[PATCH] difftool --dir-diff: copy back all files matching the working tree

[PATCH] difftool --dir-diff: copy back all files matching the working tree

[Kenichi Saita]

After running the user's diff tool, "git difftool --dir-dif --no-symlink"
currently copied back a temporary file to working tree only when a file
contains unstaged changes in the working tree.

Change this behavior so that temporary files are copied back to working
tree whenever the right-hand side of the comparison has the same SHA1
as the file in the working tree.

Signed-off-by: Kenichi Saita <nitoyon@gmail.com>
---
 git-difftool.perl   |    9 ++-------
 t/t7800-difftool.sh |   19 +++++++++++++++++++
 2 files changed, 21 insertions(+), 7 deletions(-)

diff --git a/git-difftool.perl b/git-difftool.perl
index 8a75205..e57d3d1 100755
--- a/git-difftool.perl
+++ b/git-difftool.perl
@@ -85,13 +85,9 @@ sub exit_cleanup
 
 sub use_wt_file
 {
-	my ($repo, $workdir, $file, $sha1, $symlinks) = @_;
+	my ($repo, $workdir, $file, $sha1) = @_;
 	my $null_sha1 = '0' x 40;
 
-	if ($sha1 ne $null_sha1 and not $symlinks) {
-		return 0;
-	}
-
 	if (! -e "$workdir/$file") {
 		# If the file doesn't exist in the working tree, we cannot
 		# use it.
@@ -213,8 +209,7 @@ EOF
 
 		if ($rmode ne $null_mode) {
 			my ($use, $wt_sha1) = use_wt_file($repo, $workdir,
-							  $dst_path, $rsha1,
-							  $symlinks);
+							  $dst_path, $rsha1);
 			if ($use) {
 				push @working_tree, $dst_path;
 				$wtindex .= "$rmode $wt_sha1\t$dst_path\0";
diff --git a/t/t7800-difftool.sh b/t/t7800-difftool.sh
index d46f041..2418528 100755
--- a/t/t7800-difftool.sh
+++ b/t/t7800-difftool.sh
@@ -385,6 +385,25 @@ test_expect_success PERL,SYMLINKS 'difftool --dir-diff --symlink without unstage
 	test_cmp actual expect
 '
 
+write_script modify-right-file <<\EOF
+echo "new content" >"$2/file"
+EOF
+
+run_dir_diff_test 'difftool --dir-diff syncs worktree with unstaged change' '
+	test_when_finished git reset --hard &&
+	echo "orig content" >file &&
+	git difftool -d $symlinks --extcmd "$(pwd)/modify-right-file" branch &&
+	echo "new content" >expect &&
+	test_cmp expect file
+'
+
+run_dir_diff_test 'difftool --dir-diff syncs worktree without unstaged change' '
+	test_when_finished git reset --hard &&
+	git difftool -d $symlinks --extcmd "$(pwd)/modify-right-file" branch &&
+	echo "new content" >expect &&
+	test_cmp expect file
+'
+
 write_script modify-file <<\EOF
 echo "new content" >file
 EOF
-- 
1.7.1

Re: [PATCH] difftool --dir-diff: copy back all files matching the working tree

[John Keeping]

On Mon, May 27, 2013 at 12:00:46AM +0900, Kenichi Saita wrote:
> After running the user's diff tool, "git difftool --dir-dif --no-symlink"
> currently copied back a temporary file to working tree only when a file
> contains unstaged changes in the working tree.
> 
> Change this behavior so that temporary files are copied back to working
> tree whenever the right-hand side of the comparison has the same SHA1
> as the file in the working tree.
> 
> Signed-off-by: Kenichi Saita <nitoyon@gmail.com>

This change looks sensible to me, but I found the commit message quite
confusing.

