Copying part of my comment on the previous discussion:

I'm also a bit put off by adding a meaningless member on non-Linux systems. Trying to think of alternatives...

I'm going to hold off on this for a bit while I think about stuff related to #190. :-)

☔ The latest upstream changes (presumably #362) made this pull request unmergeable. Please resolve the merge conflicts.

Coming back to this, I'd be happier if the extra variant and methods were cfg'ed to only be present on Linux, or whichever systems support it.

I was thinking about this again, and how to handle this in a way that isn't terrible across platforms. What would you think about adding another entry to the WaitStatus enum, like WaitStatus::PtraceEvent? Then the if status::stopped case could check for this and return that value. It'd still be useless on non-Linux systems, but it seems like it'd be easier to work with a platform-conditional enum variant than a conditional field inside an enum variant. #[cfg(...)] seems to work OK on enum variants and match arms:
https://play.rust-lang.org/?gist=15519135f09722bf6d8653912592c079&version=stable&backtrace=0

Sigh, I still haven't returned to this (haven't actually got a chance to touch Rust for a long time already). I understand that this can be frustrating, and also -- if anyone wants to continue this work please do so!

I hope I can return to this someday...

@abbradar this is not frustrating at all! And thanks for your contributions :-)

@luser

What would you think about adding another entry to the WaitStatus enum, like WaitStatus::PtraceEvent?

Could you sketch out what you mean a tiny bit?

Oh, I can do you one better! I actually wrote the patch because I wanted to use it for something, I just forgot to do anything with it. Here it is:
luser@92a3cf7

Here's the code I wrote that uses it:
https://github.com/luser/tracetree/blob/master/src/main.rs#L65

I didn't actually try to make that code portable yet, but making it build should be straightforward. (Making it actually work right is probably harder).

Is this still relevant? If so, @abbradar would you be willing to update this patch?

This was superseded by #438

You can see an example of using it here: https://github.com/luser/tracetree/blob/2dcde59a9b2bd8dd6343a147a6d09f5d4428068e/src/main.rs#L141

Okay, then I'm going to close this. Thanks, @luser.