Make cast_object handler required

Avoid subtle differences in behavior depending on whether the
handler is absent or returns FAILURE.

If you previously set cast_object to NULL, create a handler that
always returns FAILURE instead.

8 files changed, 73 insertions, 86 deletions

diff --git a/UPGRADING.INTERNALS b/UPGRADING.INTERNALS
index e7c3f5495b..599a024a4e 100644
--- a/UPGRADING.INTERNALS
+++ b/UPGRADING.INTERNALS
@@ -15,6 +15,7 @@ PHP 8.0 INTERNALS UPGRADE NOTES
   l. Some VM instructions switched to IS_TMP_VAR result instead of IS_VAR
   m. All internal functions must have arginfo
   n. zend_hash_sort compare function signature change
+  o. cast_object() object handler is now required
 
 2. Build system changes
   a. Abstract
@@ -110,6 +111,9 @@ PHP 8.0 INTERNALS UPGRADE NOTES
 
      Previously compare_func_t was used, which accepted void pointers.
 
+  o. The cast_object() handler is now required, i.e. must be non-null. You can
+     indicate that casting is not supported by always returning FAILURE.
+
 ========================
 2. Build system changes
 ========================
diff --git a/Zend/zend_API.c b/Zend/zend_API.c
index acb4366527..00b8076b3d 100644
--- a/Zend/zend_API.c
+++ b/Zend/zend_API.c
@@ -472,15 +472,12 @@ ZEND_API int ZEND_FASTCALL zend_parse_arg_str_weak(zval *arg, zend_string **dest
 		*dest = Z_STR_P(arg);
 	} else if (UNEXPECTED(Z_TYPE_P(arg) == IS_OBJECT)) {
 		zend_object *zobj = Z_OBJ_P(arg);
-
-		if (Z_OBJ_HANDLER_P(arg, cast_object)) {
-			zval obj;
-			if (zobj->handlers->cast_object(zobj, &obj, IS_STRING) == SUCCESS) {
-				OBJ_RELEASE(zobj);
-				ZVAL_COPY_VALUE(arg, &obj);
-				*dest = Z_STR_P(arg);
-				return 1;
-			}
+		zval obj;
+		if (zobj->handlers->cast_object(zobj, &obj, IS_STRING) == SUCCESS) {
+			OBJ_RELEASE(zobj);
+			ZVAL_COPY_VALUE(arg, &obj);
+			*dest = Z_STR_P(arg);
+			return 1;
 		}
 		return 0;
 	} else {
diff --git a/Zend/zend_builtin_functions.c b/Zend/zend_builtin_functions.c
index 87c40acf4f..f00996619a 100644
--- a/Zend/zend_builtin_functions.c
+++ b/Zend/zend_builtin_functions.c
@@ -664,11 +664,9 @@ ZEND_FUNCTION(define)
 			}
 			break;
 		case IS_OBJECT:
-			if (Z_OBJ_HT_P(val)->cast_object) {
-				if (Z_OBJ_HT_P(val)->cast_object(Z_OBJ_P(val), &val_free, IS_STRING) == SUCCESS) {
-					val = &val_free;
-					break;
-				}
+			if (Z_OBJ_HT_P(val)->cast_object(Z_OBJ_P(val), &val_free, IS_STRING) == SUCCESS) {
+				val = &val_free;
+				break;
 			}
 			/* no break */
 		default:
diff --git a/Zend/zend_object_handlers.c b/Zend/zend_object_handlers.c
index fb3b7509df..f678277fd2 100644
--- a/Zend/zend_object_handlers.c
+++ b/Zend/zend_object_handlers.c
@@ -1572,50 +1572,46 @@ ZEND_API int zend_std_compare_objects(zval *o1, zval *o2) /* {{{ */
 		zval casted;
 		if (Z_TYPE_P(o1) == IS_OBJECT) {
 			ZEND_ASSERT(Z_TYPE_P(o2) != IS_OBJECT);
-			if (Z_OBJ_HT_P(o1)->cast_object) {
-				zend_uchar target_type = (Z_TYPE_P(o2) == IS_FALSE || Z_TYPE_P(o2) == IS_TRUE)
-					? _IS_BOOL : Z_TYPE_P(o2);
-				if (Z_OBJ_HT_P(o1)->cast_object(Z_OBJ_P(o1), &casted, target_type) == FAILURE) {
-					// TODO: Less crazy.
-					if (target_type == IS_LONG || target_type == IS_DOUBLE) {
-						zend_error(E_NOTICE, "Object of class %s could not be converted to %s",
-							ZSTR_VAL(Z_OBJCE_P(o1)->name), zend_get_type_by_const(target_type));
-						if (target_type == IS_LONG) {
-							ZVAL_LONG(&casted, 1);
-						} else {
-							ZVAL_DOUBLE(&casted, 1.0);
-						}
+			zend_uchar target_type = (Z_TYPE_P(o2) == IS_FALSE || Z_TYPE_P(o2) == IS_TRUE)
+				? _IS_BOOL : Z_TYPE_P(o2);
+			if (Z_OBJ_HT_P(o1)->cast_object(Z_OBJ_P(o1), &casted, target_type) == FAILURE) {
+				// TODO: Less crazy.
+				if (target_type == IS_LONG || target_type == IS_DOUBLE) {
+					zend_error(E_NOTICE, "Object of class %s could not be converted to %s",
