Fixed bug #65768: DateTimeImmutable::diff does not work

This commit also prevents user classes from directly implementing
DateTimeInterface, because ext/date relies on classes implementing
it to support certain internal structures.

NEWS

@@ -7,6 +7,7 @@ PHP                                                                        NEWS
 
 - Date:
   . Fixed bug #66060 (Heap buffer over-read in DateInterval). (Remi)
+  . Fixed bug #65768 (DateTimeImmutable::diff does not work). (Nikita Nefedov)
 
 ?? ??? 2013, PHP 5.5.7
 

ext/date/php_date.c

@@ -1989,12 +1989,25 @@ zend_object_iterator *date_object_period_get_iterator(zend_class_entry *ce, zval
 	return (zend_object_iterator*)iterator;
 }
 
+static int implement_date_interface_handler(zend_class_entry *interface, zend_class_entry *implementor TSRMLS_DC)
+{
+	if (implementor->type == ZEND_USER_CLASS &&
+		!instanceof_function(implementor, date_ce_date TSRMLS_CC) &&
+		!instanceof_function(implementor, date_ce_immutable TSRMLS_CC)
+	) {
+		zend_error(E_ERROR, "DateTimeInterface can't be implemented by user classes");
+	}
+
+	return SUCCESS;
+}
+
 static void date_register_classes(TSRMLS_D)
 {
 	zend_class_entry ce_date, ce_immutable, ce_timezone, ce_interval, ce_period, ce_interface;
 
 	INIT_CLASS_ENTRY(ce_interface, "DateTimeInterface", date_funcs_interface);
 	date_ce_interface = zend_register_internal_interface(&ce_interface TSRMLS_CC);
+	date_ce_interface->interface_gets_implemented = implement_date_interface_handler;
 
 	INIT_CLASS_ENTRY(ce_date, "DateTime", date_funcs_date);
 	ce_date.create_object = date_object_new_date;
@@ -3612,13 +3625,13 @@ PHP_FUNCTION(date_diff)
 	php_interval_obj *interval;
 	long          absolute = 0;
 
-	if (zend_parse_method_parameters(ZEND_NUM_ARGS() TSRMLS_CC, getThis(), "OO|l", &object1, date_ce_date, &object2, date_ce_date, &absolute) == FAILURE) {
+	if (zend_parse_method_parameters(ZEND_NUM_ARGS() TSRMLS_CC, getThis(), "OO|l", &object1, date_ce_interface, &object2, date_ce_interface, &absolute) == FAILURE) {
 		RETURN_FALSE;
 	}
 	dateobj1 = (php_date_obj *) zend_object_store_get_object(object1 TSRMLS_CC);
 	dateobj2 = (php_date_obj *) zend_object_store_get_object(object2 TSRMLS_CC);
-	DATE_CHECK_INITIALIZED(dateobj1->time, DateTime);
+	DATE_CHECK_INITIALIZED(dateobj1->time, DateTimeInterface);
-	DATE_CHECK_INITIALIZED(dateobj2->time, DateTime);
+	DATE_CHECK_INITIALIZED(dateobj2->time, DateTimeInterface);
 	timelib_update_ts(dateobj1->time, NULL);
 	timelib_update_ts(dateobj2->time, NULL);
 
@@ -4396,7 +4409,7 @@ PHP_METHOD(DatePeriod, __construct)
 	
 	zend_replace_error_handling(EH_THROW, NULL, &error_handling TSRMLS_CC);
 	if (zend_parse_parameters_ex(ZEND_PARSE_PARAMS_QUIET, ZEND_NUM_ARGS() TSRMLS_CC, "OOl|l", &start, date_ce_interface, &interval, date_ce_interval, &recurrences, &options) == FAILURE) {
-		if (zend_parse_parameters_ex(ZEND_PARSE_PARAMS_QUIET, ZEND_NUM_ARGS() TSRMLS_CC, "OOO|l", &start, date_ce_interface, &interval, date_ce_interval, &end, date_ce_date, &options) == FAILURE) {
+		if (zend_parse_parameters_ex(ZEND_PARSE_PARAMS_QUIET, ZEND_NUM_ARGS() TSRMLS_CC, "OOO|l", &start, date_ce_interface, &interval, date_ce_interval, &end, date_ce_interface, &options) == FAILURE) {
 			if (zend_parse_parameters_ex(ZEND_PARSE_PARAMS_QUIET, ZEND_NUM_ARGS() TSRMLS_CC, "s|l", &isostr, &isostr_len, &options) == FAILURE) {
 				php_error_docref(NULL TSRMLS_CC, E_WARNING, "This constructor accepts either (DateTimeInterface, DateInterval, int) OR (DateTimeInterface, DateInterval, DateTime) OR (string) as arguments.");
 				zend_restore_error_handling(&error_handling TSRMLS_CC);

tests/classes/bug65768.phpt

@@ -0,0 +1,36 @@
+--TEST--
+Bug #65768: date_diff accepts only DateTime instance even though docs say about DateTimeInterface
+--INI--
+date.timezone=Europe/London
+--FILE--
+<?php
+
+$dt1 = new DateTime("2010-10-20");
+$dti1 = new DateTimeImmutable("2010-10-25");
+$dti2 = new DateTimeImmutable("2010-10-28");
+
+$diff1 = $dt1->diff($dti1);
+echo $diff1->y, " ", $diff1->m, " ", $diff1->d, " ",
+     $diff1->h, " ", $diff1->i, " ", $diff1->s, "\n";
+
+$diff2 = $dti1->diff($dti2);
+echo $diff2->y, " ", $diff2->m, " ", $diff2->d, " ",
+     $diff2->h, " ", $diff2->i, " ", $diff2->s, "\n";
+
+$diff3 = date_diff($dt1, $dti2);
+echo $diff3->y, " ", $diff3->m, " ", $diff3->d, " ",
+     $diff3->h, " ", $diff3->i, " ", $diff3->s, "\n";
+
+class cdt1 extends DateTime implements DateTimeInterface {}
+
+class cdt2 extends DateTimeImmutable implements DateTimeInterface {}
+
+class cdt3 implements DateTimeInterface {}
+
+?>
+--EXPECTF--
+0 0 5 0 0 0
+0 0 3 0 0 0
+0 0 8 0 0 0
+
+Fatal error: DateTimeInterface can't be implemented by user classes in %sbug65768.php on line %d