zend_portability: Add ZEND_CONTAINER_OF()

UPGRADING.INTERNALS

@@ -107,6 +107,7 @@ PHP 8.6 INTERNALS UPGRADE NOTES
     zend_fci_consumed_arg(), which allows moving a selected callback argument
     instead of copying it in zend_call_function(). Currently only a single
     consumed argument is supported.
+  . Added ZEND_CONTAINER_OF().
 
 ========================
 2. Build system changes

Zend/Optimizer/zend_optimizer.c

@@ -780,7 +780,7 @@ static bool zend_optimizer_ignore_class(zval *ce_zv, const zend_string *filename
 		if (CG(compiler_options) & ZEND_COMPILE_WITH_FILE_CACHE) {
 			return true;
 		}
-		const Bucket *ce_bucket = (const Bucket*)((uintptr_t)ce_zv - offsetof(Bucket, val));
+		const Bucket *ce_bucket = ZEND_CONTAINER_OF(ce_zv, Bucket, val);
 		size_t offset = ce_bucket - EG(class_table)->arData;
 		if (offset < EG(persistent_classes_count)) {
 			return false;
@@ -801,7 +801,7 @@ static bool zend_optimizer_ignore_function(zval *fbc_zv, const zend_string *file
 			if (CG(compiler_options) & ZEND_COMPILE_WITH_FILE_CACHE) {
 				return true;
 			}
-			const Bucket *fbc_bucket = (const Bucket*)((uintptr_t)fbc_zv - offsetof(Bucket, val));
+			const Bucket *fbc_bucket = ZEND_CONTAINER_OF(fbc_zv, Bucket, val);
 			size_t offset = fbc_bucket - EG(function_table)->arData;
 			if (offset < EG(persistent_functions_count)) {
 				return false;

Zend/zend_closures.c

@@ -830,7 +830,7 @@ static void zend_create_closure_ex(zval *res, zend_function *func, zend_class_en
 		/* wrap internal function handler to avoid memory leak */
 		if (UNEXPECTED(closure->func.internal_function.handler == zend_closure_internal_handler)) {
 			/* avoid infinity recursion, by taking handler from nested closure */
-			zend_closure *nested = (zend_closure*)((char*)func - offsetof(zend_closure, func));
+			zend_closure *nested = ZEND_CONTAINER_OF(func, zend_closure, func);
 			ZEND_ASSERT(nested->std.ce == zend_ce_closure);
 			closure->orig_internal_handler = nested->orig_internal_handler;
 		} else {

Zend/zend_compile.c

@@ -5175,7 +5175,7 @@ static zend_result zend_compile_func_array_map(znode *result, zend_ast_list *arg
 	opline->lineno = lineno;
 	opline->extended_value = (2 << 16) | IS_ARRAY;
 	const zval *fbc_zv = zend_hash_find(CG(function_table), lcname);
-	const Bucket *fbc_bucket = (const Bucket*)((uintptr_t)fbc_zv - offsetof(Bucket, val));
+	const Bucket *fbc_bucket = ZEND_CONTAINER_OF(fbc_zv, Bucket, val);
 	Z_EXTRA_P(CT_CONSTANT(opline->op1)) = fbc_bucket - CG(function_table)->arData;
 
 	/* Initialize the result array. */
@@ -5472,7 +5472,7 @@ static void zend_compile_call(znode *result, const zend_ast *ast, uint32_t type)
 
 		/* Store offset to function from symbol table in op2.extra. */
 		if (fbc->type == ZEND_INTERNAL_FUNCTION) {
-			const Bucket *fbc_bucket = (const Bucket*)((uintptr_t)fbc_zv - offsetof(Bucket, val));
+			const Bucket *fbc_bucket = ZEND_CONTAINER_OF(fbc_zv, Bucket, val);
 			Z_EXTRA_P(CT_CONSTANT(opline->op2)) = fbc_bucket - CG(function_table)->arData;
 		}
 

