8312163: Crash in dominance check when compiling unnamed patterns

Reviewed-by: jlahoda
Backport-of: 1fc726a

Author: biboudis

src/jdk.compiler/share/classes/com/sun/tools/javac/comp/Check.java

@@ -4733,10 +4733,13 @@ private boolean patternDominated(JCPattern existingPattern, JCPattern currentPat
                     return false;
                 }
             }
-            if (currentPattern instanceof JCBindingPattern) {
-                return existingPattern instanceof JCBindingPattern;
+            if (currentPattern instanceof JCBindingPattern ||
+                currentPattern instanceof JCAnyPattern) {
+                return existingPattern instanceof JCBindingPattern ||
+                       existingPattern instanceof JCAnyPattern;
             } else if (currentPattern instanceof JCRecordPattern currentRecordPattern) {
-                if (existingPattern instanceof JCBindingPattern) {
+                if (existingPattern instanceof JCBindingPattern ||
+                    existingPattern instanceof JCAnyPattern) {
                     return true;
                 } else if (existingPattern instanceof JCRecordPattern existingRecordPattern) {
                     List<JCPattern> existingNested = existingRecordPattern.nested;

src/jdk.compiler/share/classes/com/sun/tools/javac/parser/JavacParser.java

@@ -879,6 +879,7 @@ public JCPattern parsePattern(int pos, JCModifiers mods, JCExpression parsedType
         JCExpression e;
         if (token.kind == UNDERSCORE && parsedType == null) {
             nextToken();
+            checkSourceLevel(Feature.UNNAMED_VARIABLES);
             pattern = toP(F.at(token.pos).AnyPattern());
         }
         else {

test/langtools/tools/javac/T8312163.java

@@ -0,0 +1,57 @@
+/*
+ * @test /nodynamiccopyright/
+ * @bug 8312163
+ * @summary Crash in dominance check when compiling unnamed patterns
+ * @enablePreview
+ * @compile/fail/ref=T8312163.out -XDrawDiagnostics T8312163.java
+ */
+public class T8312163 {
+    sealed interface A permits B {}
+    record B() implements A {}
+
+    record Rec(A a, A b) {}
+
+    public void test(Rec r)
+    {
+        switch (r) {
+            case Rec(_, _): break;
+            case Rec(_, B()):   // dominated
+        }
+
+        switch (r) {
+            case Rec(_, B()): break;
+            case Rec(_, _):
+        }
+
+        switch (r) {
+            case Rec(_, _): break;
+            case Rec(_, A a):   // dominated
+        }
+
+        switch (r) {
+            case Rec(_, A a): break;
+            case Rec(_, _): // dominated
+        }
+
+        // duplicated unnamed patterns with unnamed pattern variables for reference
+        switch (r) {
+            case Rec(var _, var _): break;
+            case Rec(var _, B()):   // dominated
+        }
+
+        switch (r) {
+            case Rec(var _, B()): break;
+            case Rec(var _, var _):
+        }
+
+        switch (r) {
+            case Rec(var _, var _): break;
+            case Rec(var _, A a):   // dominated
+        }
+
+        switch (r) {
+            case Rec(var _, A a): break;
+            case Rec(var _, var _): // dominated
+        }
+    }
+}

test/langtools/tools/javac/T8312163.out

@@ -0,0 +1,9 @@
+T8312163.java:18:18: compiler.err.pattern.dominated
+T8312163.java:28:18: compiler.err.pattern.dominated
+T8312163.java:33:18: compiler.err.pattern.dominated
+T8312163.java:39:18: compiler.err.pattern.dominated
+T8312163.java:49:18: compiler.err.pattern.dominated
+T8312163.java:54:18: compiler.err.pattern.dominated
+- compiler.note.preview.filename: T8312163.java, DEFAULT
+- compiler.note.preview.recompile
+6 errors