git-gui: Improve the merge check interface for branch deletion.

Just like how we split out the local and remote branches into two
different pick lists for branch creation, we should do the same
thing for branch deletion.  This means that  there are really 3
modes of operation here:

  * delete only if merged into designated local branch;
  * delete only if merged into designated tracking (remote) branch;
  * delete no matter what

So we now use radio buttons to select between these operations.

We still default to checking for merge into the current branch,
as that is probably the most commonly used behavior. It also is
what core Git's command line tools do.

Signed-off-by: Shawn O. Pearce <spearce@spearce.org>

git-gui.sh

@@ -1867,16 +1867,34 @@ proc do_create_branch {} {
 
 proc do_delete_branch_action {w} {
 	global all_heads
-	global delete_branch_checkhead delete_branch_head
+	global delete_branch_checktype delete_branch_head delete_branch_trackinghead
+
+	set check_rev {}
+	switch -- $delete_branch_checktype {
+	head {set check_rev $delete_branch_head}
+	tracking {set check_rev $delete_branch_trackinghead}
+	always {set check_rev {:none}}
+	}
+	if {$check_rev eq {:none}} {
+		set check_cmt {}
+	} elseif {[catch {set check_cmt [exec git rev-parse --verify "${check_rev}^0"]}]} {
+		tk_messageBox \
+			-icon error \
+			-type ok \
+			-title [wm title $w] \
+			-parent $w \
+			-message "Invalid check revision: $check_rev"
+		return
+	}
 
 	set to_delete [list]
 	set not_merged [list]
 	foreach i [$w.list.l curselection] {
 		set b [$w.list.l get $i]
 		if {[catch {set o [exec git rev-parse --verify $b]}]} continue
-		if {$delete_branch_checkhead} {
-			if {$b eq $delete_branch_head} continue
-			if {[catch {set m [exec git merge-base $o $delete_branch_head]}]} continue
+		if {$check_cmt ne {}} {
+			if {$b eq $check_rev} continue
+			if {[catch {set m [exec git merge-base $o $check_cmt]}]} continue
 			if {$o ne $m} {
 				lappend not_merged $b
 				continue
@@ -1885,7 +1903,7 @@ proc do_delete_branch_action {w} {
 		lappend to_delete [list $b $o]
 	}
 	if {$not_merged ne {}} {
-		set msg "The following branches are not completely merged into $delete_branch_head:
+		set msg "The following branches are not completely merged into $check_rev:
 
  - [join $not_merged "\n - "]"
 		tk_messageBox \
@@ -1896,7 +1914,7 @@ proc do_delete_branch_action {w} {
 			-message $msg
 	}
 	if {$to_delete eq {}} return
-	if {!$delete_branch_checkhead} {
+	if {$delete_branch_checktype eq {always}} {
 		set msg {Recovering deleted branches is difficult.
 
 Delete the selected branches?}
@@ -1940,10 +1958,11 @@ Delete the selected branches?}
 
 proc do_delete_branch {} {
 	global all_heads tracking_branches current_branch
-	global delete_branch_checkhead delete_branch_head
+	global delete_branch_checktype delete_branch_head delete_branch_trackinghead
 
-	set delete_branch_checkhead 1
+	set delete_branch_checktype head
 	set delete_branch_head $current_branch
+	set delete_branch_trackinghead {}
 
 	set w .branch_editor
 	toplevel $w
@@ -1985,21 +2004,37 @@ proc do_delete_branch {} {
 		regsub ^refs/(heads|remotes)/ $b {} b
 		lappend all_trackings $b
 	}
+	set all_trackings [lsort -unique $all_trackings]
+	if {$all_trackings ne {} && $delete_branch_trackinghead eq {}} {
+		set delete_branch_trackinghead [lindex $all_trackings 0]
+	}
 
 	labelframe $w.validate \
-		-text {Only Delete If} \
+		-text {Delete Only If} \
 		-font font_ui
-	frame $w.validate.head
-	checkbutton $w.validate.head.r \
-		-text {Already Merged Into:} \
-		-variable delete_branch_checkhead \
+	radiobutton $w.validate.head_r \
+		-text {Merged Into Local Branch:} \
+		-value head \
+		-variable delete_branch_checktype \
 		-font font_ui
-	eval tk_optionMenu $w.validate.head.m delete_branch_head \
-		$all_heads \
-		[lsort -unique $all_trackings]
-	pack $w.validate.head.r -side left
-	pack $w.validate.head.m -side left
-	pack $w.validate.head -padx 5 -fill x -expand 1
+	eval tk_optionMenu $w.validate.head_m delete_branch_head $all_heads
+	grid $w.validate.head_r $w.validate.head_m -sticky w
+	radiobutton $w.validate.tracking_r \
+		-text {Merged Into Tracking Branch:} \
+		-value tracking \
+		-variable delete_branch_checktype \
+		-font font_ui
+	eval tk_optionMenu $w.validate.tracking_m \
+		delete_branch_trackinghead \
+		$all_trackings
+	grid $w.validate.tracking_r $w.validate.tracking_m -sticky w
+	radiobutton $w.validate.always_r \
+		-text {Always (Do not perform merge checks)} \
+		-value always \
+		-variable delete_branch_checktype \
+		-font font_ui
+	grid $w.validate.always_r -columnspan 2 -sticky w
+	grid columnconfigure $w.validate 1 -weight 1
 	pack $w.validate -anchor nw -fill x -pady 5 -padx 5
 
 	bind $w <Visibility> "grab $w; focus $w"