gitk: Fix diff this->selected and selected->this functions

The change in 8b7e5d76e836396a097bb6f61cf930ea872a7bd3, which makes
a couple of git-diff-tree calls supply only one id rather than two,
fixes the display when showing what a single commit did with dense
revlists, but broke the diff this->selected and diff selected->this
right-click menu functions.

Yann Dirson pointed this out and had a patch that fixed the diff
menu functions by passing a "singlecommit" flag around.  This fixes
it a bit differently, by making the ids and diffids variables be
either a single id, in the case of showing what a commit did, or
{oldid newid}, in the case of the diff menu functions.  That way
we can just pass $ids to git-diff-tree as is.  Most of the changes
in fact are just reversing the order of ids in $ids and $diffids,
because they used to be {child parent}, but git-diff-tree requires
old id before new id.

Signed-off-by: Paul Mackerras <paulus@samba.org>

diff --git a/gitk b/gitk
index ecc1688..e1c3954 100755 (executable)
--- a/gitk
+++ b/gitk
@@ -2165,7 +2165,7 @@ proc selectline {l isnew} {
     $cflist delete 0 end
     $cflist insert end "Comments"
     if {$nparents($id) == 1} {
-       startdiff [concat $id $parents($id)]
+       startdiff $id
     } elseif {$nparents($id) > 1} {
        mergediff $id
     }
@@ -2274,12 +2274,12 @@ proc contmergediff {ids} {
     # diff the child against each of the parents, and diff
     # each of the parents against the GCA.
     while 1 {
-       if {[lindex $ids 0] == $diffmergeid && $diffmergegca ne {}} {
-           set ids [list [lindex $ids 1] $diffmergegca]
+       if {[lindex $ids 1] == $diffmergeid && $diffmergegca ne {}} {
+           set ids [list $diffmergegca [lindex $ids 0]]
        } else {
            if {[incr diffpindex] >= $nparents($diffmergeid)} break
            set p [lindex $parents($diffmergeid) $diffpindex]
-           set ids [list $diffmergeid $p]
+           set ids [list $p $diffmergeid]
        }
        if {![info exists treediffs($ids)]} {
            set diffids $ids
@@ -2297,8 +2297,8 @@ proc contmergediff {ids} {
     if {$diffmergegca ne {}} {
        set files {}
        foreach p $parents($diffmergeid) {
-           set gcadiffs $treediffs([list $p $diffmergegca])
-           foreach f $treediffs([list $diffmergeid $p]) {
+           set gcadiffs $treediffs([list $diffmergegca $p])
+           foreach f $treediffs([list $p $diffmergeid]) {
                if {[lsearch -exact $files $f] < 0
                    && [lsearch -exact $gcadiffs $f] >= 0} {
                    lappend files $f
@@ -2311,7 +2311,7 @@ proc contmergediff {ids} {
        set files $treediffs([list $diffmergeid $p])
        for {set i 1} {$i < $nparents($diffmergeid) && $files ne {}} {incr i} {
            set p [lindex $parents($diffmergeid) $i]
-           set df $treediffs([list $diffmergeid $p])
+           set df $treediffs([list $p $diffmergeid])
            set nf {}
            foreach f $files {
                if {[lsearch -exact $df $f] >= 0} {
@@ -2788,8 +2788,7 @@ proc gettreediffs {ids} {
     global treediff parents treepending
     set treepending $ids
     set treediff {}
-    set id [lindex $ids 0]
-    if [catch {set gdtf [open "|git-diff-tree --no-commit-id -r $id" r]}] return
+    if [catch {set gdtf [open [concat | git-diff-tree --no-commit-id -r $ids] r]}] return
     fconfigure $gdtf -blocking 0
     fileevent $gdtf readable [list gettreediffline $gdtf $ids]
 }
@@ -2822,9 +2821,8 @@ proc getblobdiffs {ids} {
     global diffopts blobdifffd diffids env curdifftag curtagstart
     global difffilestart nextupdate diffinhdr treediffs
 
-    set id [lindex $ids 0]
     set env(GIT_DIFF_OPTS) $diffopts
-    set cmd [list | git-diff-tree --no-commit-id -r -p -C $id]
+    set cmd [concat | git-diff-tree --no-commit-id -r -p -C $ids]
     if {[catch {set bdf [open $cmd r]} err]} {
        puts "error getting diffs: $err"
        return
@@ -3341,7 +3339,7 @@ proc doseldiff {oldid newid} {
     $ctext conf -state disabled
     $ctext tag delete Comments
     $ctext tag remove found 1.0 end
-    startdiff [list $newid $oldid]
+    startdiff [list $oldid $newid]
 }
 
 proc mkpatch {} {