CascadiaPHP 2024

Other Changes

Performance Improvements

PHP Core

A specialized VM opcode for the array_key_exists() function has been added, which improves performance of this function if it can be statically resolved. In namespaced code, this may require writing \array_key_exists() or explicitly importing the function.

Regular Expressions (Perl-Compatible)

When preg_match() in UTF-8 mode ("u" modifier) is repeatedly called on the same string (but possibly different offsets), it will only be checked for UTF-8 validity once.

Changes to INI File Handling

zend.exception_ignore_args is a new INI directive for including or excluding arguments from stack traces generated from exceptions.

opcache.preload_user is a new INI directive for specifying the user account under which preloading code is execute if it would otherwise be run as root (which is not allowed for security reasons).

Migration to pkg-config

A number of extensions have been migrated to exclusively use pkg-config for the detection of library dependencies. Generally, this means that instead of using --with-foo-dir=DIR or similar only --with-foo is used. Custom library paths can be specified either by adding additional directories to PKG_CONFIG_PATH or by explicitly specifying compilation options through FOO_CFLAGS and FOO_LIBS.

The following extensions and SAPIs are affected:

  • CURL:
    • --with-curl no longer accepts a directory.
  • Enchant:
    • --with-enchant no longer accepts a directory.
  • FPM:
    • --with-fpm-systemd now uses only pkg-config for libsystem checks. The libsystemd minimum required version is 209.
  • GD:
    • --with-gd becomes --enable-gd (whether to enable the extension at all) and --with-external-gd (to opt into using an external libgd, rather than the bundled one).
    • --with-png-dir has been removed. libpng is required.
    • --with-zlib-dir has been removed. zlib is required.
    • --with-freetype-dir becomes --with-freetype
    • --with-jpeg-dir becomes --with-jpeg
    • --with-webp-dir becomes --with-webp
    • --with-xpm-dir becomes --with-xpm
  • IMAP:
    • --with-kerberos-systemd no longer accepts a directory.
  • Intl:
    • --with-icu-dir has been removed. If --enable-intl is passed, then libicu is always required.
  • LDAP:
    • --with-ldap-sasl no longer accepts a directory.
  • Libxml:
    • --with-libxml-dir has been removed.
    • --enable-libxml becomes --with-libxml.
    • --with-libexpat-dir has been renamed to --with-expat and no longer accepts a directory.
  • Litespeed:
    • --with-litespeed becomes --enable-litespeed.
  • Mbstring:
    • --with-onig has been removed. Unless --disable-mbregex has been passed, libonig is required.
  • ODBC:
    • --with-iodbc no longer accepts a directory.
    • --with-unixODBC without a directory now uses pkg-config (preferred). Directory is still accepted for old versions without libodbc.pc.
  • OpenSSL:
    • --with-openssl no longer accepts a directory.
  • PCRE:
    • --with-pcre-regex has been removed. Instead --with-external-pcre is provided to opt into using an external PCRE library, rather than the bundled one.
  • PDO_SQLite:
    • --with-pdo-sqlite no longer accepts a directory.
  • Readline:
    • --with-libedit no longer accepts a directory.
  • Sodium:
    • --with-sodium no longer accepts a directory.
  • SQLite3:
    • --with-sqlite3 no longer accepts a directory.
  • XSL:
    • --with-xsl no longer accepts a directory.
  • Zip:
    • --with-libzip has been removed.
    • --enable-zip becomes --with-zip.

CSV escaping

fputcsv(), fgetcsv(), SplFileObject::fputcsv(), SplFileObject::fgetcsv(), and SplFileObject::setCsvControl() now accept an empty string as $escape argument, which disables the proprietary PHP escaping mechanism.

The behavior of str_getcsv() has been adjusted accordingly (formerly, an empty string was identical to using the default).

SplFileObject::getCsvControl() now may also return an empty string for the third array element, accordingly.

Data Filtering

The filter extension no longer exposes --with-pcre-dir for Unix builds and can now reliably be built as shared when using ./configure


The behavior of imagecropauto() in the bundled libgd has been synced with that of system libgd:

  • IMG_CROP_DEFAULT is no longer falling back to IMG_CROP_SIDES
  • Threshold-cropping now uses the algorithm of system libgd

The default $mode parameter of imagecropauto() has been changed to IMG_CROP_DEFAULT; passing -1 is now deprecated.

imagescale() now supports aspect ratio preserving scaling to a fixed height by passing -1 as $new_width.

HASH Message Digest Framework

The hash extension cannot be disabled anymore and is always an integral part of any PHP build, similar to the date extension.


The intl extension now requires at least ICU 50.1.

ResourceBundle now implements Countable.

Lightweight Directory Access Protocol

Support for nsldap and umich_ldap has been removed.


All libxml-based extensions now require libxml 2.7.6 or newer.

Multibyte String

The oniguruma library is no longer bundled with PHP, instead libonig needs to be available on the system. Alternatively --disable-mbregex can be used to disable the mbregex component.


The --disable-opcache-file and --enable-opcache-file configure options have been removed in favor of the opcache.file_cache INI directive.

Password Hashing

The password_hash() and password_needs_rehash() functions now accept nullable string and int for $algo argument.


Installation of PEAR (including PECL) is no longer enabled by default. It can be explicitly enabled using --with-pear. This option is deprecated and may be removed in the future.


The numeric values of the modifier constants (IS_ABSTRACT, IS_DEPRECATED, IS_EXPLICIT_ABSTRACT, IS_FINAL, IS_IMPLICIT_ABSTRACT, IS_PRIVATE, IS_PROTECTED, IS_PUBLIC, and IS_STATIC) on the ReflectionClass, ReflectionFunction, ReflectionMethod, ReflectionObject, and ReflectionProperty classes have changed.


SimpleXMLElement now implements Countable.


The bundled libsqlite has been removed. To build the SQLite3 extension a system libsqlite3 ≥ 3.7.4 is now required. To build the PDO_SQLite extension a system libsqlite3 ≥ 3.5.0 is now required.

Serialization and unserialization of SQLite3, SQLite3Stmt and SQLite3Result is now explicitly forbidden. Formerly, serialization of instances of these classes was possible, but unserialization yielded unusable objects.

The @param notation can now also be used to denote SQL query parameters.


The bundled libzip library has been removed. A system libzip >= 0.11 is now necessary to build the zip extension.

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User Contributed Notes 3 notes

Florent H (Sowapps)
4 years ago
This version brings an important changes with the directive zend.exception_ignore_args set to On by default.
In all stack traces, the args key is now missing.
All php frameworks have to handle this to report errors & exceptions.
ohcc at 163 dot com
4 years ago
As of PHP 7.4, an exception thrown within the user-defined shutdown function can be caught by the user-defined exception handler.

$level, $error, $file, $line){
0 === error_reporting()){
throw new
ErrorException($error, -1, $level, $file, $line);

$error = error_get_last();
throw new
ErrorException($error['message'], -1, $error['type'], $error['file'], $error['line']);

// ... more code ...

santi at mola dot io
3 years ago
Note for internals/extensions:

Many opcode values changed between PHP 7.3 and 7.4, so most documentation resources are outdated in that regard. You can look the definitions at Zend/zend_vm_opcodes.h in php-src. For example, ZEND_ECHO changes from 40 to 136.

While opcode changes happen in a lot of PHP versions, the change in 7.4 is quite significant.
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