Zend/zend_enum.h

@@ -36,7 +36,7 @@ typedef struct zend_enum_obj {
 
 static inline zend_enum_obj *zend_enum_obj_from_obj(zend_object *zobj) {
 	ZEND_ASSERT(zobj->ce->ce_flags & ZEND_ACC_ENUM);
-	return (zend_enum_obj*)((char*)(zobj) - offsetof(zend_enum_obj, std));
+	return ZEND_CONTAINER_OF(zobj, zend_enum_obj, std);
 }
 
 void zend_enum_startup(void);

Zend/zend_fibers.h

@@ -154,7 +154,7 @@ static zend_always_inline zend_fiber *zend_fiber_from_context(zend_fiber_context
 {
 	ZEND_ASSERT(context->kind == zend_ce_fiber && "Fiber context does not belong to a Zend fiber");
 
-	return (zend_fiber *)(((char *) context) - offsetof(zend_fiber, context));
+	return ZEND_CONTAINER_OF(context, zend_fiber, context);
 }
 
 static zend_always_inline zend_fiber_context *zend_fiber_get_context(zend_fiber *fiber)

Zend/zend_portability.h

@@ -387,6 +387,34 @@ char *alloca();
 #define ZEND_ELEMENT_COUNT(m)
 #endif
 
+#if __cplusplus
+extern "C++" {
+# include <cstddef>
+	template<typename T, typename M>
+	const T* zend_container_of(const M *ptr, size_t offset) {
+		return reinterpret_cast<const T*>(reinterpret_cast<const char*>(ptr) - offset);
+	}
+	template<typename T, typename M>
+	T* zend_container_of(M *ptr, size_t offset) {
+		return reinterpret_cast<T*>(reinterpret_cast<char*>(ptr) - offset);
+	}
+
+	# define ZEND_CONTAINER_OF(ptr, Type, member) zend_container_of<Type, decltype(Type::member)>(ptr, offsetof(Type, member))
+}
+#elif __STDC_VERSION__ >= 202311L || ZEND_GCC_VERSION
+/* typeof is C23 or a GCC extension */
+# define ZEND_CONTAINER_OF(ptr, Type, member) \
+	_Generic( \
+		ptr, \
+		const typeof(((Type*)0)->member) *: ((const Type*)((char*)(ptr) - offsetof(Type, member))), \
+		typeof(((Type*)0)->member) *: ((Type*)((char*)(ptr) - offsetof(Type, member))) \
+	)
+#else
+/* Define a variant that does not keep const-ness for older compilers. Mismatches
+ * are expected to be caught by CI running modern compilers. */
+# define ZEND_CONTAINER_OF(ptr, Type, member) ((Type*)((char*)(ptr) - offsetof(Type, member)))
+#endif
+
 #ifdef HAVE_BUILTIN_CONSTANT_P
 # define ZEND_CONST_COND(_condition, _default) \
 	(__builtin_constant_p(_condition) ? (_condition) : (_default))

Zend/zend_weakrefs.c

@@ -58,10 +58,10 @@ static zend_class_entry *zend_ce_weakmap;
 static zend_object_handlers zend_weakref_handlers;
 static zend_object_handlers zend_weakmap_handlers;
 
-#define zend_weakref_from(o) ((zend_weakref*)(((char*) o) - offsetof(zend_weakref, std)))
+#define zend_weakref_from(o) (ZEND_CONTAINER_OF(o, zend_weakref, std))
 #define zend_weakref_fetch(z) zend_weakref_from(Z_OBJ_P(z))
 
-#define zend_weakmap_from(o) ((zend_weakmap*)(((char*) o) - offsetof(zend_weakmap, std)))
+#define zend_weakmap_from(o) (ZEND_CONTAINER_OF(o, zend_weakmap, std))
 #define zend_weakmap_fetch(z) zend_weakmap_from(Z_OBJ_P(z))
 
 static inline void zend_weakref_unref_single(

ext/bcmath/bcmath.c

@@ -875,10 +875,7 @@ static int bcmath_number_compare(zval *op1, zval *op2);
 #endif
 #define CHECK_SCALE_OVERFLOW(scale) (scale > INT_MAX)
 
