On 6/20/12, Ian Lance Taylor <iant@xxxxxxxxxx> wrote: > ohav chochmah <philomath868@xxxxxxxxx> writes: > >> #define HIDDEN "\0this string starts with a NUL" >> ... >> AFAICT, the puts and printf are both no-ops, as the C-string stops >> before it starts. yet when doing 'gcc -S tst.c -O2 -march=native' or >> even 'gcc -S tst.c -O3 -march=native', GCC generates the following: >> ... >> in short, the printf was removed but not the puts. which left me >> wondering why? > > You are describing an optimization in which GCC looks in constant string > literals passed to puts and truncates them at \0. Nobody has > implemented that optimization. It sounds like it would affect very very > very few programs, so I'm not sure why anybody would bother to implement right, but then why is the printf omitted entirely? > it. If anything I think it would be more useful to have a warning. But a warning is issued for printf (tst.c:8:5: warning: embedded ‘\0’ in format [-Wformat-contains-nul]), but not for puts. thanks.
