mergetools: add description to all diff/merge tools

The output of `git mergetool --tool-help` and `git difftool --tool-help`
only showed the `alias` of each available merge/diff tool.

It is not always obvious what tool these `aliases` end up using (ex:
`opendiff` runs `FileMerge` and `bc` runs `Beyond Compare`).

This commit adds a short description to each of them to help the user
identify the `alias` they want.

Signed-off-by: Fernando Ramos <greenfoo@u92.eu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

20 files changed, 160 insertions, 0 deletions

diff --git a/mergetools/araxis b/mergetools/araxis
index e2407b65b7..eb32a7da95 100644
--- a/mergetools/araxis
+++ b/mergetools/araxis
@@ -2,6 +2,10 @@ diff_cmd () {
 	"$merge_tool_path" -wait -2 "$LOCAL" "$REMOTE" >/dev/null 2>&1
 }
 
+diff_cmd_help () {
+	echo "Use Araxis Merge (requires a graphical session)"
+}
+
 merge_cmd () {
 	if $base_present
 	then
@@ -13,6 +17,10 @@ merge_cmd () {
 	fi
 }
 
+merge_cmd_help () {
+	echo "Use Araxis Merge (requires a graphical session)"
+}
+
 translate_merge_tool_path() {
 	echo compare
 }
diff --git a/mergetools/bc b/mergetools/bc
index 26c19d46a5..2922667ddd 100644
--- a/mergetools/bc
+++ b/mergetools/bc
@@ -2,6 +2,10 @@ diff_cmd () {
 	"$merge_tool_path" "$LOCAL" "$REMOTE"
 }
 
+diff_cmd_help () {
+	echo "Use Beyond Compare (requires a graphical session)"
+}
+
 merge_cmd () {
 	if $base_present
 	then
@@ -13,6 +17,10 @@ merge_cmd () {
 	fi
 }
 
+merge_cmd_help () {
+	echo "Use Beyond Compare (requires a graphical session)"
+}
+
 translate_merge_tool_path() {
 	if type bcomp >/dev/null 2>/dev/null
 	then
diff --git a/mergetools/codecompare b/mergetools/codecompare
index 9f60e8da65..610963d377 100644
--- a/mergetools/codecompare
+++ b/mergetools/codecompare
@@ -2,6 +2,10 @@ diff_cmd () {
 	"$merge_tool_path" "$LOCAL" "$REMOTE"
 }
 
+diff_cmd_help () {
+	echo "Use Code Compare (requires a graphical session)"
+}
+
 merge_cmd () {
 	if $base_present
 	then
@@ -13,6 +17,10 @@ merge_cmd () {
 	fi
 }
 
+merge_cmd_help () {
+	echo "Use Code Compare (requires a graphical session)"
+}
+
 translate_merge_tool_path() {
 	if merge_mode
 	then
diff --git a/mergetools/deltawalker b/mergetools/deltawalker
index ee6f374bce..efae4c285c 100644
--- a/mergetools/deltawalker
+++ b/mergetools/deltawalker
@@ -2,6 +2,10 @@ diff_cmd () {
 	"$merge_tool_path" "$LOCAL" "$REMOTE" >/dev/null 2>&1
 }
 
+diff_cmd_help () {
+	echo "Use DeltaWalker (requires a graphical session)"
+}
+
 merge_cmd () {
 	# Adding $(pwd)/ in front of $MERGED should not be necessary.
 	# However without it, DeltaWalker (at least v1.9.8 on Windows)
@@ -16,6 +20,10 @@ merge_cmd () {
 	fi >/dev/null 2>&1
 }
 
+merge_cmd_help () {
+	echo "Use DeltaWalker (requires a graphical session)"
+}
+
 translate_merge_tool_path () {
 	echo DeltaWalker
 }
diff --git a/mergetools/diffmerge b/mergetools/diffmerge
index 9b6355b98a..9b5b62d1ca 100644
--- a/mergetools/diffmerge
+++ b/mergetools/diffmerge
@@ -2,6 +2,10 @@ diff_cmd () {
 	"$merge_tool_path" "$LOCAL" "$REMOTE" >/dev/null 2>&1
 }
 
