[FFmpeg-devel] [PATCH] libavformat: Separate assertions of the form "av_assertN(a && b)" to "av_assertN(a); av_assertN(b)" for more precise diagnostics.

[Adam Richter]

This is the first of what I expect to be several patches to convert
assertions of the
form "assert(a && b)" to "assert(a); assert(b)".

Here are some reasons why I think this would be an improvement.  This
lengthy argument is not included in the patch attachment.

1. Assertion failures are often sporadic, and users who report them may
   not be in a position to efficiently narrow them down further, so it
   is important to get as much precision from each assertion failure as
   possible.

2. It is a more efficient use of developers time when a bug report
   arrives if the problem has been narrowed down that much more.  A
   new bug report may initially attract more interest, so, if the
   problem has been narrowed down that much more, it may increase the
   chance that developers may invest the time to try to resolve the
   problem, and also reduce unnecessary traffic on the developer mailing
   list about possible causes of the bug that separating the assertion
   was able to rule out.

3. It's often more readable, sometimes eliminating parentheses or
   changing multi-line conditions to separate single line conditions.

4. When using a debugger to step over an assertion failure in the
   first part of the statement, the second part is still tested.

5. Providing separate likelihood hints to the compiler in the form
   of separate assert statements does not require the compiler to
   be quite as smart to recognize that it should optimize both branches,
   although I do not know if that makes a difference for any compiler
   commonly used to compile X (that is, I suspect that they are all
   smart enough to realize is that "a && b" is likely true, then "a"
   is likely true and "b" is likely true).

I have confirmed that the resulting tree built without any apparent
complaints about the assert statements and that "make fate" completed
with a zero exit code.  I have not done any other tests though.

Thanks in advance for considering this patch.

Adam
-------------- next part --------------
A non-text attachment was scrubbed...
Name: 0001-libavformat-Separate-assertions-of-the-form-av_asser.patch
Type: text/x-diff
Size: 5825 bytes
Desc: not available
URL: <http://ffmpeg.org/pipermail/ffmpeg-devel/attachments/20190512/521e7147/attachment.patch>