The code being changed here is to do with choosing whether to copy the
working tree file to the temporary directory (or symlink it) and hence
only indirectly related to whether it will be copied back.  It might be
clearer to phrase it like this:

    difftool --dir-diff: always use identical working tree file

    When deciding whether or not we should link a working tree file into
    the temporary right-hand directory for a directory diff, we
    currently behave differently in the --symlink and --no-symlink
    cases.  If using symlinks any identical files are linked across but
    with --no-symlink only files that contain unstaged changes are
    copied.

    Change this so that identical files are copied across as well.  This
    is beneficial because it widens the set of circumstances in which we
    copy changes made by the user back into the working tree.

> ---
>  git-difftool.perl   |    9 ++-------
>  t/t7800-difftool.sh |   19 +++++++++++++++++++
>  2 files changed, 21 insertions(+), 7 deletions(-)
> 
> diff --git a/git-difftool.perl b/git-difftool.perl
> index 8a75205..e57d3d1 100755
> --- a/git-difftool.perl
> +++ b/git-difftool.perl
> @@ -85,13 +85,9 @@ sub exit_cleanup
>  
>  sub use_wt_file
>  {
> -	my ($repo, $workdir, $file, $sha1, $symlinks) = @_;
> +	my ($repo, $workdir, $file, $sha1) = @_;
>  	my $null_sha1 = '0' x 40;
>  
> -	if ($sha1 ne $null_sha1 and not $symlinks) {
> -		return 0;
> -	}
> -
>  	if (! -e "$workdir/$file") {
>  		# If the file doesn't exist in the working tree, we cannot
>  		# use it.
> @@ -213,8 +209,7 @@ EOF
>  
>  		if ($rmode ne $null_mode) {
>  			my ($use, $wt_sha1) = use_wt_file($repo, $workdir,
> -							  $dst_path, $rsha1,
> -							  $symlinks);
> +							  $dst_path, $rsha1);
>  			if ($use) {
>  				push @working_tree, $dst_path;
>  				$wtindex .= "$rmode $wt_sha1\t$dst_path\0";
> diff --git a/t/t7800-difftool.sh b/t/t7800-difftool.sh
> index d46f041..2418528 100755
> --- a/t/t7800-difftool.sh
> +++ b/t/t7800-difftool.sh
> @@ -385,6 +385,25 @@ test_expect_success PERL,SYMLINKS 'difftool --dir-diff --symlink without unstage
>  	test_cmp actual expect
>  '
>  
> +write_script modify-right-file <<\EOF
> +echo "new content" >"$2/file"
> +EOF
> +
> +run_dir_diff_test 'difftool --dir-diff syncs worktree with unstaged change' '
> +	test_when_finished git reset --hard &&
> +	echo "orig content" >file &&
> +	git difftool -d $symlinks --extcmd "$(pwd)/modify-right-file" branch &&
> +	echo "new content" >expect &&
> +	test_cmp expect file
> +'
> +
> +run_dir_diff_test 'difftool --dir-diff syncs worktree without unstaged change' '
> +	test_when_finished git reset --hard &&
> +	git difftool -d $symlinks --extcmd "$(pwd)/modify-right-file" branch &&
> +	echo "new content" >expect &&
> +	test_cmp expect file
> +'
> +
>  write_script modify-file <<\EOF
>  echo "new content" >file
>  EOF
> -- 
> 1.7.1

[PATCH v2] difftool --dir-diff: always use identical working tree file

[Kenichi Saita]

When deciding whether or not we should link a working tree file into
the temporary right-hand directory for a directory diff, we
currently behave differently in the --symlink and --no-symlink
cases.  If using symlinks any identical files are linked across but
with --no-symlink only files that contain unstaged changes are
copied back into the working tree.

Change this so that identical files are copied back as well.  This
is beneficial because it widens the set of circumstances in which we
copy changes made by the user back into the working tree.

