php 8.4: Implicitly marking parameter $params as nullable is deprecated, the explicit nullable type must be used instead

[tenzap]

When running the tests of ci3 with php8.4, I get these deprecation warnings:

PHP Deprecated:  CI_Encryption::encrypt(): Implicitly marking parameter $params as nullable is deprecated, the explicit nullable type must be used instead in .../system/libraries/Encryption.php on line 372
PHP Deprecated:  CI_Encryption::decrypt(): Implicitly marking parameter $params as nullable is deprecated, the explicit nullable type must be used instead in .../system/libraries/Encryption.php on line 507
.
Deprecated: CI_Encryption::encrypt(): Implicitly marking parameter $params as nullable is deprecated, the explicit nullable type must be used instead in .../system/libraries/Encryption.php on line 372

Deprecated: CI_Encryption::decrypt(): Implicitly marking parameter $params as nullable is deprecated, the explicit nullable type must be used instead in .../system/libraries/Encryption.php on line 507

[rhickmott]

Essentially means replacing any function that allows nulls to nullable types.

such as

function base_url(string $uri = '', string $protocol = NULL, bool $use_skin = true) : string

to

function base_url(string $uri = '', ?string $protocol = NULL, bool $use_skin = true) : string

̶I̶t̶ ̶a̶l̶s̶o̶ ̶m̶e̶a̶n̶s̶ ̶t̶h̶a̶t̶ ̶a̶n̶y̶ ̶f̶u̶n̶c̶t̶i̶o̶n̶ ̶t̶h̶a̶t̶ ̶s̶p̶e̶c̶i̶f̶i̶e̶s̶ ̶p̶a̶r̶a̶m̶e̶t̶e̶r̶ ̶a̶n̶d̶ ̶r̶e̶t̶u̶r̶n̶ ̶t̶y̶p̶e̶s̶ ̶w̶i̶l̶l̶ ̶p̶r̶o̶b̶a̶b̶l̶y̶ ̶b̶r̶e̶a̶k̶ ̶b̶e̶f̶o̶r̶e̶ ̶P̶H̶P̶ ̶7̶.̶1̶?̶ ̶a̶n̶d̶ ̶g̶i̶v̶e̶n̶ ̶t̶h̶a̶t̶ ̶t̶h̶e̶ ̶t̶a̶r̶g̶e̶t̶ ̶c̶o̶m̶p̶a̶t̶i̶b̶i̶l̶i̶t̶y̶ ̶f̶o̶r̶ ̶C̶o̶d̶e̶I̶g̶n̶i̶t̶e̶r̶ ̶3̶ ̶w̶a̶s̶ ̶>̶=̶ ̶5̶.̶6̶ ̶i̶t̶ ̶w̶i̶l̶l̶ ̶p̶r̶o̶b̶a̶b̶l̶y̶ ̶m̶e̶a̶n̶ ̶t̶h̶i̶s̶ ̶v̶e̶r̶s̶i̶o̶n̶ ̶w̶i̶l̶l̶ ̶p̶r̶o̶b̶a̶b̶l̶y̶ ̶g̶e̶t̶ ̶s̶t̶u̶c̶k̶ ̶i̶n̶ ̶l̶i̶m̶b̶o̶ ̶w̶i̶t̶h̶o̶u̶t̶ ̶a̶ ̶l̶a̶r̶g̶e̶ ̶a̶m̶o̶u̶n̶t̶ ̶o̶f̶ ̶b̶r̶a̶n̶c̶h̶i̶n̶g̶ ̶f̶o̶r̶ ̶d̶i̶f̶f̶e̶r̶e̶n̶t̶ ̶f̶u̶n̶c̶t̶i̶o̶n̶s̶.̶ ̶
̶
̶O̶r̶ ̶r̶e̶m̶o̶v̶e̶ ̶t̶h̶e̶ ̶t̶y̶p̶e̶ ̶h̶i̶n̶t̶i̶n̶g̶ ̶f̶o̶r̶ ̶t̶h̶o̶s̶e̶ ̶f̶u̶n̶c̶t̶i̶o̶n̶s̶,̶ ̶n̶o̶t̶ ̶s̶u̶r̶e̶ ̶h̶o̶w̶ ̶m̶a̶n̶y̶ ̶t̶h̶e̶r̶e̶ ̶a̶r̶e̶.̶ ̶T̶h̶e̶ ̶o̶n̶c̶e̶ ̶I̶ ̶c̶a̶n̶ ̶s̶e̶e̶ ̶t̶h̶a̶t̶ ̶a̶r̶e̶ ̶o̶b̶v̶i̶o̶u̶s̶ ̶a̶r̶e̶ ̶a̶l̶l̶ ̶i̶n̶ ̶o̶u̶r̶ ̶o̶w̶n̶ ̶c̶o̶d̶e̶.̶ ̶

Edit : It seems there's many functions that take typed parameters. A couple in Encryption from what I can see but most of the ones I removed to get my own projects working were ones we added.