[PATCH 0/5] git-mergetool: improve error code paths and messages

[PATCH 0/5] git-mergetool: improve error code paths and messages

[Philippe Blain via GitGitGadget]

These are a few improvements to improve existing error messages in 'git
mergetool', and make sure that errors are not quiet, along with a small
completion update in 1/1.

Philippe Blain (5):
  completion: complete '--tool-help' in 'git mergetool'
  git-mergetool--lib.sh: use TOOL_MODE when erroring about unknown tool
  git-mergetool--lib.sh: add error message in 'setup_user_tool'
  git-mergetool--lib.sh: add error message for unknown tool variant
  git-difftool--helper.sh: exit upon initialize_merge_tool errors

 contrib/completion/git-completion.bash |  2 +-
 git-difftool--helper.sh                |  8 ++------
 git-mergetool--lib.sh                  | 13 +++++++++----
 t/t7610-mergetool.sh                   |  8 ++++++++
 4 files changed, 20 insertions(+), 11 deletions(-)


base-commit: b31fb630c0fc6869a33ed717163e8a1210460d94
Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-1827%2Fphil-blain%2Fabsent-mergetool-v1
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-1827/phil-blain/absent-mergetool-v1
Pull-Request: https://github.com/gitgitgadget/git/pull/1827
-- 
gitgitgadget

[PATCH 1/5] completion: complete '--tool-help' in 'git mergetool'

[Philippe Blain via GitGitGadget]

From: Philippe Blain <levraiphilippeblain@gmail.com>

Signed-off-by: Philippe Blain <levraiphilippeblain@gmail.com>
---
 contrib/completion/git-completion.bash | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/contrib/completion/git-completion.bash b/contrib/completion/git-completion.bash
index 3d4dff3185c..b3b6aa3bae2 100644
--- a/contrib/completion/git-completion.bash
+++ b/contrib/completion/git-completion.bash
@@ -2331,7 +2331,7 @@ _git_mergetool ()
 		return
 		;;
 	--*)
-		__gitcomp "--tool= --prompt --no-prompt --gui --no-gui"
+		__gitcomp "--tool= --tool-help --prompt --no-prompt --gui --no-gui"
 		return
 		;;
 	esac
-- 
gitgitgadget

[PATCH 2/5] git-mergetool--lib.sh: use TOOL_MODE when erroring about unknown tool

[Philippe Blain via GitGitGadget]

From: Philippe Blain <levraiphilippeblain@gmail.com>

In git-mergetool--lib.sh::get_merge_tool_path, we check if the chosen
tool is valid via valid_tool and exit with an error message if not. This
error message mentions "Unknown merge tool", even if the command the
user tried was 'git difftool --tool=unknown'. Use the global 'TOOL_MODE'
variable for a more correct error message.

Signed-off-by: Philippe Blain <levraiphilippeblain@gmail.com>
---
 git-mergetool--lib.sh | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/git-mergetool--lib.sh b/git-mergetool--lib.sh
index 1ff26170ffc..269a60ea44c 100644
--- a/git-mergetool--lib.sh
+++ b/git-mergetool--lib.sh
@@ -474,7 +474,7 @@ get_merge_tool_path () {
 	merge_tool="$1"
 	if ! valid_tool "$merge_tool"
 	then
-		echo >&2 "Unknown merge tool $merge_tool"
+		echo >&2 "Unknown $TOOL_MODE tool $merge_tool"
 		exit 1
 	fi
 	if diff_mode
-- 
gitgitgadget

Re: [PATCH 2/5] git-mergetool--lib.sh: use TOOL_MODE when erroring about unknown tool

[Junio C Hamano]

"Philippe Blain via GitGitGadget" <gitgitgadget@gmail.com> writes:

> From: Philippe Blain <levraiphilippeblain@gmail.com>
>
> In git-mergetool--lib.sh::get_merge_tool_path, we check if the chosen
> tool is valid via valid_tool and exit with an error message if not. This
> error message mentions "Unknown merge tool", even if the command the
> user tried was 'git difftool --tool=unknown'. Use the global 'TOOL_MODE'
> variable for a more correct error message.

Makes sense.  Is this something we can easily test to catch future
regression, or is it too trivial to matter?

I wouldn't mind if the answer were "the latter" ;-)

Thanks.

