The GNU Compiler Collection (GCC) support for the C23 programming language standard is now considered "essentially feature-complete" with GCC 15. As such they are preparing to enable the C23 language version (using the GNU23 dialect) by default for the C language version of GCC when not otherwise specified.

Preparations are now underway to set the default C language version of GCC to GNU23 as the GNU dialect of C23. Or in other words, implying -std=gnu23 when no other C standard is specified.

Joseph Myers of Red Hat sent out [1]a patch to begin preparing for the -std=gnu23 default.

"Now that C23 support is essentially feature-complete, I'd like to switch the default language version for C compilation to -std=gnu23.

This requires updating a large number of testcases that fail with the new language version if left unchanged. In this patch, update most of the tests for which there is a safe change that works both before and after the update to default language version - typically adding the option -std=gnu17 or -Wno-old-style-definition to the tests..."

Jakub Jelinek of Red Hat's compiler team as well separately started [2]this mailing list thread today for updating the compiler support page on cppreference.com for reflecting the latest C23/GNU23 additions to GCC. There are a few C23 features currently marked as unimplemented in GCC 15 but their status is being pursued.

So it's looking like soon GCC could be setting C23/GNU23 as its default C language version. It's in mid-November when [3]GCC 15 "stage one" feature development is wrapping up to focus on bug-fixing ahead of GCC 15.1 stable debuting early next year.



[1] https://gcc.gnu.org/pipermail/gcc-patches/2024-October/665612.html

[2] https://gcc.gnu.org/pipermail/gcc/2024-October/244954.html

[3] https://www.phoronix.com/news/GCC-15-Stage-1-Ends-November