This is an auto-filed bug because sys-apps/firejail-lts calls cc 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 CC implementation (like clang) by setting the CC variable. So this issue has been reproduced by setting the CC variable to x86_64-pc-linux-gnu-gcc and by removing the /usr/bin/cc - /usr/bin/gcc binaries.
Created attachment 642054 [details]
build log and emerge --info
The bug has been closed via the following commit(s):
Author: Dennis Lamm <email@example.com>
AuthorDate: 2020-07-23 13:14:28 +0000
Commit: Dennis Lamm <firstname.lastname@example.org>
CommitDate: 2020-08-22 10:17:48 +0000
sys-apps/firejail: don't call CC directly
Signed-off-by: Dennis Lamm <email@example.com>
.../firejail-lts/firejail-lts-0.9.56.2-r2.ebuild | 54 ++++++++++++++
sys-apps/firejail/firejail-0.9.62-1.ebuild | 82 ++++++++++++++++++++++
2 files changed, 136 insertions(+)