core: replace header guards with #pragma once

[JerelJr]

Contribution description

Updated header files in the core directory and its subdirectories by switching from header guards to #pragma once

Testing procedure

I used this script to find and correct header files that need to be changed. Change RIOT_PATH to the directory to be fixed

Issues/PRs references

See issue #21335

[riot-ci]

Murdock results

✔️ PASSED

04dafd5 core: replace header guards with #pragma once

Success	Failures	Total	Runtime
10299	0	10299	11m:30s

Artifacts

• Documentation preview

[crasbe]

Hello @JerelJr,

First all all welcome to the RIOT community and thank you for your first contribution. :)

It seems like the changes broke something, as the CI build does not complete anymore: https://ci.riot-os.org/details/9d47c2b748804fc4820232a5810c9d0e

Generally speaking, the core is the most critical part of RIOT and therefore requires special care when handling it, which is why I added the "needs >1 ACK" label.
Therefore it would've been better to start with an area with lower impact, but we'll see what we can do now.

Today the Hard Freeze will start and the Soft Freeze is already in place, so this is not a feature that could be merged before the next release: https://forum.riot-os.org/t/release-2025-04-soft-freeze-in-effect/4497/1

Perhaps you can look at the error in the CI system to try to locate which change broke the build in the meantime :)

[JerelJr]

Thank you for your feedback!

I started with core because it seemed like a relatively small amount of file changes, but I did not consider how critical that part of the code base is. I'll make sure to keep that in mind in the future. I will look into the CI output now to see what went wrong.

[maribu]

Thanks a lot! Would you mind squashing the commits into one?

[maribu]

Since an agreement to use #pragma once has been reached in the weekly coordination, let's consider this an implicit 2nd ACK.

[maribu]

Thx a lot!