-static zend_always_inline bcmath_number_obj_t *get_bcmath_number_from_obj(const zend_object *obj)
-{
-	return (bcmath_number_obj_t*)((char*)(obj) - offsetof(bcmath_number_obj_t, std));
-}
+#define get_bcmath_number_from_obj(obj) ZEND_CONTAINER_OF(obj, bcmath_number_obj_t, std)
 
 static zend_always_inline bcmath_number_obj_t *get_bcmath_number_from_zval(const zval *zv)
 {
@@ -1214,7 +1211,7 @@ static zend_result bc_num_from_obj_or_str_or_long(
 	bc_num *num, size_t *full_scale, const zend_object *obj, const zend_string *str, zend_long lval)
 {
 	if (obj) {
-		bcmath_number_obj_t *intern = get_bcmath_number_from_obj(obj);
+		const bcmath_number_obj_t *intern = get_bcmath_number_from_obj(obj);
 		*num = intern->num;
 		if (full_scale) {
 			*full_scale = intern->scale;

ext/curl/curl_private.h

@@ -152,13 +152,13 @@ void _php_setup_easy_copy_handlers(php_curl *ch, php_curl *source);
 zend_long php_curl_get_long(zval *zv);
 
 static inline php_curl *curl_from_obj(zend_object *obj) {
-	return (php_curl *)((char *)(obj) - offsetof(php_curl, std));
+	return ZEND_CONTAINER_OF(obj, php_curl, std);
 }
 
 #define Z_CURL_P(zv) curl_from_obj(Z_OBJ_P(zv))
 
 static inline php_curlsh *curl_share_from_obj(zend_object *obj) {
-	return (php_curlsh *)((char *)(obj) - offsetof(php_curlsh, std));
+	return ZEND_CONTAINER_OF(obj, php_curlsh, std);
 }
 
 #define Z_CURL_SHARE_P(zv) curl_share_from_obj(Z_OBJ_P(zv))

ext/curl/multi.c

@@ -49,7 +49,7 @@
 zend_class_entry *curl_multi_ce;
 
 static inline php_curlm *curl_multi_from_obj(zend_object *obj) {
-	return (php_curlm *)((char *)(obj) - offsetof(php_curlm, std));
+	return ZEND_CONTAINER_OF(obj, php_curlm, std);
 }
 
 #define Z_CURL_MULTI_P(zv) curl_multi_from_obj(Z_OBJ_P(zv))

ext/date/php_date.h

@@ -59,7 +59,7 @@ struct _php_date_obj {
 };
 
 static inline php_date_obj *php_date_obj_from_obj(zend_object *obj) {
-	return (php_date_obj*)((char*)(obj) - offsetof(php_date_obj, std));
+	return ZEND_CONTAINER_OF(obj, php_date_obj, std);
 }
 
 #define Z_PHPDATE_P(zv)  php_date_obj_from_obj(Z_OBJ_P((zv)))
@@ -76,7 +76,7 @@ struct _php_timezone_obj {
 };
 
 static inline php_timezone_obj *php_timezone_obj_from_obj(zend_object *obj) {
-	return (php_timezone_obj*)((char*)(obj) - offsetof(php_timezone_obj, std));
+	return ZEND_CONTAINER_OF(obj, php_timezone_obj, std);
 }
 
 #define Z_PHPTIMEZONE_P(zv)  php_timezone_obj_from_obj(Z_OBJ_P((zv)))
@@ -94,7 +94,7 @@ struct _php_interval_obj {
 };
 
 static inline php_interval_obj *php_interval_obj_from_obj(zend_object *obj) {
-	return (php_interval_obj*)((char*)(obj) - offsetof(php_interval_obj, std));
+	return ZEND_CONTAINER_OF(obj, php_interval_obj, std);
 }
 
 #define Z_PHPINTERVAL_P(zv)  php_interval_obj_from_obj(Z_OBJ_P((zv)))
@@ -113,7 +113,7 @@ struct _php_period_obj {
 };
 
 static inline php_period_obj *php_period_obj_from_obj(zend_object *obj) {
-	return (php_period_obj*)((char*)(obj) - offsetof(php_period_obj, std));
+	return ZEND_CONTAINER_OF(obj, php_period_obj, std);
 }
 
