[PATCH v7] Support auto-merge for meld to follow the vim-diff behavior

From: "sunlin via GitGitGadget" <gitgitgadget@gmail.com>
To: git@vger.kernel.org
Cc: sunlin <sunlin7@yahoo.com>, Lin Sun <lin.sun@zoom.us>
Subject: [PATCH v7] Support auto-merge for meld to follow the vim-diff behavior
Date: Fri, 03 Jul 2020 03:26:45 +0000	[thread overview]
Message-ID: <pull.781.v7.git.git.1593746805771.gitgitgadget@gmail.com> (raw)
In-Reply-To: <pull.781.v6.git.git.1593650687697.gitgitgadget@gmail.com>

From: Lin Sun <lin.sun@zoom.us>

Make the mergetool used with "meld" backend behave similarly to
"vimdiff" by telling it to auto-merge non-conflicting parts and
highlight the conflicting parts when `mergetool.meld.useAutoMerge` is
configured with `true`, or `auto` for detecting the `--auto-merge`
option automatically.

Helped-by: Đoàn Trần Công Danh <congdanhqx@gmail.com>
Helped-by: Junio C Hamano <gitster@pobox.com>
Helped-by: David Aguilar <davvid@gmail.com>
Signed-off-by: Lin Sun <lin.sun@zoom.us>
---
    Enable auto-merge for meld to follow the vimdiff beharior
    
    Hi, the mergetool "meld" does NOT merge the no-conflict changes, while
    the mergetool "vimdiff" will merge the no-conflict changes and highlight
    the conflict parts. This patch will make the mergetool "meld" similar to
    "vimdiff", auto-merge the no-conflict changes, highlight conflict parts.

Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-781%2Fsunlin7%2Fmaster-v7
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-781/sunlin7/master-v7
Pull-Request: https://github.com/git/git/pull/781

Range-diff vs v6:

 1:  63ee3406d2 ! 1:  ec2b49b9b8 Support auto-merge for meld to follow the vim-diff behavior
     @@ Metadata
       ## Commit message ##
          Support auto-merge for meld to follow the vim-diff behavior
      
     -    Make the mergetool used with "meld" backend behave similarly to how
     -    "vimdiff" behavior by telling it to auto-merge parts without conflicts
     -    and highlight the parts with conflicts when configuring
     -    `mergetool.meld.useAutoMerge` with `true`, or `auto` for automatically
     -    detecting the option.
     +    Make the mergetool used with "meld" backend behave similarly to
     +    "vimdiff" by telling it to auto-merge non-conflicting parts and
     +    highlight the conflicting parts when `mergetool.meld.useAutoMerge` is
     +    configured with `true`, or `auto` for detecting the `--auto-merge`
     +    option automatically.
      
          Helped-by: Đoàn Trần Công Danh <congdanhqx@gmail.com>
          Helped-by: Junio C Hamano <gitster@pobox.com>
     @@ Documentation/config/mergetool.txt: mergetool.meld.hasOutput::
       	and `false` avoids using `--output`.
       
      +mergetool.meld.useAutoMerge::
     -+	Older versions of `meld` do not support the `--auto-merge` option.
     -+	Setting `mergetool.meld.useAutoMerge` to `true` tells Git to
     -+	unconditionally use the `--auto-merge` option with `meld`.  Setting
     -+	this value to `auto` makes git detect whether `--auto-merge` is
     -+	supported and will only use `--auto-merge` when available.  A value
     -+	of `false` avoids using `--auto-merge` altogether, and is the default
     -+	value.
     ++	When the `--auto-merge` is given, meld will merges all non-conflicting
     ++	part automatically, highlight the conflicting part and waiting for user
     ++	decision.  Setting `mergetool.meld.useAutoMerge` to `true` tells Git to
     ++	unconditionally use the `--auto-merge` option with `meld`.  Setting this
     ++	value to `auto` makes git detect whether `--auto-merge` is supported and
     ++	will only use `--auto-merge` when available.  A value of `false` avoids
     ++	using `--auto-merge` altogether, and is the default value.
      +
       mergetool.keepBackup::
       	After performing a merge, the original file with conflict markers
     @@ mergetools/meld: diff_cmd () {
      -	meld_path="${meld_path:-meld}"
      +# Get meld help message
      +init_meld_help_msg () {
     -+	if test -z "${meld_help_msg:+set}"
     ++	if test -z "${meld_help_msg}"
      +	then
      +		meld_path="$(git config mergetool.meld.path || echo meld)"
      +		meld_help_msg=$($meld_path --help 2>&1)
     @@ mergetools/meld: diff_cmd () {
      +# Check the features and set flags
      +check_meld_for_features () {
      +	# Check whether we should use 'meld --output <file>'
     -+	if test -z "${meld_has_output_option:+set}"
     ++	if test -z "${meld_has_output_option}"
       	then
      -		: use configured value
      -	elif "$meld_path" --help 2>&1 |
     @@ mergetools/meld: diff_cmd () {
      +			: use configured value
      +			;;
      +		*)
     -+			: treat meld_has_output_option as "auto"
     ++			: empty or invalid configured value, detecting "--output" automatically
      +			init_meld_help_msg
      +
      +			case "$meld_help_msg" in
     @@ mergetools/meld: diff_cmd () {
      +		esac
      +	fi
      +	# Check whether we should use 'meld --auto-merge ...'
     -+	if test -z "${meld_use_auto_merge_option:+set}"
     ++	if test -z "${meld_use_auto_merge_option}"
       	then
      -		: old ones mention --output and new ones just say OPTION...
      -		meld_has_output_option=true
      -	else
      -		meld_has_output_option=false
      +		meld_use_auto_merge_option=$(git config mergetool.meld.useAutoMerge)
     -+		case "$meld_use_auto_merge_option" in
     -+		[Tt]rue|[Yy]es|[Oo]n|1)
     ++		case "${meld_use_auto_merge_option,,*}" in
     ++		true|yes|on|1)
      +			meld_use_auto_merge_option=true
      +			;;
      +		auto)