Signed-off-by: Kenichi Saita <nitoyon@gmail.com>
---
 git-difftool.perl   |    9 ++-------
 t/t7800-difftool.sh |   19 +++++++++++++++++++
 2 files changed, 21 insertions(+), 7 deletions(-)

diff --git a/git-difftool.perl b/git-difftool.perl
index 8a75205..e57d3d1 100755
--- a/git-difftool.perl
+++ b/git-difftool.perl
@@ -85,13 +85,9 @@ sub exit_cleanup
 
 sub use_wt_file
 {
-	my ($repo, $workdir, $file, $sha1, $symlinks) = @_;
+	my ($repo, $workdir, $file, $sha1) = @_;
 	my $null_sha1 = '0' x 40;
 
-	if ($sha1 ne $null_sha1 and not $symlinks) {
-		return 0;
-	}
-
 	if (! -e "$workdir/$file") {
 		# If the file doesn't exist in the working tree, we cannot
 		# use it.
@@ -213,8 +209,7 @@ EOF
 
 		if ($rmode ne $null_mode) {
 			my ($use, $wt_sha1) = use_wt_file($repo, $workdir,
-							  $dst_path, $rsha1,
-							  $symlinks);
+							  $dst_path, $rsha1);
 			if ($use) {
 				push @working_tree, $dst_path;
 				$wtindex .= "$rmode $wt_sha1\t$dst_path\0";
diff --git a/t/t7800-difftool.sh b/t/t7800-difftool.sh
index d46f041..2418528 100755
--- a/t/t7800-difftool.sh
+++ b/t/t7800-difftool.sh
@@ -385,6 +385,25 @@ test_expect_success PERL,SYMLINKS 'difftool --dir-diff --symlink without unstage
 	test_cmp actual expect
 '
 
+write_script modify-right-file <<\EOF
+echo "new content" >"$2/file"
+EOF
+
+run_dir_diff_test 'difftool --dir-diff syncs worktree with unstaged change' '
+	test_when_finished git reset --hard &&
+	echo "orig content" >file &&
+	git difftool -d $symlinks --extcmd "$(pwd)/modify-right-file" branch &&
+	echo "new content" >expect &&
+	test_cmp expect file
+'
+
+run_dir_diff_test 'difftool --dir-diff syncs worktree without unstaged change' '
+	test_when_finished git reset --hard &&
+	git difftool -d $symlinks --extcmd "$(pwd)/modify-right-file" branch &&
+	echo "new content" >expect &&
+	test_cmp expect file
+'
+
 write_script modify-file <<\EOF
 echo "new content" >file
 EOF
-- 
1.7.1

Re: [PATCH v2] difftool --dir-diff: always use identical working tree file

[Junio C Hamano]

Kenichi Saita <nitoyon@gmail.com> writes:

> When deciding whether or not we should link a working tree file into
> the temporary right-hand directory for a directory diff, we
> currently behave differently in the --symlink and --no-symlink
> cases.  If using symlinks any identical files are linked across but
> with --no-symlink only files that contain unstaged changes are
> copied back into the working tree.

I may have missed an earlier discussion, but I do not follow the
last sentence.  The former part (i.e. symlinks) talks about what is
done to populate the temporary tree (i.e. everything is linked), but
the latter part (i.e. not symlinks) only talks about what is copied
back, i.e. it is not a contrast between the behaviour of symlink vs
no-symlink case wrt how the temporary tree is populated.

Confused...

> Change this so that identical files are copied back as well.  This
> is beneficial because it widens the set of circumstances in which we
> copy changes made by the user back into the working tree.

Ah, OK, you meant that the set of files we keep in @working_tree
array for later copying back are different between the two.