+diff_cmd_help () {
+	echo "Use DiffMerge (requires a graphical session)"
+}
+
 merge_cmd () {
 	if $base_present
 	then
@@ -13,6 +17,10 @@ merge_cmd () {
 	fi
 }
 
+merge_cmd_help () {
+	echo "Use DiffMerge (requires a graphical session)"
+}
+
 exit_code_trustable () {
 	true
 }
diff --git a/mergetools/diffuse b/mergetools/diffuse
index 5a3ae8b569..ebfaba5172 100644
--- a/mergetools/diffuse
+++ b/mergetools/diffuse
@@ -2,6 +2,10 @@ diff_cmd () {
 	"$merge_tool_path" "$LOCAL" "$REMOTE" | cat
 }
 
+diff_cmd_help () {
+	echo "Use Diffuse (requires a graphical session)"
+}
+
 merge_cmd () {
 	if $base_present
 	then
@@ -13,3 +17,7 @@ merge_cmd () {
 			"$LOCAL" "$MERGED" "$REMOTE" | cat
 	fi
 }
+
+merge_cmd_help () {
+	echo "Use Diffuse (requires a graphical session)"
+}
diff --git a/mergetools/ecmerge b/mergetools/ecmerge
index 6c5101c4f7..0d4d609874 100644
--- a/mergetools/ecmerge
+++ b/mergetools/ecmerge
@@ -2,6 +2,10 @@ diff_cmd () {
 	"$merge_tool_path" --default --mode=diff2 "$LOCAL" "$REMOTE"
 }
 
+diff_cmd_help () {
+	echo "Use ECMerge (requires a graphical session)"
+}
+
 merge_cmd () {
 	if $base_present
 	then
@@ -12,3 +16,7 @@ merge_cmd () {
 			--default --mode=merge2 --to="$MERGED"
 	fi
 }
+
+merge_cmd_help () {
+	echo "Use ECMerge (requires a graphical session)"
+}
diff --git a/mergetools/emerge b/mergetools/emerge
index d1ce513ff5..fc6892cc95 100644
--- a/mergetools/emerge
+++ b/mergetools/emerge
@@ -2,6 +2,10 @@ diff_cmd () {
 	"$merge_tool_path" -f emerge-files-command "$LOCAL" "$REMOTE"
 }
 
+diff_cmd_help () {
+	echo "Use Emacs' Emerge"
+}
+
 merge_cmd () {
 	if $base_present
 	then
@@ -17,6 +21,10 @@ merge_cmd () {
 	fi
 }
 
+merge_cmd_help () {
+	echo "Use Emacs' Emerge"
+}
+
 translate_merge_tool_path() {
 	echo emacs
 }
diff --git a/mergetools/examdiff b/mergetools/examdiff
index e72b06fc4d..6f53ca9161 100644
--- a/mergetools/examdiff
+++ b/mergetools/examdiff
@@ -2,6 +2,10 @@ diff_cmd () {
 	"$merge_tool_path" "$LOCAL" "$REMOTE" -nh
 }
 
+diff_cmd_help () {
+	echo "Use ExamDiff Pro (requires a graphical session)"
+}
+
 merge_cmd () {
 	if $base_present
 	then
@@ -11,6 +15,10 @@ merge_cmd () {
 	fi
 }
 
+merge_cmd_help () {
+	echo "Use ExamDiff Pro (requires a graphical session)"
+}
+
 translate_merge_tool_path() {
 	mergetool_find_win32_cmd "ExamDiff.com" "ExamDiff Pro"
 }
diff --git a/mergetools/guiffy b/mergetools/guiffy
index 8b23a13c41..3ed07efd16 100644
--- a/mergetools/guiffy
+++ b/mergetools/guiffy
@@ -2,6 +2,10 @@ diff_cmd () {
 	"$merge_tool_path" "$LOCAL" "$REMOTE"
 }
 
