PHP RFC: Deprecations for PHP 8.0

• Date: 2019-07-23
• Author: Nikita Popov nikic@php.net, George Peter Banyard girgias@php.net
• Status: Under Discussion

The RFC proposes to deprecate the listed functionality in PHP 8.0 and remove it in PHP 9.

The following list provides a short overview of the functionality targeted for deprecation, while more detailed explanation is provided in the Proposal section:

• date_sunrise() and date_sunset()
• key(), current(), next(), prev(), and reset() on objects
• mb_check_encoding() without argument
• get_class(), get_parent_class() and get_called_class() without argument
• FILE_BINARY and FILE_TEXT constants
• t fopen mode
• Passing bool for $amountOrUpOrDown argument of IntlCalendar::roll()
• Accessing static members on traits

Each feature proposed for deprecation is voted separately and requires a 2/3 majority. All votes refer to deprecation in PHP 8.0 and removal in PHP 9.0.

These two functions have the signature:

function date_sunset(
    int $timestamp,
    int $format = SUNFUNCS_RET_STRING,
    float $latitude = ini_get("date.default_latitude"),
    float $longitude = ini_get("date.default_longitude"),
    float $zenith = ini_get("date.sunset_zenith"),
    float $gmt_offset = 0
): mixed;

This function depends on ini settings that specify the “default” latitude and longitude, a concept that makes very little sense. Additionally it requires familiarity with appropriate zenith values to use for different purposes.

date_sunset() and date_sunrise() have since been superseded by date_sun_info():

function date_sun_info(int $time, float $latitude, float $longitude): array;

This function does not use “default” latitude and longitude, and returns an associative array of multiple different definitions of the sunrise/sunset concept.

The proposal is to deprecate date_sunset() and date_sunrise() in favor of date_sun_info(). The ini settings date.default_latitude, date.default_longitude and date.sunset_zenith are marked as deprecated in the documentation. In the next major version, both the functions and the ini settings will be removed. This was initially discussed in: https://github.com/php/php-src/pull/4423.

The key() family of functions, which are used to manipulate the internal array pointer, also accept objects. In this case they work on the mangled property table. That is, using key() and friends on an object is essentially the same as using them on get_mangled_object_vars($object).

This catches many people off guard, because they expect key() etc. to integrate with the iterator interface. That is, if the passed object implements Iterator then key($object) should perform an $object→key() call. The water here have been further muddied by ArrayObject, which prior to PHP 7.4 was the only object where key() etc. did effectively integrate with the iterator interface.

There are principally two ways to resolve this: The first is to deprecate the use of key() etc on objects, and instead require people to perform an explicit (array) cast or get_mangled_object_vars() call beforehand. The other is to actually make these functions integrate with iterators. The issue I see with the latter is that we would only be able to support the Iterator interface proper, but not general Traversables: For these IteratorAggregate::getIterator(), or the internal get_iterator() handler need to be called once at the start, which is not possible through the array iteration interface, as it consists of multiple independent functions. Additionally, the prev() function cannot be implemented for iterators.

As such, the proposal is to deprecate key(), current(), next(), prev() and reset() on objects. The suggested replacement is to cast the object to array first, or call get_mangled_object_vars(), depending on what the intention is.

The mb_check_encoding() usually accepts a string and an encoding, but can also be called without arguments. The documentation says:

If it is omitted, this function checks all the input from the beginning of the request.

The implementation says:

/* FIXME: Actually check all inputs, except $_FILES file content. */
if (MBSTRG(illegalchars) == 0) {
    RETURN_TRUE;
}
RETURN_FALSE;

This FIXME does not induce a sense of confidence in this function…

Further research shows that the documentation is correct, in that any encoding checking or conversion functionality invoked during a request will increment MBSTRG(illegalchars). As such, mb_check_encoding() tells you whether any illegal encoding has been encountered at any point. My best guess is that this was intended to be used in conjunction with the encoding_translation feature, which “treats” incoming SAPI data.

Overall this functionality is confusing, and the implementation is unfinished or broken. There are no calls to mb_check_encoding() without argument in popular composer packages.

The proposal is to deprecate calling mb_check_encoding() without arguments.

In PHP 7.2, passing null to ''get_class()'' was forbidden, because this behavior was very bug prone. However, the ability to call get_class() without argument was retained. In that case get_class() is approximately the same as self::class. get_parent_class() exhibits the same behavior.

The proposal is to deprecate argument-less get_class(), get_parent_class() and get_called_class() in favor of the dedicated self::class, parent::class and static::class syntax, which was introduced in PHP 5.5. (get_called_class() only has an argument-less form, so it would be deprecated entirely.)

As a caveat, if get_parent_class() is used to check whether the class has a parent, it is necessary to use get_parent_class(self::class) instead, because parent::class will generate an error if used inside a class without parent.

These were introduced in PHP 5.2.7 for forward compatibility with PHP 6, but don't have any effect. These constants are especially confusing because fopen() supports b (binary) and t (text) modes, which do have an effect, but a completely unrelated one.

The proposal is to deprecate the FILE_BINARY and FILE_TEXT constants.

This was pointed out in: https://github.com/php/php-src/pull/5556

Next to the standard modes, fopen also accepts t and b modes, which are only meaningful on Windows. When b is used (which is the default), the file is treated as usual. If t is specified, automatic conversion between LF and CRLF line endings is performed. The documentation says:

Again, for portability, it is also strongly recommended that you re-write code that uses or relies upon the 't' mode so that it uses the correct line endings and 'b' mode instead.

The proposal is to deprecate the use of t mode in fopen(). Explicitly specifying the b mode remains supported.

There is a complication here: While fopen() itself defaults to binary mode, some other functions like proc_open() on pipe descriptors still default to text mode. The default for these functions should be swapped for PHP 8, independently of this deprecation proposal.

IntlCalendar::roll() accepts an integer which specifies how much to add to a given field. The integer can be negative to subtract.

However, it also accepts a boolean argument, in which case true is interpreted as 1 and false is interpreted as -1. This does not appear to be actually useful for anything, makes for a confusing function signature, and violates PHP's usual type coercion rules.

The proposal is to deprecate passing a boolean to this method argument.

Currently, it is possible to directly access static trait members, rather than accessing them on the class using the trait:

trait T {
    public static $foo;
}
class C {
    use T;
}
var_dump(T::$foo); // Allowed.

This is conceptually wrong, and causes various complications. For example, the meaning of self is ill-defined (which normally refers to the using class, not the trait), the behavior of static variables in methods may change depending on whether a trait method has been called prior to being used, and opcache preloading requires constant initializers in traits to be fully resolved (as they may be used directly).

There is a somewhat dated analysis of projects using this “feature” at https://github.com/php/php-src/pull/4829#issuecomment-542224541.

The proposal is to deprecate the ability to access static properties and static methods directly on traits.

For PHP 8.0 additional deprecation notices will appear. For PHP 9.0 the previously deprecated functionality will no longer be available.

The following entries were originally added to this proposal and then dropped.

The documentation says:

Note: This format is not compatible with ISO-8601, but is left this way for backward compatibility reasons. Use DateTime::ATOM or DATE_ATOM for compatibility with ISO-8601 instead.

There's a number of bug reports related to this. From what I understand, the core problem here is not that the ISO8601 format is wrong, it's just one of multiple legal ISO-8601 formats. As DateTime formats always refer to a specific format, not a set of multiple possible ones, there doesn't seem to be anything actionable here.

This was originally included on the rationale that get_browser() is much slower than userland browscap implementations. However, this is no longer the case since a PHP 7.0 patch release, see https://github.com/php/php-src/pull/2242.