[PATCH] git gui: use apply --unidiff-zero when staging hunks without context

[Clemens Buchacher <drizzd@aon.at>]

git apply does not work correctly with zero-context patches. It does a
little better with --unidiff-zero.
---

This appears to fix staging hunks with zero context lines in the majority of
cases. Staging individual lines still is a problem frequently.

In any case, it's easy enough to break zero-context diff & patch like this:

echo a > victim
git add victim
echo b >> victim
git diff -U0 | git apply --cached --unidiff-zero
git diff

So before delving into this problem to deeply, I'd like to find out who
needs fixing exactly. Is there documentation defining how zero-context git
diff output should look like? Or is git apply the culprit in the bug above?

Or do we even want to support applying zero-context patches? If not, we
should detect and fail such attempts.

Clemens

 git-gui/lib/diff.tcl |   10 ++++++++--
 1 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/git-gui/lib/diff.tcl b/git-gui/lib/diff.tcl
index 52b79e4..78c1b56 100644
--- a/git-gui/lib/diff.tcl
+++ b/git-gui/lib/diff.tcl
@@ -302,12 +302,15 @@ proc read_diff {fd scroll_pos} {
 
 proc apply_hunk {x y} {
 	global current_diff_path current_diff_header current_diff_side
-	global ui_diff ui_index file_states
+	global ui_diff ui_index file_states repo_config
 
 	if {$current_diff_path eq {} || $current_diff_header eq {}} return
 	if {![lock_index apply_hunk]} return
 
 	set apply_cmd {apply --cached --whitespace=nowarn}
+	if {$repo_config(gui.diffcontext) eq 0} {
+		lappend apply_cmd --unidiff-zero
+	}
 	set mi [lindex $file_states($current_diff_path) 0]
 	if {$current_diff_side eq $ui_index} {
 		set failed_msg [mc "Failed to unstage selected hunk."]
@@ -375,12 +378,15 @@ proc apply_hunk {x y} {
 
 proc apply_line {x y} {
 	global current_diff_path current_diff_header current_diff_side
-	global ui_diff ui_index file_states
+	global ui_diff ui_index file_states repo_config
 
 	if {$current_diff_path eq {} || $current_diff_header eq {}} return
 	if {![lock_index apply_hunk]} return
 
 	set apply_cmd {apply --cached --whitespace=nowarn}
+	if {$repo_config(gui.diffcontext) eq 0} {
+		lappend apply_cmd --unidiff-zero
+	}
 	set mi [lindex $file_states($current_diff_path) 0]
 	if {$current_diff_side eq $ui_index} {
 		set failed_msg [mc "Failed to unstage selected line."]
-- 
1.6.0