Re: [libvirt] [PATCH] build: trivial fix error: implicit declaration of function 'malloc'

On 11/22/2012 06:46 AM, Natanael Copa wrote: >> If your headers are defining this in terms of malloc(), then IMHO, >> the sched.h should be including stdlib.h on our behalf. IOW, I >> think this is a bug in the c library headers > > You are right. uclibc does this: > > #if 0 /* in uClibc we use macros */ > extern cpu_set_t *__sched_cpualloc (size_t __count) __THROW __wur; > extern void __sched_cpufree (cpu_set_t *__set) __THROW; > #else > # define __sched_cpualloc(cnt) ((cpu_set_t *)malloc(__CPU_ALLOC_SIZE(cnt))) Ouch. > # define __sched_cpufree(__set) free(__set) > #endif > > And since this is only a warning, I don't think its worth the effort. And that's where you're wrong. Using malloc() without a prototype means you are attempting to call 'int malloc(int)' instead of 'void *malloc(size_t)'; and if sizeof(size_t)>sizeof(int) (as on most 64-bit platforms), you have silently miscompiled. The warning exists for a reason, and we only have K&R C to blame that this is just a warning rather than a hard error by default (at least C++ did it right by mandating it as a hard error).