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bug#11894: 24.1.50; [PATCH] diff-apply-hunk can be off by 1 line when th
bug#11894: 24.1.50; [PATCH] diff-apply-hunk can be off by 1 line when the hunk is 0-context pure removal
Wed, 18 Jul 2012 21:25:10 +0400
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On 18.07.2012 16:53, Stefan Monnier wrote:
Not sure if we can rely on the line number being always off by 1 in such
hunks (there's no insertion, so, technically, the second line number in the
header could be arbitrary), but at least 3 versions of diff across
2 different OSes work the same in this regard.
This looks like a bug in those versions of diff (not that I know
a non-buggy version, tho). Could you report it to GNU diffutils.
As per Andreas' comment, this is probably not a bug.
Note that if you try to create such hunk with `diff-split-hunk' (by slicing
it off a bigger hunk), the line number won't be off by 1.
Oh, right, so there is a "version of diff" that doesn't have this bug ;-)
Yep, and I'll use it as a workaround if this bug won't be fixed.
Maybe that's a bug in `diff-split-hunk'.
I doubt it. At least `patch' seems to agree with diff-mode.el:
% diff -c0 footest1 footest2 |patch -o footest3 footest1
patching file footest1
patch: **** replacement text or line numbers mangled in hunk at line 8
`info diff` says: "For proper operation, `patch' typically needs at
least two lines of context.", so this just may be a documented problem
nobody cares about.
- (goto-char (point-min)) (forward-line (1- (string-to-number line)))
+ (let ((line-num (string-to-number line)))
+ ;; When the hunk is pure deletion, line number is off by 1.
+ (when (string= (if reverse (car old) (car new)) "")
+ (incf line-num))
+ (goto-char (point-min)) (forward-line (1- line-num)))
Context/unified diffs with 0 context are pretty rare, so I'd rather not
work around such a bug if I don't really have to.
I'm fine either way, just wanted to report this.