Software: groff, private repository that is updated regulary with GNU gnulib.
with gnulib_modules=" git-version-gen havelib wcwidth fprintf-posix snprintf vsnprintf stdint setlocale vsnprintf-posix warnings gen-header manywarnings mkstemp fmod getcwd putenv strcase strerror strtol stdckdint assert assert-h idx string strings nullptr " Changes in "lib/dirfd.c" this year are from commit 3f0950f65ab (2023-04-27 01:42:25 +0200). The compiler reports: CC lib/libgnu_a-dirfd.o ../lib/dirfd.c: In function 'rpl_dirfd': ../lib/dirfd.c:83:13: warning: unused parameter 'dir_p' [-Wunused-parameter] 83 | dirfd (DIR *dir_p) | ~~~~~^~~~~ CC lib/libgnu_a-dirname-lgpl.o From the code, I can't see how the paremeter can not get used while the code is traversed.