This is an auto-filed bug because dev-db/firebird 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.
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 643184 [details]
build log and emerge --info