[v5] Enable auto-merge for meld to follow the vim-diff beharior
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Message ID pull.781.v5.git.git.1593587206520.gitgitgadget@gmail.com
State New
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  • [v5] Enable auto-merge for meld to follow the vim-diff beharior
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Commit Message

Matthew Rogers via GitGitGadget July 1, 2020, 7:06 a.m. UTC
From: Lin Sun <lin.sun@zoom.us>

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.hasAutoMerge` with `true`, or `auto` for
automatically detecting the option.

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-v5
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-781/sunlin7/master-v5
Pull-Request: https://github.com/git/git/pull/781

Range-diff vs v4:

 1:  93ae3ec011 ! 1:  344817d579 Enable auto-merge for meld to follow the vim-diff beharior
     @@
       ## Metadata ##
     -Author: lin.sun <lin.sun@zoom.us>
     +Author: Lin Sun <lin.sun@zoom.us>
      
       ## Commit message ##
          Enable auto-merge for meld to follow the vim-diff beharior
      
          Make the mergetool used with "meld" backend behave similarly to
     -    how "vimdiff" beheaves by telling it to auto-merge parts without
     -    conflicts and highlight the parts with conflicts.
     +    how "vimdiff" behavior by telling it to auto-merge parts without
     +    conflicts and highlight the parts with conflicts when configuring
     +    `mergetool.meld.hasAutoMerge` with `true`, or `auto` for
     +    automatically detecting the option.
      
     -    Signed-off-by: lin.sun <lin.sun@zoom.us>
     +    Signed-off-by: Lin Sun <lin.sun@zoom.us>
     +
     + ## Documentation/config/mergetool.txt ##
     +@@ Documentation/config/mergetool.txt: mergetool.meld.hasOutput::
     + 	to `true` tells Git to unconditionally use the `--output` option,
     + 	and `false` avoids using `--output`.
     + 
     ++mergetool.meld.hasAutoMerge::
     ++	Older versions of `meld` do not support the `--auto-merge` option.
     ++	Setting `mergetool.meld.hasOutput` to `true` tells Git to
     ++	unconditionally use the `--auto-merge` option, and `false` avoids using
     ++	`--auto-merge`, and `auto` detect whether `meld` supports `--auto-merge`
     ++	by inspecting the output of `meld --help`, otherwise, follow meld's
     ++	default behavior.
     ++
     + 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
      
       ## mergetools/meld ##
      @@ mergetools/meld: diff_cmd () {
     @@ mergetools/meld: diff_cmd () {
      +# Get meld help message
      +get_meld_help_msg () {
      +	meld_path="$(git config mergetool.meld.path || echo meld)"
     -+  $meld_path --help 2>&1
     ++	$meld_path --help 2>&1
      +}
       
      -	if meld_has_output_option=$(git config --bool mergetool.meld.hasOutput)
     @@ mergetools/meld: diff_cmd () {
      -		grep -e '--output=' -e '\[OPTION\.\.\.\]' >/dev/null
      +		meld_has_output_option=$(git config --bool mergetool.meld.hasOutput)
      +		if test "$meld_has_output_option" = true -o \
     -+						"$meld_has_output_option" = false
     ++			"$meld_has_output_option" = false
      +		then
      +			: use configured value
     -+		else												# treat meld_has_output_option as "auto"
     ++		else
     ++			# treat meld_has_output_option as "auto"
      +			if test -z "$meld_help_msg"
      +			then
      +				meld_help_msg="$(get_meld_help_msg)"
      +			fi
      +
     -+			if echo "$meld_help_msg" |
     -+							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
     -+			fi
     ++			case "$meld_help_msg" in
     ++				*"--output="* | *"[OPTION"???"]"*)
     ++					# old ones mention --output and new ones just say OPTION...
     ++					meld_has_output_option=true ;;
     ++				*)
     ++					meld_has_output_option=false ;;
     ++			esac
      +		fi
      +	fi
      +	# Check whether we should use 'meld --auto-merge ...'
     @@ mergetools/meld: diff_cmd () {
      -		meld_has_output_option=true
      -	else
      -		meld_has_output_option=false
     -+		meld_has_auto_merge_option=$(git config --bool mergetool.meld.hasAutoMerge)
     -+		if test "$meld_has_auto_merge_option" = true -o \
     -+						"$meld_has_auto_merge_option" = false
     ++		meld_has_auto_merge_option=$(git config mergetool.meld.hasAutoMerge)
     ++		if test "$meld_has_auto_merge_option" = auto
      +		then
     -+			: use configured value
     -+		else												# treat meld_has_auto_merge_option as "auto"
     ++			# testing the "--auto-merge" option only if config is "auto"
      +			if test -z "$meld_help_msg"
      +			then
      +					meld_help_msg="$(get_meld_help_msg)"
      +			fi
      +
     -+			if echo "$meld_help_msg" | grep -e '--auto-merge' >/dev/null
     -+			then
     -+					meld_has_auto_merge_option=true
     -+			else
     -+				meld_has_auto_merge_option=false
     -+			fi
     ++			case "$meld_help_msg" in
     ++				*"--auto-merge"*)
     ++					: old ones mention --output and new ones just say OPTION...
     ++					meld_has_auto_merge_option=true ;;
     ++				*)
     ++					meld_has_auto_merge_option=false ;;
     ++			esac
      +		fi
       	fi
       }


