https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95496
Paul Eggert <eggert at cs dot ucla.edu> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |eggert at cs dot ucla.edu --- Comment #10 from Paul Eggert <eggert at cs dot ucla.edu> --- Created attachment 58838 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=58838&action=edit 12-line file illustrating the false positive I ran into a similar problem today when building bleeding-edge GNU Make with gcc (GCC) 14.1.1 20240701 (Red Hat 14.1.1-7) on x86-64. Compile the attached 12-line file with: gcc -O2 -fsanitize=undefined -Wall -S v.i and the false positive is: v.i: In function ‘file_timestamp_sprintf’: v.i:7:3: warning: null destination pointer [-Wformat-overflow=] 7 | sprintf (p, ".%09d", ns); | ^~~~~~~~~~~~~~~~~~~~~~~~ I guess the moral of the story is: don't combine -fsanitize=undefined with -Wall, which is unfortunate.