legacy_mbstring/mb_detect_encoding

Old behavior of mbstring(mb_detect_encoding) (PHP 8.0)

v0.2.1 2026-04-08 04:12 UTC

Requires

• php: ^8.1

LGPL-2.1-only

Extension name: ext-legacy_mbstring

Supports Zend Thread Safety (ZTS): ✅

Supports non-Thread Safe mode (NTS): ✅

Supported operating systems: no restrictions

Configure flags:

• --enable-legacy_mbstring Old behavior of mbstring support (this suggest shared only)

README

PHP 8.0 fallback mbstring functions. However, I hope without using this...

Why legacy_mbstring?

mb_detect_encoding is not have backward compatible since PHP 8.1. I'm not have interesting this function's changes behavior, but many PHP users are seems confused.

examples:

• mb_detect_encoding() results for UTF-7 differ between PHP 8.0 and 8.1 (if UTF-7 is present in the encodings list and the string contains '+' character) #10192
• mb_detect_encoding() detects UTF-8 emoji byte sequence as ISO-8859-1 since PHP 8.1 #7871

mbstring should to moving forward. However, some PHP users left behind old behavior. This fact is created that motivate it.

Instllation

I recommend using phpize.

$ git clone https://github.com/youkidearitai/legacy_mbstring
$ cd legacy_mbstring
$ phpize
$ ./configure
$ make
$ make install

Functions

legacy_mb_detect_encoding

Old behavior (<= PHP 8.0) mb_detect_encoding

legacy_mb_detect_encoding(string $string, array|string|null $encodings = null, bool $strict = false): string|false