The ancient programming language of the Linux kernel is about to be replaced with a much newer one. It is currently written by the C89 code; it is the 1989 version of the C language. Linus Torvalds is targetting to upgrade it to the C11; 2011 version.
From 1989 to 2011
The 1989 version of the C programming language is not capable of declaring variables in loops
The necessity of the new version of the C programming language in the Linux kernel has appeared while fixing a bug. While fixing a potential security bug, Linus Torvalds has faced a problem with declaring a variable in a loop. C89 is not capable of doing that while C99 (1999 version) can. But Torvalds has decided to go way up to C11 (2011 version) since C99 was not popular and C11 has some cool features as well such as standardized multithreading.
Taking Linux kernel programming language from C89 to C11 sounds like something hard to achieve but because the C language is backward compatible, it is actually pretty easy. Torvalds is aiming to make the move until the Linux kernel 5.18 merge window which is likely to happen in mid-late March 2022.