PHP: rfc:random_ext

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====== PHP RFC: Move to RNG functions into ext/random ======
  * Version: 1.1
  * Date: 2021-09-07
  * Author: Go Kudo <zeriyoshi@gmail.com>
  * Status: Decline

===== Note =====

This RFC has been moved to Decline, as it is no longer needed due to changes in the proposal.

===== Introduction =====

This is due to the historical background, starting with lcg.c / php_lcg.h, the first implementation of the linear congruential generator (LCG), followed by rand.c / php_rand.c, which calls the libc random number implementation, and the Mersenne Twister implementation. mt_rand.c / php_mt_rand.h, an implementation of the Mersenne Twister, and random.c / php_random.h, a CSPRNG implementation, respectively, in the ext/standard extension.

The rand.c / php_rand.h to call the libc implementation is no longer relevant due to its alias to the Mersenne Twister in PHP 7.1, and is left for compatibility only.

RNGs are a frequently used feature in various implementations, and it is suggested that RNG-related functionality be carved out of the ext/standard extension and kindly made into an ext/random extension to reduce complexity and allow for future extensibility.

===== Proposal =====

Create a new ext/random extension and move all the following functions of the ext/standard extension.

Userland Functions:

  * lcg_value()
  * srand()
  * rand()
  * mt_srand()
  * mt_rand()
  * random_int()
  * random_bytes()

Internal APIs:

  * php_random_int_throw()
  * php_random_int_silent()
  * php_combined_lcg()
  * php_srand()
  * php_rand()
  * php_mt_srand()
  * php_mt_rand()
  * php_mt_rand_range()
  * php_mt_rand_common()
  * php_random_bytes()
  * php_random_int()

These features are provided in a single random.c / php_random.h, and ext/random is always bundled with all builds of PHP, as is ext/standard.

In addition, header files containing the following contents will continue to be provided for extensions and downstream projects that previously depended on ext/standard features. These are a transitional measure until the next major version and will be removed in the future.

  * standard/php_lcg.h
  * standard/php_rand.h
  * standard/php_mt_rand.h
  * standard/php_random.h

===== Backward Incompatible Changes =====
none

===== Proposed PHP Version(s) =====
PHP 8.2

===== RFC Impact =====
==== To SAPIs ====
none

==== To Existing Extensions ====
Will need to change the including header file.

==== To Opcache ====
none

==== New Constants ====
none

==== php.ini Defaults ====
none

===== Open Issues =====
none

===== Patches and Tests =====
https://github.com/php/php-src/pull/7473

===== Implementation =====
https://github.com/php/php-src/pull/7473

===== References =====
https://externals.io/message/115918
https://wiki.php.net/rfc/rng_extension
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