[PATCH 0/4] Fix "git difftool --tool-help"

The "--tool-help" option to git-difftool currently displays incorrect
output since it uses the names of the files in
"$GIT_EXEC_PATH/mergetools/" rather than the list of command names in
git-mergetool--lib.

This series fixes this by changing it to simply delegate to a function
in git-mergetool--lib.

The first three patches are just refactorings to move the show_tool_help
function from git-mergetool to git-mergetool--lib and make it usable by
git-difftool.  The final patch switches git-difftool to use this
function.


John Keeping (4):
  git-mergetool: move show_tool_help to mergetool--lib
  git-mergetool: remove redundant assignment
  git-mergetool: don't hardcode 'mergetool' in show_tool_help
  git-difftool: use git-mergetool--lib for "--tool-help"

 git-difftool.perl     | 57 ++++++++-------------------------------------------
 git-mergetool--lib.sh | 38 ++++++++++++++++++++++++++++++++++
 git-mergetool.sh      | 37 ---------------------------------
 3 files changed, 46 insertions(+), 86 deletions(-)

-- 
1.8.1

This is the first step in unifying "git difftool --tool-help" and
"git mergetool --tool-help".

Signed-off-by: John Keeping <redacted>
---
 git-mergetool--lib.sh | 37 +++++++++++++++++++++++++++++++++++++
 git-mergetool.sh      | 37 -------------------------------------
 2 files changed, 37 insertions(+), 37 deletions(-)

diff --git a/git-mergetool--lib.sh b/git-mergetool--lib.sh
index f013a03..89a857f 100644
--- a/git-mergetool--lib.sh
+++ b/git-mergetool--lib.sh

@@ -174,6 +174,43 @@ list_merge_tool_candidates () {
 	esac
 }
 
+show_tool_help () {
+	TOOL_MODE=merge
+	list_merge_tool_candidates
+	unavailable= available= LF='
+'
+	for i in $tools
+	do
+		merge_tool_path=$(translate_merge_tool_path "$i")
+		if type "$merge_tool_path" >/dev/null 2>&1
+		then
+			available="$available$i$LF"
+		else
+			unavailable="$unavailable$i$LF"
+		fi
+	done
+	if test -n "$available"
+	then
+		echo "'git mergetool --tool=<tool>' may be set to one of the following:"
+		echo "$available" | sort | sed -e 's/^/	/'
+	else
+		echo "No suitable tool for 'git mergetool --tool=<tool>' found."
+	fi
+	if test -n "$unavailable"
+	then
+		echo
+		echo 'The following tools are valid, but not currently available:'
+		echo "$unavailable" | sort | sed -e 's/^/	/'
+	fi
+	if test -n "$unavailable$available"
+	then
+		echo
+		echo "Some of the tools listed above only work in a windowed"
+		echo "environment. If run in a terminal-only session, they will fail."
+	fi
+	exit 0
+}
+
 guess_merge_tool () {
 	list_merge_tool_candidates
 	echo >&2 "merge tool candidates: $tools"

diff --git a/git-mergetool.sh b/git-mergetool.sh
index c50e18a..c0ee9aa 100755
--- a/git-mergetool.sh
+++ b/git-mergetool.sh

@@ -315,43 +315,6 @@ merge_file () {
 	return 0
 }
 
-show_tool_help () {
-	TOOL_MODE=merge
-	list_merge_tool_candidates
-	unavailable= available= LF='
-'
-	for i in $tools
-	do
-		merge_tool_path=$(translate_merge_tool_path "$i")
-		if type "$merge_tool_path" >/dev/null 2>&1
-		then
-			available="$available$i$LF"
-		else
-			unavailable="$unavailable$i$LF"
-		fi
-	done
-	if test -n "$available"
-	then
-		echo "'git mergetool --tool=<tool>' may be set to one of the following:"
-		echo "$available" | sort | sed -e 's/^/	/'
-	else
-		echo "No suitable tool for 'git mergetool --tool=<tool>' found."
-	fi
-	if test -n "$unavailable"
-	then
-		echo
-		echo 'The following tools are valid, but not currently available:'
-		echo "$unavailable" | sort | sed -e 's/^/	/'
-	fi
-	if test -n "$unavailable$available"
-	then
-		echo
-		echo "Some of the tools listed above only work in a windowed"
-		echo "environment. If run in a terminal-only session, they will fail."
-	fi
-	exit 0
-}
-
 prompt=$(git config --bool mergetool.prompt || echo true)
 
 while test $# != 0

-- 
1.8.1

TOOL_MODE is set at the top of git-mergetool.sh so there is no need to
set it again in show_tool_help.  Removing this lets us re-use
show_tool_help in git-difftool.

