8281560: Matcher.hitEnd returns unexpected results in presence of CANON_EQ flag.

Reviewed-by: rriggs, lancea

src/java.base/share/classes/java/util/regex/Pattern.java

@@ -4005,8 +4005,9 @@ loop:   for(int x=0, offset=0; x<nCodePoints; x++, offset+=len) {
                 }
                 if (j < matcher.to)
                     return false;
-            }
+            } else {
                 matcher.hitEnd = true;
+            }
             return false;
         }
 

test/jdk/java/util/regex/RegExTest.java

@@ -4557,12 +4557,36 @@ public class RegExTest {
         assertTrue(e.getMessage().contains("Bad intersection syntax"));
     }
 
+    //This test is for 8281560
+    @Test
+    public static void prematureHitEndInNFCCharProperty() {
+        var testInput = "a1a1";
+        var pat1 = "(a+|1+)";
+        var pat2 = "([a]+|[1]+)";
+
+        var matcher1 = Pattern.compile(pat1, Pattern.CANON_EQ).matcher(testInput);
+        var matcher2 = Pattern.compile(pat2, Pattern.CANON_EQ).matcher(testInput);
+
+        ArrayList<Boolean> results1 = new ArrayList<>();
+        ArrayList<Boolean> results2 = new ArrayList<>();
+
+        while (matcher1.find()) {
+            results1.add(matcher1.hitEnd());
+        }
+
+        while (matcher2.find()) {
+            results2.add(matcher2.hitEnd());
+        }
+
+        assertEquals(results1, results2);
+    }
+
     //This test is for 8281315
     @Test
     public static void iOOBForCIBackrefs(){
         String line = "\ud83d\udc95\ud83d\udc95\ud83d\udc95";
         var pattern2 = Pattern.compile("(?i)(.)\\1{2,}");
         assertTrue(pattern2.matcher(line).find());
+    }
+}
 
-    }
-}