> Signed-off-by: Kenichi Saita <nitoyon@gmail.com>
> ---
>  git-difftool.perl   |    9 ++-------
>  t/t7800-difftool.sh |   19 +++++++++++++++++++
>  2 files changed, 21 insertions(+), 7 deletions(-)
>
> diff --git a/git-difftool.perl b/git-difftool.perl
> index 8a75205..e57d3d1 100755
> --- a/git-difftool.perl
> +++ b/git-difftool.perl
> @@ -85,13 +85,9 @@ sub exit_cleanup
>  
>  sub use_wt_file
>  {
> -	my ($repo, $workdir, $file, $sha1, $symlinks) = @_;
> +	my ($repo, $workdir, $file, $sha1) = @_;
>  	my $null_sha1 = '0' x 40;
>  
> -	if ($sha1 ne $null_sha1 and not $symlinks) {
> -		return 0;
> -	}
> -
>  	if (! -e "$workdir/$file") {
>  		# If the file doesn't exist in the working tree, we cannot
>  		# use it.
> @@ -213,8 +209,7 @@ EOF
>  
>  		if ($rmode ne $null_mode) {
>  			my ($use, $wt_sha1) = use_wt_file($repo, $workdir,
> -							  $dst_path, $rsha1,
> -							  $symlinks);
> +							  $dst_path, $rsha1);
>  			if ($use) {
>  				push @working_tree, $dst_path;
>  				$wtindex .= "$rmode $wt_sha1\t$dst_path\0";
> diff --git a/t/t7800-difftool.sh b/t/t7800-difftool.sh
> index d46f041..2418528 100755
> --- a/t/t7800-difftool.sh
> +++ b/t/t7800-difftool.sh
> @@ -385,6 +385,25 @@ test_expect_success PERL,SYMLINKS 'difftool --dir-diff --symlink without unstage
>  	test_cmp actual expect
>  '
>  
> +write_script modify-right-file <<\EOF
> +echo "new content" >"$2/file"
> +EOF
> +
> +run_dir_diff_test 'difftool --dir-diff syncs worktree with unstaged change' '
> +	test_when_finished git reset --hard &&
> +	echo "orig content" >file &&
> +	git difftool -d $symlinks --extcmd "$(pwd)/modify-right-file" branch &&
> +	echo "new content" >expect &&
> +	test_cmp expect file
> +'
> +
> +run_dir_diff_test 'difftool --dir-diff syncs worktree without unstaged change' '
> +	test_when_finished git reset --hard &&
> +	git difftool -d $symlinks --extcmd "$(pwd)/modify-right-file" branch &&
> +	echo "new content" >expect &&
> +	test_cmp expect file
> +'
> +
>  write_script modify-file <<\EOF
>  echo "new content" >file
>  EOF

Re: [PATCH v2] difftool --dir-diff: always use identical working tree file

[John Keeping]

On Tue, May 28, 2013 at 11:06:13AM -0700, Junio C Hamano wrote:
> Kenichi Saita <nitoyon@gmail.com> writes:
> 
> > When deciding whether or not we should link a working tree file into
> > the temporary right-hand directory for a directory diff, we
> > currently behave differently in the --symlink and --no-symlink
> > cases.  If using symlinks any identical files are linked across but
> > with --no-symlink only files that contain unstaged changes are
> > copied back into the working tree.
> 
> I may have missed an earlier discussion, but I do not follow the
> last sentence.  The former part (i.e. symlinks) talks about what is
> done to populate the temporary tree (i.e. everything is linked), but
> the latter part (i.e. not symlinks) only talks about what is copied
> back, i.e. it is not a contrast between the behaviour of symlink vs
> no-symlink case wrt how the temporary tree is populated.
> 
> Confused...

Yeah, the commit message is still quite focused on the end effect of
copying files back.  But that's not what's being changed here.

In my suggested commit message I tried to make it clear that we're
changing when we decide to copy a file across to the temporary tree.
This has the beneficial (side-)effect of changing the set of files we
consider for copying back into the working tree after the diff tool has
been run.