> Signed-off-by: Philippe Blain <levraiphilippeblain@gmail.com>
> ---
>  git-mergetool--lib.sh | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/git-mergetool--lib.sh b/git-mergetool--lib.sh
> index 1ff26170ffc..269a60ea44c 100644
> --- a/git-mergetool--lib.sh
> +++ b/git-mergetool--lib.sh
> @@ -474,7 +474,7 @@ get_merge_tool_path () {
>  	merge_tool="$1"
>  	if ! valid_tool "$merge_tool"
>  	then
> -		echo >&2 "Unknown merge tool $merge_tool"
> +		echo >&2 "Unknown $TOOL_MODE tool $merge_tool"
>  		exit 1
>  	fi
>  	if diff_mode

Re: [PATCH 2/5] git-mergetool--lib.sh: use TOOL_MODE when erroring about unknown tool

[Philippe Blain]

Hi Junio (sorry for a late response),

Le 2024-11-12 à 20:27, Junio C Hamano a écrit :
> "Philippe Blain via GitGitGadget" <gitgitgadget@gmail.com> writes:
> 
>> From: Philippe Blain <levraiphilippeblain@gmail.com>
>>
>> In git-mergetool--lib.sh::get_merge_tool_path, we check if the chosen
>> tool is valid via valid_tool and exit with an error message if not. This
>> error message mentions "Unknown merge tool", even if the command the
>> user tried was 'git difftool --tool=unknown'. Use the global 'TOOL_MODE'
>> variable for a more correct error message.
> 
> Makes sense.  Is this something we can easily test to catch future
> regression, or is it too trivial to matter?
> 
> I wouldn't mind if the answer were "the latter" ;-)

With the changes in the next commit of the series, this particular error
becomes hard to trigger, as setup_user_tool will return with an error
before the error message change in this patch is reached. So I would way
it is not worth to add a test for this particular code path since it seems like
it becomes unreachable in the next commit (but I could be wrong). So mostly
"the latter" is my answer.

Thanks,
Philippe.

Re: [PATCH 2/5] git-mergetool--lib.sh: use TOOL_MODE when erroring about unknown tool

[Philippe Blain]

Le 2024-11-22 à 13:57, Philippe Blain a écrit :
> Hi Junio (sorry for a late response),
> 
> Le 2024-11-12 à 20:27, Junio C Hamano a écrit :
>> "Philippe Blain via GitGitGadget" <gitgitgadget@gmail.com> writes:
>>
>>> From: Philippe Blain <levraiphilippeblain@gmail.com>
>>>
>>> In git-mergetool--lib.sh::get_merge_tool_path, we check if the chosen
>>> tool is valid via valid_tool and exit with an error message if not. This
>>> error message mentions "Unknown merge tool", even if the command the
>>> user tried was 'git difftool --tool=unknown'. Use the global 'TOOL_MODE'
>>> variable for a more correct error message.
>>
>> Makes sense.  Is this something we can easily test to catch future
>> regression, or is it too trivial to matter?
>>
>> I wouldn't mind if the answer were "the latter" ;-)
> 
> With the changes in the next commit of the series,

correction: with the changes in 3/5 and 5/5,

> this particular error
> becomes hard to trigger, as setup_user_tool will return with an error
> before the error message change in this patch is reached. So I would way
> it is not worth to add a test for this particular code path since it seems like
> it becomes unreachable in the next commit (but I could be wrong). So mostly
> "the latter" is my answer.

[PATCH 3/5] git-mergetool--lib.sh: add error message in 'setup_user_tool'

[Philippe Blain via GitGitGadget]

From: Philippe Blain <levraiphilippeblain@gmail.com>

In git-mergetool--lib.sh::setup_tool, we check if the given tool is a
known builtin tool, a known variant, or a user-defined tool by calling
setup_user_tool, and we return with the exit code from setup_user_tool
if it was called. setup_user_tool checks if {diff,merge}tool.$tool.cmd
is set and quietly returns with an error if not.

This leads to the following invocation quietly failing:

	git mergetool --tool=unknown

which is not very user-friendly. Adjust setup_user_tool to output an
error message before returning if {diff,merge}tool.$tool.cmd is not set.

Adjust the second call to setup_user_tool in setup_tool to silence this
new error, as this call is only meant to allow users to redefine 'cmd'
for a builtin tool; it is not an error if they have not done so (which
is why we do not check the return status of this call).

Note that this behaviour of quietly failing is a regression dating back
to de8dafbada (mergetool: break setup_tool out into separate
initialization function, 2021-02-09), as before this commit an unknown
mergetool would be diagnosed in get_merge_tool_path when called from
run_merge_tool.

Signed-off-by: Philippe Blain <levraiphilippeblain@gmail.com>
---
 git-mergetool--lib.sh | 10 +++++++---
 t/t7610-mergetool.sh  |  8 ++++++++
 2 files changed, 15 insertions(+), 3 deletions(-)

diff --git a/git-mergetool--lib.sh b/git-mergetool--lib.sh
index 269a60ea44c..f4786afc63f 100644
--- a/git-mergetool--lib.sh
+++ b/git-mergetool--lib.sh
@@ -159,14 +159,18 @@ check_unchanged () {
 }
 
 valid_tool () {
-	setup_tool "$1" && return 0
+	setup_tool "$1" 2>/dev/null && return 0
 	cmd=$(get_merge_tool_cmd "$1")
 	test -n "$cmd"
 }
 
