Merge branch 'tb/external-diff-renamed'

* tb/external-diff-renamed:
  gitk: add external diff file rename detection

Author: j6t

gitk

@@ -3787,6 +3787,34 @@ proc external_diff_get_one_file {diffid filename diffdir} {
                "revision $diffid"]
 }
 
+proc check_for_renames_in_diff {filepath} { # renames
+    global difffilestart ctext
+
+    set filename [file tail $filepath]
+    set renames {}
+
+    foreach loc $difffilestart {
+        set loclineend [string map {.0 .end} $loc]
+        set fromlineloc "$loc + 2 lines"
+        set tolineloc "$loc + 3 lines"
+        set renfromline [$ctext get $fromlineloc [string map {.0 .end} $fromlineloc]]
+        set rentoline [$ctext get $tolineloc [string map {.0 .end} $tolineloc]]
+        if {[string equal -length 12 "rename from " $renfromline]
+            && [string equal -length 10 "rename to " $rentoline]} {
+            set renfrom [string range $renfromline 12 end]
+            set rento [string range $rentoline 10 end]
+            if {[string first $filename $renfrom] != -1
+                || [string first $filename $rento] != -1} {
+                lappend renames $renfrom
+                lappend renames $rento
+                break
+            }
+        }
+    }
+
+    return $renames
+}
+
 proc external_diff {} {
     global nullid nullid2
     global flist_menu_file
@@ -3817,8 +3845,16 @@ proc external_diff {} {
     if {$diffdir eq {}} return
 
     # gather files to diff
-    set difffromfile [external_diff_get_one_file $diffidfrom $flist_menu_file $diffdir]
-    set difftofile [external_diff_get_one_file $diffidto $flist_menu_file $diffdir]
+    set renames [check_for_renames_in_diff $flist_menu_file]
+    set renamefrom [lindex $renames 0]
+    set renameto [lindex $renames 1]
+    if {$renamefrom ne {} && $renameto ne {}} {
+        set difffromfile [external_diff_get_one_file $diffidfrom $renamefrom $diffdir]
+        set difftofile [external_diff_get_one_file $diffidto $renameto $diffdir]
+    } else {
+        set difffromfile [external_diff_get_one_file $diffidfrom $flist_menu_file $diffdir]
+        set difftofile [external_diff_get_one_file $diffidto $flist_menu_file $diffdir]
+    }
 
     if {$difffromfile ne {} && $difftofile ne {}} {
         set cmd [list [shellsplit $extdifftool] $difffromfile $difftofile]