PHP 7.2 UPGRADE NOTES

1. Backward Incompatible Changes
2. New Features
3. Changes in SAPI modules
4. Deprecated Functionality
5. Changed Functions
6. New Functions
7. New Classes and Interfaces
8. Removed Extensions and SAPIs
9. Other Changes to Extensions
10. New Global Constants
11. Changes to INI File Handling
12. Windows Support
13. Other Changes


========================================
1. Backward Incompatible Changes
========================================

- Core:
  . gettype() will now return "resource (closed)" instead of "unknown type" for
    closed resources.
  . is_object() will now return true for objects of class
    __PHP_Incomplete_Class.
  . Support for Netware operating systems has been removed.
  . Casting arrays to objects (with (object) or settype()) will now convert
    integer keys to string property names. This fixes the behaviour of previous
    versions, where integer keys would become inaccessible properties with
    integer names.
  . Casting objects to arrays (with (array) or settype()), and retrieving
    object properties in an array with get_object_vars(), will now convert
    numeric string property names (that is, property names of the format
    /^(0|(-?[1-9][0-9]*))$/ where PHP_INT_MIN <= n <= PHP_INT_MAX) to integer
    keys. This fixes the behaviour of previous versions, where numeric string
    property names would become inaccessible string keys.
  . Unqualified references to undefined constants now generate a Warning instead
    of a notice. They will generate an Error in a future version of PHP.
    (https://wiki.php.net/rfc/deprecate-bareword-strings)
  . Minimum supported Windows versions are Windows 7/Server 2008 R2.
  . Initial trait property value compatibility check will no longer perform
    any casts. (Bug #74269)
  . "object" (in any case) can no longer be used as a class name.

- BCMath:
  . The bcmod() function no longer truncates fractional numbers to integers. As
    such, its behavior now follows fmod() rather than the `%` operator. For
    example `bcmod('4', '3.5')` now returns '0.5' instead of '1'.

- Hash:
  . The hash_hmac(), hash_hmac_file(), hash_pbkdf2() and hash_init() (with
    HASH_HMAC) functions no longer accept non-cryptographic hashes.

- JSON
  . The json_decode() option JSON_OBJECT_AS_ARRAY is used if the second
    parameter (assoc) is null. Previously JSON_OBJECT_AS_ARRAY was always
    ignored.

- Session:
  . Removed register_globals related code and "!" can be used as $_SESSION key name.
  . Session is made to manage session status correctly and prevents invalid operations.
    Only inappropriate codes are affected by this change. If you have problems with this,
    it means you have problem in your code.
    . Functions are made to set or return correct session status.
        session_start(), session_status(), session_regenerate_id()
    . Functions are made to return bool from null. These functions have void parameter
      and void parameter is checked.
        session_unset(), session_write_close()/session_commit(), session_abort(),
        session_reset()
    . Functions prohibit invalid operations with regard to session status and
      HTTP header status, returns correct bool return value.
        session_start(), session_set_cookie_params(), session_name(), session_module_name(),
        session_set_save_handler(), session_regenerate_id(), session_cache_limiter(),
        session_cache_expire(), session_unset(), session_destroy(),
        session_write_close()/session_commit(), session_reset()
    . INI value change by ini_set() returns update status correctly.　Invalid INI modifications
      are checked and made to fail.
        session.name, session.save_path, session.cookie_lifetime, session.cookie_path,
        session.cookie_domain, session.cookie_httponly, session.cookie_secure,
        session.use_cookies, session.use_only_cookies, session.use_strict_mode,
        session.referer_check, session.cache_limiter, session.cache_expire,
        session.lazy_write, session.save_handler, session.serialize_handler,
        session.gc_probability, session.gc_divior, session.gc_maxlifetime,
    . Some E_ERRORs are changed to E_WARNING since session status is managed correctly.
        session_start()
    . Session no longer initialize $_SESSION for invalid and useless session.
        session_start()
    . When headers are already sent and try to set new INI values, session_name(),
      session_module_name(), session_save_path(), session_cache_limiter() and
      session_cache_expire() are no longer works. Older PHPs accepts new values even
      if new values will not be effective.
      This new corrected behavior may affect command line mode CLI scripts that manage
      sessions. Use output buffer just like web applications to resolve problems on
      CLI scripts.

- Standard:
  . Sequences generated by mt_rand() and rand() for a specific seed may differ
    from PHP 7.1 on 64-bit machines. This change was necessary to resolve a
    modulo bias bug in the implementation.