 Documentation/config/mergetool.txt |  9 ++++
 mergetools/meld                    | 80 ++++++++++++++++++++++++------
 2 files changed, 73 insertions(+), 16 deletions(-)

diff --git a/Documentation/config/mergetool.txt b/Documentation/config/mergetool.txt
index 09ed31dbfa..b7657734a0 100644
--- a/Documentation/config/mergetool.txt
+++ b/Documentation/config/mergetool.txt
@@ -30,6 +30,15 @@ mergetool.meld.hasOutput::
 	to `true` tells Git to unconditionally use the `--output` option,
 	and `false` avoids using `--output`.
 
+mergetool.meld.useAutoMerge::
+	When the `--auto-merge` is given, meld will merges all non-conflicting
+	part automatically, highlight the conflicting part and waiting for user
+	decision.  Setting `mergetool.meld.useAutoMerge` to `true` tells Git to
+	unconditionally use the `--auto-merge` option with `meld`.  Setting this
+	value to `auto` makes git detect whether `--auto-merge` is supported and
+	will only use `--auto-merge` when available.  A value of `false` avoids
+	using `--auto-merge` altogether, and is the default value.
+
 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 7a08470f88..5e6b50d480 100644
--- a/mergetools/meld
+++ b/mergetools/meld
@@ -3,34 +3,82 @@ diff_cmd () {
 }
 
 merge_cmd () {
-	if test -z "${meld_has_output_option:+set}"
+	check_meld_for_features
+
+	option_auto_merge=
+	if test "$meld_use_auto_merge_option" = true
 	then
-		check_meld_for_output_version
+		option_auto_merge="--auto-merge"
 	fi
 
 	if test "$meld_has_output_option" = true
 	then
-		"$merge_tool_path" --output="$MERGED" \
+		"$merge_tool_path" $option_auto_merge --output="$MERGED" \
 			"$LOCAL" "$BASE" "$REMOTE"
 	else
-		"$merge_tool_path" "$LOCAL" "$MERGED" "$REMOTE"
+		"$merge_tool_path" $option_auto_merge "$LOCAL" "$MERGED" "$REMOTE"
 	fi
 }
 
-# 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}"
+# Get meld help message
+init_meld_help_msg () {
+	if test -z "${meld_help_msg}"
+	then
+		meld_path="$(git config mergetool.meld.path || echo meld)"
+		meld_help_msg=$($meld_path --help 2>&1)
+	fi
+}
 
-	if meld_has_output_option=$(git config --bool mergetool.meld.hasOutput)
+# Check the features and set flags
+check_meld_for_features () {
+	# Check whether we should use 'meld --output <file>'
+	if test -z "${meld_has_output_option}"
 	then
-		: use configured value
-	elif "$meld_path" --help 2>&1 |
-		grep -e '--output=' -e '\[OPTION\.\.\.\]' >/dev/null
+		meld_has_output_option=$(git config --bool mergetool.meld.hasOutput)
+		case "$meld_has_output_option" in
+		true|false)
+			: use configured value
+			;;
+		*)
+			: empty or invalid configured value, detecting "--output" automatically
+			init_meld_help_msg
+
+			case "$meld_help_msg" in
+			*"--output="* | *'[OPTION...]'*)
+				# All version that has [OPTION...] supports --output
+				meld_has_output_option=true
+				;;
+			*)
+				meld_has_output_option=false
+				;;
+			esac
+			;;
+		esac
+	fi
+	# Check whether we should use 'meld --auto-merge ...'
+	if test -z "${meld_use_auto_merge_option}"
 	then
-		: old ones mention --output and new ones just say OPTION...
-		meld_has_output_option=true
-	else
-		meld_has_output_option=false
+		meld_use_auto_merge_option=$(git config mergetool.meld.useAutoMerge)
+		case "${meld_use_auto_merge_option,,*}" in
+		true|yes|on|1)
+			meld_use_auto_merge_option=true
+			;;
+		auto)
+			# testing the "--auto-merge" option only if config is "auto"
+			init_meld_help_msg
+
+			case "$meld_help_msg" in
+			*"--auto-merge"*)
+				meld_use_auto_merge_option=true
+				;;
+			*)
+				meld_use_auto_merge_option=false
+				;;
+			esac
+			;;
+		*)
+			meld_use_auto_merge_option=false
+			;;
+		esac
 	fi
 }

base-commit: 07d8ea56f2ecb64b75b92264770c0a664231ce17
-- 
gitgitgadget