+						ZSTR_VAL(Z_OBJCE_P(o1)->name), zend_get_type_by_const(target_type));
+					if (target_type == IS_LONG) {
+						ZVAL_LONG(&casted, 1);
 					} else {
-						return 1;
+						ZVAL_DOUBLE(&casted, 1.0);
 					}
+				} else {
+					return 1;
 				}
-				int ret = zend_compare(&casted, o2);
-				zval_ptr_dtor(&casted);
-				return ret;
 			}
+			int ret = zend_compare(&casted, o2);
+			zval_ptr_dtor(&casted);
+			return ret;
 		} else {
 			ZEND_ASSERT(Z_TYPE_P(o2) == IS_OBJECT);
-			if (Z_OBJ_HT_P(o2)->cast_object) {
-				zend_uchar target_type = (Z_TYPE_P(o1) == IS_FALSE || Z_TYPE_P(o1) == IS_TRUE)
-					? _IS_BOOL : Z_TYPE_P(o1);
-				if (Z_OBJ_HT_P(o2)->cast_object(Z_OBJ_P(o2), &casted, target_type) == FAILURE) {
-					// TODO: Less crazy.
-					if (target_type == IS_LONG || target_type == IS_DOUBLE) {
-						zend_error(E_NOTICE, "Object of class %s could not be converted to %s",
-							ZSTR_VAL(Z_OBJCE_P(o2)->name), zend_get_type_by_const(target_type));
-						if (target_type == IS_LONG) {
-							ZVAL_LONG(&casted, 1);
-						} else {
-							ZVAL_DOUBLE(&casted, 1.0);
-						}
+			zend_uchar target_type = (Z_TYPE_P(o1) == IS_FALSE || Z_TYPE_P(o1) == IS_TRUE)
+				? _IS_BOOL : Z_TYPE_P(o1);
+			if (Z_OBJ_HT_P(o2)->cast_object(Z_OBJ_P(o2), &casted, target_type) == FAILURE) {
+				// TODO: Less crazy.
+				if (target_type == IS_LONG || target_type == IS_DOUBLE) {
+					zend_error(E_NOTICE, "Object of class %s could not be converted to %s",
+						ZSTR_VAL(Z_OBJCE_P(o2)->name), zend_get_type_by_const(target_type));
+					if (target_type == IS_LONG) {
+						ZVAL_LONG(&casted, 1);
 					} else {
-						return -1;
+						ZVAL_DOUBLE(&casted, 1.0);
 					}
+				} else {
+					return -1;
 				}
-				int ret = zend_compare(o1, &casted);
-				zval_ptr_dtor(&casted);
-				return ret;
 			}
+			int ret = zend_compare(o1, &casted);
+			zval_ptr_dtor(&casted);
+			return ret;
 		}
 		return ZEND_UNCOMPARABLE;
 	}
diff --git a/Zend/zend_object_handlers.h b/Zend/zend_object_handlers.h
index 19b7ff993f..b401d72ca2 100644
--- a/Zend/zend_object_handlers.h
+++ b/Zend/zend_object_handlers.h
@@ -158,7 +158,7 @@ struct _zend_object_handlers {
 	zend_object_get_method_t				get_method;           /* required */
 	zend_object_get_constructor_t			get_constructor;      /* required */
 	zend_object_get_class_name_t			get_class_name;       /* required */
-	zend_object_cast_t						cast_object;          /* optional */
+	zend_object_cast_t						cast_object;          /* required */
 	zend_object_count_elements_t			count_elements;       /* optional */
 	zend_object_get_debug_info_t			get_debug_info;       /* optional */
 	zend_object_get_closure_t				get_closure;          /* optional */
diff --git a/Zend/zend_operators.c b/Zend/zend_operators.c
index 600aad7bb7..f90b4ca377 100644
--- a/Zend/zend_operators.c
+++ b/Zend/zend_operators.c
@@ -137,13 +137,11 @@ ZEND_API zend_long ZEND_FASTCALL zend_atol(const char *str, size_t str_len) /* {
 /* {{{ convert_object_to_type: dst will be either ctype or UNDEF */
 #define convert_object_to_type(op, dst, ctype, conv_func)									\
 	ZVAL_UNDEF(dst);																		\
-	if (Z_OBJ_HT_P(op)->cast_object) {														\
-		if (Z_OBJ_HT_P(op)->cast_object(Z_OBJ_P(op), dst, ctype) == FAILURE) {				\
-			zend_error(E_NOTICE,															\
-				"Object of class %s could not be converted to %s", ZSTR_VAL(Z_OBJCE_P(op)->name),\
-			zend_get_type_by_const(ctype));													\
-		} 																					\
-	}
+	if (Z_OBJ_HT_P(op)->cast_object(Z_OBJ_P(op), dst, ctype) == FAILURE) {					\
+		zend_error(E_NOTICE,																\
+			"Object of class %s could not be converted to %s", ZSTR_VAL(Z_OBJCE_P(op)->name),\
+		zend_get_type_by_const(ctype));														\
+	} 																						\
 
