尽管本节没有明确说明，但每个新函数、类、interface、枚举或常量都可能导致抛出重复声明 Error。
exit()（和 die()）语言结构现在的行为更像函数。这意味着现在可以传递
callable，受 strict_types 声明语句的影响，并且现在执行往常的类型强制，而不是将任何非整数值转换为字符串。
不再允许在 __clone() 里间接修改 readonly 属性，例如 $ref = &$this->readonly。这在 readonly
初始化中已禁止，并且是“克隆期间 readlony 重新初始化”实现中的一个疏忽。
上传文件和 tempnam() 函数创建的文件名现在为 13 个字节。总长度仍取决于平台。
多个 resource 已迁移到 object。除非另有说明，否则 is_resource()
的返回值检查应替换为 false 检查。
DBA 函数现在接受并返回
Dba\Connection 对象，而不是
dba_connection resource。
ODBC 函数现在接受并返回
Odbc\Result 对象，而不是
odbc_result resource。
ODBC 函数现在接受并返回
Odbc\Connection 对象，而不是
odbc_connection resource。
SoapClient::$httpurl 属性现在是
Soap\Url 对象，而不是
soap_url resource。
检查使用 is_resource()（即
is_resource($client->httpurl)）应该替换为检查
是否为 null（即 $client->httpurl !== null）。
SoapClient::$sdl 属性现在是
Soap\Sdl 对象，而不是
soap_sdl resource。
检查使用 is_resource()（即
is_resource($client->sdl)）应该替换为检查
是否为 null（即 $client->sdl !== null）。
添加了因编程错误（即将无效值提供给参数）而触发新的警告和异常。
如果 timeout 参数小于 0 或大于
PHP_INT_MAX，curl_multi_select()
现在会抛出 ValueError。
当传入无效的 quality
时，imagejpeg(), imagewebp(), imagepng(), imageavif()
现在抛出 ValueError。
当传递无效的 speed 参数值时，imageavif()
现在将抛出 ValueError。
如果 width 或 height
参数溢出，imagescale() 现在将抛出 ValueError。
当传入无效的 mode 参数时，imagescale()
现在将抛出 ValueError。
如果 sub 或 plus
参数溢出，imagefilter() 现在使用 IMG_FILTER_SCATTER
过滤器将抛出 ValueError。
如果 domain 是空字符串，bind_textdomain_codeset(), textdomain(), d()*gettext() 现在 抛出 ValueError。
resourcebundle_get()、ResourceBundle::get() 和在 ResourceBundle 对象上访问偏移量现在会抛出：
如果 locale 无效，则
IntlDateFormatter::__construct() 抛出
ValueError。
如果 locale 无效，则
NumberFormatter::__construct() 抛出
ValueError。
mb_encode_numericentity() 和
mb_decode_numericentity() 现在检测
map 是否仅由 int
构成，如果不是，则抛出 ValueError。
如果 type 无效，mb_http_input()
现在始终抛出 ValueError。
mb_http_output() 现在检测
encoding 是不是不包含 null 字节，如果包含，会抛出
ValueError。
当 row 小于或等于 0
时，odbc_fetch_row() 返回 false。在这种情况下会发出 warning。
pcntl_sigprocmask()、pcntl_sigwaitinfo() 和 pcntl_sigtimedwait() 函数现在会抛出：
signals 数组为空，则抛出 ValueError（如果
mode SIG_SETMASK 则
pcntl_sigprocmask() 除外）
signals 数组的值不是 int，则抛出 TypeError
signals 数组不是有效的信号编号，则抛出 ValueError
如果 mode 不是 SIG_BLOCK、SIG_UNBLOCK
或 SIG_SETMASK 中的一个，pcntl_sigprocmask()
现在将抛出 ValueError。
pcntl_sigtimedwait() 函数现在将抛出：
seconds 小于 0 则抛出 ValueError
nanoseconds 小于 0 或者大于
1e9，则抛出 ValueError
seconds 和 nanoseconds
是 0，则抛出 ValueError
使用非 XML 对象调用 simplexml_import_dom() 将抛出 TypeError 而不是 ValueError
round() 函数现在会验证 mode
的值，如果无效，则抛出 ValueError。之前无效模式会解释为 PHP_ROUND_HALF_UP。
当 separator 和 enclosure 参数值的长度不为一个字节，或者
escape 参数值不为一个字节或者空字符串，str_getcsv() 现在将抛出
ValueError。该行为已与 fputcsv() 和
fgetcsv() 行为相同。
如果 mode 无效，php_uname()
函数现在会抛出 ValueError。
unserialize() 的 "allowed_classes"
选项如果不是类名 array，现在会抛出 TypeError
和 ValueError。
Passing an invalid character encoding to XMLReader::open() or XMLReader::XML() now throws a ValueError.