 Documentation/config/mergetool.txt |  8 ++++
 mergetools/meld                    | 72 +++++++++++++++++++++++-------
 2 files changed, 64 insertions(+), 16 deletions(-)


base-commit: 07d8ea56f2ecb64b75b92264770c0a664231ce17

Comments

lin.sun@zoom.us July 1, 2020, 7:23 a.m. UTC | #1
Hi Danh,

The [PATH v5] is changed to following the comments from you, Junio, David. 
Please review this newer version. Thank you.
The raw files is https://github.com/git/git/blob/344817d57970e3ac0910cdd8ad47bf97334ab2a6/mergetools/meld

Regards
Lin
-----Original Message-----
From: sunlin via GitGitGadget <gitgitgadget@gmail.com> 
Sent: Wednesday, July 1, 2020 15:07
To: git@vger.kernel.org
Cc: sunlin <sunlin7@yahoo.com>; Lin Sun <lin.sun@zoom.us>
Subject: [PATCH v5] Enable auto-merge for meld to follow the vim-diff beharior

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

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.hasAutoMerge` with `true`, or `auto` for automatically detecting the option.

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-v5
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-781/sunlin7/master-v5
Pull-Request: https://github.com/git/git/pull/781

Range-diff vs v4:

 1:  93ae3ec011 ! 1:  344817d579 Enable auto-merge for meld to follow the vim-diff beharior
     @@
       ## Metadata ##
     -Author: lin.sun <lin.sun@zoom.us>
     +Author: Lin Sun <lin.sun@zoom.us>
      
       ## Commit message ##
          Enable auto-merge for meld to follow the vim-diff beharior
      
          Make the mergetool used with "meld" backend behave similarly to
     -    how "vimdiff" beheaves by telling it to auto-merge parts without
     -    conflicts and highlight the parts with conflicts.
     +    how "vimdiff" behavior by telling it to auto-merge parts without
     +    conflicts and highlight the parts with conflicts when configuring
     +    `mergetool.meld.hasAutoMerge` with `true`, or `auto` for
     +    automatically detecting the option.
      
     -    Signed-off-by: lin.sun <lin.sun@zoom.us>
     +    Signed-off-by: Lin Sun <lin.sun@zoom.us>
     +
     + ## Documentation/config/mergetool.txt ##
     +@@ Documentation/config/mergetool.txt: mergetool.meld.hasOutput::
     + 	to `true` tells Git to unconditionally use the `--output` option,
     + 	and `false` avoids using `--output`.
     + 
     ++mergetool.meld.hasAutoMerge::
     ++	Older versions of `meld` do not support the `--auto-merge` option.
     ++	Setting `mergetool.meld.hasOutput` to `true` tells Git to
     ++	unconditionally use the `--auto-merge` option, and `false` avoids using
     ++	`--auto-merge`, and `auto` detect whether `meld` supports `--auto-merge`
     ++	by inspecting the output of `meld --help`, otherwise, follow meld's
     ++	default behavior.
     ++
     + 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
      
       ## mergetools/meld ##
      @@ mergetools/meld: diff_cmd () {
     @@ mergetools/meld: diff_cmd () {
      +# Get meld help message
      +get_meld_help_msg () {
      +	meld_path="$(git config mergetool.meld.path || echo meld)"
     -+  $meld_path --help 2>&1
     ++	$meld_path --help 2>&1
      +}
       
      -	if meld_has_output_option=$(git config --bool mergetool.meld.hasOutput)
     @@ mergetools/meld: diff_cmd () {
      -		grep -e '--output=' -e '\[OPTION\.\.\.\]' >/dev/null
      +		meld_has_output_option=$(git config --bool mergetool.meld.hasOutput)
      +		if test "$meld_has_output_option" = true -o \
     -+						"$meld_has_output_option" = false
     ++			"$meld_has_output_option" = false
      +		then
      +			: use configured value
     -+		else												# treat meld_has_output_option as "auto"
     ++		else
     ++			# treat meld_has_output_option as "auto"
      +			if test -z "$meld_help_msg"
      +			then
      +				meld_help_msg="$(get_meld_help_msg)"
      +			fi
      +
     -+			if echo "$meld_help_msg" |
     -+							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
     -+			fi
     ++			case "$meld_help_msg" in
     ++				*"--output="* | *"[OPTION"???"]"*)
     ++					# old ones mention --output and new ones just say OPTION...
     ++					meld_has_output_option=true ;;
     ++				*)
     ++					meld_has_output_option=false ;;
     ++			esac
      +		fi
      +	fi
      +	# Check whether we should use 'meld --auto-merge ...'
     @@ mergetools/meld: diff_cmd () {
      -		meld_has_output_option=true
      -	else
      -		meld_has_output_option=false
     -+		meld_has_auto_merge_option=$(git config --bool mergetool.meld.hasAutoMerge)
     -+		if test "$meld_has_auto_merge_option" = true -o \
     -+						"$meld_has_auto_merge_option" = false
     ++		meld_has_auto_merge_option=$(git config mergetool.meld.hasAutoMerge)
     ++		if test "$meld_has_auto_merge_option" = auto
      +		then
     -+			: use configured value
     -+		else												# treat meld_has_auto_merge_option as "auto"
     ++			# testing the "--auto-merge" option only if config is "auto"
      +			if test -z "$meld_help_msg"
      +			then
      +					meld_help_msg="$(get_meld_help_msg)"
      +			fi
      +
     -+			if echo "$meld_help_msg" | grep -e '--auto-merge' >/dev/null
     -+			then
     -+					meld_has_auto_merge_option=true
     -+			else
     -+				meld_has_auto_merge_option=false
     -+			fi
     ++			case "$meld_help_msg" in
     ++				*"--auto-merge"*)
     ++					: old ones mention --output and new ones just say OPTION...
     ++					meld_has_auto_merge_option=true ;;
     ++				*)
     ++					meld_has_auto_merge_option=false ;;
     ++			esac
      +		fi
       	fi
       }


