git-gui: Use git diff --submodule when available

Doing so is much faster and gives the same output.
Here are some numbers:

$ time git submodule summary
real	0m0.219s
user	0m0.050s
sys	0m0.111s

$ time git diff --submodule
real	0m0.012s
user	0m0.003s
sys	0m0.009s

Signed-off-by: Jens Lehmann <Jens.Lehmann@web.de>
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>

diff --git a/lib/diff.tcl b/lib/diff.tcl
index 066755b864b587e073a820aa2eb729a6c930d7b0..cd5b74c7280de3471dca9669c80cd2e105cb46bd 100644 (file)
--- a/lib/diff.tcl
+++ b/lib/diff.tcl
@@ -281,6 +281,15 @@ proc start_show_diff {cont_info {add_opts {}}} {
                }
        }
 
+       if {[string match {160000 *} [lindex $s 2]]
+        || [string match {160000 *} [lindex $s 3]]} {
+               set is_submodule_diff 1
+
+               if {[git-version >= "1.6.6"]} {
+                       lappend cmd --submodule
+               }
+       }
+
        lappend cmd -p
        lappend cmd --no-color
        if {$repo_config(gui.diffcontext) >= 1} {
@@ -296,9 +305,7 @@ proc start_show_diff {cont_info {add_opts {}}} {
                lappend cmd $path
        }
 
-       if {[string match {160000 *} [lindex $s 2]]
-        || [string match {160000 *} [lindex $s 3]]} {
-               set is_submodule_diff 1
+       if {$is_submodule_diff && [git-version < "1.6.6"]} {
                if {$w eq $ui_index} {
                        set cmd [list submodule summary --cached -- $path]
                } else {
@@ -387,7 +394,9 @@ proc read_diff {fd cont_info} {
                        }
                } elseif {$is_submodule_diff} {
                        if {$line == ""} continue
-                       if {[regexp {^\* } $line]} {
+                       if {[regexp {^Submodule } $line]} {
+                               set tags d_@
+                       } elseif {[regexp {^\* } $line]} {
                                set line [string replace $line 0 1 {Submodule }]
                                set tags d_@
                        } else {