 setup_user_tool () {
 	merge_tool_cmd=$(get_merge_tool_cmd "$tool")
-	test -n "$merge_tool_cmd" || return 1
+	if test -z "$merge_tool_cmd"
+	then
+		echo >&2 "error: ${TOOL_MODE}tool.$tool.cmd not set for tool '$tool'"
+		return 1
+	fi
 
 	diff_cmd () {
 		( eval $merge_tool_cmd )
@@ -255,7 +259,7 @@ setup_tool () {
 
 	# Now let the user override the default command for the tool.  If
 	# they have not done so then this will return 1 which we ignore.
-	setup_user_tool
+	setup_user_tool 2>/dev/null
 
 	if ! list_tool_variants | grep -q "^$tool$"
 	then
diff --git a/t/t7610-mergetool.sh b/t/t7610-mergetool.sh
index 22b3a85b3e9..82a88107850 100755
--- a/t/t7610-mergetool.sh
+++ b/t/t7610-mergetool.sh
@@ -898,4 +898,12 @@ test_expect_success 'mergetool with guiDefault' '
 	git commit -m "branch1 resolved with mergetool"
 '
 
+test_expect_success 'mergetool with non-existent tool' '
+	test_when_finished "git reset --hard" &&
+	git checkout -b test$test_count branch1 &&
+	test_must_fail git merge main &&
+	yes "" | test_must_fail git mergetool --tool=absent >out 2>&1 &&
+	test_grep -i "not set for tool" out
+'
+
 test_done
-- 
gitgitgadget

Re: [PATCH 3/5] git-mergetool--lib.sh: add error message in 'setup_user_tool'

[Junio C Hamano]

"Philippe Blain via GitGitGadget" <gitgitgadget@gmail.com> writes:

>  valid_tool () {
> -	setup_tool "$1" && return 0
> +	setup_tool "$1" 2>/dev/null && return 0
>  	cmd=$(get_merge_tool_cmd "$1")
>  	test -n "$cmd"
>  }

As we are checking if a tool is valid, it is normal for setup_tool
to fail when we are checking is not valid (aka "fails to get set
up").  There is no need to show an error message for such a failure,
as the callers of valid_tool would do so if they wish.  OK.

>  setup_user_tool () {
>  	merge_tool_cmd=$(get_merge_tool_cmd "$tool")
> -	test -n "$merge_tool_cmd" || return 1
> +	if test -z "$merge_tool_cmd"
> +	then
> +		echo >&2 "error: ${TOOL_MODE}tool.$tool.cmd not set for tool '$tool'"
> +		return 1
> +	fi

There are only two callers of setup_user_tool, and one of them
squelches this message by sending it to /dev/null.  The error
message composed here does not use anything that is unique to the
function (in other words, $tool and ${TOOL_MODE} are available to
its callers).

I wonder if it is a better design to leave this one as-is, and
instead show the error message from the other caller of
setup_user_tool that does not squelch the message?  Are we planning
to add more callers of this function that want to show the same
message?

>  	diff_cmd () {
>  		( eval $merge_tool_cmd )
> @@ -255,7 +259,7 @@ setup_tool () {
>  
>  	# Now let the user override the default command for the tool.  If
>  	# they have not done so then this will return 1 which we ignore.
> -	setup_user_tool
> +	setup_user_tool 2>/dev/null

If we did that, then this change can be dropped.  Instead, a few
lines above this hunk, we can give the error message ourselves from
this setup_tool function.

>  	if ! list_tool_variants | grep -q "^$tool$"
>  	then
> diff --git a/t/t7610-mergetool.sh b/t/t7610-mergetool.sh
> index 22b3a85b3e9..82a88107850 100755
> --- a/t/t7610-mergetool.sh
> +++ b/t/t7610-mergetool.sh
> @@ -898,4 +898,12 @@ test_expect_success 'mergetool with guiDefault' '
>  	git commit -m "branch1 resolved with mergetool"
>  '
>  
> +test_expect_success 'mergetool with non-existent tool' '
> +	test_when_finished "git reset --hard" &&
> +	git checkout -b test$test_count branch1 &&
> +	test_must_fail git merge main &&
> +	yes "" | test_must_fail git mergetool --tool=absent >out 2>&1 &&
> +	test_grep -i "not set for tool" out
> +'

Why "-i"?  I do not offhand see the reason why we want to be loose
here.

The "${TOOL_MODE}tool" part may also want to be verified, perhaps,
which was related to the topic of the fix in [2/5]?

