copying: fold in graph copying (shared nodes, cycles, identity-map fix), serialization rules (constructors, record canonical constructor, ObjectInputFilter), record array components, clone() as a defensive copy, two more compile-error exhibits; 24 tests

Co-Authored-By: Claude Sonnet 5.5 <[email protected]>
Claude-Session: https://claude.ai/code/session_017ic4b4BL3cEPHQTk2McE7C

copying/output/09-tests.txt

@@ -1,3 +1,4 @@
-[INFO] Tests run: 17, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.145 s -- in com.ankurm.copying.CopyingTest
-[INFO] Tests run: 17, Failures: 0, Errors: 0, Skipped: 0
+[INFO] Tests run: 17, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.150 s -- in com.ankurm.copying.CopyingTest
+[INFO] Tests run: 7, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.053 s -- in com.ankurm.copying.CopyingExtrasTest
+[INFO] Tests run: 24, Failures: 0, Errors: 0, Skipped: 0
 [INFO] BUILD SUCCESS

copying/output/12-graph-copy.txt

@@ -0,0 +1,11 @@
+== 1. Diamond: root.left and root.right are the same node ==
+  original                : left == right : true
+  copy constructor        : left == right : false
+  identity-map copy       : left == right : true
+  serialization copy      : left == right : true
+
+== 2. Cycle: a -> b -> a ==
+  original                : a.left.left == a : true
+  copy constructor        : StackOverflowError
+  identity-map copy       : copy.left.left == copy : true
+  identity-map copy       : copy != original       : true

copying/output/13-serialization-rules.txt

@@ -0,0 +1,11 @@
+== 1. Classes: only the first non-serializable superclass constructor runs ==
+  after new Child()   : Child runs = 1, Parent runs = 1
+  after the copy      : Child runs = 1, Parent runs = 2
+
+== 2. Records: the canonical constructor DOES run ==
+  after new Money(..) : canonical runs = 1
+  after the copy      : canonical runs = 2
+
+== 3. An allow-list filter on the reading side ==
+  list of String and Money     : [text, Money[paise=1]]
+  list holding an AtomicInteger : InvalidClassException: filter status: REJECTED

copying/output/14-record-arrays.txt

@@ -0,0 +1,9 @@
+== 1. RawPacket keeps the caller's array and returns its own ==
+  after raw[0] = 99        : [99, 2, 3]
+  after rp.data()[1] = 88  : [99, 88, 3]
+
+== 2. Packet copies in the constructor and in the accessor ==
+  after the same two writes : [1, 2, 3]
+
+== 3. The generated equals() still compares the arrays by identity ==
+  new Packet({1}).equals(new Packet({1})) : false

copying/output/15-defensive-clone.txt

@@ -0,0 +1,7 @@
+== 1. A 'defensive' copy made with clone() trusts the argument's own clone() ==
+  clone() result is the attacker's object : true
+  clone() result class                    : EvilDate
+
+== 2. A copy made with the constructor does not ==
+  new Date(getTime()) is the attacker's object : false
+  new Date(getTime()) result class             : Date

copying/output/16-forgot-override.txt

@@ -0,0 +1,5 @@
+$ javac src/broken/ForgotToOverride.java
+src/broken/ForgotToOverride.java:10: error: clone() has protected access in Object
+        Object copy = foo.clone();
+                         ^
+1 error

copying/output/17-with-expression.txt

@@ -0,0 +1,11 @@
+$ javac src/broken/WithExpression.java
+src/broken/WithExpression.java:8: error: ';' expected
+        Point q = p with { x = 10; };
+                   ^
+src/broken/WithExpression.java:8: error: not a statement
+        Point q = p with { x = 10; };
+                    ^
+src/broken/WithExpression.java:8: error: ';' expected
+        Point q = p with { x = 10; };
+                        ^
+3 errors