);
+        for (int i = 0; i < min; i++) {
+            char c1 = s1.charAt(i);
+            char c2 = s2.charAt(i);
+             if (c1 != c2) {
+                 c1 = Character.toUpperCase(c1);
+                 c2 = Character.toUpperCase(c2);
+                 if (c1 != c2) {
+                     return c1 - c2;
+                 }
+             }
+        }
+        return n1 - n2;
     }
 
     @Override

test/jdk/java/io/File/CompareTo.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1998, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1998, 2025, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -22,12 +22,15 @@
  */
 
 /* @test
-   @bug 4131169
-   @summary Test respecified compareTo method
+ * @bug 4131169 8191963
+ * @summary Test compareTo and equals methods
+ * @library .. /test/lib
+ * @build jdk.test.lib.Platform
+ * @run main CompareTo
  */
 
-import java.io.*;
-
+import java.io.File;
+import jdk.test.lib.Platform;
 
 public class CompareTo {
 
@@ -36,6 +39,19 @@ private static void testWin32() throws Exception {
         File f2 = new File("B");
         if (!(f1.compareTo(f2) < 0))
             throw new Exception("compareTo incorrect");
+
+        // U+0131 = ı 'LATIN SMALL LETTER DOTLESS I'
+        File smallDotlessI = new File("\u0131");
+        // U+0130 = İ 'LATIN CAPITAL LETTER I WITH DOT ABOVE'
+        File largeDotfullI = new File("\u0130");
+        File latinCapitalI = new File("I");
+
+        boolean shouldBeEqual= smallDotlessI.equals(latinCapitalI);
+        if (!shouldBeEqual)
+            throw new Exception("Small dotless \"i\" does not equal \"I\"");
+        boolean shouldNotBeEqual = largeDotfullI.equals(latinCapitalI);
+        if (shouldNotBeEqual)
+            throw new Exception("Large dotted \"I\" equals \"I\"");
     }
 
     private static void testUnix() throws Exception {
@@ -46,8 +62,10 @@ private static void testUnix() throws Exception {
     }
 
     public static void main(String[] args) throws Exception {
-        if (File.separatorChar == '\\') testWin32();
-        if (File.separatorChar == '/') testUnix();
+        if (Platform.isWindows())
+            testWin32();
+        else
+            testUnix();
     }
 
 }