Re: [PATCH 3/5] git-mergetool--lib.sh: add error message in 'setup_user_tool'

[Philippe Blain]

Hi Junio,

Le 2024-11-12 à 20:48, Junio C Hamano a écrit :
> "Philippe Blain via GitGitGadget" <gitgitgadget@gmail.com> writes:
> 
>>  setup_user_tool () {
>>  	merge_tool_cmd=$(get_merge_tool_cmd "$tool")
>> -	test -n "$merge_tool_cmd" || return 1
>> +	if test -z "$merge_tool_cmd"
>> +	then
>> +		echo >&2 "error: ${TOOL_MODE}tool.$tool.cmd not set for tool '$tool'"
>> +		return 1
>> +	fi
> 
> There are only two callers of setup_user_tool, and one of them
> squelches this message by sending it to /dev/null.  The error
> message composed here does not use anything that is unique to the
> function (in other words, $tool and ${TOOL_MODE} are available to
> its callers).
> 
> I wonder if it is a better design to leave this one as-is, and
> instead show the error message from the other caller of
> setup_user_tool that does not squelch the message?  Are we planning
> to add more callers of this function that want to show the same
> message?

I don't think we are planning to add more callers, no.

> 
>>  	diff_cmd () {
>>  		( eval $merge_tool_cmd )
>> @@ -255,7 +259,7 @@ setup_tool () {
>>  
>>  	# Now let the user override the default command for the tool.  If
>>  	# they have not done so then this will return 1 which we ignore.
>> -	setup_user_tool
>> +	setup_user_tool 2>/dev/null
> 
> If we did that, then this change can be dropped.  Instead, a few
> lines above this hunk, we can give the error message ourselves from
> this setup_tool function.

I agree it could be done this way, I can change if it we wish.


>>  	if ! list_tool_variants | grep -q "^$tool$"
>>  	then
>> diff --git a/t/t7610-mergetool.sh b/t/t7610-mergetool.sh
>> index 22b3a85b3e9..82a88107850 100755
>> --- a/t/t7610-mergetool.sh
>> +++ b/t/t7610-mergetool.sh
>> @@ -898,4 +898,12 @@ test_expect_success 'mergetool with guiDefault' '
>>  	git commit -m "branch1 resolved with mergetool"
>>  '
>>  
>> +test_expect_success 'mergetool with non-existent tool' '
>> +	test_when_finished "git reset --hard" &&
>> +	git checkout -b test$test_count branch1 &&
>> +	test_must_fail git merge main &&
>> +	yes "" | test_must_fail git mergetool --tool=absent >out 2>&1 &&
>> +	test_grep -i "not set for tool" out
>> +'
> 
> Why "-i"?  I do not offhand see the reason why we want to be loose
> here.

Indeed this is a leftover from my bisection test in which I had to 
be a bit more loose. I'll remove that flag.
 
> The "${TOOL_MODE}tool" part may also want to be verified, perhaps,
> which was related to the topic of the fix in [2/5]?

Yes, I guess I could make the pattern stricter. I'll update that.

[PATCH 4/5] git-mergetool--lib.sh: add error message for unknown tool variant

[Philippe Blain via GitGitGadget]

From: Philippe Blain <levraiphilippeblain@gmail.com>

In setup_tool, we check if the given tool is a known variant of a tool,
and quietly return with an error if not. This leads to the following
invocation quietly failing:

	git mergetool --tool=vimdiff4

Add an error message before returning in this case.

Signed-off-by: Philippe Blain <levraiphilippeblain@gmail.com>
---
 git-mergetool--lib.sh | 1 +
 1 file changed, 1 insertion(+)

diff --git a/git-mergetool--lib.sh b/git-mergetool--lib.sh
index f4786afc63f..9a00fabba27 100644
--- a/git-mergetool--lib.sh
+++ b/git-mergetool--lib.sh
@@ -263,6 +263,7 @@ setup_tool () {
 
 	if ! list_tool_variants | grep -q "^$tool$"
 	then
+		echo "error: unknown ${tool%[0-9]} variant '$tool'" >&2
 		return 1
 	fi
 
-- 
gitgitgadget

Re: [PATCH 4/5] git-mergetool--lib.sh: add error message for unknown tool variant

[Junio C Hamano]

"Philippe Blain via GitGitGadget" <gitgitgadget@gmail.com> writes:

> From: Philippe Blain <levraiphilippeblain@gmail.com>
>
> In setup_tool, we check if the given tool is a known variant of a tool,
> and quietly return with an error if not. This leads to the following
> invocation quietly failing:
>
> 	git mergetool --tool=vimdiff4
>
> Add an error message before returning in this case.

Makes sense, but ...

> Signed-off-by: Philippe Blain <levraiphilippeblain@gmail.com>
> ---
>  git-mergetool--lib.sh | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/git-mergetool--lib.sh b/git-mergetool--lib.sh
> index f4786afc63f..9a00fabba27 100644
> --- a/git-mergetool--lib.sh
> +++ b/git-mergetool--lib.sh
> @@ -263,6 +263,7 @@ setup_tool () {
>  
>  	if ! list_tool_variants | grep -q "^$tool$"
>  	then
> +		echo "error: unknown ${tool%[0-9]} variant '$tool'" >&2

... I do not understand why you strip a single digit from the end.

    git mergetool --tool=nvimdiff4

says 'nvimdiff4' is not known as a variant of 'nvimdiff', but
wouldn't it still be a variant of 'vimdiff'?  Of course,

    git mergetool --tool=nvimdiff48

gets a vastly different error message ;-)

Saying

	echo >&2 "error: unknown variant '$tool'"

may be sufficient, perhaps?  I dunno.