 Documentation/config/mergetool.txt |  8 ++++
 mergetools/meld                    | 72 +++++++++++++++++++++++-------
 2 files changed, 64 insertions(+), 16 deletions(-)

diff --git a/Documentation/config/mergetool.txt b/Documentation/config/mergetool.txt
index 09ed31dbfa..9a74bd98dc 100644
--- a/Documentation/config/mergetool.txt
+++ b/Documentation/config/mergetool.txt
@@ -30,6 +30,14 @@ mergetool.meld.hasOutput::
 	to `true` tells Git to unconditionally use the `--output` option,
 	and `false` avoids using `--output`.
 
+mergetool.meld.hasAutoMerge::
+	Older versions of `meld` do not support the `--auto-merge` option.
+	Setting `mergetool.meld.hasOutput` to `true` tells Git to
+	unconditionally use the `--auto-merge` option, and `false` avoids using
+	`--auto-merge`, and `auto` detect whether `meld` supports `--auto-merge`
+	by inspecting the output of `meld --help`, otherwise, follow meld's
+	default behavior.
+
 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..9ee835b1e5 100644
--- a/mergetools/meld
+++ b/mergetools/meld
@@ -3,34 +3,74 @@ diff_cmd () {
 }
 
 merge_cmd () {
-	if test -z "${meld_has_output_option:+set}"
+	check_meld_for_features
+
+	option_auto_merge=
+	if test "$meld_has_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
+get_meld_help_msg () {
+	meld_path="$(git config mergetool.meld.path || echo meld)"
+	$meld_path --help 2>&1
+}
 
-	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:+set}"
 	then
-		: use configured value
-	elif "$meld_path" --help 2>&1 |
-		grep -e '--output=' -e '\[OPTION\.\.\.\]' >/dev/null
+		meld_has_output_option=$(git config --bool mergetool.meld.hasOutput)
+		if test "$meld_has_output_option" = true -o \
+			"$meld_has_output_option" = false
+		then
+			: use configured value
+		else
+			# treat meld_has_output_option as "auto"
+			if test -z "$meld_help_msg"
+			then
+				meld_help_msg="$(get_meld_help_msg)"
+			fi
+
+			case "$meld_help_msg" in
+				*"--output="* | *"[OPTION"???"]"*)
+					# old ones mention --output and new ones just say OPTION...
+					meld_has_output_option=true ;;
+				*)
+					meld_has_output_option=false ;;
+			esac
+		fi
+	fi
+	# Check whether we should use 'meld --auto-merge ...'
+	if test -z "${meld_has_auto_merge_option:+set}"
 	then
-		: old ones mention --output and new ones just say OPTION...
-		meld_has_output_option=true
-	else
-		meld_has_output_option=false
+		meld_has_auto_merge_option=$(git config mergetool.meld.hasAutoMerge)
+		if test "$meld_has_auto_merge_option" = auto
+		then
+			# testing the "--auto-merge" option only if config is "auto"
+			if test -z "$meld_help_msg"
+			then
+					meld_help_msg="$(get_meld_help_msg)"
+			fi
+
+			case "$meld_help_msg" in
+				*"--auto-merge"*)
+					: old ones mention --output and new ones just say OPTION...
+					meld_has_auto_merge_option=true ;;
+				*)
+					meld_has_auto_merge_option=false ;;
+			esac
+		fi
 	fi
 }

base-commit: 07d8ea56f2ecb64b75b92264770c0a664231ce17
--
gitgitgadget
Đoàn Trần Công Danh July 1, 2020, 2:17 p.m. UTC | #2
On 2020-07-01 07:06:46+0000, sunlin via GitGitGadget <gitgitgadget@gmail.com> wrote:
> From: Lin Sun <lin.sun@zoom.us>
> 
> 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.hasAutoMerge` with `true`, or `auto` for
> automatically detecting the option.
> 
> Signed-off-by: Lin Sun <lin.sun@zoom.us>
> ---
> diff --git a/Documentation/config/mergetool.txt b/Documentation/config/mergetool.txt
> index 09ed31dbfa..9a74bd98dc 100644
> --- a/Documentation/config/mergetool.txt
> +++ b/Documentation/config/mergetool.txt
> @@ -30,6 +30,14 @@ mergetool.meld.hasOutput::
>  	to `true` tells Git to unconditionally use the `--output` option,
>  	and `false` avoids using `--output`.
>  
> +mergetool.meld.hasAutoMerge::
> +	Older versions of `meld` do not support the `--auto-merge` option.
> +	Setting `mergetool.meld.hasOutput` to `true` tells Git to

s/hasOutput/hasAutoMerge/

Bikeshed opinion: I don't know if hasAutoMerge is a good name :)

> +	unconditionally use the `--auto-merge` option, and `false` avoids using
> +	`--auto-merge`, and `auto` detect whether `meld` supports `--auto-merge`
> +	by inspecting the output of `meld --help`, otherwise, follow meld's
> +	default behavior.
> +
>  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..9ee835b1e5 100644
> --- a/mergetools/meld
> +++ b/mergetools/meld
> @@ -3,34 +3,74 @@ diff_cmd () {
>  }
>  
>  merge_cmd () {
> -	if test -z "${meld_has_output_option:+set}"
> +	check_meld_for_features
> +
> +	option_auto_merge=
> +	if test "$meld_has_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
> +get_meld_help_msg () {
> +	meld_path="$(git config mergetool.meld.path || echo meld)"
> +	$meld_path --help 2>&1
> +}

I'm actually prefer this change in 2 separated patches to reduce noise.
But given that mergetool/meld doesn't attract much attention, I don't know.