Signed-off-by: John Keeping <redacted>
---
 git-mergetool--lib.sh | 1 -
 1 file changed, 1 deletion(-)

diff --git a/git-mergetool--lib.sh b/git-mergetool--lib.sh
index 89a857f..1748315 100644
--- a/git-mergetool--lib.sh
+++ b/git-mergetool--lib.sh

@@ -175,7 +175,6 @@ list_merge_tool_candidates () {
 }
 
 show_tool_help () {
-	TOOL_MODE=merge
 	list_merge_tool_candidates
 	unavailable= available= LF='
 '

-- 
1.8.1

When using show_tool_help from git-difftool we will want it to print
"git difftool" not "git mergetool" so use "git ${TOOL_MODE}tool".

Signed-off-by: John Keeping <redacted>
---
 git-mergetool--lib.sh | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/git-mergetool--lib.sh b/git-mergetool--lib.sh
index 1748315..4c1e129 100644
--- a/git-mergetool--lib.sh
+++ b/git-mergetool--lib.sh

@@ -188,12 +188,14 @@ show_tool_help () {
 			unavailable="$unavailable$i$LF"
 		fi
 	done
+
+	cmd_name=${TOOL_MODE}tool
 	if test -n "$available"
 	then
-		echo "'git mergetool --tool=<tool>' may be set to one of the following:"
+		echo "'git $cmd_name --tool=<tool>' may be set to one of the following:"
 		echo "$available" | sort | sed -e 's/^/	/'
 	else
-		echo "No suitable tool for 'git mergetool --tool=<tool>' found."
+		echo "No suitable tool for 'git $cmd_name --tool=<tool>' found."
 	fi
 	if test -n "$unavailable"
 	then

-- 
1.8.1

The "--tool-help" option to git-difftool currently displays incorrect
output since it uses the names of the files in
"$GIT_EXEC_PATH/mergetools/" rather than the list of command names in
git-mergetool--lib.

Fix this by simply delegating the "--tool-help" argument to the
show_tool_help function in git-mergetool--lib.

Signed-off-by: John Keeping <redacted>
---
 git-difftool.perl | 57 ++++++++-----------------------------------------------
 1 file changed, 8 insertions(+), 49 deletions(-)

diff --git a/git-difftool.perl b/git-difftool.perl
index edd0493..0a90de4 100755
--- a/git-difftool.perl
+++ b/git-difftool.perl

@@ -59,57 +59,16 @@ sub find_worktree
 	return $worktree;
 }
 
-sub filter_tool_scripts
-{
-	my ($tools) = @_;
-	if (-d $_) {
-		if ($_ ne ".") {
-			# Ignore files in subdirectories
-			$File::Find::prune = 1;
-		}
-	} else {
-		if ((-f $_) && ($_ ne "defaults")) {
-			push(@$tools, $_);
-		}
-	}
-}
-
 sub print_tool_help
 {
-	my ($cmd, @found, @notfound, @tools);
-	my $gitpath = Git::exec_path();
-
-	find(sub { filter_tool_scripts(\@tools) }, "$gitpath/mergetools");
-
-	foreach my $tool (@tools) {
-		$cmd  = "TOOL_MODE=diff";
-		$cmd .= ' && . "$(git --exec-path)/git-mergetool--lib"';
-		$cmd .= " && get_merge_tool_path $tool >/dev/null 2>&1";
-		$cmd .= " && can_diff >/dev/null 2>&1";
-		if (system('sh', '-c', $cmd) == 0) {
-			push(@found, $tool);
-		} else {
-			push(@notfound, $tool);
-		}
-	}
-
-	print << 'EOF';
-'git difftool --tool=<tool>' may be set to one of the following:
-EOF
-	print "\t$_\n" for (sort(@found));
-
-	print << 'EOF';
-
-The following tools are valid, but not currently available:
-EOF
-	print "\t$_\n" for (sort(@notfound));
-
-	print << 'EOF';
-
-NOTE: Some of the tools listed above only work in a windowed
-environment. If run in a terminal-only session, they will fail.
-EOF
-	exit(0);
+	my $cmd = 'TOOL_MODE=diff';
+	$cmd .= ' && . "$(git --exec-path)/git-mergetool--lib"';
+	$cmd .= ' && show_tool_help';
+
+	# See the comment at the bottom of file_diff() for the reason behind
+	# using system() followed by exit() instead of exec().
+	my $rc = system('sh', '-c', $cmd);
+	exit($rc | ($rc >> 8));
 }
 
 sub exit_cleanup

-- 
1.8.1

On Thu, Jan 24, 2013 at 11:55 AM, John Keeping [off-list ref] wrote:

The "--tool-help" option to git-difftool currently displays incorrect
output since it uses the names of the files in
"$GIT_EXEC_PATH/mergetools/" rather than the list of command names in
git-mergetool--lib.

