mergetool: support --tool-help option like difftool does

This way we do not have to risk the list of tools going out of sync
between the implementation and the documentation.

In the same spirit as bf73fc2 (difftool: print list of valid tools
with '--tool-help', 2012-03-29), trim the list of merge backends in
the documentation.  We do not want to have a complete list of valid
tools; we only want a list to help people guess what kind of things
the tools do to be specified there, and refer them to --tool-help
for a complete list.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/Documentation/git-mergetool.txt b/Documentation/git-mergetool.txt
index 2a49de7cfe5188b531bc02f1115e253bfa10e0e0..d7207bd9b9bba59a0e1f97341fb77927026e1b52 100644 (file)
--- a/Documentation/git-mergetool.txt
+++ b/Documentation/git-mergetool.txt
@@ -27,9 +27,9 @@ OPTIONS
 -t <tool>::
 --tool=<tool>::
        Use the merge resolution program specified by <tool>.
-       Valid merge tools are:
-       araxis, bc3, diffuse, ecmerge, emerge, gvimdiff, kdiff3,
-       meld, opendiff, p4merge, tkdiff, tortoisemerge, vimdiff and xxdiff.
+       Valid values include emerge, gvimdiff, kdiff3,
+       meld, vimdiff, and tortoisemerge. Run `git mergetool --tool-help`
+       for the list of valid <tool> settings.
 +
 If a merge resolution program is not specified, 'git mergetool'
 will use the configuration variable `merge.tool`.  If the

diff --git a/git-mergetool--lib.sh b/git-mergetool--lib.sh
index ed630b208a80a36d729b5074a39bc53df0cabd59..f730253c0eac181ec8507d2c837d4ec85a0ae991 100644 (file)
--- a/git-mergetool--lib.sh
+++ b/git-mergetool--lib.sh
@@ -111,7 +111,7 @@ run_merge_tool () {
        return $status
 }
 
-guess_merge_tool () {
+list_merge_tool_candidates () {
        if merge_mode
        then
                tools="tortoisemerge"
@@ -136,6 +136,10 @@ guess_merge_tool () {
                tools="$tools emerge vimdiff"
                ;;
        esac
+}
+
+guess_merge_tool () {
+       list_merge_tool_candidates
        echo >&2 "merge tool candidates: $tools"
 
        # Loop over each candidate and stop when a valid merge tool is found.

diff --git a/git-mergetool.sh b/git-mergetool.sh
index a9f23f7fcdff610f2b206bc121db7c9217bbf0c7..0db0c44845f54920e26d97391f577e76305ecc56 100755 (executable)
--- a/git-mergetool.sh
+++ b/git-mergetool.sh
@@ -8,7 +8,7 @@
 # at the discretion of Junio C Hamano.
 #
 
-USAGE='[--tool=tool] [-y|--no-prompt|--prompt] [file to merge] ...'
+USAGE='[--tool=tool] [--tool-help] [-y|--no-prompt|--prompt] [file to merge] ...'
 SUBDIRECTORY_OK=Yes
 OPTIONS_SPEC=
 TOOL_MODE=merge
@@ -284,11 +284,51 @@ merge_file () {
     return 0
 }
 
+show_tool_help () {
+       TOOL_MODE=merge
+       list_merge_tool_candidates
+       unavailable= available= LF='
+'
+       for i in $tools
+       do
+               merge_tool_path=$(translate_merge_tool_path "$i")
+               if type "$merge_tool_path" >/dev/null 2>&1
+               then
+                       available="$available$i$LF"
+               else
+                       unavailable="$unavailable$i$LF"
+               fi
+       done
+       if test -n "$available"
+       then
+               echo "'git mergetool --tool=<tool>' may be set to one of the following:"
+               echo "$available" | sort | sed -e 's/^/ /'
+       else
+               echo "No suitable tool for 'git mergetool --tool=<tool>' found."
+       fi
+       if test -n "$unavailable"
+       then
+               echo
+               echo 'The following tools are valid, but not currently available:'
+               echo "$unavailable" | sort | sed -e 's/^/       /'
+       fi
+       if test -n "$unavailable$available"
+       then
+               echo
+               echo "Some of the tools listed above only work in a windowed"
+               echo "environment. If run in a terminal-only session, they will fail."
+       fi
+       exit 0
+}
+
 prompt=$(git config --bool mergetool.prompt || echo true)
 
 while test $# != 0
 do
     case "$1" in
+       --tool-help)
+               show_tool_help
+               ;;
        -t|--tool*)
            case "$#,$1" in
                *,*=*)