>  
> -	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:+set}"
>  	then
> -		: use configured value
> -	elif "$meld_path" --help 2>&1 |
> -		grep -e '--output=' -e '\[OPTION\.\.\.\]' >/dev/null
> +		meld_has_output_option=$(git config --bool mergetool.meld.hasOutput)
> +		if test "$meld_has_output_option" = true -o \
> +			"$meld_has_output_option" = false

The coding guideline seems to not like "test -o".
I think it's acceptable in this case since we control its input.
The output is comming out of "git config --bool" anyway,
so meld_has_output_option must be either "", "true", or "false"

I think we're better to do this instead:

	if test -n "$meld_has_output_option"
	then
		: use configured output
	else
		: messing with help
	fi

> +		then
> +			: use configured value
> +		else
> +			# treat meld_has_output_option as "auto"
> +			if test -z "$meld_help_msg"
> +			then
> +				meld_help_msg="$(get_meld_help_msg)"
> +			fi

If I were writing this patch, I probably changed get_meld_help_msg to

	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
	}

And call init_meld_help_msg unconditionally here,
(and in --auto-merge arm below, maybe other arms in the future).

I'm writing without much thought into this,
please take my word with a grain of salt :)

> +}


> +
> +			case "$meld_help_msg" in
> +				*"--output="* | *"[OPTION"???"]"*)

I think Git project prefer aligning case arm with case,
IOW, move left 1 TAB.

> +					# old ones mention --output and new ones just say OPTION...
> +					meld_has_output_option=true ;;

It's nice to see this update, good.
The comment is no longer correct, though.
The version 3.20.2 has --output but not OPTIONS.

It's not introduced by your change, but I think it's better to say:

	# All versions that has [OPTIONS???] supports --output

> +				*)
> +					meld_has_output_option=false ;;
> +			esac
> +		fi
> +	fi
> +	# Check whether we should use 'meld --auto-merge ...'
> +	if test -z "${meld_has_auto_merge_option:+set}"
>  	then
> -		: old ones mention --output and new ones just say OPTION...
> -		meld_has_output_option=true
> -	else
> -		meld_has_output_option=false
> +		meld_has_auto_merge_option=$(git config mergetool.meld.hasAutoMerge)
> +		if test "$meld_has_auto_merge_option" = auto

Since we don't canonicallise to bool output of
mergetool.meld.hasAutoMerge, I think we would need:

	case "$meld_has_auto_merge_option" in
	[Tt]rue|[Yy]es|[Oo]n)
		meld_has_auto_merge_option=true ;;
	auto)
		: this shenanigan ;;
	esac

But, that's a bit messy. Let's see other's opinions.

> +		then
> +			# testing the "--auto-merge" option only if config is "auto"
> +			if test -z "$meld_help_msg"
> +			then
> +					meld_help_msg="$(get_meld_help_msg)"
> +			fi
> +
> +			case "$meld_help_msg" in
> +				*"--auto-merge"*)
> +					: old ones mention --output and new ones just say OPTION...

This comment doesn't apply here.

> +					meld_has_auto_merge_option=true ;;
> +				*)
> +					meld_has_auto_merge_option=false ;;
> +			esac
> +		fi
>  	fi
>  }
> 
> base-commit: 07d8ea56f2ecb64b75b92264770c0a664231ce17
> -- 
> gitgitgadget
lin.sun@zoom.us July 1, 2020, 3:32 p.m. UTC | #3
Hi Danh,

Thank you for your comments, and changes apply to the last patch with your suggestions. Please refer the attachment for [PATH v6].
Thank you.

Regards
Lin 

-----Original Message-----
From: Đoàn Trần Công Danh <congdanhqx@gmail.com> 
Sent: Wednesday, July 1, 2020 22:18
To: sunlin via GitGitGadget <gitgitgadget@gmail.com>
Cc: git@vger.kernel.org; sunlin <sunlin7@yahoo.com>; Lin Sun <lin.sun@zoom.us>
Subject: Re: [PATCH v5] Enable auto-merge for meld to follow the vim-diff beharior

On 2020-07-01 07:06:46+0000, sunlin via GitGitGadget <gitgitgadget@gmail.com> wrote:
> From: Lin Sun <lin.sun@zoom.us>
> 
> 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.hasAutoMerge` with `true`, or `auto` for automatically 
> detecting the option.
> 
> Signed-off-by: Lin Sun <lin.sun@zoom.us>
> ---
> diff --git a/Documentation/config/mergetool.txt 
> b/Documentation/config/mergetool.txt
> index 09ed31dbfa..9a74bd98dc 100644
> --- a/Documentation/config/mergetool.txt
> +++ b/Documentation/config/mergetool.txt
> @@ -30,6 +30,14 @@ mergetool.meld.hasOutput::
>  	to `true` tells Git to unconditionally use the `--output` option,
>  	and `false` avoids using `--output`.
>  
> +mergetool.meld.hasAutoMerge::
> +	Older versions of `meld` do not support the `--auto-merge` option.
> +	Setting `mergetool.meld.hasOutput` to `true` tells Git to

s/hasOutput/hasAutoMerge/

Bikeshed opinion: I don't know if hasAutoMerge is a good name :)