 #define Z_PHPPERIOD_P(zv)  php_period_obj_from_obj(Z_OBJ_P((zv)))

ext/dba/dba.c

@@ -337,7 +337,7 @@ static zend_result dba_connection_cast_object(zend_object *obj, zval *result, in
 
 static inline dba_connection *dba_connection_from_obj(zend_object *obj)
 {
-	return (dba_connection *)((char *)(obj) - offsetof(dba_connection, std));
+	return ZEND_CONTAINER_OF(obj, dba_connection, std);
 }
 
 #define Z_DBA_CONNECTION_P(zv) dba_connection_from_obj(Z_OBJ_P(zv))

ext/dom/token_list.h

@@ -30,7 +30,7 @@ static inline dom_token_list_object *php_dom_token_list_from_obj(zend_object *ob
 
 static inline dom_token_list_object *php_dom_token_list_from_dom_obj(dom_object *obj)
 {
-	return (dom_token_list_object *)((char *) obj - offsetof(dom_token_list_object, dom));
+	return ZEND_CONTAINER_OF(obj, dom_token_list_object, dom);
 }
 
 void dom_ordered_set_parser(HashTable *token_set, const char *position, bool to_lowercase);

ext/dom/xml_common.h

@@ -28,7 +28,7 @@ typedef struct _dom_object {
 } dom_object;
 
 static inline dom_object *php_dom_obj_from_obj(zend_object *obj) {
-	return (dom_object*)((char*)(obj) - offsetof(dom_object, std));
+	return ZEND_CONTAINER_OF(obj, dom_object, std);
 }
 
 #define Z_DOMOBJ_P(zv)  php_dom_obj_from_obj(Z_OBJ_P((zv)))

ext/dom/xpath.c

@@ -189,7 +189,7 @@ zend_result dom_xpath_document_read(dom_object *obj, zval *retval)
 
 /* {{{ registerNodeNamespaces bool*/
 static inline dom_xpath_object *php_xpath_obj_from_dom_obj(dom_object *obj) {
-	return (dom_xpath_object*)((char*)(obj) - offsetof(dom_xpath_object, dom));
+	return ZEND_CONTAINER_OF(obj, dom_xpath_object, dom);
 }
 
 zend_result dom_xpath_register_node_ns_read(dom_object *obj, zval *retval)

ext/enchant/enchant.c

@@ -49,7 +49,7 @@ zend_class_entry *enchant_broker_ce;
 static zend_object_handlers enchant_broker_handlers;
 
 static inline enchant_broker *enchant_broker_from_obj(zend_object *obj) {
-	return (enchant_broker *)((char *)(obj) - offsetof(enchant_broker, std));
+	return ZEND_CONTAINER_OF(obj, enchant_broker, std);
 }
 
 #define Z_ENCHANT_BROKER_P(zv) enchant_broker_from_obj(Z_OBJ_P(zv))
@@ -67,7 +67,7 @@ zend_class_entry *enchant_dict_ce;
 static zend_object_handlers enchant_dict_handlers;
 
 static inline enchant_dict *enchant_dict_from_obj(zend_object *obj) {
-	return (enchant_dict *)((char *)(obj) - offsetof(enchant_dict, std));
+	return ZEND_CONTAINER_OF(obj, enchant_dict, std);
 }
 
 #define Z_ENCHANT_DICT_P(zv) enchant_dict_from_obj(Z_OBJ_P(zv))

ext/fileinfo/fileinfo.c

@@ -44,7 +44,7 @@ typedef struct _finfo_object {
 } finfo_object;
 
 static inline finfo_object *php_finfo_fetch_object(zend_object *obj) {
-	return (finfo_object *)((char*)(obj) - offsetof(finfo_object, zo));
+	return ZEND_CONTAINER_OF(obj, finfo_object, zo);
 }
 
 #define Z_FINFO_P(zv) php_finfo_fetch_object(Z_OBJ_P((zv)))

ext/gd/gd.c

@@ -150,7 +150,7 @@ static zend_function *php_gd_image_object_get_constructor(zend_object *object)
 
 static zend_always_inline php_gd_image_object* php_gd_exgdimage_from_zobj_p(zend_object* obj)
 {
-	return (php_gd_image_object *) ((char *) (obj) - offsetof(php_gd_image_object, std));
+	return ZEND_CONTAINER_OF(obj, php_gd_image_object, std);
 }
 
