| Message ID | 20210214165228.11547-1-nuomi2021@gmail.com |
|---|---|
| State | New |
| Headers | show |
| Series | [FFmpeg-devel] avformat/protocols: fix discarded-qualifiers compiler warning | expand |
| Context | Check | Description |
|---|---|---|
| andriy/x86_make | success | Make finished |
| andriy/x86_make_fate | success | Make fate finished |
| andriy/PPC64_make | success | Make finished |
| andriy/PPC64_make_fate | success | Make fate finished |
Am So., 14. Feb. 2021 um 17:53 Uhr schrieb Nuo Mi <nuomi2021@gmail.com>: > > --- > libavformat/protocols.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/libavformat/protocols.c b/libavformat/protocols.c > index 7df18fbb3b..0b43f66baf 100644 > --- a/libavformat/protocols.c > +++ b/libavformat/protocols.c > @@ -111,10 +111,10 @@ const AVClass *ff_urlcontext_child_class_iterate(void **iter) > > const char *avio_enum_protocols(void **opaque, int output) > { > - const URLProtocol **p = *opaque; > + const URLProtocol *const *p = *opaque; > > p = p ? p + 1 : url_protocols; > - *opaque = p; > + *opaque = (void*)p; I suspect that this is wrong, only avconv's protocols were const. Carl Eugen
On Sun, Feb 14, 2021 at 5:58 PM Carl Eugen Hoyos <ceffmpeg@gmail.com> wrote: > Am So., 14. Feb. 2021 um 17:53 Uhr schrieb Nuo Mi <nuomi2021@gmail.com>: > > > > --- > > libavformat/protocols.c | 4 ++-- > > 1 file changed, 2 insertions(+), 2 deletions(-) > > > > diff --git a/libavformat/protocols.c b/libavformat/protocols.c > > index 7df18fbb3b..0b43f66baf 100644 > > --- a/libavformat/protocols.c > > +++ b/libavformat/protocols.c > > @@ -111,10 +111,10 @@ const AVClass > *ff_urlcontext_child_class_iterate(void **iter) > > > > const char *avio_enum_protocols(void **opaque, int output) > > { > > - const URLProtocol **p = *opaque; > > + const URLProtocol *const *p = *opaque; > > > > p = p ? p + 1 : url_protocols; > > - *opaque = p; > > + *opaque = (void*)p; > > I suspect that this is wrong, only avconv's protocols were const. > > That is not valid explanation. > Carl Eugen > _______________________________________________ > ffmpeg-devel mailing list > ffmpeg-devel@ffmpeg.org > https://ffmpeg.org/mailman/listinfo/ffmpeg-devel > > To unsubscribe, visit link above, or email > ffmpeg-devel-request@ffmpeg.org with subject "unsubscribe".