> +	unconditionally use the `--auto-merge` option, and `false` avoids using
> +	`--auto-merge`, and `auto` detect whether `meld` supports `--auto-merge`
> +	by inspecting the output of `meld --help`, otherwise, follow meld's
> +	default behavior.
> +
>  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..9ee835b1e5 100644
> --- a/mergetools/meld
> +++ b/mergetools/meld
> @@ -3,34 +3,74 @@ diff_cmd () {
>  }
>  
>  merge_cmd () {
> -	if test -z "${meld_has_output_option:+set}"
> +	check_meld_for_features
> +
> +	option_auto_merge=
> +	if test "$meld_has_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
> +get_meld_help_msg () {
> +	meld_path="$(git config mergetool.meld.path || echo meld)"
> +	$meld_path --help 2>&1
> +}

I'm actually prefer this change in 2 separated patches to reduce noise.
But given that mergetool/meld doesn't attract much attention, I don't know.

>  
> -	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:+set}"
>  	then
> -		: use configured value
> -	elif "$meld_path" --help 2>&1 |
> -		grep -e '--output=' -e '\[OPTION\.\.\.\]' >/dev/null
> +		meld_has_output_option=$(git config --bool mergetool.meld.hasOutput)
> +		if test "$meld_has_output_option" = true -o \
> +			"$meld_has_output_option" = false

The coding guideline seems to not like "test -o".
I think it's acceptable in this case since we control its input.
The output is comming out of "git config --bool" anyway, so meld_has_output_option must be either "", "true", or "false"

I think we're better to do this instead:

	if test -n "$meld_has_output_option"
	then
		: use configured output
	else
		: messing with help
	fi

> +		then
> +			: use configured value
> +		else
> +			# treat meld_has_output_option as "auto"
> +			if test -z "$meld_help_msg"
> +			then
> +				meld_help_msg="$(get_meld_help_msg)"
> +			fi

If I were writing this patch, I probably changed get_meld_help_msg to

	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
	}

And call init_meld_help_msg unconditionally here, (and in --auto-merge arm below, maybe other arms in the future).

I'm writing without much thought into this, please take my word with a grain of salt :)

> +}


> +
> +			case "$meld_help_msg" in
> +				*"--output="* | *"[OPTION"???"]"*)

I think Git project prefer aligning case arm with case, IOW, move left 1 TAB.

> +					# old ones mention --output and new ones just say OPTION...
> +					meld_has_output_option=true ;;

It's nice to see this update, good.
The comment is no longer correct, though.
The version 3.20.2 has --output but not OPTIONS.

It's not introduced by your change, but I think it's better to say:

	# All versions that has [OPTIONS???] supports --output

> +				*)
> +					meld_has_output_option=false ;;
> +			esac
> +		fi
> +	fi
> +	# Check whether we should use 'meld --auto-merge ...'
> +	if test -z "${meld_has_auto_merge_option:+set}"
>  	then
> -		: old ones mention --output and new ones just say OPTION...
> -		meld_has_output_option=true
> -	else
> -		meld_has_output_option=false
> +		meld_has_auto_merge_option=$(git config mergetool.meld.hasAutoMerge)
> +		if test "$meld_has_auto_merge_option" = auto

Since we don't canonicallise to bool output of mergetool.meld.hasAutoMerge, I think we would need:

	case "$meld_has_auto_merge_option" in
	[Tt]rue|[Yy]es|[Oo]n)
		meld_has_auto_merge_option=true ;;
	auto)
		: this shenanigan ;;
	esac

But, that's a bit messy. Let's see other's opinions.

> +		then
> +			# testing the "--auto-merge" option only if config is "auto"
> +			if test -z "$meld_help_msg"
> +			then
> +					meld_help_msg="$(get_meld_help_msg)"
> +			fi
> +
> +			case "$meld_help_msg" in
> +				*"--auto-merge"*)
> +					: old ones mention --output and new ones just say OPTION...

This comment doesn't apply here.

> +					meld_has_auto_merge_option=true ;;
> +				*)
> +					meld_has_auto_merge_option=false ;;
> +			esac
> +		fi
>  	fi
>  }
> 
> base-commit: 07d8ea56f2ecb64b75b92264770c0a664231ce17
> --
> gitgitgadget

--
Danh
David Aguilar July 1, 2020, 6:19 p.m. UTC | #4
On Wed, Jul 01, 2020 at 03:23:56PM +0800, lin.sun@zoom.us wrote:
> Hi Danh,
> 
> The [PATH v5] is changed to following the comments from you, Junio, David. 
> Please review this newer version. Thank you.
> The raw files is https://github.com/git/git/blob/344817d57970e3ac0910cdd8ad47bf97334ab2a6/mergetools/meld
> 
> Regards
> Lin
> -----Original Message-----
> From: sunlin via GitGitGadget <gitgitgadget@gmail.com> 
> Sent: Wednesday, July 1, 2020 15:07
> To: git@vger.kernel.org
> Cc: sunlin <sunlin7@yahoo.com>; Lin Sun <lin.sun@zoom.us>
> Subject: [PATCH v5] Enable auto-merge for meld to follow the vim-diff beharior
> 
> From: Lin Sun <lin.sun@zoom.us>
> 
> 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.hasAutoMerge` with `true`, or `auto` for automatically detecting the option.

Please word-wrap commit messages to 72 chars or less.