Passing a string containing null bytes previously emitted a warning and now throws a ValueError.
Passing a string containing null bytes previously emitted a warning and now throws a ValueError.
XSLTProcessor::setParameter() will now throw a ValueError when its arguments contain null bytes. This never actually worked correctly in the first place, which is why it throws an exception now.
Calling XSLTProcessor::importStyleSheet() with a non-XML object now throws a TypeError instead of a ValueError.
Failure to call a PHP function callback during evaluation now throws instead of emitting a warning.
Some DOM methods previously returned false or a
DOMException with code
DOM_PHP_ERR if a new node could not be allocated.
They now consistently throw a DOMException
with code DOM_INVALID_STATE_ERR.
This situation is extremely unlikely and the probability of being affected
is low.
As a result DOMImplementation::createDocument()
now has a tentative return type of DOMDocument
instead of DOMDocument|false.
Previously, DOMXPath objects could be cloned, but resulted in an unusable object. This is no longer possible, and cloning a DOMXPath object now throws an Error.
The DOMImplementation::getFeature() method has been removed.
The GMP class is now final and cannot be extended anymore.
On invalid strings (those with encoding errors), mb_substr() now interprets character indices in the same manner as most other mbstring functions. This means that character indices returned by mb_strpos() can be passed to mb_substr().
For SJIS-Mac (MacJapanese) strings, character indices passed to mb_substr() now refer to the indices of the Unicode codepoints which are produced when the string is converted to Unicode. This is significant because around 40 SJIS-Mac characters convert to a sequence of multiple Unicode codepoints.
The unused and undocumented constant
MYSQLI_SET_CHARSET_DIR has been removed.
The MYSQLI_STMT_ATTR_PREFETCH_ROWS constant has been
removed. The feature is unavailable with mysqlnd.
The MYSQLI_CURSOR_TYPE_FOR_UPDATE and
MYSQLI_CURSOR_TYPE_SCROLLABLE constants have been
removed. This functionality was never implemented,
neither with mysqlnd nor with libmysql.
The unused MYSQLI_TYPE_INTERVAL constant, which is
currently a stub and an alias for MYSQLI_TYPE_ENUM,
has been removed.
The error code reported for MySQL server wait timeouts has been changed from
2006 to 4031 for MySQL server
versions 8.0.24 and above.
The maximum value of the
opcache.interned_strings_buffer
setting on 64bit architectures is now 32767.
Previously it was 4095.
The default configuration values for the JIT changed from
opcache.jit=tracing
and opcache.jit_buffer_size=0
to opcache.jit=disable
and opcache.jit_buffer_size=64M, respectively.
This does not affect the default observable behavior, as the JIT is still disabled by default. However, it is now disabled through the opcache.jit setting, rather than opcache.jit_buffer_size. This may affect users who previously enabled JIT through opcache.jit_buffer_size exclusively, without also specifying a JIT mode using opcache.jit. To enable JIT compilation, set the opcache.jit config value accordingly.
If JIT compilation is enabled, PHP will now exit with a fatal error on startup if the initialization of the JIT compiler failed for any reason.