 /**

ext/gmp/php_gmp_int.h

@@ -36,7 +36,7 @@ typedef struct _gmp_object {
 } gmp_object;
 
 static inline gmp_object *php_gmp_object_from_zend_object(zend_object *zobj) {
-	return (gmp_object *)( ((char *)zobj) - offsetof(gmp_object, std) );
+	return ZEND_CONTAINER_OF(zobj, gmp_object, std);
 }
 
 PHP_GMP_API zend_class_entry *php_gmp_class_entry(void);

ext/intl/breakiterator/breakiterator_class.h

@@ -42,7 +42,7 @@ typedef struct {
 } BreakIterator_object;
 
 static inline BreakIterator_object *php_intl_breakiterator_fetch_object(zend_object *obj) {
-	return (BreakIterator_object *)((char*)(obj) - offsetof(BreakIterator_object, zo));
+	return ZEND_CONTAINER_OF(obj, BreakIterator_object, zo);
 }
 #define Z_INTL_BREAKITERATOR_P(zv) php_intl_breakiterator_fetch_object(Z_OBJ_P(zv))
 

ext/intl/calendar/calendar_class.h

@@ -39,7 +39,7 @@ typedef struct {
 } Calendar_object;
 
 static inline Calendar_object *php_intl_calendar_fetch_object(zend_object *obj) {
-	return (Calendar_object *)((char*)(obj) - offsetof(Calendar_object, zo));
+	return ZEND_CONTAINER_OF(obj, Calendar_object, zo);
 }
 #define Z_INTL_CALENDAR_P(zv) php_intl_calendar_fetch_object(Z_OBJ_P(zv))
 

ext/intl/collator/collator_class.h

@@ -48,7 +48,7 @@ typedef struct {
 #define COLLATOR_ERROR_CODE_P(co) &(INTL_ERROR_CODE(COLLATOR_ERROR(co)))
 
 static inline Collator_object *php_intl_collator_fetch_object(zend_object *obj) {
-	return (Collator_object *)((char*)(obj) - offsetof(Collator_object, zo));
+	return ZEND_CONTAINER_OF(obj, Collator_object, zo);
 }
 #define Z_INTL_COLLATOR_P(zv) php_intl_collator_fetch_object(Z_OBJ_P(zv))
 

ext/intl/common/common_enum.h

@@ -53,7 +53,7 @@ typedef struct {
 
 
 static inline IntlIterator_object *php_intl_iterator_fetch_object(zend_object *obj) {
-	return (IntlIterator_object *)((char*)(obj) - offsetof(IntlIterator_object, zo));
+	return ZEND_CONTAINER_OF(obj, IntlIterator_object, zo);
 }
 #define Z_INTL_ITERATOR_P(zv) php_intl_iterator_fetch_object(Z_OBJ_P(zv))
 

ext/intl/dateformat/dateformat_class.h

@@ -37,7 +37,7 @@ typedef struct {
 } IntlDateFormatter_object;
 
 static inline IntlDateFormatter_object *php_intl_dateformatter_fetch_object(zend_object *obj) {
-	return (IntlDateFormatter_object *)((char*)(obj) - offsetof(IntlDateFormatter_object, zo));
+	return ZEND_CONTAINER_OF(obj, IntlDateFormatter_object, zo);
 }
 #define Z_INTL_DATEFORMATTER_P(zv) php_intl_dateformatter_fetch_object(Z_OBJ_P(zv))
 

ext/intl/dateformat/datepatterngenerator_class.h

@@ -37,7 +37,7 @@ typedef struct {
 } IntlDatePatternGenerator_object;
 
 static inline IntlDatePatternGenerator_object *php_intl_datepatterngenerator_fetch_object(zend_object *obj) {
-	return (IntlDatePatternGenerator_object *)((char*)(obj) - offsetof(IntlDatePatternGenerator_object, zo));
+	return ZEND_CONTAINER_OF(obj, IntlDatePatternGenerator_object, zo);
 }
 #define Z_INTL_DATEPATTERNGENERATOR_P(zv) php_intl_datepatterngenerator_fetch_object(Z_OBJ_P(zv))
 