> 
> Signed-off-by: Lin Sun <lin.sun@zoom.us>
> ---
>  Documentation/config/mergetool.txt |  8 ++++
>  mergetools/meld                    | 72 +++++++++++++++++++++++-------
>  2 files changed, 64 insertions(+), 16 deletions(-)
> 
> diff --git a/Documentation/config/mergetool.txt b/Documentation/config/mergetool.txt
> index 09ed31dbfa..9a74bd98dc 100644
> --- a/Documentation/config/mergetool.txt
> +++ b/Documentation/config/mergetool.txt
> @@ -30,6 +30,14 @@ mergetool.meld.hasOutput::
>  	to `true` tells Git to unconditionally use the `--output` option,
>  	and `false` avoids using `--output`.
>  
> +mergetool.meld.hasAutoMerge::
> +	Older versions of `meld` do not support the `--auto-merge` option.
> +	Setting `mergetool.meld.hasOutput` to `true` tells Git to
> +	unconditionally use the `--auto-merge` option, and `false` avoids using
> +	`--auto-merge`, and `auto` detect whether `meld` supports `--auto-merge`
> +	by inspecting the output of `meld --help`, otherwise, follow meld's
> +	default behavior.
> +

Now that we've decided that "false" should be the default behavior, the
naming of this option don't make sense.  "hasAutoMerge" doesn't
really convey what this option does anymore.  I would suggest calling it
"mergetool.meld.automerge".

Perhaps something like this?

mergetool.meld.automerge::
	Older versions of `meld` do not support the `--auto-merge`
	option.  Setting `mergetool.meld.automerge` 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.

> @@ -3,34 +3,74 @@ diff_cmd () {
>  }
>  
>  merge_cmd () {
> -	if test -z "${meld_has_output_option:+set}"
> +	check_meld_for_features
> +
> +	option_auto_merge=
> +	if test "$meld_has_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
> +get_meld_help_msg () {

This comment seems redundant when the function is called
get_meld_help_msg().


> +	meld_path="$(git config mergetool.meld.path || echo meld)"
> +	$meld_path --help 2>&1
> +}
>  
> -	if meld_has_output_option=$(git config --bool mergetool.meld.hasOutput)
> +# Check the features and set flags
> +check_meld_for_features () {

Ditto for this comment.


> +	# Check whether we should use 'meld --output <file>'
> +	if test -z "${meld_has_output_option:+set}"
>  	then
> -		: use configured value
> -	elif "$meld_path" --help 2>&1 |
> -		grep -e '--output=' -e '\[OPTION\.\.\.\]' >/dev/null
> +		meld_has_output_option=$(git config --bool mergetool.meld.hasOutput)
> +		if test "$meld_has_output_option" = true -o \
> +			"$meld_has_output_option" = false

Documentation/CodingGuidelines mentions:

 - We do not write our "test" command with "-a" and "-o" and use "&&"
   or "||" to concatenate multiple "test" commands instead, because
   the use of "-a/-o" is often error-prone.  E.g.

This would be written as:

	if test "$meld_has_output_option" = true ||
		test "$meld_has_output_option" = false
	then
		...
	fi

Instead of two checks, would it be better to instead just check:
	if test -n "$meld_has_output_option"
?
git config --bool will only ever produce true/false, so we really only
need to check that it's a non-empty value, perhaps?


> +			case "$meld_help_msg" in
> +				*"--output="* | *"[OPTION"???"]"*)
> +					# old ones mention --output and new ones just say OPTION...
> +					meld_has_output_option=true ;;
> +				*)
> +					meld_has_output_option=false ;;
> +			esac

We typically avoid the extra indentation level for the case labels.
eg. this would be written like this (with ";;" on its own line):

	case "$meld_help_msg" in
	*--output=*|*"[OPTION"???"]"*)
		# old ones mention --output and new ones just say OPTION...
		meld_has_output_option=true
		;;
	*)
		meld_has_output_option=false
		;;
	esac


Also, if you're matching [OPTION ...] would it work to just use
a single-quoted value in the case label?  eg: *'[OPTION...]'* ?


> +	if test -z "${meld_has_auto_merge_option:+set}"
>  	then
> -		: old ones mention --output and new ones just say OPTION...
> -		meld_has_output_option=true
> -	else
> -		meld_has_output_option=false
> +		meld_has_auto_merge_option=$(git config mergetool.meld.hasAutoMerge)
> +		if test "$meld_has_auto_merge_option" = auto
> +		then
> +			# testing the "--auto-merge" option only if config is "auto"
> +			if test -z "$meld_help_msg"
> +			then
> +					meld_help_msg="$(get_meld_help_msg)"

This can just be:

	meld_help_msg=$(get_meld_help_msg)

and can do without the surrounding " " double quotes.



> +			case "$meld_help_msg" in
> +				*"--auto-merge"*)
> +					: old ones mention --output and new ones just say OPTION...
> +					meld_has_auto_merge_option=true ;;
> +				*)
> +					meld_has_auto_merge_option=false ;;
> +			esac

As above -- unindent the case statements, and put the ";;" case
statement terminators on their own line.

cheers,
Junio C Hamano July 1, 2020, 7:51 p.m. UTC | #5
Đoàn Trần Công Danh  <congdanhqx@gmail.com> writes:

>> +mergetool.meld.hasAutoMerge::
>> +	Older versions of `meld` do not support the `--auto-merge` option.
>> +	Setting `mergetool.meld.hasOutput` to `true` tells Git to
>
> s/hasOutput/hasAutoMerge/
>
> Bikeshed opinion: I don't know if hasAutoMerge is a good name :)

I do not think "has" is a good choice for this one, even though
hasOutput may very well be a good one for "output".  As the
paragraph describes (below), this lets the user "avoid" using
"--auto-merge", even if the version of "meld" the user has does have
the automerge capability.

