On 2018-11-25 17:29, James Almer wrote: > On 11/25/2018 10:01 PM, Michael Niedermayer wrote: >> On Sat, Nov 24, 2018 at 01:02:02PM -0800, Mark Harris wrote: >>> The alloc_size attribute is valid only on functions that return a >>> pointer. GCC 9 (not yet released) warns about invalid usage: >>> >>> ./libavutil/mem.h:342:1: warning: 'alloc_size' attribute ignored on a >>> function returning int' [-Wattributes] >>> 342 | av_alloc_size(2, 3) int av_reallocp_array(void *ptr, size_t nmemb, >>> size_t size); >>> | ^~~~~~~~~~~~~ >> >> Is the attribute also useless on all other compilers ? > > The attribute is only used when __GNUC__ is defined, so it should for > any such compiler (GCC and Clang). > > https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html >
The Clang documentation does note a minor difference from GCC, but both GCC and Clang agree that it applies to functions that return a pointer. The size is the number of bytes allocated at that pointer. It doesn't support an indirect reference to the allocated memory; if it did it would likely need an additional parameter to indicate which argument was the indirect reference. https://clang.llvm.org/docs/AttributeReference.html#alloc-size - Mark _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