>  		return 1
>  	fi

Re: [PATCH 4/5] git-mergetool--lib.sh: add error message for unknown tool variant

[Philippe Blain]

Le 2024-11-12 à 21:01, Junio C Hamano a écrit :
> "Philippe Blain via GitGitGadget" <gitgitgadget@gmail.com> writes:
> 
>> From: Philippe Blain <levraiphilippeblain@gmail.com>
>>
>> In setup_tool, we check if the given tool is a known variant of a tool,
>> and quietly return with an error if not. This leads to the following
>> invocation quietly failing:
>>
>> 	git mergetool --tool=vimdiff4
>>
>> Add an error message before returning in this case.
> 
> Makes sense, but ...
> 
>> Signed-off-by: Philippe Blain <levraiphilippeblain@gmail.com>
>> ---
>>  git-mergetool--lib.sh | 1 +
>>  1 file changed, 1 insertion(+)
>>
>> diff --git a/git-mergetool--lib.sh b/git-mergetool--lib.sh
>> index f4786afc63f..9a00fabba27 100644
>> --- a/git-mergetool--lib.sh
>> +++ b/git-mergetool--lib.sh
>> @@ -263,6 +263,7 @@ setup_tool () {
>>  
>>  	if ! list_tool_variants | grep -q "^$tool$"
>>  	then
>> +		echo "error: unknown ${tool%[0-9]} variant '$tool'" >&2
> 
> ... I do not understand why you strip a single digit from the end.
> 
>     git mergetool --tool=nvimdiff4
> 
> says 'nvimdiff4' is not known as a variant of 'nvimdiff', but
> wouldn't it still be a variant of 'vimdiff'?  Of course,
> 
>     git mergetool --tool=nvimdiff48
> 
> gets a vastly different error message ;-)
> 
> Saying
> 
> 	echo >&2 "error: unknown variant '$tool'"
> 
> may be sufficient, perhaps?  I dunno.

the stripping of the last digit is just because I copied from 
the 'if' a few lines above, where we source "$MERGE_TOOLS_DIR/${tool%[0-9]}".
In MERGE_TOOLS_DIR we have 'nvimdiff' and 'gvimdiff' that simply source vimdiff,
so this works. But I agree that we can simplify the error message, I'll do that.

[PATCH 5/5] git-difftool--helper.sh: exit upon initialize_merge_tool errors

[Philippe Blain via GitGitGadget]

From: Philippe Blain <levraiphilippeblain@gmail.com>

Since the introduction of 'initialize_merge_tool' in de8dafbada
(mergetool: break setup_tool out into separate initialization function,
2021-02-09), any errors from this function are ignored in
git-difftool--helper.sh::launch_merge_tool, which is not the case for
its call in git-mergetool.sh::merge_file.

Despite the in-code comment, initialize_merge_tool (via its call to
setup_tool) does different checks than run_merge_tool, so it makes sense
to abort early if it encounters errors. Add exit calls if
initialize_merge_tool fails.

Signed-off-by: Philippe Blain <levraiphilippeblain@gmail.com>
---
 git-difftool--helper.sh | 8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/git-difftool--helper.sh b/git-difftool--helper.sh
index dd0c9a5b7f2..d32e47cc09e 100755
--- a/git-difftool--helper.sh
+++ b/git-difftool--helper.sh
@@ -61,9 +61,7 @@ launch_merge_tool () {
 		export BASE
 		eval $GIT_DIFFTOOL_EXTCMD '"$LOCAL"' '"$REMOTE"'
 	else
-		initialize_merge_tool "$merge_tool"
-		# ignore the error from the above --- run_merge_tool
-		# will diagnose unusable tool by itself
+		initialize_merge_tool "$merge_tool" || exit 1
 		run_merge_tool "$merge_tool"
 	fi
 }
@@ -87,9 +85,7 @@ if test -n "$GIT_DIFFTOOL_DIRDIFF"
 then
 	LOCAL="$1"
 	REMOTE="$2"
-	initialize_merge_tool "$merge_tool"
-	# ignore the error from the above --- run_merge_tool
-	# will diagnose unusable tool by itself
+	initialize_merge_tool "$merge_tool" || exit 1
 	run_merge_tool "$merge_tool" false
 
 	status=$?
-- 
gitgitgadget

[PATCH v2 0/5] git-mergetool: improve error code paths and messages

[Philippe Blain via GitGitGadget]

Changes in v2: As suggested by Junio:

 * 3/5: moved the error message to setup_tool itself, and adjusted the
   commit message
 * 3/5: made the test more robust
 * 4/5: adjusted the error message

v1: These are a few improvements to improve existing error messages in 'git
mergetool', and make sure that errors are not quiet, along with a small
completion update in 1/1.