So perhaps say "mergetool.meld.useAutoMerge"; that will let the users
express exactly their wish---don't use it (false), do forcibly try
to use it (true), or use it when able (auto).
lin.sun@zoom.us July 1, 2020, 10:02 p.m. UTC | #6
Hi Danh,

I'll push the patch to GitGitGadget so that it's will sending from the system mail. Sorry for this noise.

Regards
Lin

-----Original Message-----
From: lin.sun@zoom.us <lin.sun@zoom.us> 
Sent: Wednesday, July 1, 2020 23:32
To: 'Đoàn Trần Công Danh' <congdanhqx@gmail.com>; 'sunlin via GitGitGadget' <gitgitgadget@gmail.com>
Cc: git@vger.kernel.org; 'Lin Sun' <lin.sun@zoom.us>
Subject: RE: [PATCH v5] Enable auto-merge for meld to follow the vim-diff beharior

Hi Danh,

Thank you for your comments, and changes apply to the last patch with your suggestions. Please refer the attachment for [PATH v6].
Thank you.

Regards
Lin 

-----Original Message-----
From: Đoàn Trần Công Danh <congdanhqx@gmail.com>
Sent: Wednesday, July 1, 2020 22:18
To: sunlin via GitGitGadget <gitgitgadget@gmail.com>
Cc: git@vger.kernel.org; sunlin <sunlin7@yahoo.com>; Lin Sun <lin.sun@zoom.us>
Subject: Re: [PATCH v5] Enable auto-merge for meld to follow the vim-diff beharior

On 2020-07-01 07:06:46+0000, sunlin via GitGitGadget <gitgitgadget@gmail.com> wrote:
> From: Lin Sun <lin.sun@zoom.us>
> 
> 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.hasAutoMerge` with `true`, or `auto` for automatically 
> detecting the option.
> 
> Signed-off-by: Lin Sun <lin.sun@zoom.us>
> ---
> diff --git a/Documentation/config/mergetool.txt
> b/Documentation/config/mergetool.txt
> index 09ed31dbfa..9a74bd98dc 100644
> --- a/Documentation/config/mergetool.txt
> +++ b/Documentation/config/mergetool.txt
> @@ -30,6 +30,14 @@ mergetool.meld.hasOutput::
>  	to `true` tells Git to unconditionally use the `--output` option,
>  	and `false` avoids using `--output`.
>  
> +mergetool.meld.hasAutoMerge::
> +	Older versions of `meld` do not support the `--auto-merge` option.
> +	Setting `mergetool.meld.hasOutput` to `true` tells Git to

s/hasOutput/hasAutoMerge/

Bikeshed opinion: I don't know if hasAutoMerge is a good name :)

> +	unconditionally use the `--auto-merge` option, and `false` avoids using
> +	`--auto-merge`, and `auto` detect whether `meld` supports `--auto-merge`
> +	by inspecting the output of `meld --help`, otherwise, follow meld's
> +	default behavior.
> +
>  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..9ee835b1e5 100644
> --- a/mergetools/meld
> +++ b/mergetools/meld
> @@ -3,34 +3,74 @@ diff_cmd () {
>  }
>  
>  merge_cmd () {
> -	if test -z "${meld_has_output_option:+set}"
> +	check_meld_for_features
> +
> +	option_auto_merge=
> +	if test "$meld_has_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
> +get_meld_help_msg () {
> +	meld_path="$(git config mergetool.meld.path || echo meld)"
> +	$meld_path --help 2>&1
> +}

I'm actually prefer this change in 2 separated patches to reduce noise.
But given that mergetool/meld doesn't attract much attention, I don't know.

>  
> -	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:+set}"
>  	then
> -		: use configured value
> -	elif "$meld_path" --help 2>&1 |
> -		grep -e '--output=' -e '\[OPTION\.\.\.\]' >/dev/null
> +		meld_has_output_option=$(git config --bool mergetool.meld.hasOutput)
> +		if test "$meld_has_output_option" = true -o \
> +			"$meld_has_output_option" = false

The coding guideline seems to not like "test -o".
I think it's acceptable in this case since we control its input.
The output is comming out of "git config --bool" anyway, so meld_has_output_option must be either "", "true", or "false"

I think we're better to do this instead:

	if test -n "$meld_has_output_option"
	then
		: use configured output
	else
		: messing with help
	fi

> +		then
> +			: use configured value
> +		else
> +			# treat meld_has_output_option as "auto"
> +			if test -z "$meld_help_msg"
> +			then
> +				meld_help_msg="$(get_meld_help_msg)"
> +			fi

If I were writing this patch, I probably changed get_meld_help_msg to

	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
	}

And call init_meld_help_msg unconditionally here, (and in --auto-merge arm below, maybe other arms in the future).

I'm writing without much thought into this, please take my word with a grain of salt :)

> +}


> +
> +			case "$meld_help_msg" in
> +				*"--output="* | *"[OPTION"???"]"*)

I think Git project prefer aligning case arm with case, IOW, move left 1 TAB.

> +					# old ones mention --output and new ones just say OPTION...
> +					meld_has_output_option=true ;;

It's nice to see this update, good.
The comment is no longer correct, though.
The version 3.20.2 has --output but not OPTIONS.

