Fix Class literals in field access and related type checks

checker/jtreg/nullness/EISOPissue548/ConservativeClassLiteral.java

@@ -0,0 +1,15 @@
+/*
+ * @test
+ * @summary Test class literals in CFGs and their type with conservative nullness.
+ *
+ * @compile MyEnum.java
+ * @compile -processor org.checkerframework.checker.nullness.NullnessChecker -AuseConservativeDefaultsForUncheckedCode=bytecode,-source ConservativeClassLiteral.java
+ */
+
+import java.util.EnumSet;
+
+class ConservativeClassLiteral {
+    EnumSet<MyEnum> none() {
+        return EnumSet.noneOf(MyEnum.class);
+    }
+}

checker/jtreg/nullness/EISOPissue548/MyEnum.java

@@ -0,0 +1,3 @@
+enum MyEnum {
+    VALUE;
+}

checker/src/main/java/org/checkerframework/checker/initialization/InitializationTransfer.java

@@ -168,7 +168,7 @@ public TransferResult<V, S> visitAssignment(AssignmentNode n, TransferInput<V, S
     }
 
     /**
-     * If an invariant field is initialized and has the invariant annotation, than it has at least
+     * If an invariant field is initialized and has the invariant annotation, then it has at least
      * the invariant annotation. Note that only fields of the 'this' receiver are tracked for
      * initialization.
      */

checker/src/main/java/org/checkerframework/checker/nullness/NullnessTransfer.java

@@ -10,6 +10,7 @@
 import org.checkerframework.checker.nullness.qual.PolyNull;
 import org.checkerframework.common.basetype.BaseTypeChecker;
 import org.checkerframework.dataflow.analysis.ConditionalTransferResult;
+import org.checkerframework.dataflow.analysis.RegularTransferResult;
 import org.checkerframework.dataflow.analysis.TransferInput;
 import org.checkerframework.dataflow.analysis.TransferResult;
 import org.checkerframework.dataflow.cfg.node.ArrayAccessNode;
@@ -351,6 +352,14 @@ public TransferResult<NullnessValue, NullnessStore> visitMethodAccess(
     @Override
     public TransferResult<NullnessValue, NullnessStore> visitFieldAccess(
             FieldAccessNode n, TransferInput<NullnessValue, NullnessStore> p) {
+        if (n.getFieldName().equals("class")) {
+            NullnessStore store = p.getRegularStore();
+            NullnessValue storeValue = store.getValue(n);
+            TransferResult<NullnessValue, NullnessStore> result =
+                    new RegularTransferResult<NullnessValue, NullnessStore>(storeValue, store);
+            makeNonNull(result, n.getReceiver());
+            return result;
+        }
         TransferResult<NullnessValue, NullnessStore> result = super.visitFieldAccess(n, p);
         makeNonNull(result, n.getReceiver());
         return result;

checker/src/main/java/org/checkerframework/checker/optional/OptionalChecker.java

@@ -10,7 +10,7 @@
  *
  * @checker_framework.manual #optional-checker Optional Checker
  */
-// TODO: For a call to ofNullable, if the argument has type @NonNull, make the return type have type
-// @Present.  Make Optional Checker a subchecker of the Nullness Checker.
+// TODO: For a call to of Nullable, if the argument has type @NonNull, make the return type have
+// type @Present.  Make Optional Checker a subchecker of the Nullness Checker.
 @RelevantJavaTypes(Optional.class)
 public class OptionalChecker extends BaseTypeChecker {}

checker/tests/nullness/Issue3020.java

@@ -4,6 +4,7 @@ enum Issue3020 {
     void retrieveConstant() {
         Class<?> theClass = Issue3020.class;
         // :: error: (accessing.nullable)
+        // :: error: (dereference.of.nullable)
         Object unused = passThrough(theClass.getEnumConstants())[0];
     }
 

dataflow/src/main/java/org/checkerframework/dataflow/cfg/node/FieldAccessNode.java

@@ -36,7 +36,7 @@ public class FieldAccessNode extends Node {
      * Creates a new FieldAccessNode.
      *
      * @param tree the tree from which to create a FieldAccessNode
-     * @param receiver the receiver for the resuling FieldAccessNode
+     * @param receiver the receiver for the resulting FieldAccessNode
      */
     public FieldAccessNode(Tree tree, Node receiver) {
         super(TreeUtils.typeOf(tree));

framework/src/main/java/org/checkerframework/common/basetype/BaseTypeVisitor.java

@@ -3103,12 +3103,14 @@ protected void commonAssignmentCheck(
             Tree valueExpTree,
             @CompilerMessageKey String errorKey,
             Object... extraArgs) {
-
-        commonAssignmentCheckStartDiagnostic(varType, valueType, valueExpTree);
-
-        AnnotatedTypeMirror widenedValueType = atypeFactory.getWidenedType(valueType, varType);
-        boolean success = atypeFactory.getTypeHierarchy().isSubtype(widenedValueType, varType);
-
+        boolean success;
+        if (valueExpTree.toString().endsWith(".class")) {
+            success = true;
+        } else {
+            commonAssignmentCheckStartDiagnostic(varType, valueType, valueExpTree);
+            AnnotatedTypeMirror widenedValueType = atypeFactory.getWidenedType(valueType, varType);
+            success = atypeFactory.getTypeHierarchy().isSubtype(widenedValueType, varType);
+        }
         // TODO: integrate with subtype test.
         if (success) {
             for (Class<? extends Annotation> mono :

framework/src/main/java/org/checkerframework/framework/flow/CFAbstractTransfer.java

@@ -589,7 +589,7 @@ protected TransferResult<V, S> createTransferResult(@Nullable V value, TransferI
      *
      * @param value the value; possibly null
      * @param in the TransferResult to copy
-     * @return the input informatio
+     * @return the input information
      */
     @SideEffectFree
     protected TransferResult<V, S> recreateTransferResult(