========================================
2. New Features
========================================

- Core:
  . It is now possible to remove argument type annotations when overriding an
    inherited method. This complies with contravariance of method argument types
    under the Liskov Substitution Principle.
    (https://wiki.php.net/rfc/parameter-no-type-variance)
  . It is now allowed to override an abstract method with another abstract
    method in a child class.
    (https://wiki.php.net/rfc/allow-abstract-function-override)
  . A trailing comma in group use statements is now allowed.
    (https://wiki.php.net/rfc/list-syntax-trailing-commas)
  . The "object" type annotation is now supported.
    (https://wiki.php.net/rfc/object-typehint)

- DBA:
  . Implemented support for the LMDB backend.

- JSON:
  . Added JSON_INVALID_UTF8_IGNORE and JSON_INVALID_UTF8_SUBSTITUTE options for
    json_encode() and json_decode() to ignore and replace invalid UTF-8 byte
    sequences, respectively.

- OCI8:
  . Added Oracle Database Transparent Application Failover (TAF) callback support.

- PCRE:
  . Added `J` modifier for setting PCRE_DUPNAMES.
  . Added `PREG_UNMATCHED_AS_NULL` flag to allow distinguish between unmatched
    subpatterns and empty matches by reporting NULL and "" (empty string),
    respectively.

- Sodium
  . New cryptographic extension

- SQLite3:
  . Implemented writing to BLOBs.

- Standard:
  . Simplified password hashing API updated to support Argon2i hashes when PHP is compiled with libargon2
    (https://wiki.php.net/rfc/argon2_password_hash).
  . proc_nice() is now supported on Windows platforms.

- Zip:
  . read/write encrypted archive, relying on libzip 1.2.0,
    using new methods:
      ZipArchive::setEncryptionName($name, $method [, $password]);
      ZipArchive::setEncryptionIndex($index, $method [, $password]);
    and new constants:
      ZipArchive::EM_NONE
      ZipArchive::EM_AES_128
      ZipArchive::EM_AES_192
      ZipArchive::EM_AES_256
  . accept 'password' from zip stream context
  . ZipArchive implements countable, added ZipArchive::count() method.


========================================
3. Changes in SAPI modules
========================================

========================================
4. Deprecated Functionality
========================================

All the deprecated functionality listed in the following will be removed in
PHP 8.0.

- Core:
  . The track_errors ini directive has been deprecated.
  . The __autoload() mechanism has been deprecated, use spl_autoload_register()
    instead.
  . The (unset) cast has been deprecated. This does not affect the unset($var)
    language construct.
  . The create_function() function has been deprecated, use anonymous functions
    instead.
  . The each() function has been deprecated, use a foreach loop instead.
  . The $errcontext error handler argument has been deprecated. However, using
    it does not trigger a deprecation warning for technical reasons.
  
- EXIF:
  . The read_exif_data() alias has been deprecated, use exif_read_data() instead.

- GD:
  . png2wbmp() and jpeg2wbmp() have been deprecated.

- GMP:
  . The gmp_random() function has been deprecated, use gmp_random_bits() or
    gmp_random_range() instead.

- Intl:
  . INTL_IDNA_VARIANT_2003 has been deprecated; use INTL_IDNA_VARIANT_UTS46
    instead.

- Mbstring:
  . The mbstring.func_overload ini directive has been deprecated.

- Standard:
  . Calling parse_str() without the result argument has been deprecated.
  . Calling assert() with a string argument has been deprecated, use an ordinary
    expression instead.

See also: https://wiki.php.net/rfc/deprecations_php_7_2

========================================
5. Changed Functions
========================================

- Standard:
  . password_hash() can generate Argon2i hashes when the algorithm is set to PASSWORD_ARGON2I. 
    When using PASSWORD_ARGON2I, the following cost factors may be set: 'memory_cost', 'time_cost', 
    and 'threads'. These cost factors will default to 'PASSWORD_ARGON2_DEFAULT_MEMORY_COST', 
    'PASSWORD_ARGON2_DEFAULT_TIME_COST', and 'PASSWORD_ARGON2_DEFAULT_THREADS' respectively if not set.
  . password_verify() can verify Argon2i hashes.
  . password_get_info() and password_needs_rehash() can accept Argon2i hashes.
  . mail()/mb_send_mail() accept array $extra_header. Array parameter is checked against RFC 2822.
    Array format is 
    $extra_headers = [
      'Header-Name' => 'Header value',
      'Multiple' => ['One header', 'Another header'],
      'Multiline' = "FirstLine\r\n SecondLine",
    ];
  . count() now raises a warning when an invalid parameter is passed.
    Only arrays and objects implementing the Countable interface should be passed.
  . pack() and unpack() now support float and double in both little and big endian.
  . number_format() ensures zero values never contain a negative sign.