> > Change this so that identical files are copied back as well.  This
> > is beneficial because it widens the set of circumstances in which we
> > copy changes made by the user back into the working tree.
> 
> Ah, OK, you meant that the set of files we keep in @working_tree
> array for later copying back are different between the two.
> 
> > Signed-off-by: Kenichi Saita <nitoyon@gmail.com>
> > ---
> >  git-difftool.perl   |    9 ++-------
> >  t/t7800-difftool.sh |   19 +++++++++++++++++++
> >  2 files changed, 21 insertions(+), 7 deletions(-)
> >
> > diff --git a/git-difftool.perl b/git-difftool.perl
> > index 8a75205..e57d3d1 100755
> > --- a/git-difftool.perl
> > +++ b/git-difftool.perl
> > @@ -85,13 +85,9 @@ sub exit_cleanup
> >  
> >  sub use_wt_file
> >  {
> > -	my ($repo, $workdir, $file, $sha1, $symlinks) = @_;
> > +	my ($repo, $workdir, $file, $sha1) = @_;
> >  	my $null_sha1 = '0' x 40;
> >  
> > -	if ($sha1 ne $null_sha1 and not $symlinks) {
> > -		return 0;
> > -	}
> > -
> >  	if (! -e "$workdir/$file") {
> >  		# If the file doesn't exist in the working tree, we cannot
> >  		# use it.
> > @@ -213,8 +209,7 @@ EOF
> >  
> >  		if ($rmode ne $null_mode) {
> >  			my ($use, $wt_sha1) = use_wt_file($repo, $workdir,
> > -							  $dst_path, $rsha1,
> > -							  $symlinks);
> > +							  $dst_path, $rsha1);
> >  			if ($use) {
> >  				push @working_tree, $dst_path;
> >  				$wtindex .= "$rmode $wt_sha1\t$dst_path\0";
> > diff --git a/t/t7800-difftool.sh b/t/t7800-difftool.sh
> > index d46f041..2418528 100755
> > --- a/t/t7800-difftool.sh
> > +++ b/t/t7800-difftool.sh
> > @@ -385,6 +385,25 @@ test_expect_success PERL,SYMLINKS 'difftool --dir-diff --symlink without unstage
> >  	test_cmp actual expect
> >  '
> >  
> > +write_script modify-right-file <<\EOF
> > +echo "new content" >"$2/file"
> > +EOF
> > +
> > +run_dir_diff_test 'difftool --dir-diff syncs worktree with unstaged change' '
> > +	test_when_finished git reset --hard &&
> > +	echo "orig content" >file &&
> > +	git difftool -d $symlinks --extcmd "$(pwd)/modify-right-file" branch &&
> > +	echo "new content" >expect &&
> > +	test_cmp expect file
> > +'
> > +
> > +run_dir_diff_test 'difftool --dir-diff syncs worktree without unstaged change' '
> > +	test_when_finished git reset --hard &&
> > +	git difftool -d $symlinks --extcmd "$(pwd)/modify-right-file" branch &&
> > +	echo "new content" >expect &&
> > +	test_cmp expect file
> > +'
> > +
> >  write_script modify-file <<\EOF
> >  echo "new content" >file
> >  EOF
> --
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Re: [PATCH v2] difftool --dir-diff: always use identical working tree file

[Junio C Hamano]

John Keeping <john@keeping.me.uk> writes:

> Yeah, the commit message is still quite focused on the end effect of
> copying files back.  But that's not what's being changed here.
>
> In my suggested commit message I tried to make it clear that we're
> changing when we decide to copy a file across to the temporary tree.
> This has the beneficial (side-)effect of changing the set of files we
> consider for copying back into the working tree after the diff tool has
> been run.

I actually think the effect of copying files back _is_ the primary
motivation of this change, and stressing that end effect is a much
better description.  After all, if the working tree files do not
have any difference from the RHS of the comparison, copying from the
working tree and stuffing the $rsha1 to the RHS temporary index and
running "checkout -f" should produce identical temporary directory
for the user to start viewing.

The _only_ difference in behaviour before and after this patch that
matters to the end user is if that path is in @working_tree, which
is returned to @worktree of dir_diff sub to be later copied back,
no?  I would view this change as a mere means, an implementation
detail, to achieve that end of stuffing more paths in the @worktree
array.

Perhaps

	difftool --dir-diff: allow changing any clean working tree file

	The temporary directory prepared by "difftool --dir-diff" to
	show the result of a change can be modified by the user via
	the tree diff program, and we try hard not to lose changes
	to them after tree diff program returns to us.