Am So., 14. Feb. 2021 um 18:00 Uhr schrieb Paul B Mahol <onemda@gmail.com>: > > On Sun, Feb 14, 2021 at 5:58 PM Carl Eugen Hoyos <ceffmpeg@gmail.com> wrote: > > > Am So., 14. Feb. 2021 um 17:53 Uhr schrieb Nuo Mi <nuomi2021@gmail.com>: > > > > > > --- > > > libavformat/protocols.c | 4 ++-- > > > 1 file changed, 2 insertions(+), 2 deletions(-) > > > > > > diff --git a/libavformat/protocols.c b/libavformat/protocols.c > > > index 7df18fbb3b..0b43f66baf 100644 > > > --- a/libavformat/protocols.c > > > +++ b/libavformat/protocols.c > > > @@ -111,10 +111,10 @@ const AVClass > > *ff_urlcontext_child_class_iterate(void **iter) > > > > > > const char *avio_enum_protocols(void **opaque, int output) > > > { > > > - const URLProtocol **p = *opaque; > > > + const URLProtocol *const *p = *opaque; > > > > > > p = p ? p + 1 : url_protocols; > > > - *opaque = p; > > > + *opaque = (void*)p; > > > > I suspect that this is wrong, only avconv's protocols were const. > > > > > That is not valid explanation. The warning is a regression since a merge commit from Clement (?), FFmpeg's protocols are not const iirc. Carl Eugen
On Sun, Feb 14, 2021 at 6:36 PM Carl Eugen Hoyos <ceffmpeg@gmail.com> wrote: > Am So., 14. Feb. 2021 um 18:00 Uhr schrieb Paul B Mahol <onemda@gmail.com > >: > > > > On Sun, Feb 14, 2021 at 5:58 PM Carl Eugen Hoyos <ceffmpeg@gmail.com> > wrote: > > > > > Am So., 14. Feb. 2021 um 17:53 Uhr schrieb Nuo Mi <nuomi2021@gmail.com > >: > > > > > > > > --- > > > > libavformat/protocols.c | 4 ++-- > > > > 1 file changed, 2 insertions(+), 2 deletions(-) > > > > > > > > diff --git a/libavformat/protocols.c b/libavformat/protocols.c > > > > index 7df18fbb3b..0b43f66baf 100644 > > > > --- a/libavformat/protocols.c > > > > +++ b/libavformat/protocols.c > > > > @@ -111,10 +111,10 @@ const AVClass > > > *ff_urlcontext_child_class_iterate(void **iter) > > > > > > > > const char *avio_enum_protocols(void **opaque, int output) > > > > { > > > > - const URLProtocol **p = *opaque; > > > > + const URLProtocol *const *p = *opaque; > > > > > > > > p = p ? p + 1 : url_protocols; > > > > - *opaque = p; > > > > + *opaque = (void*)p; > > > > > > I suspect that this is wrong, only avconv's protocols were const. > > > > > > > > That is not valid explanation. > > The warning is a regression since a merge commit from Clement (?), > FFmpeg's protocols are not const iirc. Look at every protocol definition, they are const. > > Carl Eugen > _______________________________________________ > ffmpeg-devel mailing list > ffmpeg-devel@ffmpeg.org > https://ffmpeg.org/mailman/listinfo/ffmpeg-devel > > To unsubscribe, visit link above, or email > ffmpeg-devel-request@ffmpeg.org with subject "unsubscribe".
Carl Eugen Hoyos: > Am So., 14. Feb. 2021 um 18:00 Uhr schrieb Paul B Mahol <onemda@gmail.com>: >> >> On Sun, Feb 14, 2021 at 5:58 PM Carl Eugen Hoyos <ceffmpeg@gmail.com> wrote: >> >>> Am So., 14. Feb. 2021 um 17:53 Uhr schrieb Nuo Mi <nuomi2021@gmail.com>: >>>> >>>> --- >>>> libavformat/protocols.c | 4 ++-- >>>> 1 file changed, 2 insertions(+), 2 deletions(-) >>>> >>>> diff --git a/libavformat/protocols.c b/libavformat/protocols.c >>>> index 7df18fbb3b..0b43f66baf 100644 >>>> --- a/libavformat/protocols.c >>>> +++ b/libavformat/protocols.c >>>> @@ -111,10 +111,10 @@ const AVClass >>> *ff_urlcontext_child_class_iterate(void **iter) >>>> >>>> const char *avio_enum_protocols(void **opaque, int output) >>>> { >>>> - const URLProtocol **p = *opaque; >>>> + const URLProtocol *const *p = *opaque; >>>> >>>> p = p ? p + 1 : url_protocols; >>>> - *opaque = p; >>>> + *opaque = (void*)p; >>> >>> I suspect that this is wrong, only avconv's protocols were const. >>> >>> >> That is not valid explanation. > > The