8343286: Missing unchecked cast warning in polymorphic method call

Reviewed-by: mcimadamore

Author: Vicente Romero

src/java.base/share/classes/java/util/concurrent/atomic/AtomicReference.java

@@ -279,6 +279,7 @@ public String toString() {
      * @return the value
      * @since 9
      */
+    @SuppressWarnings("unchecked")
     public final V getPlain() {
         return (V)VALUE.get(this);
     }
@@ -302,6 +303,7 @@ public final void setPlain(V newValue) {
      * @return the value
      * @since 9
      */
+    @SuppressWarnings("unchecked")
     public final V getOpaque() {
         return (V)VALUE.getOpaque(this);
     }
@@ -324,6 +326,7 @@ public final void setOpaque(V newValue) {
      * @return the value
      * @since 9
      */
+    @SuppressWarnings("unchecked")
     public final V getAcquire() {
         return (V)VALUE.getAcquire(this);
     }
@@ -351,6 +354,7 @@ public final void setRelease(V newValue) {
      * expected value if successful
      * @since 9
      */
+    @SuppressWarnings("unchecked")
     public final V compareAndExchange(V expectedValue, V newValue) {
         return (V)VALUE.compareAndExchange(this, expectedValue, newValue);
     }
@@ -367,6 +371,7 @@ public final V compareAndExchange(V expectedValue, V newValue) {
      * expected value if successful
      * @since 9
      */
+    @SuppressWarnings("unchecked")
     public final V compareAndExchangeAcquire(V expectedValue, V newValue) {
         return (V)VALUE.compareAndExchangeAcquire(this, expectedValue, newValue);
     }
@@ -383,6 +388,7 @@ public final V compareAndExchangeAcquire(V expectedValue, V newValue) {
      * expected value if successful
      * @since 9
      */
+    @SuppressWarnings("unchecked")
     public final V compareAndExchangeRelease(V expectedValue, V newValue) {
         return (V)VALUE.compareAndExchangeRelease(this, expectedValue, newValue);
     }

src/java.base/share/classes/java/util/concurrent/atomic/AtomicReferenceArray.java

@@ -358,6 +358,7 @@ private void readObject(java.io.ObjectInputStream s)
      * @return the value
      * @since 9
      */
+    @SuppressWarnings("unchecked")
     public final E getPlain(int i) {
         return (E)AA.get(array, i);
     }
@@ -383,6 +384,7 @@ public final void setPlain(int i, E newValue) {
      * @return the value
      * @since 9
      */
+    @SuppressWarnings("unchecked")
     public final E getOpaque(int i) {
         return (E)AA.getOpaque(array, i);
     }
@@ -407,6 +409,7 @@ public final void setOpaque(int i, E newValue) {
      * @return the value
      * @since 9
      */
+    @SuppressWarnings("unchecked")
     public final E getAcquire(int i) {
         return (E)AA.getAcquire(array, i);
     }
@@ -437,6 +440,7 @@ public final void setRelease(int i, E newValue) {
      * expected value if successful
      * @since 9
      */
+    @SuppressWarnings("unchecked")
     public final E compareAndExchange(int i, E expectedValue, E newValue) {
         return (E)AA.compareAndExchange(array, i, expectedValue, newValue);
     }
@@ -455,6 +459,7 @@ public final E compareAndExchange(int i, E expectedValue, E newValue) {
      * expected value if successful
      * @since 9
      */
+    @SuppressWarnings("unchecked")
     public final E compareAndExchangeAcquire(int i, E expectedValue, E newValue) {
         return (E)AA.compareAndExchangeAcquire(array, i, expectedValue, newValue);
     }
@@ -473,6 +478,7 @@ public final E compareAndExchangeAcquire(int i, E expectedValue, E newValue) {
      * expected value if successful
      * @since 9
      */
+    @SuppressWarnings("unchecked")
     public final E compareAndExchangeRelease(int i, E expectedValue, E newValue) {
         return (E)AA.compareAndExchangeRelease(array, i, expectedValue, newValue);
     }

src/java.base/share/classes/java/util/stream/ForEachOps.java

@@ -505,6 +505,7 @@ else if (spliterator != null) {
             // "happens-before" completion of the associated left-most leaf task
             // of right subtree (if any, which can be this task's right sibling)
             //
+            @SuppressWarnings("unchecked")
             var leftDescendant = (ForEachOrderedTask<S, T>)NEXT.getAndSet(this, null);
             if (leftDescendant != null)
                 leftDescendant.tryComplete();

src/jdk.compiler/share/classes/com/sun/tools/javac/code/Source.java

@@ -263,6 +263,7 @@ public enum Feature {
         FLEXIBLE_CONSTRUCTORS(JDK22, Fragments.FeatureFlexibleConstructors, DiagKind.NORMAL),
         MODULE_IMPORTS(JDK23, Fragments.FeatureModuleImports, DiagKind.PLURAL),
         PRIVATE_MEMBERS_IN_PERMITS_CLAUSE(JDK19),
+        ERASE_POLY_SIG_RETURN_TYPE(JDK24),
         ;
 
         enum DiagKind {

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

@@ -100,6 +100,8 @@ public class Infer {
 
     private final boolean dumpStacktraceOnError;
 