 /* }}} */
 
@@ -565,13 +563,10 @@ try_again:
 			break;
 		case IS_OBJECT: {
 			zval tmp;
-
-			if (Z_OBJ_HT_P(op)->cast_object) {
-				if (Z_OBJ_HT_P(op)->cast_object(Z_OBJ_P(op), &tmp, IS_STRING) == SUCCESS) {
-					zval_ptr_dtor(op);
-					ZVAL_COPY_VALUE(op, &tmp);
-					return;
-				}
+			if (Z_OBJ_HT_P(op)->cast_object(Z_OBJ_P(op), &tmp, IS_STRING) == SUCCESS) {
+				zval_ptr_dtor(op);
+				ZVAL_COPY_VALUE(op, &tmp);
+				return;
 			}
 			if (!EG(exception)) {
 				zend_throw_error(NULL, "Object of class %s could not be converted to string", ZSTR_VAL(Z_OBJCE_P(op)->name));
@@ -874,10 +869,8 @@ try_again:
 				NULL : ZSTR_KNOWN(ZEND_STR_ARRAY_CAPITALIZED);
 		case IS_OBJECT: {
 			zval tmp;
-			if (Z_OBJ_HT_P(op)->cast_object) {
-				if (Z_OBJ_HT_P(op)->cast_object(Z_OBJ_P(op), &tmp, IS_STRING) == SUCCESS) {
-					return Z_STR(tmp);
-				}
+			if (Z_OBJ_HT_P(op)->cast_object(Z_OBJ_P(op), &tmp, IS_STRING) == SUCCESS) {
+				return Z_STR(tmp);
 			}
 			if (!EG(exception)) {
 				zend_throw_error(NULL, "Object of class %s could not be converted to string", ZSTR_VAL(Z_OBJCE_P(op)->name));
@@ -2422,14 +2415,11 @@ ZEND_API int ZEND_FASTCALL zend_is_true(zval *op) /* {{{ */
 ZEND_API int ZEND_FASTCALL zend_object_is_true(zval *op) /* {{{ */
 {
 	zend_object *zobj = Z_OBJ_P(op);
-
-	if (zobj->handlers->cast_object) {
-		zval tmp;
-		if (zobj->handlers->cast_object(zobj, &tmp, _IS_BOOL) == SUCCESS) {
-			return Z_TYPE(tmp) == IS_TRUE;
-		}
-		zend_error(E_RECOVERABLE_ERROR, "Object of class %s could not be converted to bool", ZSTR_VAL(zobj->ce->name));
+	zval tmp;
+	if (zobj->handlers->cast_object(zobj, &tmp, _IS_BOOL) == SUCCESS) {
+		return Z_TYPE(tmp) == IS_TRUE;
 	}
+	zend_error(E_RECOVERABLE_ERROR, "Object of class %s could not be converted to bool", ZSTR_VAL(zobj->ce->name));
 	return 1;
 }
 /* }}} */
diff --git a/ext/ffi/ffi.c b/ext/ffi/ffi.c
index 7658558ee8..3d1eaaf831 100644
--- a/ext/ffi/ffi.c
+++ b/ext/ffi/ffi.c
@@ -4659,6 +4659,11 @@ static HashTable *zend_fake_get_gc(zend_object *ob, zval **table, int *n) /* {{{
 }
 /* }}} */
 
