8230829: Matcher matches a surrogate pair that crosses border of the region

Reviewed-by: naoto

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

@@ -3931,12 +3931,14 @@ loop:   for(int x=0, offset=0; x<nCodePoints; x++, offset+=len) {
         boolean match(Matcher matcher, int i, CharSequence seq) {
             if (i < matcher.to) {
                 int ch = Character.codePointAt(seq, i);
-                return predicate.is(ch) &&
+                i += Character.charCount(ch);
-                       next.match(matcher, i + Character.charCount(ch), seq);
+                if (i <= matcher.to) {
-            } else {
+                    return predicate.is(ch) &&
-                matcher.hitEnd = true;
+                           next.match(matcher, i, seq);
-                return false;
+                }
             }
+            matcher.hitEnd = true;
+            return false;
         }
         boolean study(TreeInfo info) {
             info.minLength++;

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

@@ -35,7 +35,7 @@
  * 8027645 8035076 8039124 8035975 8074678 6854417 8143854 8147531 7071819
  * 8151481 4867170 7080302 6728861 6995635 6736245 4916384 6328855 6192895
  * 6345469 6988218 6693451 7006761 8140212 8143282 8158482 8176029 8184706
- * 8194667 8197462 8184692 8221431 8224789 8228352
+ * 8194667 8197462 8184692 8221431 8224789 8228352 8230829
  *
  * @library /test/lib
  * @library /lib/testlibrary/java/lang
@@ -1070,6 +1070,22 @@ public class RegExTest {
         matcher.useAnchoringBounds(false);
         if (matcher.find())
            failCount++;
+
+        // JDK-8230829
+        pattern = Pattern.compile("\\ud800\\udc61");
+        matcher = pattern.matcher("\ud800\udc61");
+        matcher.region(0, 1);
+        if (matcher.find()) {
+            failCount++;
+            System.out.println("Matched a surrogate pair" +
+                    " that crosses border of region");
+        }
+        if (!matcher.hitEnd()) {
+            failCount++;
+            System.out.println("Expected to hit the end when" +
+                    " matching a surrogate pair crossing region");
+        }
+
         report("Regions");
     }