We don't need to dup zend_class_constant here.

quote why the internal class is still using duplication:
```
for internal classes, the zend_class_constant is malloc-ed. we need to
free it.

if (const->ce == ce) {
zval_ptr_dtor(&const->value);
free(const)
}
so, if two classes share one const, and it(parent class) was freed
before, this read(in child class, const->ce) is invalid..

and destroy_zend_class is called via zend_hash_destroy(class_table).
which is not in reverse order... so, parent classes are dtor first.

if we want this work, we should change that order.
```

Author: laruence

Zend/zend_inheritance.c

@@ -724,15 +724,15 @@ static void do_inherit_class_constant(zend_string *name, zend_class_constant *pa
 		if (Z_CONSTANT(parent_const->value)) {
 			ce->ce_flags &= ~ZEND_ACC_CONSTANTS_UPDATED;
 		}
-		if (Z_REFCOUNTED(parent_const->value)) {
-			Z_ADDREF(parent_const->value);
-		}
 		if (ce->type & ZEND_INTERNAL_CLASS) {
+			if (Z_REFCOUNTED(parent_const->value)) {
+				Z_ADDREF(parent_const->value);
+			}
 			c = pemalloc(sizeof(zend_class_constant), 1);
+			memcpy(c, parent_const, sizeof(zend_class_constant));
 		} else {
-			c = zend_arena_alloc(&CG(arena), sizeof(zend_class_constant));
+			c = parent_const;
 		}
-		memcpy(c, parent_const, sizeof(zend_class_constant));
 		_zend_hash_append_ptr(&ce->constants_table, name, c);
 	}
 }
@@ -934,18 +934,18 @@ static void do_inherit_iface_constant(zend_string *name, zend_class_constant *c,
 {
 	if (do_inherit_constant_check(&ce->constants_table, c, name, iface)) {
 		zend_class_constant *ct;
-		if (Z_REFCOUNTED(c->value)) {
-			Z_ADDREF(c->value);
-		}
 		if (Z_CONSTANT(c->value)) {
 			ce->ce_flags &= ~ZEND_ACC_CONSTANTS_UPDATED;
 		}
 		if (ce->type & ZEND_INTERNAL_CLASS) {
+			if (Z_REFCOUNTED(c->value)) {
+				Z_ADDREF(c->value);
+			}
 			ct = pemalloc(sizeof(zend_class_constant), 1);
+			memcpy(ct, c, sizeof(zend_class_constant));
 		} else {
-			ct = zend_arena_alloc(&CG(arena), sizeof(zend_class_constant));
+			ct = c;
 		}
-		memcpy(ct, c, sizeof(zend_class_constant));
 		zend_hash_update_ptr(&ce->constants_table, name, ct);
 	}
 }

Zend/zend_opcode.c

@@ -291,9 +291,11 @@ ZEND_API void destroy_zend_class(zval *zv)
 				zend_class_constant *c;
 
 				ZEND_HASH_FOREACH_PTR(&ce->constants_table, c) {
-					zval_ptr_dtor(&c->value);
-					if (c->doc_comment && c->ce == ce) {
-						zend_string_release(c->doc_comment);
+					if (c->ce == ce) {
+						zval_ptr_dtor(&c->value);
+						if (c->doc_comment) {
+							zend_string_release(c->doc_comment);
+						}
 					}
 				} ZEND_HASH_FOREACH_END();
 				zend_hash_destroy(&ce->constants_table);