+static int zend_fake_cast_object(zend_object *obj, zval *result, int type)
+{
+	return FAILURE;
+}
+
 static ZEND_COLD zend_never_inline void zend_ffi_use_after_free(void) /* {{{ */
 {
 	zend_throw_error(zend_ffi_exception_ce, "Use after free()");
@@ -4911,7 +4916,7 @@ ZEND_MINIT_FUNCTION(ffi)
 	zend_ffi_handlers.unset_dimension      = zend_fake_unset_dimension;
 	zend_ffi_handlers.get_method           = zend_ffi_get_func;
 	zend_ffi_handlers.compare              = NULL;
-	zend_ffi_handlers.cast_object          = NULL;
+	zend_ffi_handlers.cast_object          = zend_fake_cast_object;
 	zend_ffi_handlers.get_debug_info       = NULL;
 	zend_ffi_handlers.get_closure          = NULL;
 	zend_ffi_handlers.get_properties       = zend_fake_get_properties;
@@ -4990,7 +4995,7 @@ ZEND_MINIT_FUNCTION(ffi)
 	zend_ffi_cdata_free_handlers.get_method           = zend_fake_get_method;
 	zend_ffi_cdata_free_handlers.get_class_name       = zend_ffi_cdata_get_class_name;
 	zend_ffi_cdata_free_handlers.compare              = zend_ffi_cdata_compare_objects;
-	zend_ffi_cdata_free_handlers.cast_object          = NULL;
+	zend_ffi_cdata_free_handlers.cast_object          = zend_fake_cast_object;
 	zend_ffi_cdata_free_handlers.count_elements       = NULL;
 	zend_ffi_cdata_free_handlers.get_debug_info       = zend_ffi_free_get_debug_info;
 	zend_ffi_cdata_free_handlers.get_closure          = NULL;
@@ -5020,7 +5025,7 @@ ZEND_MINIT_FUNCTION(ffi)
 	zend_ffi_ctype_handlers.get_method           = zend_fake_get_method;
 	zend_ffi_ctype_handlers.get_class_name       = zend_ffi_ctype_get_class_name;
 	zend_ffi_ctype_handlers.compare              = zend_ffi_ctype_compare_objects;
-	zend_ffi_ctype_handlers.cast_object          = NULL;
+	zend_ffi_ctype_handlers.cast_object          = zend_fake_cast_object;
 	zend_ffi_ctype_handlers.count_elements       = NULL;
 	zend_ffi_ctype_handlers.get_debug_info       = zend_ffi_ctype_get_debug_info;
 	zend_ffi_ctype_handlers.get_closure          = NULL;
diff --git a/ext/intl/collator/collator_convert.c b/ext/intl/collator/collator_convert.c
index e19bb719f6..88177a04f6 100644
--- a/ext/intl/collator/collator_convert.c
+++ b/ext/intl/collator/collator_convert.c
@@ -224,16 +224,13 @@ zval* collator_convert_object_to_string( zval* obj, zval *rv )
 	}
 
 	/* Try object's handlers. */
-	if( Z_OBJ_HT_P(obj)->cast_object )
-	{
-		zstr = rv;
+	zstr = rv;
 
-		if( Z_OBJ_HT_P(obj)->cast_object( Z_OBJ_P(obj), zstr, IS_STRING ) == FAILURE )
-		{
-			/* cast_object failed => bail out. */
-			zval_ptr_dtor( zstr );
-			COLLATOR_CONVERT_RETURN_FAILED( obj );
-		}
+	if( Z_OBJ_HT_P(obj)->cast_object( Z_OBJ_P(obj), zstr, IS_STRING ) == FAILURE )
+	{
+		/* cast_object failed => bail out. */
+		zval_ptr_dtor( zstr );
+		COLLATOR_CONVERT_RETURN_FAILED( obj );
 	}
 
 	/* Object wasn't successfully converted => bail out. */