Bug 159067 – prepare-ChangeLog lists methods that were not modified when deleting other methods

• Status: RESOLVED
• Resolution: DUPLICATE
• Component: Tools / Tests

[David Kilzer (:ddkilzer)]

In the patch for Bug 158819 (Attachment #281464 [details]), many methods are listed in the ChangeLog as having been modified when they were not.

This appears to be a bug in prepare-ChangeLog that occurs when an adjacent method is deleted in full.

See also:
Bug 144829: prepare-ChangeLog lists renamed functions and methods as having been deleted
Bug 148437: prepare-ChangeLog lists modified methods as having been deleted

[David Kilzer (:ddkilzer)]

Also, this issue appears to only happen on Subversion repositories.  When I applied the patch in Bug 158819 (Attachment #281464 [details]) on a git-svn repository at r202384, then ran prepare-ChangeLog, I didn't get the extraneous functions listed in the commit log.

[Alexey Proskuryakov]

Related to this, we may want to consider using a better diff tool in svn-create-patch and in webkit-patch. There must be something written in a scripting language, so that it doesn't need compiling.

[Alexey Proskuryakov]

Some interesting options mentioned in discussion here: https://news.ycombinator.com/item?id=11915287

[David Kilzer (:ddkilzer)]

(In reply to comment #1)
> Also, this issue appears to only happen on Subversion repositories.  When I
> applied the patch in Bug 158819 (Attachment #281464 [details]) on a git-svn
> repository at r202384, then ran prepare-ChangeLog, I didn't get the
> extraneous functions listed in the commit log.

I have an untested hypothesis:

What could be happening is that when prepare-ChangeLog tries to grab the "pristine" (unmodified) source to determine the line ranges for functions (to compare to the local modified copy), it's actually grabbing the trunk (-rHEAD) from the svn server, where line numbers have shifted since the local working copy's revision, and that causes prepare-ChangeLog to list methods that weren't actually changed.

If this is the case, then we just need to check how prepare-ChangeLog is grating the pristine source version, and make sure it's grabbing the pristine source relative to the local working copy (not to trunk on the svn server).

[Daniel Bates]

(In reply to comment #1)
> Also, this issue appears to only happen on Subversion repositories.  When I
> applied the patch in Bug 158819 (Attachment #281464 [details]) on a git-svn
> repository at r202384, then ran prepare-ChangeLog, I didn't get the
> extraneous functions listed in the commit log.

Notice that prepare-ChangeLog's function overlap logic of assumes a unified diff with 0 lines of context. When using a Git checkout, prepare-ChangeLog generates such a diff by <https://trac.webkit.org/browser/trunk/Tools/Scripts/prepare-ChangeLog?rev=204544#L1973>. But when using a Subversion checkout, prepare-ChangeLog generates a unified diff with 3 lines of context per the default behavior of svn diff and by <https://trac.webkit.org/browser/trunk/Tools/Scripts/prepare-ChangeLog?rev=204544#L1970>.

[Daniel Bates]

*** This bug has been marked as a duplicate of bug 148437 ***

[Aakash Jain]

This issue doesn't look Duplicate of 148437 to me. Bug 148437 list modified methods incorrectly (as deleted), but this bug is about methods which were not at all modified.

I hit this issue almost every single time while running prepare-ChangeLog (even when I do not delete any method). prepare-ChangeLog creates a lot more entries then the functions I modify. Usually all the nearby functions from the function which I modify are listed by prepare-ChangeLog as modified. Probably your logic about "unified diff with 3 lines of context" might explain it.

[Daniel Bates]

(In reply to comment #7)
> This issue doesn't look Duplicate of 148437 to me. Bug 148437 list modified
> methods incorrectly (as deleted), but this bug is about methods which were
> not at all modified.
> 
> I hit this issue almost every single time while running prepare-ChangeLog
> (even when I do not delete any method). prepare-ChangeLog creates a lot more
> entries then the functions I modify. Usually all the nearby functions from
> the function which I modify are listed by prepare-ChangeLog as modified.
> Probably your logic about "unified diff with 3 lines of context" might
> explain it.

I suspect that the root cause of both this bug and bug #148437 are the same. Therefore, I duped this bug to bug #148437.

*** This bug has been marked as a duplicate of bug 148437 ***