514802 - Interdiff is missing some changes between patches

Status: NEW

(Bugzilla :: Attachments & Requests, defect)

Description

[Jesse Ruderman]

https://bugzilla.mozilla.org/attachment.cgi?oldid=395372&action=interdiff&newid=398801&headers=1 is missing some of the changes between the two patches.  For example, the two patches make different changes to nsFrameList.h, and the interdiff doesn't show anything for nsFrameList.h.

Interdiff is significantly less useful when you can't rely on it not to lie :(

bz pointed this out and asked me to file.

Comment 1

[Bobby Holley (:bholley)]

also happens here:
https://bugzilla.mozilla.org/attachment.cgi?oldid=398656&action=interdiff&newid=399614&headers=1

Comment 2

[Max Kanat-Alexander]

Note that this is most likely a bug in "interdiff" itself, which is what we're using in the backend (we actually call the binary).

Comment 3

[Boris Zbarsky [:bzbarsky]]

Max, could it be that when interdiff fails bugzilla silently ignores the error?

Comment 4

[Max Kanat-Alexander]

  That's a possibility; I can look into it. interdiff is also somewhat unreliable in various strange circumstances. I'll check it out using the two patches that Jesse posted, though.

Comment 5

[Boris Zbarsky [:bzbarsky]]

If you need some other examples where the bugzilla interdiff just silently leaves hunks out, just let me know.

Comment 6

[Max Kanat-Alexander]

Indeed, bz is correct, at least from my brief investigation. Running interdiff manually returns a valid interdiff, but it also throws:

1 out of 3 hunks FAILED -- saving rejects to file /tmp/interdiff-1.UDLniZ.rej
interdiff: Error applying patch1 to reconstructed file

My guess is that in this situation, there's something in Bugzilla or PatchReader that causes it to fail.

Comment 7

[Frédéric Buclin]

Bugzilla 3.6 is now restricted to security fixes only, and this bug got no traction for several months. We will retarget this bug once it has a patch ready for checkin.