8309515: Stale cached data from Matcher.namedGroups() after Matcher.usePattern()

Reviewed-by: rriggs

Author: rgiulietti

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

@@ -390,6 +390,7 @@ public Matcher usePattern(Pattern newPattern) {
         if (newPattern == null)
             throw new IllegalArgumentException("Pattern cannot be null");
         parentPattern = newPattern;
+        namedGroups = null;
 
         // Reallocate state storage
         int parentGroupCount = Math.max(newPattern.capturingGroupCount, 10);

test/jdk/java/util/regex/NamedGroupsTests.java

@@ -23,7 +23,7 @@
 
 /*
  * @test
- * @bug 8065554
+ * @bug 8065554 8309515
  * @run main NamedGroupsTests
  */
 
@@ -86,6 +86,8 @@ public static void main(String[] args) {
 
         testMatchResultStartEndGroupBeforeMatchOp();
         testMatchResultStartEndGroupAfterMatchOp();
+
+        testMatchAfterUsePattern();
     }
 
     private static void testMatchResultNoDefault() {
@@ -346,4 +348,24 @@ private static void testPatternNamedGroupsTwoNamedGroups() {
         }
     }
 
+    private static void testMatchAfterUsePattern() {
+        Pattern p1 = Pattern.compile("(?<a>...)(?<b>...)");
+        Matcher m = p1.matcher("foobar");
+        if (!m.matches()) {
+            throw new RuntimeException("matches() expected");
+        }
+        if (!m.group("a").equals("foo")) {
+            throw new RuntimeException("\"foo\" expected for group(\"a\")");
+        }
+
+        Pattern p2 = Pattern.compile("(?<b>...)(?<a>...)");
+        m.usePattern(p2);
+        if (!m.matches()) {
+            throw new RuntimeException("matches() expected");
+        }
+        if (!m.group("a").equals("bar")) {
+            throw new RuntimeException("\"bar\" expected for group(\"a\")");
+        }
+    }
+
 }