Backward Incompatible Changes
PHP Core
Heredoc/Nowdoc Ending Label Interpretation
Due to the introduction of flexible heredoc/nowdoc syntax, doc strings that contain the ending label inside their body may cause syntax errors or change in interpretation. For example in:
<?php
$str = <<<FOO
abcdefg
FOO
FOO;
?>
Continue Targeting Switch issues Warning
continue statements targeting switch control flow structures will now generate a warning. In PHP such continue statements are equivalent to break, while they behave as continue 2 in other languages.
<?php
while ($foo) {
switch ($bar) {
case "baz":
continue;
// Warning: "continue" targeting switch is equivalent to
// "break". Did you mean to use "continue 2"?
}
}
?>
Strict Interpretation of Integer String Keys on ArrayAccess
Array accesses of type $obj["123"], where $obj implements ArrayAccess and "123" is an integer string literal will no longer result in an implicit conversion to integer, i.e., $obj->offsetGet("123") will be called instead of $obj->offsetGet(123). This matches existing behavior for non-literals. The behavior of arrays is not affected in any way, they continue to implicitly convert integeral string keys to integers.
Static Properties no longer separated by Reference Assignment
In PHP, static properties are shared between inheriting classes, unless the static property is explicitly overridden in a child class. However, due to an implementation artifact it was possible to separate the static properties by assigning a reference. This loophole has been fixed.
<?php
class Test {
public static $x = 0;
}
class Test2 extends Test { }
Test2::$x = &$x;
$x = 1;
var_dump(Test::$x, Test2::$x);
// Previously: int(0), int(1)
// Now: int(1), int(1)
?>
References returned by Array and Property Accesses are immediately unwrapped
References returned by array and property accesses are now unwrapped as part of the access. This means that it is no longer possible to modify the reference between the access and the use of the accessed value:
<?php
$arr = [1];
$ref =& $arr[0];
var_dump($arr[0] + ($arr[0] = 2));
// Previously: int(4), Now: int(3)
?>
Argument Unpacking of Traversables with non-Integer Keys no longer supported
Argument unpacking stopped working with Traversables with non-integer keys. The following code worked in PHP 5.6-7.2 by accident.
<?php
function foo(...$args) {
var_dump($args);
}
function gen() {
yield 1.23 => 123;
}
foo(...gen());
?>
Miscellaneous
The ext_skel utility has been completely redesigned with new options and some old options removed. This is now written in PHP and has no external dependencies.
Support for BeOS has been dropped.
Exceptions thrown due to automatic conversion of warnings into exceptions in EH_THROW mode (e.g. some DateTime exceptions) no longer populate error_get_last() state. As such, they now work the same way as manually thrown exceptions.
TypeError now reports wrong types as int and bool instead of integer and boolean, respectively.
Undefined variables passed to compact() will now be reported as a notice.
getimagesize() and related functions now report the mime type of BMP images as image/bmp instead of image/x-ms-bmp, since the former has been registered with the IANA (see » RFC 7903).
stream_socket_get_name() will now return IPv6 addresses wrapped in brackets. For example "[::1]:1337" will be returned instead of "::1:1337".
BCMath Arbitrary Precision Mathematics
All warnings thrown by BCMath functions are now using PHP's error handling. Formerly some warnings have directly been written to stderr.
bcmul() and bcpow() now return numbers with the requested scale. Formerly, the returned numbers may have omitted trailing decimal zeroes.
IMAP, POP3 and NNTP
rsh/ssh logins are disabled by default. Use imap.enable_insecure_rsh if you want to enable them. Note that the IMAP library does not filter mailbox names before passing them to the rsh/ssh command, thus passing untrusted data to this function with rsh/ssh enabled is insecure.
Multibyte String
Due to added support for named captures, mb_ereg_*() patterns using named captures will behave differently. In particular named captures will be part of matches and mb_ereg_replace() will interpret additional syntax. See Named Captures for more information.
MySQL Improved Extension
Prepared statements now properly report the fractional seconds for DATETIME, TIME and TIMESTAMP columns with decimals specifier (e.g. TIMESTAMP(6) when using microseconds). Formerly, the fractional seconds part was simply omitted from the returned values.
MySQL Functions (PDO_MYSQL)
Prepared statements now properly report the fractional seconds for
DATETIME, TIME and
TIMESTAMP columns with decimals specifier (e.g.
TIMESTAMP(6) when using microseconds). Formerly, the
fractional seconds part was simply omitted from the returned values. Please
note that this only affects the usage of PDO_MYSQL with emulated prepares turned off
(e.g. using the native preparation functionality). Statements using
connections having PDO::ATTR_EMULATE_PREPARES=TRUE
(which is the default) were not affected by the bug fixed and have already
been getting the proper fractional seconds values from the engine.
Reflection
Reflection export to string now uses int and bool instead of integer and boolean, respectively.
Standard PHP Library (SPL)
If an SPL autoloader throws an exception, following autoloaders will not be executed. Previously all autoloaders were executed and exceptions were chained.