mergetools/meld: make usage of `--output` configurable and more robust

Older versions of meld listed --output in `meld --help`.
Newer versions only mention `meld [OPTIONS...]`.
Improve the checks to catch these newer versions.

Add a `mergetool.meld.hasOutput` configuration to allow
overriding the heuristic.

Reported-by: Andrey Novoseltsev <novoselt@gmail.com>
Helped-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: David Aguilar <davvid@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/Documentation/config.txt b/Documentation/config.txt
index c55c22ab7be94e798164a48622aca21dd4daa44f..382e12c69efc520978390fc97483ac388b7e4a94 100644 (file)
--- a/Documentation/config.txt
+++ b/Documentation/config.txt
@@ -1754,6 +1754,15 @@ mergetool.<tool>.trustExitCode::
        if the file has been updated, otherwise the user is prompted to
        indicate the success of the merge.
 
+mergetool.meld.hasOutput::
+       Older versions of `meld` do not support the `--output` option.
+       Git will attempt to detect whether `meld` supports `--output`
+       by inspecting the output of `meld --help`.  Configuring
+       `mergetool.meld.hasOutput` will make Git skip these checks and
+       use the configured value instead.  Setting `mergetool.meld.hasOutput`
+       to `true` tells Git to unconditionally use the `--output` option,
+       and `false` avoids using `--output`.
+
 mergetool.keepBackup::
        After performing a merge, the original file with conflict markers
        can be saved as a file with a `.orig` extension.  If this variable

diff --git a/mergetools/meld b/mergetools/meld
index cb672a55192cb44335aa2cbe1f10004bb26d86ff..83ebdfb4c328ac79af38bfe935f0dbfa7fb6f53b 100644 (file)
--- a/mergetools/meld
+++ b/mergetools/meld
@@ -18,13 +18,18 @@ merge_cmd () {
        check_unchanged
 }
 
-# Check whether 'meld --output <file>' is supported
+# Check whether we should use 'meld --output <file>'
 check_meld_for_output_version () {
        meld_path="$(git config mergetool.meld.path)"
        meld_path="${meld_path:-meld}"
 
-       if "$meld_path" --help 2>&1 | grep -e --output >/dev/null
+       if meld_has_output_option=$(git config --bool mergetool.meld.hasOutput)
        then
+               : use configured value
+       elif "$meld_path" --help 2>&1 |
+               grep -e '--output=' -e '\[OPTION\.\.\.\]' >/dev/null
+       then
+               : old ones mention --output and new ones just say OPTION...
                meld_has_output_option=true
        else
                meld_has_output_option=false