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 integral 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".