+diff_cmd_help () {
+	echo "Use Guiffy's Diff Tool (requires a graphical session)"
+}
+
 merge_cmd () {
 	if $base_present
 	then
@@ -13,6 +17,10 @@ merge_cmd () {
 	fi
 }
 
+merge_cmd_help () {
+	echo "Use Guiffy's Diff Tool (requires a graphical session)"
+}
+
 exit_code_trustable () {
 	true
 }
diff --git a/mergetools/kdiff3 b/mergetools/kdiff3
index 520cb914a1..ee8b3a0570 100644
--- a/mergetools/kdiff3
+++ b/mergetools/kdiff3
@@ -4,6 +4,10 @@ diff_cmd () {
 		"$LOCAL" "$REMOTE" >/dev/null 2>&1
 }
 
+diff_cmd_help () {
+	echo "Use KDiff3 (requires a graphical session)"
+}
+
 merge_cmd () {
 	if $base_present
 	then
@@ -22,6 +26,10 @@ merge_cmd () {
 	fi
 }
 
+merge_cmd_help () {
+	echo "Use KDiff3 (requires a graphical session)"
+}
+
 exit_code_trustable () {
 	true
 }
diff --git a/mergetools/kompare b/mergetools/kompare
index e8c0bfa678..4ce23dbe8b 100644
--- a/mergetools/kompare
+++ b/mergetools/kompare
@@ -2,10 +2,18 @@ can_merge () {
 	return 1
 }
 
+diff_cmd_help () {
+	echo "Use Kompare (requires a graphical session)"
+}
+
 diff_cmd () {
 	"$merge_tool_path" "$LOCAL" "$REMOTE"
 }
 
+merge_cmd_help () {
+	echo "Use Kompare (requires a graphical session)"
+}
+
 exit_code_trustable () {
 	true
 }
diff --git a/mergetools/meld b/mergetools/meld
index aab4ebb935..8ec0867e03 100644
--- a/mergetools/meld
+++ b/mergetools/meld
@@ -2,6 +2,10 @@ diff_cmd () {
 	"$merge_tool_path" "$LOCAL" "$REMOTE"
 }
 
+diff_cmd_help () {
+	echo "Use Meld (requires a graphical session)"
+}
+
 merge_cmd () {
 	check_meld_for_features
 
@@ -20,6 +24,10 @@ merge_cmd () {
 	fi
 }
 
+merge_cmd_help () {
+	echo "Use Meld (requires a graphical session) with optional \`auto merge\` (see \`git help mergetool\`'s \`CONFIGURATION\` section)"
+}
+
 # Get meld help message
 init_meld_help_msg () {
 	if test -z "$meld_help_msg"
diff --git a/mergetools/opendiff b/mergetools/opendiff
index b608dd6de3..44adf8f951 100644
--- a/mergetools/opendiff
+++ b/mergetools/opendiff
@@ -2,6 +2,10 @@ diff_cmd () {
 	"$merge_tool_path" "$LOCAL" "$REMOTE" | cat
 }
 
+diff_cmd_help () {
+	echo "Use FileMerge (requires a graphical session)"
+}
+
 merge_cmd () {
 	if $base_present
 	then
@@ -12,3 +16,7 @@ merge_cmd () {
 			-merge "$MERGED" | cat
 	fi
 }
+
+merge_cmd_help () {
+	echo "Use FileMerge (requires a graphical session)"
+}
diff --git a/mergetools/p4merge b/mergetools/p4merge
index 7a5b291dd2..f3cb197e58 100644
--- a/mergetools/p4merge
+++ b/mergetools/p4merge
@@ -19,6 +19,10 @@ diff_cmd () {
 	fi
 }
 
