[PATCH 0/4] Various merge / diff tool related minor clean-ups and improvements

@@ -1325,17 +1325,24 @@ _git_diff ()
 	__git_complete_revlist_file
 }
 
+# Tools that support both merging and diffing.
 __git_mergetools_common="araxis bc3 diffuse ecmerge emerge gvimdiff
 			kdiff3 meld opendiff p4merge tkdiff vimdiff xxdiff
 "
 
+# Tools that support diffing.
+__git_difftools="$__git_mergetools_common kcompare"
+
+# Tools that support merging.
+__git_mergetools="$__git_mergetools_common tortoisemerge"
+
 _git_difftool ()
 {
 	__git_has_doubledash && return
 
 	case "$cur" in
 	--tool=*)
-		__gitcomp "$__git_mergetools_common kompare" "" "${cur##--tool=}"
+		__gitcomp "$__git_difftools" "" "${cur##--tool=}"
 		return
 		;;
 	--*)

@@ -1623,7 +1630,7 @@ _git_mergetool ()
 {
 	case "$cur" in
 	--tool=*)
-		__gitcomp "$__git_mergetools_common tortoisemerge" "" "${cur##--tool=}"
+		__gitcomp "$__git_mergetools" "" "${cur##--tool=}"
 		return
 		;;
 	--*)

@@ -1325,8 +1325,8 @@ _git_diff ()
 	__git_complete_revlist_file
 }
 
-__git_mergetools_common="diffuse ecmerge emerge kdiff3 meld opendiff
-			tkdiff vimdiff gvimdiff xxdiff araxis p4merge bc3
+__git_mergetools_common="araxis bc3 diffuse ecmerge emerge gvimdiff
+			kdiff3 meld opendiff p4merge tkdiff vimdiff xxdiff
 "
 
 _git_difftool ()

@@ -16,5 +16,11 @@ merge_cmd () {
 }
 
 translate_merge_tool_path() {
-	echo compare
+	# Make sure to use Araxis' "compare" and not e.g. ImageMagick's.
+	if ls "$(dirname "$(which compare)")"/Araxis* >/dev/null 2>&1
+	then
+		echo compare
+	else
+		echo "$1"
+	fi
 }

@@ -112,14 +112,17 @@ run_merge_tool () {
 }
 
 guess_merge_tool () {
+	# Add tools that can either do merging or diffing, but not both.
 	if merge_mode
 	then
 		tools="tortoisemerge"
 	else
 		tools="kompare"
 	fi
+
 	if test -n "$DISPLAY"
 	then
+		# Prefer GTK-based tools under Gnome.
 		if test -n "$GNOME_DESKTOP_SESSION_ID"
 		then
 			tools="meld opendiff kdiff3 tkdiff xxdiff $tools"

@@ -128,6 +131,8 @@ guess_merge_tool () {
 		fi
 		tools="$tools gvimdiff diffuse ecmerge p4merge araxis bc3"
 	fi
+
+	# Prefer vimdiff if vim is the default editor.
 	case "${VISUAL:-$EDITOR}" in
 	*vim*)
 		tools="$tools vimdiff emerge"

@@ -136,6 +141,7 @@ guess_merge_tool () {
 		tools="$tools emerge vimdiff"
 		;;
 	esac
+
 	echo >&2 "merge tool candidates: $tools"
 
 	# Loop over each candidate and stop when a valid merge tool is found.

@@ -36,9 +36,12 @@ OPTIONS
 
 -t <tool>::
 --tool=<tool>::
-	Use the diff tool specified by <tool>.  Valid values include
-	emerge, kompare, meld, and vimdiff. Run `git difftool --tool-help`
-	for the list of valid <tool> settings.
+	Use the diff tool specified by <tool>.  Valid diff tools are:
+	araxis, bc3, diffuse, ecmerge, emerge, gvimdiff, kcompare, kdiff3,
+	meld, opendiff, p4merge, tkdiff, vimdiff and xxdiff.
+
+--tool-help::
+	List the supported and available diff tools.
 +
 If a diff tool is not specified, 'git difftool'
 will use the configuration variable `diff.tool`.  If the