Philippe Blain (5):
  completion: complete '--tool-help' in 'git mergetool'
  git-mergetool--lib.sh: use TOOL_MODE when erroring about unknown tool
  git-mergetool--lib.sh: add error message if 'setup_user_tool' fails
  git-mergetool--lib.sh: add error message for unknown tool variant
  git-difftool--helper.sh: exit upon initialize_merge_tool errors

 contrib/completion/git-completion.bash |  2 +-
 git-difftool--helper.sh                |  8 ++------
 git-mergetool--lib.sh                  | 12 +++++++++---
 t/t7610-mergetool.sh                   |  8 ++++++++
 4 files changed, 20 insertions(+), 10 deletions(-)


base-commit: b31fb630c0fc6869a33ed717163e8a1210460d94
Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-1827%2Fphil-blain%2Fabsent-mergetool-v2
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-1827/phil-blain/absent-mergetool-v2
Pull-Request: https://github.com/gitgitgadget/git/pull/1827

Range-diff vs v1:

 1:  24933ba7130 = 1:  24933ba7130 completion: complete '--tool-help' in 'git mergetool'
 2:  6f7f553b283 = 2:  6f7f553b283 git-mergetool--lib.sh: use TOOL_MODE when erroring about unknown tool
 3:  79c3a6ffe8f ! 3:  1d9e95c6cb1 git-mergetool--lib.sh: add error message in 'setup_user_tool'
     @@ Metadata
      Author: Philippe Blain <levraiphilippeblain@gmail.com>
      
       ## Commit message ##
     -    git-mergetool--lib.sh: add error message in 'setup_user_tool'
     +    git-mergetool--lib.sh: add error message if 'setup_user_tool' fails
      
          In git-mergetool--lib.sh::setup_tool, we check if the given tool is a
          known builtin tool, a known variant, or a user-defined tool by calling
     @@ Commit message
      
                  git mergetool --tool=unknown
      
     -    which is not very user-friendly. Adjust setup_user_tool to output an
     -    error message before returning if {diff,merge}tool.$tool.cmd is not set.
     +    which is not very user-friendly. Adjust setup_tool to output an error
     +    message before returning if setup_user_tool returned with an error.
      
     -    Adjust the second call to setup_user_tool in setup_tool to silence this
     -    new error, as this call is only meant to allow users to redefine 'cmd'
     -    for a builtin tool; it is not an error if they have not done so (which
     -    is why we do not check the return status of this call).
     +    Note that we do not check the result of the second call to
     +    setup_user_tool in setup_tool, as this call is only meant to allow users
     +    to redefine 'cmd' for a builtin tool; it is not an error if they have
     +    not done so.
      
          Note that this behaviour of quietly failing is a regression dating back
          to de8dafbada (mergetool: break setup_tool out into separate
     @@ git-mergetool--lib.sh: check_unchanged () {
       	cmd=$(get_merge_tool_cmd "$1")
       	test -n "$cmd"
       }
     - 
     - setup_user_tool () {
     - 	merge_tool_cmd=$(get_merge_tool_cmd "$tool")
     --	test -n "$merge_tool_cmd" || return 1
     -+	if test -z "$merge_tool_cmd"
     -+	then
     -+		echo >&2 "error: ${TOOL_MODE}tool.$tool.cmd not set for tool '$tool'"
     -+		return 1
     -+	fi
     - 
     - 	diff_cmd () {
     - 		( eval $merge_tool_cmd )
      @@ git-mergetool--lib.sh: setup_tool () {
     + 		. "$MERGE_TOOLS_DIR/${tool%[0-9]}"
     + 	else
     + 		setup_user_tool
     +-		return $?
     ++		rc=$?
     ++		if test $rc -ne 0
     ++		then
     ++			echo >&2 "error: ${TOOL_MODE}tool.$tool.cmd not set for tool '$tool'"
     ++		fi
     ++		return $rc
     + 	fi
       
       	# Now let the user override the default command for the tool.  If
     - 	# they have not done so then this will return 1 which we ignore.
     --	setup_user_tool
     -+	setup_user_tool 2>/dev/null
     - 
     - 	if ! list_tool_variants | grep -q "^$tool$"
     - 	then
      