+diff_cmd_help () {
+	echo "Use HelixCore P4Merge (requires a graphical session)"
+}
+
 merge_cmd () {
 	if ! $base_present
 	then
@@ -34,3 +38,7 @@ create_empty_file () {
 
 	printf "%s" "$empty_file"
 }
+
+merge_cmd_help () {
+	echo "Use HelixCore P4Merge (requires a graphical session)"
+}
diff --git a/mergetools/smerge b/mergetools/smerge
index 9c2e6f6fd7..5410835a6b 100644
--- a/mergetools/smerge
+++ b/mergetools/smerge
@@ -2,6 +2,10 @@ diff_cmd () {
 	"$merge_tool_path" mergetool "$LOCAL" "$REMOTE" -o "$MERGED"
 }
 
+diff_cmd_help () {
+	echo "Use Sublime Merge (requires a graphical session)"
+}
+
 merge_cmd () {
 	if $base_present
 	then
@@ -10,3 +14,7 @@ merge_cmd () {
 		"$merge_tool_path" mergetool "$LOCAL" "$REMOTE" -o "$MERGED"
 	fi
 }
+
+merge_cmd_help () {
+	echo "Use Sublime Merge (requires a graphical session)"
+}
diff --git a/mergetools/tkdiff b/mergetools/tkdiff
index eee5cb57e3..66906a720d 100644
--- a/mergetools/tkdiff
+++ b/mergetools/tkdiff
@@ -2,6 +2,10 @@ diff_cmd () {
 	"$merge_tool_path" "$LOCAL" "$REMOTE"
 }
 
+diff_cmd_help () {
+	echo "Use TkDiff (requires a graphical session)"
+}
+
 merge_cmd () {
 	if $base_present
 	then
@@ -14,3 +18,7 @@ merge_cmd () {
 exit_code_trustable () {
 	true
 }
+
+merge_cmd_help () {
+	echo "Use TkDiff (requires a graphical session)"
+}
diff --git a/mergetools/tortoisemerge b/mergetools/tortoisemerge
index d7ab666a59..507edcd444 100644
--- a/mergetools/tortoisemerge
+++ b/mergetools/tortoisemerge
@@ -2,6 +2,10 @@ can_diff () {
 	return 1
 }
 
+diff_cmd_help () {
+	echo "Use TortoiseMerge (requires a graphical session)"
+}
+
 merge_cmd () {
 	if $base_present
 	then
@@ -30,3 +34,7 @@ translate_merge_tool_path() {
 		echo tortoisemerge
 	fi
 }
+
+merge_cmd_help () {
+	echo "Use TortoiseMerge (requires a graphical session)"
+}
diff --git a/mergetools/winmerge b/mergetools/winmerge
index 74d03259fd..36c72dde6e 100644
--- a/mergetools/winmerge
+++ b/mergetools/winmerge
@@ -3,6 +3,10 @@ diff_cmd () {
 	return 0
 }
 
+diff_cmd_help () {
+	echo "Use WinMerge (requires a graphical session)"
+}
+
 merge_cmd () {
 	# mergetool.winmerge.trustExitCode is implicitly false.
 	# touch $BACKUP so that we can check_unchanged.
@@ -13,3 +17,7 @@ merge_cmd () {
 translate_merge_tool_path() {
 	mergetool_find_win32_cmd "WinMergeU.exe" "WinMerge"
 }
+
+merge_cmd_help () {
+	echo "Use WinMerge (requires a graphical session)"
+}
diff --git a/mergetools/xxdiff b/mergetools/xxdiff
index d5ce467995..cd205f9842 100644
--- a/mergetools/xxdiff
+++ b/mergetools/xxdiff
@@ -12,6 +12,10 @@ diff_cmd () {
 	fi
 }
 
+diff_cmd_help () {
+	echo "Use xxdiff (requires a graphical session)"
+}
+
 merge_cmd () {
 	if $base_present
 	then
@@ -28,3 +32,7 @@ merge_cmd () {
 			--merged-file "$MERGED" "$LOCAL" "$REMOTE"
 	fi
 }
+
+merge_cmd_help () {
+	echo "Use xxdiff (requires a graphical session)"
+}