| Message ID | 20230115224741.3446965-1-martin@martin.st |
|---|---|
| State | Accepted |
| Commit | 01f58f36465a13db069641cca47fa9777f03b875 |
| Headers | show |
| Series | [FFmpeg-devel] lavu/video_enc_params: Avoid relying on an undefined C construct | expand |
| Context | Check | Description |
|---|---|---|
| yinshiyou/make_loongarch64 | success | Make finished |
| yinshiyou/make_fate_loongarch64 | success | Make fate finished |
Quoting Martin Storsjö (2023-01-15 23:47:41) > The construct of using offsetof on a (potentially anonymous) struct > defined within the offsetof expression, while supported by all > current compilers, has been declared explicitly undefined by the > C standards committee [1]. > > Current Clang git main got a patch [2] which changed this construct > into a hard error. It seems like this will be softened into a > warning [3] soon though, as it did break a fair number of projects. > > Nevertheless - in this particular case, it's trivial to fix the > code not to rely on the construct that the standards committee has > explicitly called out as undefined. > > [1] https://www.open-std.org/jtc1/sc22/wg14/www/docs/n2350.htm > [2] https://github.com/llvm/llvm-project/commit/e327b52766ed497e4779f4e652b9ad237dfda8e6 > [3] https://reviews.llvm.org/D133574#4053647 > > Signed-off-by: Martin Storsjö <martin@martin.st> > --- > libavutil/video_enc_params.c | 10 +++++----- > 1 file changed, 5 insertions(+), 5 deletions(-) > > diff --git a/libavutil/video_enc_params.c b/libavutil/video_enc_params.c > index 54bfed0ed9..33592dc128 100644 > --- a/libavutil/video_enc_params.c > +++ b/libavutil/video_enc_params.c > @@ -27,11 +27,11 @@ > AVVideoEncParams *av_video_enc_params_alloc(enum AVVideoEncParamsType type, > unsigned int nb_blocks, size_t *out_size) > { > - const size_t blocks_offset = offsetof( > - struct { > - AVVideoEncParams p; > - AVVideoBlockParams b; > - }, b); > + struct TestStruct { > + AVVideoEncParams p; > + AVVideoBlockParams b; > + }; > + const size_t blocks_offset = offsetof(struct TestStruct, b); > size_t size = blocks_offset; > AVVideoEncParams *par; > > -- > 2.34.1 LGTM
On Wed, 18 Jan 2023, Anton Khirnov wrote: > Quoting Martin Storsjö (2023-01-15 23:47:41) >> The construct of using offsetof on a (potentially anonymous) struct >> defined within the offsetof expression, while supported by all >> current compilers, has been declared explicitly undefined by the >> C standards committee [1]. >> >> Current Clang git main got a patch [2] which changed this construct >> into a hard error. It seems like this will be softened into a >> warning [3] soon though, as it did break a fair number of projects. >> >> Nevertheless - in this particular case, it's trivial to fix the >> code not to rely on the construct that the standards committee has >> explicitly called out as undefined. >> >> [1] https://www.open-std.org/jtc1/sc22/wg14/www/docs/n2350.htm >> [2] https://github.com/llvm/llvm-project/commit/e327b52766ed497e4779f4e652b9ad237dfda8e6 >> [3] https://reviews.llvm.org/D133574#4053647 >> >> Signed-off-by: Martin Storsjö <martin@martin.st> >> --- >> libavutil/video_enc_params.c | 10 +++++----- >> 1 file changed, 5 insertions(+), 5 deletions(-) >> >> diff --git a/libavutil/video_enc_params.c b/libavutil/video_enc_params.c >> index 54bfed0ed9..33592dc128 100644 >> --- a/libavutil/video_enc_params.c >> +++ b/libavutil/video_enc_params.c >> @@ -27,11 +27,11 @@ >> AVVideoEncParams *av_video_enc_params_alloc(enum AVVideoEncParamsType type, >> unsigned int nb_blocks, size_t *out_size) >> { >> - const size_t blocks_offset = offsetof( >> - struct { >> - AVVideoEncParams p; >> - AVVideoBlockParams b; >> - }, b); >> + struct TestStruct { >> + AVVideoEncParams p; >> + AVVideoBlockParams b; >> + }; >> + const size_t blocks_offset = offsetof(struct TestStruct, b); >> size_t size = blocks_offset; >> AVVideoEncParams *par; >> >> -- >> 2.34.1 > > LGTM Thanks, pushed now. // Martin
diff --git a/libavutil/video_enc_params.c b/libavutil/video_enc_params.c index 54bfed0ed9..33592dc128 100644 --- a/libavutil/video_enc_params.c +++ b/libavutil/video_enc_params.c @@ -27,11 +27,11 @@ AVVideoEncParams *av_video_enc_params_alloc(enum AVVideoEncParamsType type, unsigned int nb_blocks, size_t *out_size) { - const size_t blocks_offset = offsetof( - struct { - AVVideoEncParams p; - AVVideoBlockParams b; - }, b); + struct TestStruct { + AVVideoEncParams p; + AVVideoBlockParams b; + }; + const size_t blocks_offset = offsetof(struct TestStruct, b); size_t size = blocks_offset; AVVideoEncParams *par;
The construct of using offsetof on a (potentially anonymous) struct defined within the offsetof expression, while supported by all current compilers, has been declared explicitly undefined by the C standards committee [1]. Current Clang git main got a patch [2] which changed this construct into a hard error. It seems like this will be softened into a warning [3] soon though, as it did break a fair number of projects. Nevertheless - in this particular case, it's trivial to fix the code not to rely on the construct that the standards committee has explicitly called out as undefined. [1] https://www.open-std.org/jtc1/sc22/wg14/www/docs/n2350.htm [2] https://github.com/llvm/llvm-project/commit/e327b52766ed497e4779f4e652b9ad237dfda8e6 [3] https://reviews.llvm.org/D133574#4053647 Signed-off-by: Martin Storsjö <martin@martin.st> --- libavutil/video_enc_params.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-)