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    Backward incompatible changes

    Throw on passing too few function arguments

    Previously, a warning would be emitted for invoking user-defined functions with too few arguments. Now, this warning has been promoted to an Error exception. This change only applies to user-defined functions, not internal functions. For example:

    <?php
    function test($param){}
    test();

    위 예제의 출력 예시:

    Fatal error: Uncaught ArgumentCountError: Too few arguments to function test(), 0 passed in %s on line %d and exactly 1 expected in %s:%d

    Forbid dynamic calls to scope introspection functions

    Dynamic calls for certain functions have been forbidden (in the form of $func() or array_map('extract', ...), etc). These functions either inspect or modify another scope, and present with them ambiguous and unreliable behavior. The functions are as follows:

    <?php
    (function () {
            $func = 'func_num_args';
            $func();
    })();

    위 예제의 출력:

    Warning: Cannot call func_num_args() dynamically in %s on line %d

    Invalid class, interface, and trait names

    The following names cannot be used to name classes, interfaces, or traits:

    • void
    • iterable

    Numerical string conversions now respect scientific notation

    Integer operations and conversions on numerical strings now respect scientific notation. This also includes the (int) cast operation, and the following functions: intval() (where the base is 10), settype(), decbin(), decoct(), and dechex().

    Fixes to mt_rand() algorithm

    mt_rand() will now default to using the fixed version of the Mersenne Twister algorithm. If deterministic output from mt_srand() was relied upon, then the MT_RAND_PHP with the ability to preserve the old (incorrect) implementation via an additional optional second parameter to mt_srand().

    rand() aliased to mt_rand() and srand() aliased to mt_srand()

    rand() and srand() have now been made aliases to mt_rand() and mt_srand(), respectively. This means that the output for the following functions have changes: rand(), shuffle(), str_shuffle(), and array_rand().

    Disallow the ASCII delete control character in identifiers

    The ASCII delete control character (0x7F) can no longer be used in identifiers that are not quoted.

    error_log changes with syslog value

    If the error_log ini setting is set to syslog, the PHP error levels are mapped to the syslog error levels. This brings finer differentiation in the error logs in contrary to the previous approach where all the errors are logged with the notice level only.

    Do not call destructors on incomplete objects

    Destructors are now never called for objects that throw an exception during the execution of their constructor. In previous versions this behavior depended on whether the object was referenced outside the construcor (e.g. by an exception backtrace).

    call_user_func() handling of reference arguments

    call_user_func() will now always generate a warning upon calls to functions that expect references as arguments. Previously this depended on whether the call was fully qualified.

    Additionally, call_user_func() and call_user_func_array() will no longer abort the function call in this case. The "expected reference" warning will be emitted, but the call will proceed as usual.

    The empty index operator is not supported for strings anymore

    Applying the empty index operator to a string (e.g. $str[] = $x) throws a fatal error instead of converting silently to array.

    Removed ini directives

    The following ini directives have been removed:

    • session.entropy_file
    • session.entropy_length
    • session.hash_function
    • session.hash_bits_per_character

    Array ordering when elements are automatically created during by reference assignments has changed

    The order of the elements in an array has changed when those elements have been automatically created by referencing them in a by reference assignment. For example:

    <?php
    $array     = [];
    $array["a"] =& $array["b"];
    $array["b"] = 1;
    var_dump($array);
    ?>

    Output of the above example in PHP 7.0:

    array(2) {
  ["a"]=>
  &int(1)
  ["b"]=>
  &int(1)
}

    Output of the above example in PHP 7.1:

    array(2) {
  ["b"]=>
  &int(1)
  ["a"]=>
  &int(1)
}

    Sort order of equal elements

    The internal sorting algorithm has been improved, what may result in different sort order of elements, which compare as equal, than before.

    Note:

    Don't rely on the order of elements which compare as equal; it might change anytime.

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    User Contributed Notes 5 notes

    up
    45
    love at sickpeople dot se
    7 years ago
    For anyone migrating from 5.x to 7.1:

    About "Array ordering when elements are automatically created during by reference assignments has changed" on this page

    (http://php.net/manual/en/migration71.incompatible.php#migration71.incompatible.array-order)

    The behaviour of 7.1 is THE SAME as of PHP 5. It is only 7.0 that differs.

    See https://3v4l.org/frbUc

    <?php

    $array     = [];
    $array["a"] =& $array["b"];
    $array["b"] = 1;
    var_dump($array);
    up
    36
    kees at twekaers dot net
    7 years ago
    The backwards incompatible change 'The empty index operator is not supported for strings anymore' has a lot more implications than just a fatal error on the following code

    <?php
    $a     = "";
    $a[] = "hello world";
    var_dump($a);
    ?>

    This will give a fatal error in 7.1 but will work as expected in 7.0 or below and give you: (no notice, no warning)

    array(1) {
      [0]=>
      string(11) "hello world"
    }

    However, the following is also changed:

    <?php
    $a     = "";
    $a[0] = "hello world";
    var_dump($a);
    // 7.1: string(1) "h"
    // pre-7.1: array(1) {  [0]=>  string(11) "hello world" }

    $a = "";
    $a[5] = "hello world";
    var_dump($a);
    // 7.1: string(6) "     h"
    // pre-7.1: array(1) {  [0]=>  string(11) "hello world" }

    ?>
    up
    18
    m dot r dot sopacua at gmail dot com
    7 years ago
    "OMFG! Why was session.hash_function removed?!? Dude!"

    https://wiki.php.net/rfc/session-id-without-hashing

    There. Saved ya a search.
    up
    2
    mikem at gmail dot com
    7 years ago
    ArgumentCountError - this modification is the main reason to avoid this version on older projects.
    up
    1
    david at artefactual dot com
    5 years ago
    Regarding the ArgumentCountError, PHP 7.1+ does still support user functions with a variable number of arguments, using the "func(...$args) {}" syntax, see: https://www.php.net/manual/en/functions.arguments.php#functions.variable-arg-list
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