8312415: Expand -Xlint:serial checks to enum constants with specialized class bodies

Reviewed-by: jjg, jlahoda

Author: jddarcy

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

@@ -5213,6 +5213,17 @@ public Void visitTypeAsEnum(TypeElement e,
                             }
                         }
                     }
+
+                    // Also perform checks on any class bodies of enum constants, see JLS 8.9.1.
+                    case ENUM_CONSTANT -> {
+                        var field = (VarSymbol)enclosed;
+                        JCVariableDecl decl = (JCVariableDecl) TreeInfo.declarationFor(field, p);
+                        if (decl.init instanceof JCNewClass nc && nc.def != null) {
+                            ClassSymbol enumConstantType = nc.def.sym;
+                            visitTypeAsEnum(enumConstantType, p);
+                        }
+                    }
+
                     }});
             }
             return null;

test/langtools/tools/javac/warnings/Serial/ClassBody.out

@@ -0,0 +1,18 @@
+EnumExternClassBody.java:25:25: compiler.warn.ineffectual.extern.method.enum: readExternal
+EnumExternClassBody.java:30:25: compiler.warn.ineffectual.extern.method.enum: writeExternal
+EnumExternClassBody.java:35:38: compiler.warn.ineffectual.serial.field.enum: serialVersionUID
+EnumExternClassBody.java:36:53: compiler.warn.ineffectual.serial.field.enum: serialPersistentFields
+EnumExternClassBody.java:38:25: compiler.warn.ineffectual.serial.method.enum: writeObject
+EnumExternClassBody.java:42:27: compiler.warn.ineffectual.serial.method.enum: writeReplace
+EnumExternClassBody.java:46:25: compiler.warn.ineffectual.serial.method.enum: readObject
+EnumExternClassBody.java:51:25: compiler.warn.ineffectual.serial.method.enum: readObjectNoData
+EnumExternClassBody.java:55:27: compiler.warn.ineffectual.serial.method.enum: readResolve
+EnumExternClassBody.java:66:21: compiler.warn.ineffectual.extern.method.enum: readExternal
+EnumExternClassBody.java:71:21: compiler.warn.ineffectual.extern.method.enum: writeExternal
+EnumExternClassBody.java:83:25: compiler.warn.ineffectual.extern.method.enum: readExternal
+EnumExternClassBody.java:88:25: compiler.warn.ineffectual.extern.method.enum: writeExternal
+EnumExternClassBody.java:101:25: compiler.warn.ineffectual.extern.method.enum: readExternal
+EnumExternClassBody.java:106:25: compiler.warn.ineffectual.extern.method.enum: writeExternal
+EnumExternClassBody.java:112:30: compiler.warn.ineffectual.extern.method.enum: readExternal
+EnumExternClassBody.java:113:30: compiler.warn.ineffectual.extern.method.enum: writeExternal
+17 warnings

test/langtools/tools/javac/warnings/Serial/EnumExternClassBody.java

@@ -0,0 +1,115 @@
+/*
+ * @test /nodynamiccopyright/
+ * @bug 8312415
+ * @compile/ref=ClassBody.out -XDrawDiagnostics -Xlint:serial EnumExternClassBody.java
+ * @compile/ref=empty.out     -XDrawDiagnostics               EnumExternClassBody.java
+ */
+
+import java.io.*;
+
+/*
+ * Verify warnings are generated as appropriate for enum constants
+ * with specialized class bodies.
+ */
+class EnumExternClassBody {
+
+    /*
+     * Define externalization methods both in the enum class and a
+     * specialized enum constant.
+     */
+    private static enum ColorExtern1 implements Externalizable {
+        RED(  0xFF_00_00),
+        GREEN(0x00_FF_00),
+        BLUE( 0x00_00_FF) {
+           @Override
+            public void readExternal(ObjectInput in) {
+                throw new RuntimeException();
+            }
+
+           @Override
+            public void writeExternal(ObjectOutput out) throws IOException {
+                throw new RuntimeException();
+            }
+
+           // Look for serialization members too
+           private static final long serialVersionUID = 42;
+           private static final ObjectStreamField[] serialPersistentFields = {};
+
+           private void writeObject(ObjectOutputStream stream) throws IOException {
+                throw new RuntimeException();
+           }
+
+           private Object writeReplace() throws ObjectStreamException {
+               return null;
+           }
+
+           private void readObject(ObjectInputStream stream)
+               throws IOException, ClassNotFoundException {
+                throw new RuntimeException();
+           }
+
+           private void readObjectNoData() throws ObjectStreamException {
+               return;
+           }
+
+           private Object readResolve() throws ObjectStreamException {
+               return null;
+           }
+        };
+
+        int rgb;
+        private ColorExtern1(int rgb) {
+            this.rgb = rgb;
+        }
+
+        @Override
+        public void readExternal(ObjectInput in) {
+            throw new RuntimeException();
+        }
+
+        @Override
+        public void writeExternal(ObjectOutput out) throws IOException {
+            throw new RuntimeException();
+        }
+    }
+
+    /*
+     * Define externalization methods only on specialized enum
+     * constants.
+     */
+    private static enum ColorExtern2 implements Externalizable {
+        CYAN {
+           @Override
+            public void readExternal(ObjectInput in) {
+                throw new RuntimeException();
+            }
+
+           @Override
+            public void writeExternal(ObjectOutput out) throws IOException {
+                throw new RuntimeException();
+            }
+        };
+    }
+
+    /*
+     * Define externalization methods only on specialized enum
+     * constants.
+     */
+    private static enum ColorExtern3 implements Externalizable {
+        MAGENTA {
+           @Override
+            public void readExternal(ObjectInput in) {
+                throw new RuntimeException();
+            }
+
+           @Override
+            public void writeExternal(ObjectOutput out) throws IOException {
+                throw new RuntimeException();
+            }
+        };
+
+        // Acceptable to have ineffectual warnings for these abstract methods
+        public abstract void readExternal(ObjectInput in);
+        public abstract void writeExternal(ObjectOutput out) throws IOException ;
+    }
+}