ext/intl/formatter/formatter_class.h

@@ -34,7 +34,7 @@ typedef struct {
 } NumberFormatter_object;
 
 static inline NumberFormatter_object *php_intl_number_format_fetch_object(zend_object *obj) {
-	return (NumberFormatter_object *)((char*)(obj) - offsetof(NumberFormatter_object, zo));
+	return ZEND_CONTAINER_OF(obj, NumberFormatter_object, zo);
 }
 #define Z_INTL_NUMBERFORMATTER_P(zv) php_intl_number_format_fetch_object(Z_OBJ_P(zv))
 

ext/intl/listformatter/listformatter_class.h

@@ -37,7 +37,7 @@ typedef struct {
 } ListFormatter_object;
 
 static inline ListFormatter_object *php_intl_listformatter_fetch_object(zend_object *obj) {
-    return (ListFormatter_object *)((char*)(obj) - offsetof(ListFormatter_object, zo));
+    return ZEND_CONTAINER_OF(obj, ListFormatter_object, zo);
 }
 #define Z_INTL_LISTFORMATTER_P(zv) php_intl_listformatter_fetch_object(Z_OBJ_P(zv))
 

ext/intl/msgformat/msgformat_class.h

@@ -32,7 +32,7 @@ typedef struct {
 
 
 static inline MessageFormatter_object *php_intl_messageformatter_fetch_object(zend_object *obj) {
-	return (MessageFormatter_object *)((char*)(obj) - offsetof(MessageFormatter_object, zo));
+	return ZEND_CONTAINER_OF(obj, MessageFormatter_object, zo);
 }
 #define Z_INTL_MESSAGEFORMATTER_P(zv) php_intl_messageformatter_fetch_object(Z_OBJ_P(zv))
 

ext/intl/rangeformatter/rangeformatter_class.h

@@ -37,7 +37,7 @@ typedef struct {
 } IntlNumberRangeFormatter_object;
 
 static inline IntlNumberRangeFormatter_object *php_intl_numberrangeformatter_fetch_object(zend_object *obj) {
-    return (IntlNumberRangeFormatter_object *)((char*)(obj) - offsetof(IntlNumberRangeFormatter_object, zo));
+    return ZEND_CONTAINER_OF(obj, IntlNumberRangeFormatter_object, zo);
 }
 
 #define Z_INTL_RANGEFORMATTER_P(zv) php_intl_numberrangeformatter_fetch_object(Z_OBJ_P(zv))

ext/intl/resourcebundle/resourcebundle_class.h

@@ -36,7 +36,7 @@ typedef struct {
 } ResourceBundle_object;
 
 static inline ResourceBundle_object *php_intl_resourcebundle_fetch_object(zend_object *obj) {
-	return (ResourceBundle_object *)((char*)(obj) - offsetof(ResourceBundle_object, zend));
+	return ZEND_CONTAINER_OF(obj, ResourceBundle_object, zend);
 }
 #define Z_INTL_RESOURCEBUNDLE_P(zv) php_intl_resourcebundle_fetch_object(Z_OBJ_P(zv))
 

ext/intl/spoofchecker/spoofchecker_class.h

@@ -43,7 +43,7 @@ typedef struct {
 } Spoofchecker_object;
 
 static inline Spoofchecker_object *php_intl_spoofchecker_fetch_object(zend_object *obj) {
-	    return (Spoofchecker_object *)((char*)(obj) - offsetof(Spoofchecker_object, zo));
+	    return ZEND_CONTAINER_OF(obj, Spoofchecker_object, zo);
 }
 #define Z_INTL_SPOOFCHECKER_P(zv) php_intl_spoofchecker_fetch_object((Z_OBJ_P(zv)))
 

ext/intl/timezone/timezone_class.h

@@ -47,7 +47,7 @@ typedef struct {
 } TimeZone_object;
 
 static inline TimeZone_object *php_intl_timezone_fetch_object(zend_object *obj) {
-	return (TimeZone_object *)((char*)(obj) - offsetof(TimeZone_object, zo));
+	return ZEND_CONTAINER_OF(obj, TimeZone_object, zo);
 }
 #define Z_INTL_TIMEZONE_P(zv) php_intl_timezone_fetch_object(Z_OBJ_P(zv))