warning is a regression since a merge commit from Clement (?), > FFmpeg's protocols are not const iirc. > It is irrelevant whether they are const: The above warning exists because avio_enum_protocols returns a pointer to nonconst that points to an entry of the const url_protocols array (i.e. it points to a const pointer (that points to something const, but that doesn't matter)). There are two ways to fix this: The first is by only giving the user a pointer to const which requires changing the function signature. I once sent such a patch, see https://patchwork.ffmpeg.org/project/ffmpeg/patch/20190821090438.10260-2-andreas.rheinhardt@gmail.com/. The second way requires casts. The typical way to do so is to give the user an index in the array of protocols (by casting the pointer to intptr_t). - Andreas
On Mon, Feb 15, 2021 at 2:04 AM Andreas Rheinhardt < andreas.rheinhardt@gmail.com> wrote: > Carl Eugen Hoyos: > > Am So., 14. Feb. 2021 um 18:00 Uhr schrieb Paul B Mahol < > onemda@gmail.com>: > >> > >> On Sun, Feb 14, 2021 at 5:58 PM Carl Eugen Hoyos <ceffmpeg@gmail.com> > wrote: > >> > >>> Am So., 14. Feb. 2021 um 17:53 Uhr schrieb Nuo Mi <nuomi2021@gmail.com > >: > >>>> > >>>> --- > >>>> libavformat/protocols.c | 4 ++-- > >>>> 1 file changed, 2 insertions(+), 2 deletions(-) > >>>> > >>>> diff --git a/libavformat/protocols.c b/libavformat/protocols.c > >>>> index 7df18fbb3b..0b43f66baf 100644 > >>>> --- a/libavformat/protocols.c > >>>> +++ b/libavformat/protocols.c > >>>> @@ -111,10 +111,10 @@ const AVClass > >>> *ff_urlcontext_child_class_iterate(void **iter) > >>>> > >>>> const char *avio_enum_protocols(void **opaque, int output) > >>>> { > >>>> - const URLProtocol **p = *opaque; > >>>> + const URLProtocol *const *p = *opaque; > >>>> > >>>> p = p ? p + 1 : url_protocols; > >>>> - *opaque = p; > >>>> + *opaque = (void*)p; > >>> > >>> I suspect that this is wrong, only avconv's protocols were const. > >>> > >>> > >> That is not valid explanation. > > > > The warning is a regression since a merge commit from Clement (?), > > FFmpeg's protocols are not const iirc. > > > It is irrelevant whether they are const: The above warning exists > because avio_enum_protocols returns a pointer to nonconst that points to > an entry of the const url_protocols array (i.e. it points to a const > pointer (that points to something const, but that doesn't matter)). > There are two ways to fix this: The first is by only giving the user a > pointer to const which requires changing the function signature. I once > sent such a patch, see > > https://patchwork.ffmpeg.org/project/ffmpeg/patch/20190821090438.10260-2-andreas.rheinhardt@gmail.com/ > . > The second way requires casts. The typical way to do so is to give the > user an index in the array of protocols (by casting the pointer to > intptr_t). > I think give the user an int may be better than a pointer. we do not need to change the signature and we can check the boundary. > > - Andreas > _______________________________________________ > ffmpeg-devel mailing list > ffmpeg-devel@ffmpeg.org > https://ffmpeg.org/mailman/listinfo/ffmpeg-devel > > To unsubscribe, visit link above, or email > ffmpeg-devel-request@ffmpeg.org with subject "unsubscribe".
diff --git a/libavformat/protocols.c b/libavformat/protocols.c index 7df18fbb3b..0b43f66baf 100644 --- a/libavformat/protocols.c +++ b/libavformat/protocols.c @@ -111,10 +111,10 @@ const AVClass *ff_urlcontext_child_class_iterate(void **iter) const char *avio_enum_protocols(void **opaque, int output) { - const URLProtocol **p = *opaque; + const URLProtocol *const *p = *opaque; p = p ? p + 1 : url_protocols; - *opaque = p; + *opaque = (void*)p; if (!*p) { *opaque = NULL; return NULL;