+    private final boolean erasePolySigReturnType;
+
     public static Infer instance(Context context) {
         Infer instance = context.get(inferKey);
         if (instance == null)
@@ -123,6 +125,8 @@ protected Infer(Context context) {
 
         emptyContext = new InferenceContext(this, List.nil());
         dumpStacktraceOnError = options.isSet("dev") || options.isSet(DOE);
+        Source source = Source.instance(context);
+        erasePolySigReturnType = Source.Feature.ERASE_POLY_SIG_RETURN_TYPE.allowedInSource(source);
     }
 
     /** A value for prototypes that admit any type, including polymorphic ones. */
@@ -544,8 +548,8 @@ Type instantiatePolymorphicSignatureInstance(Env<AttrContext> env,
             case TYPECAST:
                 JCTypeCast castTree = (JCTypeCast)env.next.tree;
                 restype = (TreeInfo.skipParens(castTree.expr) == env.tree) ?
-                          castTree.clazz.type :
-                          spType;
+                              (erasePolySigReturnType ? types.erasure(castTree.clazz.type) : castTree.clazz.type) :
+                              spType;
                 break;
             case EXEC:
                 JCTree.JCExpressionStatement execTree =

src/jdk.dynalink/share/classes/jdk/dynalink/BiClassValue.java

@@ -113,6 +113,7 @@ T getReverseValue(final Class<?> c) {
         }
 
         private T compute(final VarHandle mapHandle, final Class<?> c, final Function<Class<?>, T> compute) {
+            @SuppressWarnings("unchecked")
             Map<Class<?>, T> map = (Map<Class<?>, T>) mapHandle.getVolatile(this);
             T value;
             T newValue = null;
@@ -127,6 +128,7 @@ private T compute(final VarHandle mapHandle, final Class<?> c, final Function<Cl
                 final Map.Entry<Class<?>, T>[] entries = map.entrySet().toArray(new Map.Entry[map.size() + 1]);
                 entries[map.size()] = Map.entry(c, newValue);
                 final var newMap = Map.ofEntries(entries);
+                @SuppressWarnings("unchecked")
                 final var witness = (Map<Class<?>, T>) mapHandle.compareAndExchange(this, map, newMap);
                 if (witness == map) {
                     value = newValue;

test/langtools/tools/javac/mandatoryWarnings/unchecked/PolymorphicMethodTest.java

@@ -0,0 +1,12 @@
+/*
+ * /nodynamiccopyright/
+ */
+
+import java.lang.invoke.VarHandle;
+
+class PolymorphicMethodTest<V> {
+    VarHandle vh;
+    V method(Object obj) {
+        return (V)vh.getAndSet(this, obj);
+    }
+}

test/langtools/tools/javac/mandatoryWarnings/unchecked/PolymorphicMethodTest.out

@@ -0,0 +1,2 @@
+PolymorphicMethodTest.java:10:31: compiler.warn.prob.found.req: (compiler.misc.unchecked.cast.to.type), java.lang.Object, V
+1 warning

test/langtools/tools/javac/mandatoryWarnings/unchecked/PolymorphicMethodTest_Source23.out

@@ -0,0 +1,2 @@
+- compiler.warn.source.no.system.modules.path: 23, (compiler.misc.source.no.system.modules.path: 23)
+1 warning

test/langtools/tools/javac/mandatoryWarnings/unchecked/Test.java

@@ -42,4 +42,6 @@
  * @compile/ref=Test4b.out -XDrawDiagnostics -nowarn -Xlint:unchecked -Xmaxwarns 1 A.java B.java
  * @compile/ref=Test4c.out -XDrawDiagnostics -nowarn -Xlint:unchecked -Xmaxwarns 2 A.java B.java
  * @compile/ref=Test4d.out -XDrawDiagnostics -nowarn -Xlint:unchecked -Xmaxwarns 3 A.java B.java
+ * @compile/ref=PolymorphicMethodTest.out -XDrawDiagnostics -Xlint:unchecked PolymorphicMethodTest.java
+ * @compile/ref=PolymorphicMethodTest_Source23.out -XDrawDiagnostics -Xlint:unchecked -source 23 PolymorphicMethodTest.java
  */