        However, the set of files to be copied back is computed
	differently between --symlinks and --no-symlinks modes.  The
	former checks all paths that start out as identical to the
	working tree file, while the latter checks paths that
	already had a local modification in the working tree,
	allowing changes made in the tree diff program to paths that
	did not have any local change to be lost.

or something.  This invites a few questions, though.

 - By allowing these files in the temporary directory to be
   modified, aren't we making the user's life harder by forcing them
   to handle "working tree file was already modified, made different
   changes in the temporary directory, now these changes need to be
   consolidated" case?

 - When comparing two revisions, e.g. "--dir-diff HEAD^^ HEAD^",
   that checks out (via $rsha1 to "checkout -f" codepath) a blob
   that does not match what is in the working tree of HEAD to the
   temporary directory, we still allow modifications to the copy in
   the temporary directory, but what can the user do with these
   changes that are _not_ based on HEAD, short of checking out HEAD^
   and apply the difference first?

I still cannot shake this nagging feeling that giving a writable
temporary directory might have been a mistake in the first place.
Perhaps it may be a better design to make the ones that the user
shouldn't touch (or will lead to the above confusion) read-only,
while the ones that match the working tree read-write?

Re: [PATCH v2] difftool --dir-diff: always use identical working tree file

[John Keeping]

On Tue, May 28, 2013 at 11:57:08AM -0700, Junio C Hamano wrote:
> John Keeping <john@keeping.me.uk> writes:
> 
> > Yeah, the commit message is still quite focused on the end effect of
> > copying files back.  But that's not what's being changed here.
> >
> > In my suggested commit message I tried to make it clear that we're
> > changing when we decide to copy a file across to the temporary tree.
> > This has the beneficial (side-)effect of changing the set of files we
> > consider for copying back into the working tree after the diff tool has
> > been run.
> 
> I actually think the effect of copying files back _is_ the primary
> motivation of this change, and stressing that end effect is a much
> better description.  After all, if the working tree files do not
> have any difference from the RHS of the comparison, copying from the
> working tree and stuffing the $rsha1 to the RHS temporary index and
> running "checkout -f" should produce identical temporary directory
> for the user to start viewing.
> 
> The _only_ difference in behaviour before and after this patch that
> matters to the end user is if that path is in @working_tree, which
> is returned to @worktree of dir_diff sub to be later copied back,
> no?  I would view this change as a mere means, an implementation
> detail, to achieve that end of stuffing more paths in the @worktree
> array.

I agree with this, but like you I found it confusing that the patch
touched code seemingly unrelated to copying files back.  I went toward
describing the patch more literally and giving the motivation in the
final paragraph.  Your message below is better, but I think it needs to
say that the set of files considered for copying back is the set that is
copied across to begin with.

> Perhaps
> 
> 	difftool --dir-diff: allow changing any clean working tree file
> 
> 	The temporary directory prepared by "difftool --dir-diff" to
> 	show the result of a change can be modified by the user via
> 	the tree diff program, and we try hard not to lose changes
> 	to them after tree diff program returns to us.
> 
>         However, the set of files to be copied back is computed
> 	differently between --symlinks and --no-symlinks modes.  The
> 	former checks all paths that start out as identical to the
> 	working tree file, while the latter checks paths that
> 	already had a local modification in the working tree,
> 	allowing changes made in the tree diff program to paths that
> 	did not have any local change to be lost.
> 
> or something.  This invites a few questions, though.
> 
>  - By allowing these files in the temporary directory to be
>    modified, aren't we making the user's life harder by forcing them
>    to handle "working tree file was already modified, made different
>    changes in the temporary directory, now these changes need to be
>    consolidated" case?
> 
>  - When comparing two revisions, e.g. "--dir-diff HEAD^^ HEAD^",
>    that checks out (via $rsha1 to "checkout -f" codepath) a blob
>    that does not match what is in the working tree of HEAD to the
>    temporary directory, we still allow modifications to the copy in
>    the temporary directory, but what can the user do with these
>    changes that are _not_ based on HEAD, short of checking out HEAD^
>    and apply the difference first?
> 
> I still cannot shake this nagging feeling that giving a writable
> temporary directory might have been a mistake in the first place.
> Perhaps it may be a better design to make the ones that the user
> shouldn't touch (or will lead to the above confusion) read-only,
> while the ones that match the working tree read-write?

