https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94905
--- Comment #5 from Dr. Jürgen Sauermann <bug-apl at gnu dot org> --- Hi, above is one preprocessed source file for which the warning has occurred. g++ version was 11.0.0 (latest from github). Compiled with: g++ -E -DHAVE_CONFIG_H -I. -I.. -Wall -I sql -Werror -I/usr/include -I/usr/include/postgresql -rdynamic -g -O2 -MT apl-Bif_F12_FORMAT.o -MD -MP -MF .deps/apl-Bif_F12_FORMAT.Tpo -c -o apl-Bif_F12_FORMAT.cxx Interestingly, if I compile the file apl-Bif_F12_FORMAT.cxx separately (with -Wall) then the warning does not show up. Not sure how I can create a testcase file other than preprocessing or minimizing it.