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lavu/video_enc_params: Avoid relying on an undefined C construct 

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].

Clang recently got a change to identify this as an issue [2];
initially it was treated as a hard error, but it was soon after
softened into a warning under the -Wgnu-offsetof-extensions option
(not enabled automatically as part of -Wall though).

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://reviews.llvm.org/D133574

Signed-off-by: Martin Storsjö <martin@martin.st>
This commit is contained in:
Martin Storsjö 2023-01-16 00:20:24 +02:00
parent 806ecace91
commit 01f58f3646
1 changed files with 5 additions and 5 deletions
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10
libavutil/video_enc_params.c
View File

@ -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;