Fix this by simply delegating the "--tool-help" argument to the
show_tool_help function in git-mergetool--lib.

Very nice.

One thought I had was that the unified show_tool_help should
probably check TOOL_MODE=diff and skip over the
!can_diff entries.

The current output of "git difftool --tool-help" before your
patches has the problem that it will list tools such as
"tortoisemerge" as "valid but not available" because it
does not differentiate between missing and !can_diff.

This is where we conflated can_diff with "is the tool available?".
The nice thing is that the old code did actually check can_diff,
but since it conflated these things it ended up putting them
in the @notfound list.  It should ignore those completely, IMO.

That could be a nice follow-up patch.  What do you think?
-- 
David

On Thu, Jan 24, 2013 at 09:29:58PM -0800, David Aguilar wrote:

On Thu, Jan 24, 2013 at 11:55 AM, John Keeping [off-list ref] wrote:

quoted

The "--tool-help" option to git-difftool currently displays incorrect
output since it uses the names of the files in
"$GIT_EXEC_PATH/mergetools/" rather than the list of command names in
git-mergetool--lib.

Fix this by simply delegating the "--tool-help" argument to the
show_tool_help function in git-mergetool--lib.

Very nice.

One thought I had was that the unified show_tool_help should
probably check TOOL_MODE=diff and skip over the
!can_diff entries.

The current output of "git difftool --tool-help" before your
patches has the problem that it will list tools such as
"tortoisemerge" as "valid but not available" because it
does not differentiate between missing and !can_diff.

list_merge_tool_candidates does this for us, so it should Just Work
since we use that to generate the list of tools that we loop over.


John

On Fri, Jan 25, 2013 at 1:19 AM, John Keeping [off-list ref] wrote:

On Thu, Jan 24, 2013 at 09:29:58PM -0800, David Aguilar wrote:

quoted

On Thu, Jan 24, 2013 at 11:55 AM, John Keeping [off-list ref] wrote:

quoted

The "--tool-help" option to git-difftool currently displays incorrect
output since it uses the names of the files in
"$GIT_EXEC_PATH/mergetools/" rather than the list of command names in
git-mergetool--lib.

Fix this by simply delegating the "--tool-help" argument to the
show_tool_help function in git-mergetool--lib.

Very nice.

One thought I had was that the unified show_tool_help should
probably check TOOL_MODE=diff and skip over the
!can_diff entries.

The current output of "git difftool --tool-help" before your
patches has the problem that it will list tools such as
"tortoisemerge" as "valid but not available" because it
does not differentiate between missing and !can_diff.

list_merge_tool_candidates does this for us, so it should Just Work
since we use that to generate the list of tools that we loop over.

Yup, kind of.  I looked more closely and found a lot of
special-cases around vim which I've eliminated in the series
I just sent (which includes your patches as its base).

list_merge_tool_candidates() has a bunch of other special cases
for $EDITOR, $DISPLAY, $GNOME-something and such so I think
we should keep using it only for the guess_merge_tool() path.

I honestly want to remove list_merge_tool_candidates every
time I read it, but I recognize that it does serve a purpose
for users who have not configured anything.

In order to be useful for the documentation I think the
code could be refactored a tiny bit more beyond what I've
sent so far.  The gathering of available tools can be split
off from the reporting, and then show_tool_help() can use
the gatherer.  With what I sent, though, there's at least
a 1:1 correspondance between the name of the scriptlets
and the names accepted by --tool=<tool>, which is the first
step towards doing that.

I have to check out for now but I'll keep poking at this
when the weekend rolls around.

cheers,
-- 
David

On Fri, Jan 25, 2013 at 01:55:03AM -0800, David Aguilar wrote:

list_merge_tool_candidates() has a bunch of other special cases
for $EDITOR, $DISPLAY, $GNOME-something and such so I think
we should keep using it only for the guess_merge_tool() path.

I honestly want to remove list_merge_tool_candidates every
time I read it, but I recognize that it does serve a purpose
for users who have not configured anything.

Actually, I'm not sure it does.  I asked one of my colleagues whether
he used git-mergetool the other day and he said no because he couldn't
understand the OS X FileMerge tool and was happier to edit things
manually in vim.  I don't think he'd realised that he could configure a
different mergetool.

Perhaps we're trying to be too clever by guessing what the user wants
and should instead exit with a message saying:

   You have not configured a merge tool to use.  Please select one of
   the following tools and configure it using:

        git config merge.tool <tool>

    These tools are availalble on your system:
        ...

    These tools are supported but unavailable:
        ...

This may be too much of a regression for current users though.


John