It's not introduced by your change, but I think it's better to say:

	# All versions that has [OPTIONS???] supports --output

> +				*)
> +					meld_has_output_option=false ;;
> +			esac
> +		fi
> +	fi
> +	# Check whether we should use 'meld --auto-merge ...'
> +	if test -z "${meld_has_auto_merge_option:+set}"
>  	then
> -		: old ones mention --output and new ones just say OPTION...
> -		meld_has_output_option=true
> -	else
> -		meld_has_output_option=false
> +		meld_has_auto_merge_option=$(git config mergetool.meld.hasAutoMerge)
> +		if test "$meld_has_auto_merge_option" = auto

Since we don't canonicallise to bool output of mergetool.meld.hasAutoMerge, I think we would need:

	case "$meld_has_auto_merge_option" in
	[Tt]rue|[Yy]es|[Oo]n)
		meld_has_auto_merge_option=true ;;
	auto)
		: this shenanigan ;;
	esac

But, that's a bit messy. Let's see other's opinions.

> +		then
> +			# testing the "--auto-merge" option only if config is "auto"
> +			if test -z "$meld_help_msg"
> +			then
> +					meld_help_msg="$(get_meld_help_msg)"
> +			fi
> +
> +			case "$meld_help_msg" in
> +				*"--auto-merge"*)
> +					: old ones mention --output and new ones just say OPTION...

This comment doesn't apply here.

> +					meld_has_auto_merge_option=true ;;
> +				*)
> +					meld_has_auto_merge_option=false ;;
> +			esac
> +		fi
>  	fi
>  }
> 
> base-commit: 07d8ea56f2ecb64b75b92264770c0a664231ce17
> --
> gitgitgadget

--
Danh
Đoàn Trần Công Danh July 1, 2020, 11:06 p.m. UTC | #7
On 2020-07-02 06:02:27+0800, lin.sun@zoom.us wrote:
> Hi Danh,

Hi Lin,

> 
> I'll push the patch to GitGitGadget so that it's will sending from
> the system mail. Sorry for this noise.

While you're doing it,
do you mind changing hasAutoMerge to useAutoMerge?
I think that name is better :)

c.f: https://lore.kernel.org/git/xmqq7dvndnf0.fsf@gitster.c.googlers.com/

Thanks,
lin.sun@zoom.us July 2, 2020, 12:20 a.m. UTC | #8
Hi Danh,

> While you're doing it,
> do you mind changing hasAutoMerge to useAutoMerge?
> I think that name is better :)
Okay, no problem, it will be ` useAutoMerge`.

Regards
Lin

Patch
diff mbox series

diff --git a/Documentation/config/mergetool.txt b/Documentation/config/mergetool.txt
index 09ed31dbfa..9a74bd98dc 100644
--- a/Documentation/config/mergetool.txt
+++ b/Documentation/config/mergetool.txt
@@ -30,6 +30,14 @@  mergetool.meld.hasOutput::
 	to `true` tells Git to unconditionally use the `--output` option,
 	and `false` avoids using `--output`.
 
+mergetool.meld.hasAutoMerge::
+	Older versions of `meld` do not support the `--auto-merge` option.
+	Setting `mergetool.meld.hasOutput` to `true` tells Git to
+	unconditionally use the `--auto-merge` option, and `false` avoids using
+	`--auto-merge`, and `auto` detect whether `meld` supports `--auto-merge`
+	by inspecting the output of `meld --help`, otherwise, follow meld's
+	default behavior.
+
 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..9ee835b1e5 100644
--- a/mergetools/meld
+++ b/mergetools/meld
@@ -3,34 +3,74 @@  diff_cmd () {
 }
 
 merge_cmd () {
-	if test -z "${meld_has_output_option:+set}"
+	check_meld_for_features
+
+	option_auto_merge=
+	if test "$meld_has_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
+get_meld_help_msg () {
+	meld_path="$(git config mergetool.meld.path || echo meld)"
+	$meld_path --help 2>&1
+}
 
-	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:+set}"
 	then
-		: use configured value
-	elif "$meld_path" --help 2>&1 |
-		grep -e '--output=' -e '\[OPTION\.\.\.\]' >/dev/null
+		meld_has_output_option=$(git config --bool mergetool.meld.hasOutput)
+		if test "$meld_has_output_option" = true -o \
+			"$meld_has_output_option" = false
+		then
+			: use configured value
+		else
+			# treat meld_has_output_option as "auto"
+			if test -z "$meld_help_msg"
+			then
+				meld_help_msg="$(get_meld_help_msg)"
+			fi
+
+			case "$meld_help_msg" in
+				*"--output="* | *"[OPTION"???"]"*)
+					# old ones mention --output and new ones just say OPTION...
+					meld_has_output_option=true ;;
+				*)
+					meld_has_output_option=false ;;
+			esac
+		fi
+	fi
+	# Check whether we should use 'meld --auto-merge ...'
+	if test -z "${meld_has_auto_merge_option:+set}"
 	then
-		: old ones mention --output and new ones just say OPTION...
-		meld_has_output_option=true
-	else
-		meld_has_output_option=false
+		meld_has_auto_merge_option=$(git config mergetool.meld.hasAutoMerge)
+		if test "$meld_has_auto_merge_option" = auto
+		then
+			# testing the "--auto-merge" option only if config is "auto"
+			if test -z "$meld_help_msg"
+			then
+					meld_help_msg="$(get_meld_help_msg)"
+			fi
+
+			case "$meld_help_msg" in
+				*"--auto-merge"*)
+					: old ones mention --output and new ones just say OPTION...
+					meld_has_auto_merge_option=true ;;
+				*)
+					meld_has_auto_merge_option=false ;;
+			esac
+		fi
 	fi
 }