The pcntl_sigprocmask(),
pcntl_sigwaitinfo(), and
pcntl_sigtimedwait() functions now always
return false on failure.
In some case previously it could return the value -1.
The bundled pcre2lib has been updated to version 10.44.
As a consequence, this means {,3} is now recognized
as a quantifier instead of as text.
Furthermore, the meaning of some character classes in UCP mode has changed.
Consult the » PCRE2 Changelog
for a full changelog.
The Pdo\Dblib::ATTR_STRINGIFY_UNIQUEIDENTIFIER and
Pdo\Dblib::ATTR_DATETIME_CONVERT attributes now act as
boolean attributes instead of integer attributes.
Thus setting the attribute via PDO::setAttribute()
and retrieving it via PDO::getAttribute() expects
and or return a bool.
The PDO::ATTR_AUTOCOMMIT attribute now act as
boolean attributes instead of integer attributes.
Thus setting the attribute via PDO::setAttribute()
and retrieving it via PDO::getAttribute() expects
and or return a bool.
The extension now exposes some Firebird C++ APIs, therefore building this extension now requires a C++ compiler. Moreover, the extension must now be compiled against fbclient 3.0 or higher.
The PDO::ATTR_AUTOCOMMIT,
PDO::ATTR_EMULATE_PREPARES, and
PDO::MYSQL_ATTR_DIRECT_QUERY attributes now act as
boolean attributes instead of integer attributes.
Thus setting the attribute via PDO::setAttribute()
and retrieving it via PDO::getAttribute() expects
and or return a bool.
The DSN's credentials, when set, are given priority over their PDO constructor counterparts, being closer to the documentation states.
SimpleXMLElement is not only a representation of an XML element, but it is also a RecursiveIterator. Prior to PHP 8.4.0, some of its methods (e.g. SimpleXMLElement::asXML() or SimpleXMLElement::getName()) and casting such instances to string would implicitly reset the iterator.
This could cause unexpected infinite loops as the iterator was rewound. For example:
<?php
$xmlString = "<root><a><b>1</b><b>2</b><b>3</b></a></root>";
$xml = simplexml_load_string($xmlString);
$nodes = $xml->a->b;
foreach ($nodes as $nodeData) {
echo "nodeData: " . $nodeData . "\n";
$xml = $nodes->asXml();
}would result in an infinite loop.
nodeData: 1 nodeData: 2 nodeData: 2 nodeData: 2 nodeData: 2 nodeData: 2 nodeData: 2 // ...
However, this behavior has now been corrected, and a SimpleXMLElement will no longer implicitly reset the iterator data, unless explicitly rewound. Meaning the previous example would now result in:
nodeData: 1 nodeData: 2 nodeData: 3
SoapClient::$typemap is now an array
rather than a resource.
Checks using is_resource() (i.e.
is_resource($client->typemap)) should be
replaced with checks for null (i.e. $client->typemap !== null).
The SOAP extension gained an optional dependency on the session extension. If PHP is built without the session extension and with the --enable-rtld-now configure flag enabled, startup errors will now occur if the SOAP extension is also used. To solve this either don't use rtld-now or load the session extension.
When using strcspn() with
characters being the empty string,
the length of the string is now returned instead of incorrectly stopping
at the first null byte.
http_build_query() now correctly handles backed enums.
stream_bucket_make_writeable() and stream_bucket_new() will now return a StreamBucket instance instead of an instance of stdClass.
Failures in the constructor now throw exceptions rather than emitting warnings and having a broken object.
The xml_set_()*_handler()
functions now declare and check for an effective
signature of callable|string|null for the
handler parameters.
Moreover, values of type string that correspond to method names,
of object set with xml_set_object() are now checked to
see if the method exists on the class of the previously passed object.
This means that xml_set_object() must now always be
called prior to setting method names as callables.
Passing an empty string to disable the handler is still allowed,
but deprecated.
However, as xml_set_object() and passing non-callable strings is deprecated. It is recommended to change such instances with a callable referring to the method directly.