On 24/10/17 23:34, Carl Eugen Hoyos wrote: > 2017-10-25 0:29 GMT+02:00 Mark Thompson <s...@jkqxz.net>: >> On 24/10/17 23:14, Carl Eugen Hoyos wrote: >>> 2017-10-25 0:09 GMT+02:00 Mark Thompson <g...@videolan.org>: >>>> ffmpeg | branch: master | Mark Thompson <s...@jkqxz.net> | Tue Oct 24 >>>> 22:56:48 2017 +0100| [5b2c71bb94d7cab23ee81b5c29388f5fadbcaf22] | >>>> committer: Mark Thompson >>>> >>>> cbs_mpeg2: Fix type for marker_bit reading >>>> >>>>> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=5b2c71bb94d7cab23ee81b5c29388f5fadbcaf22 >>>> --- >>>> >>>> libavcodec/cbs_mpeg2.c | 2 +- >>>> 1 file changed, 1 insertion(+), 1 deletion(-) >>>> >>>> diff --git a/libavcodec/cbs_mpeg2.c b/libavcodec/cbs_mpeg2.c >>>> index d137762227..0cac29733e 100644 >>>> --- a/libavcodec/cbs_mpeg2.c >>>> +++ b/libavcodec/cbs_mpeg2.c >>>> @@ -54,7 +54,7 @@ >>>> xui(width, name, current->name) >>>> >>>> #define marker_bit() do { \ >>>> - av_unused int one = 1; \ >>>> + av_unused uint32_t one; \ >>>> CHECK(ff_cbs_read_unsigned(ctx, rw, 1, "marker_bit", &one, 1, >>>> 1)); \ >>> >>> The commit message doesn't match the change / is this defined behaviour? >> >> It's only written and never read, so the initialisation isn't doing anything. > > I asked because I believe it was reported once that a static analyzer > protested > on passing uninitialized stuff - that was never going to be used - as > a parameter. > (But that may have been an uninitialized variable that was never used, > not a pointer.)
I don't think pointers in general can be complained about in C without knowledge of the target function - consider that there are destination pointers all over the standard library which need not be initialised, like memcpy() or scanf(). If a static analyser looks inside the called function it will find: """ int ff_cbs_read_unsigned(CodedBitstreamContext *ctx, GetBitContext *gbc, int width, const char *name, uint32_t *write_to, uint32_t range_min, uint32_t range_max) { ... stuff not involving write_to ... *write_to = value; return 0; } """ which is I think reasonably clear-cut :) Thanks, - Mark _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-devel