[PATCH v2] gitk: Use the --submodule option for displaying diffs when available

[Jens Lehmann <Jens.Lehmann@web.de>]

Instead of just showing not-quite-helpful SHA-1 pairs in the diff display
of a submodule gitk will display the first lines of the corresponding
commit messages (similar to the output of 'git submodule summary') when
the underlying git installation supports this. That makes it much easier
to evaluate the changes, as it eliminates the need to start a gitk inside
the submodule and use the superprojects hashes there to find out what the
commits are about.

This patch applies to 'next' - which will be 1.6.6 or 1.7.0 when merged -
and uses the new --submodule option of git diff when a version of 1.6.6 or
higher is detected to achieve a more human readable output of submodule
differences in gitk.

Signed-off-by: Jens Lehmann <Jens.Lehmann@web.de>
---


Thanks for the review of the first version of this patch. I tried to
address all the issues raised and moved the additions of the --submodule
flag to the getblobdiffs procedure, where the --textconv flag is handled
too.


 gitk-git/gitk |   21 ++++++++++++++++++++-
 1 files changed, 20 insertions(+), 1 deletions(-)

diff --git a/gitk-git/gitk b/gitk-git/gitk
index a0214b7..b06cac7 100644
--- a/gitk-git/gitk
+++ b/gitk-git/gitk
@@ -7343,7 +7343,11 @@ proc getblobdiffs {ids} {
     if {[package vcompare $git_version "1.6.1"] >= 0} {
 	set textconv "--textconv"
     }
-    set cmd [diffcmd $ids "-p $textconv -C --cc --no-commit-id -U$diffcontext"]
+    set submodule {}
+    if {[package vcompare $git_version "1.6.6"] >= 0} {
+	set submodule "--submodule"
+    }
+    set cmd [diffcmd $ids "-p $textconv $submodule  -C --cc --no-commit-id -U$diffcontext"]
     if {$ignorespace} {
 	append cmd " -w"
     }
@@ -7481,6 +7485,21 @@ proc getblobdiffline {bdf ids} {
 	    set diffnparents [expr {[string length $ats] - 1}]
 	    set diffinhdr 0

+	} elseif {![string compare -length 10 "Submodule " $line]} {
+	    # start of a new submodule
+	    if {[string compare [$ctext get "end - 4c" end] "\n \n\n"]} {
+		$ctext insert end "\n";     # Add newline after commit message
+	    }
+	    set curdiffstart [$ctext index "end - 1c"]
+	    lappend ctext_file_names ""
+	    set fname [string range $line 10 [expr [string last " " $line] - 1]]
+	    lappend ctext_file_lines $fname
+	    makediffhdr $fname $ids
+	    $ctext insert end "\n$line\n" filesep
+	} elseif {![string compare -length 3 "  >" $line]} {
+	    $ctext insert end "$line\n" dresult
+	} elseif {![string compare -length 3 "  <" $line]} {
+	    $ctext insert end "$line\n" d0
 	} elseif {$diffinhdr} {
 	    if {![string compare -length 12 "rename from " $line]} {
 		set fname [string range $line [expr 6 + [string first " from " $line] ] end]
-- 
1.6.5.2.182.g3d976.dirty