My ideal scenario would be that we only allow users to edit files when
they are comparing against the working tree, but that would require
git-difftool to fully understand all git-diff options since it just
passes through any it doesn't recognise.  I don't think there's an easy
way to do that, which leaves us with this confusing situation.

Re: [PATCH v2] difftool --dir-diff: always use identical working tree file

[Junio C Hamano]

John Keeping <john@keeping.me.uk> writes:

>>  - When comparing two revisions, e.g. "--dir-diff HEAD^^ HEAD^",
>>    that checks out (via $rsha1 to "checkout -f" codepath) a blob
>>    that does not match what is in the working tree of HEAD to the
>>    temporary directory, we still allow modifications to the copy in
>>    the temporary directory, but what can the user do with these
>>    changes that are _not_ based on HEAD, short of checking out HEAD^
>>    and apply the difference first?
>> 
>> I still cannot shake this nagging feeling that giving a writable
>> temporary directory might have been a mistake in the first place.
>> Perhaps it may be a better design to make the ones that the user
>> shouldn't touch (or will lead to the above confusion) read-only,
>> while the ones that match the working tree read-write?
>
> My ideal scenario would be that we only allow users to edit files when
> they are comparing against the working tree, but that would require
> git-difftool to fully understand all git-diff options since it just
> passes through any it doesn't recognise.  I don't think there's an easy
> way to do that, which leaves us with this confusing situation.

Not necessarily.

Let's assume that changing files in "diff" tool is a sensible thing
to do, as long as we make sure such a change is not lost (which I
may not 100% agree with, but let's put it aside for now).

When you are viewing a file F in "--dir-diff HEAD^^ HEAD^", if there
is no change for F in between HEAD^ and HEAD and you notice a typo
that may or may not be related to the differences between HEAD^^ and
HEAD^, it would be tempting to fix that right there.  And as long as
F in the working tree matches that of HEAD^ and the modification you
make in the temporary directory gets copied back to the working tree,
your typofix will end up to be in the working tree.

Which I _think_ is what people, who want to change files in "diff"
tool, want to do.

Of course, your working tree may have been in the middle of doing
something entirely different and you may have to "add [-p]" to
separate such a typofix with other changes you were working on, but
that is a separate issue.

And for that to work, the only think you need is "does the blob we
show on the RHS temporary tree match what is in the working tree?"
check.  You do not need to know or care if you are comparing two old
revisions, etc.

[PATCH v3] difftool --dir-diff: allow changing any clean working tree file

[Kenichi Saita]

The temporary directory prepared by "difftool --dir-diff" to
show the result of a change can be modified by the user via
the tree diff program, and we try hard not to lose changes
to them after tree diff program returns to us.

However, the set of files to be copied back is computed
differently between --symlinks and --no-symlinks modes.  The
former checks all paths that start out as identical to the
working tree file, while the latter checks paths that
already had a local modification in the working tree,
allowing changes made in the tree diff program to paths that
did not have any local change to be lost.

