This is an auto-filled bug because dev-libs/libelf calls ar directly.
The issue was originally discovered on arm64, but it may be reproducible on other arches as well.
If you think that a different summary clarifies the issue better, feel free to change it.
Attached build log and emerge --info.
This issue has been reproduced by setting the AR variable and by removing the /usr/bin/ar binary.
Created attachment 634202 [details]
build log and emerge --info