This is an auto-filed bug because x11-libs/xpa calls ar directly.
The issue was originally discovered on amd64, 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.
If you think it doesn't make sense fix these type of issues, I'd like to point out that won't be possible use a different AR implementation (like llvm-ar) by setting the AR variable. So this issue has been reproduced by setting the AR variable to x86_64-pc-linux-gnu-ar and by removing the /usr/bin/ar binary.
Created attachment 641682 [details]
build log and emerge --info
The bug has been closed via the following commit(s):
Author: David Seifert <email@example.com>
AuthorDate: 2021-03-20 11:32:41 +0000
Commit: David Seifert <firstname.lastname@example.org>
CommitDate: 2021-03-20 11:32:41 +0000
x11-libs/xpa: Port to EAPI 7
Package-Manager: Portage-3.0.17, Repoman-3.0.2
Signed-off-by: David Seifert <email@example.com>
x11-libs/xpa/files/xpa-2.1.18-makefile.patch | 44 ++++++++++++++++++++++++----
x11-libs/xpa/xpa-2.1.18.ebuild | 22 +++++++++-----
2 files changed, 52 insertions(+), 14 deletions(-)