       ## t/t7610-mergetool.sh ##
      @@ t/t7610-mergetool.sh: test_expect_success 'mergetool with guiDefault' '
     @@ t/t7610-mergetool.sh: test_expect_success 'mergetool with guiDefault' '
      +	git checkout -b test$test_count branch1 &&
      +	test_must_fail git merge main &&
      +	yes "" | test_must_fail git mergetool --tool=absent >out 2>&1 &&
     -+	test_grep -i "not set for tool" out
     ++	test_grep "mergetool.absent.cmd not set for tool" out
      +'
      +
       test_done
 4:  74b83caa1e5 ! 4:  f234e965543 git-mergetool--lib.sh: add error message for unknown tool variant
     @@ git-mergetool--lib.sh: setup_tool () {
       
       	if ! list_tool_variants | grep -q "^$tool$"
       	then
     -+		echo "error: unknown ${tool%[0-9]} variant '$tool'" >&2
     ++		echo "error: unknown tool variant '$tool'" >&2
       		return 1
       	fi
       
 5:  be0b86f0890 = 5:  c16e9229ebb git-difftool--helper.sh: exit upon initialize_merge_tool errors

-- 
gitgitgadget

[PATCH v2 1/5] completion: complete '--tool-help' in 'git mergetool'

[Philippe Blain via GitGitGadget]

From: Philippe Blain <levraiphilippeblain@gmail.com>

Signed-off-by: Philippe Blain <levraiphilippeblain@gmail.com>
---
 contrib/completion/git-completion.bash | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/contrib/completion/git-completion.bash b/contrib/completion/git-completion.bash
index 3d4dff3185c..b3b6aa3bae2 100644
--- a/contrib/completion/git-completion.bash
+++ b/contrib/completion/git-completion.bash
@@ -2331,7 +2331,7 @@ _git_mergetool ()
 		return
 		;;
 	--*)
-		__gitcomp "--tool= --prompt --no-prompt --gui --no-gui"
+		__gitcomp "--tool= --tool-help --prompt --no-prompt --gui --no-gui"
 		return
 		;;
 	esac
-- 
gitgitgadget

[PATCH v2 2/5] git-mergetool--lib.sh: use TOOL_MODE when erroring about unknown tool

[Philippe Blain via GitGitGadget]

From: Philippe Blain <levraiphilippeblain@gmail.com>

In git-mergetool--lib.sh::get_merge_tool_path, we check if the chosen
tool is valid via valid_tool and exit with an error message if not. This
error message mentions "Unknown merge tool", even if the command the
user tried was 'git difftool --tool=unknown'. Use the global 'TOOL_MODE'
variable for a more correct error message.

Signed-off-by: Philippe Blain <levraiphilippeblain@gmail.com>
---
 git-mergetool--lib.sh | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/git-mergetool--lib.sh b/git-mergetool--lib.sh
index 1ff26170ffc..269a60ea44c 100644
--- a/git-mergetool--lib.sh
+++ b/git-mergetool--lib.sh
@@ -474,7 +474,7 @@ get_merge_tool_path () {
 	merge_tool="$1"
 	if ! valid_tool "$merge_tool"
 	then
-		echo >&2 "Unknown merge tool $merge_tool"
+		echo >&2 "Unknown $TOOL_MODE tool $merge_tool"
 		exit 1
 	fi
 	if diff_mode
-- 
gitgitgadget

[PATCH v2 3/5] git-mergetool--lib.sh: add error message if 'setup_user_tool' fails

[Philippe Blain via GitGitGadget]

From: Philippe Blain <levraiphilippeblain@gmail.com>

In git-mergetool--lib.sh::setup_tool, we check if the given tool is a
known builtin tool, a known variant, or a user-defined tool by calling
setup_user_tool, and we return with the exit code from setup_user_tool
if it was called. setup_user_tool checks if {diff,merge}tool.$tool.cmd
is set and quietly returns with an error if not.

This leads to the following invocation quietly failing:

	git mergetool --tool=unknown

which is not very user-friendly. Adjust setup_tool to output an error
message before returning if setup_user_tool returned with an error.

Note that we do not check the result of the second call to
setup_user_tool in setup_tool, as this call is only meant to allow users
to redefine 'cmd' for a builtin tool; it is not an error if they have
not done so.

Note that this behaviour of quietly failing is a regression dating back
to de8dafbada (mergetool: break setup_tool out into separate
initialization function, 2021-02-09), as before this commit an unknown
mergetool would be diagnosed in get_merge_tool_path when called from
run_merge_tool.

