'__config_site' file not found on Ubuntu noble for libc++-18

[mpusz]

For about a week now, libc++-18 does not provide the /usr/include/c++/v1/__config_site header file.

Installed with:

sudo apt install libc++-18-dev libc++abi-18-dev

libc++-19 is OK.

Compilation error log:

In file included from /usr/bin/../include/c++/v1/exception:79:
In file included from /usr/bin/../include/c++/v1/__assert:13:
In file included from /usr/bin/../include/c++/v1/__assertion_handler:13:
/usr/bin/../include/c++/v1/__config:13:10: fatal error: '__config_site' file not found

More info can be found here: https://github.com/mpusz/mp-units/actions/runs/9597865534/job/26467862493.

[ldionne]

I don't think this is a libc++ issue, we didn't change anything on our side. This seems like a packaging issue to me.

@mpusz Are you able to find __config_site anywhere in your include tree?

[mpusz]

No, it is not there. The file is missing.

[ldionne]

@tstellar Is LLVM responsible for those libc++-18-dev packages on Ubuntu?

[tstellar]

@sylvestre maintains this.

[ilovepi]

@petrhosek, didn't we introduce some changes around the libcxx multilib build to address this? I have a vague recollection that this cropped up for us about a month ago, but I don't recall the full story.

[chloro-pn]

I encountered the same problem on my virtual machine.
os : 20.04.1-Ubuntu
you can find the __config_site here (Replace your installation path):

[ldionne]

@mpusz reports that the file isn't anywhere in his include tree, which would point to a different issue though. It looks like a packaging issue to me, not a libc++ issue.

[mpusz]

Yes, there is __config_site in /usr/lib/llvm-18/include/x86_64-pc-linux-gnu/c++/v1 but this is not the directory linked during installation:

/usr/include/c++$ ls -al
total 96
drwxr-xr-x  8 root root  4096 Jun 21 17:38 .
drwxr-xr-x 75 root root 20480 Jun 21 17:38 ..
drwxr-xr-x 12 root root  4096 May 27 11:30 14
lrwxrwxrwx  1 root root    32 Jun 15 09:01 v1 -> ../../lib/llvm-18/include/c++/v1

There is no __config_site file in /usr/include/c++/v1.

[sammyj85]

Same issue: Ubuntu LLVM version 18.1.8.

Package is llvm-toolchain-jammy-18

[mpusz]

Do we have any update on this issue? CI runs fail because of it for two weeks now 😢

For example: https://github.com/mpusz/mp-units/actions/runs/9732819135