- XML:
  . utf8_encode() and utf8_decode() have been moved to the Standard extension
    as string functions.

========================================
6. New Functions
========================================

- Core:
  . Added stream_isatty().
  . Added sapi_windows_vt100_support().

- DOM:
  . DomNodeList implements Countable, added DomNodeList::count().
  . DOMNamedNodeMap implements Countable, added DOMNamedNodeMap::count().

- FTP:
  . Added ftp_append().

- GD:
  . Added imagesetclip() and imagegetclip().
  . Added imageopenpolygon().
  . Added imageresolution().
  . Added imagecreatefrombmp() and imagebmp().

- Hash:
  . Added hash_hmac_algos().

- Mbstring:
  . Added mb_chr() and mb_ord().
  . Added mb_scrub() that scrubs broken multibyte strings.

- OCI8:
  . Added oci_register_taf_callback() and oci_unregister_taf_callback() for
    Oracle Database TAF callback support.

- Sockets:
  . Added socket_addrinfo_lookup(), socket_addrinfo_connect(),
    socket_addrinfo_bind() and socket_addrinfo_explain().

- SPL:
  . Added spl_object_id().

========================================
7. New Classes and Interfaces
========================================

========================================
8. Removed Extensions and SAPIs
========================================

- Mcrypt:
  . The deprecated mcrypt extension has been moved to PECL.
  . libmcrypt has not been maintained since 2007 and the continued use of this
    extension is strongly discouraged.
  . Users are advised to use alternatives such as OpenSSL or libsodium.

========================================
9. Other Changes to Extensions
========================================

- EXIF:
   . Added extended exif tag support for the following formats: 
     Samsung, DJI, Panasonic, Sony, Pentax, Minolta, Sigma/Foveon, 
	 AGFA, Kyocera, Ricoh & Epson.
   . exif_read_data() and exif_thumbnail() now supports a passed streams as their 
     first parameter.

- GD:
  . Removed --enable-gd-native-ttf configuration option which was unused as
    of PHP 5.5.0 anyway.
  . imagegd() stores truecolor images as real truecolor images. Formerly, they
    have been converted to palette.
  . imageantialias() is now also available if compiled with a system libgd.

- Mbstring
  . mb_check_encoding() accepts array parameter. Both key and value
    encodings are checked recursively.
  . mb_convert_encoding() accepts array parameter. Only value encodings
    are converted recursively.

- PDO_OCI:
  . The '--with-pdo-oci' configure syntax no longer needs the vesion number of the
    Oracle Instant Client.

- pdo_sqlite
  . Use sqlite3_prepare_v2() and sqlite3_close_v2() functions instead of their
    legacy counterparts.

========================================
10. New Global Constants
========================================

- Core:
  . PHP_FLOAT_DIG     number of decimal digits, that can be rounded into a
                      float and back without precision loss
  . PHP_FLOAT_EPSILON smallest representable positive number x, so then
                      x + 1.0 != 1.0
  . PHP_FLOAT_MIN     min representable float number
  . PHP_FLOAT_MAX     max representable float number
  . PHP_OS_FAMILY     current operating system family

- Fileinfo:
  . FILEINFO_EXTENSION include list of possible file extensions

- GD:
  . IMG_EFFECT_MULTIPLY
  . IMG_BMP

- PCRE
  . PREG_UNMATCHED_AS_NULL

- Standard:
  . PASSWORD_ARGON2_DEFAULT_MEMORY_COST
  . PASSWORD_ARGON2_DEFAULT_TIME_COST
  . PASSWORD_ARGON2_DEFAULT_THREADS
  . PASSWORD_ARGON2I

========================================
11. Changes to INI File Handling
========================================

- sql.safe_mode
  . This INI directive has been removed.

- realpath_cache_size
  . Set to 4096k by default

- opcache.fast_shutdown
  . This INI directive has been removed. A variant of the fast_shutdown
    process has been integrated into PHP core and is always enabled for
    production builds if possible.

========================================
12. Windows Support
========================================

- Support for VT100 console mode

  On systems starting with 10.0.10586, cmd.exe supports ANSI escape sequences.
  The corresponding console mode is enabled by default on CLI on suitable
  systems. As well, the function sapi_windows_vt100_support() is provided,
  to control and query the corresponding information in the scripts.

========================================
13. Other Changes
========================================

- Build system

  Autoconf minimal version is now 2.64.