Signed-off-by: Philippe Blain <levraiphilippeblain@gmail.com>
---
 git-mergetool--lib.sh | 9 +++++++--
 t/t7610-mergetool.sh  | 8 ++++++++
 2 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/git-mergetool--lib.sh b/git-mergetool--lib.sh
index 269a60ea44c..d7e410d9481 100644
--- a/git-mergetool--lib.sh
+++ b/git-mergetool--lib.sh
@@ -159,7 +159,7 @@ check_unchanged () {
 }
 
 valid_tool () {
-	setup_tool "$1" && return 0
+	setup_tool "$1" 2>/dev/null && return 0
 	cmd=$(get_merge_tool_cmd "$1")
 	test -n "$cmd"
 }
@@ -250,7 +250,12 @@ setup_tool () {
 		. "$MERGE_TOOLS_DIR/${tool%[0-9]}"
 	else
 		setup_user_tool
-		return $?
+		rc=$?
+		if test $rc -ne 0
+		then
+			echo >&2 "error: ${TOOL_MODE}tool.$tool.cmd not set for tool '$tool'"
+		fi
+		return $rc
 	fi
 
 	# Now let the user override the default command for the tool.  If
diff --git a/t/t7610-mergetool.sh b/t/t7610-mergetool.sh
index 22b3a85b3e9..c077aba7ced 100755
--- a/t/t7610-mergetool.sh
+++ b/t/t7610-mergetool.sh
@@ -898,4 +898,12 @@ test_expect_success 'mergetool with guiDefault' '
 	git commit -m "branch1 resolved with mergetool"
 '
 
+test_expect_success 'mergetool with non-existent tool' '
+	test_when_finished "git reset --hard" &&
+	git checkout -b test$test_count branch1 &&
+	test_must_fail git merge main &&
+	yes "" | test_must_fail git mergetool --tool=absent >out 2>&1 &&
+	test_grep "mergetool.absent.cmd not set for tool" out
+'
+
 test_done
-- 
gitgitgadget

[PATCH v2 4/5] git-mergetool--lib.sh: add error message for unknown tool variant

[Philippe Blain via GitGitGadget]

From: Philippe Blain <levraiphilippeblain@gmail.com>

In setup_tool, we check if the given tool is a known variant of a tool,
and quietly return with an error if not. This leads to the following
invocation quietly failing:

	git mergetool --tool=vimdiff4

Add an error message before returning in this case.

Signed-off-by: Philippe Blain <levraiphilippeblain@gmail.com>
---
 git-mergetool--lib.sh | 1 +
 1 file changed, 1 insertion(+)

diff --git a/git-mergetool--lib.sh b/git-mergetool--lib.sh
index d7e410d9481..11ea181259f 100644
--- a/git-mergetool--lib.sh
+++ b/git-mergetool--lib.sh
@@ -264,6 +264,7 @@ setup_tool () {
 
 	if ! list_tool_variants | grep -q "^$tool$"
 	then
+		echo "error: unknown tool variant '$tool'" >&2
 		return 1
 	fi
 
-- 
gitgitgadget

[PATCH v2 5/5] git-difftool--helper.sh: exit upon initialize_merge_tool errors

[Philippe Blain via GitGitGadget]

From: Philippe Blain <levraiphilippeblain@gmail.com>

Since the introduction of 'initialize_merge_tool' in de8dafbada
(mergetool: break setup_tool out into separate initialization function,
2021-02-09), any errors from this function are ignored in
git-difftool--helper.sh::launch_merge_tool, which is not the case for
its call in git-mergetool.sh::merge_file.

Despite the in-code comment, initialize_merge_tool (via its call to
setup_tool) does different checks than run_merge_tool, so it makes sense
to abort early if it encounters errors. Add exit calls if
initialize_merge_tool fails.

Signed-off-by: Philippe Blain <levraiphilippeblain@gmail.com>
---
 git-difftool--helper.sh | 8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/git-difftool--helper.sh b/git-difftool--helper.sh
index dd0c9a5b7f2..d32e47cc09e 100755
--- a/git-difftool--helper.sh
+++ b/git-difftool--helper.sh
@@ -61,9 +61,7 @@ launch_merge_tool () {
 		export BASE
 		eval $GIT_DIFFTOOL_EXTCMD '"$LOCAL"' '"$REMOTE"'
 	else
-		initialize_merge_tool "$merge_tool"
-		# ignore the error from the above --- run_merge_tool
-		# will diagnose unusable tool by itself
+		initialize_merge_tool "$merge_tool" || exit 1
 		run_merge_tool "$merge_tool"
 	fi
 }
@@ -87,9 +85,7 @@ if test -n "$GIT_DIFFTOOL_DIRDIFF"
 then
 	LOCAL="$1"
 	REMOTE="$2"
-	initialize_merge_tool "$merge_tool"
-	# ignore the error from the above --- run_merge_tool
-	# will diagnose unusable tool by itself
+	initialize_merge_tool "$merge_tool" || exit 1
 	run_merge_tool "$merge_tool" false
 
 	status=$?
-- 
gitgitgadget

Re: [PATCH v2 0/5] git-mergetool: improve error code paths and messages

[Junio C Hamano]

"Philippe Blain via GitGitGadget" <gitgitgadget@gmail.com> writes:

> Changes in v2: As suggested by Junio:
>
>  * 3/5: moved the error message to setup_tool itself, and adjusted the
>    commit message
>  * 3/5: made the test more robust
>  * 4/5: adjusted the error message

I think the above changes all looked good.

Let me mark the topic for 'next'.

Thanks.