This is an auto-filed bug because dev-lang/xsb does not respect CFLAGS. 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. NOTE: To reproduce this issue you may want to add "-frecord-gcc-switches" to CFLAGS/CXXFLAGS/FFLAGS/FCFLAGS. If this is not something about c/c++ context see this bug as an hint to hide the QA warning (with QA_FLAGS_IGNORED) where is not possible to respect CFLAGS.
Created attachment 643226 [details] build.log build log and emerge --info
This is now fixed in git with xsb-3.8.0. Thanks for reporting this bug.