Signed-off-by: Kenichi Saita <nitoyon@gmail.com>
---
 git-difftool.perl   |    9 ++-------
 t/t7800-difftool.sh |   19 +++++++++++++++++++
 2 files changed, 21 insertions(+), 7 deletions(-)

diff --git a/git-difftool.perl b/git-difftool.perl
index 8a75205..e57d3d1 100755
--- a/git-difftool.perl
+++ b/git-difftool.perl
@@ -85,13 +85,9 @@ sub exit_cleanup
 
 sub use_wt_file
 {
-	my ($repo, $workdir, $file, $sha1, $symlinks) = @_;
+	my ($repo, $workdir, $file, $sha1) = @_;
 	my $null_sha1 = '0' x 40;
 
-	if ($sha1 ne $null_sha1 and not $symlinks) {
-		return 0;
-	}
-
 	if (! -e "$workdir/$file") {
 		# If the file doesn't exist in the working tree, we cannot
 		# use it.
@@ -213,8 +209,7 @@ EOF
 
 		if ($rmode ne $null_mode) {
 			my ($use, $wt_sha1) = use_wt_file($repo, $workdir,
-							  $dst_path, $rsha1,
-							  $symlinks);
+							  $dst_path, $rsha1);
 			if ($use) {
 				push @working_tree, $dst_path;
 				$wtindex .= "$rmode $wt_sha1\t$dst_path\0";
diff --git a/t/t7800-difftool.sh b/t/t7800-difftool.sh
index d46f041..2418528 100755
--- a/t/t7800-difftool.sh
+++ b/t/t7800-difftool.sh
@@ -385,6 +385,25 @@ test_expect_success PERL,SYMLINKS 'difftool --dir-diff --symlink without unstage
 	test_cmp actual expect
 '
 
+write_script modify-right-file <<\EOF
+echo "new content" >"$2/file"
+EOF
+
+run_dir_diff_test 'difftool --dir-diff syncs worktree with unstaged change' '
+	test_when_finished git reset --hard &&
+	echo "orig content" >file &&
+	git difftool -d $symlinks --extcmd "$(pwd)/modify-right-file" branch &&
+	echo "new content" >expect &&
+	test_cmp expect file
+'
+
+run_dir_diff_test 'difftool --dir-diff syncs worktree without unstaged change' '
+	test_when_finished git reset --hard &&
+	git difftool -d $symlinks --extcmd "$(pwd)/modify-right-file" branch &&
+	echo "new content" >expect &&
+	test_cmp expect file
+'
+
 write_script modify-file <<\EOF
 echo "new content" >file
 EOF
-- 
1.7.1

Re: [PATCH v3] difftool --dir-diff: allow changing any clean working tree file

[Junio C Hamano]

Kenichi Saita <nitoyon@gmail.com> writes:

> The temporary directory prepared by "difftool --dir-diff" to
> show the result of a change can be modified by the user via
> the tree diff program, and we try hard not to lose changes
> to them after tree diff program returns to us.

Thanks; will queue (unless there are other suggestions, in which
case we can polish it further while it is on 'pu').

>
> However, the set of files to be copied back is computed
> differently between --symlinks and --no-symlinks modes.  The
> former checks all paths that start out as identical to the
> working tree file, while the latter checks paths that
> already had a local modification in the working tree,
> allowing changes made in the tree diff program to paths that
> did not have any local change to be lost.
>
> Signed-off-by: Kenichi Saita <nitoyon@gmail.com>
> ---
>  git-difftool.perl   |    9 ++-------
>  t/t7800-difftool.sh |   19 +++++++++++++++++++
>  2 files changed, 21 insertions(+), 7 deletions(-)
>
> diff --git a/git-difftool.perl b/git-difftool.perl
> index 8a75205..e57d3d1 100755
> --- a/git-difftool.perl
> +++ b/git-difftool.perl
> @@ -85,13 +85,9 @@ sub exit_cleanup
>  
>  sub use_wt_file
>  {
> -	my ($repo, $workdir, $file, $sha1, $symlinks) = @_;
> +	my ($repo, $workdir, $file, $sha1) = @_;
>  	my $null_sha1 = '0' x 40;
>  
> -	if ($sha1 ne $null_sha1 and not $symlinks) {
> -		return 0;
> -	}
> -
>  	if (! -e "$workdir/$file") {
>  		# If the file doesn't exist in the working tree, we cannot
>  		# use it.
> @@ -213,8 +209,7 @@ EOF
>  
>  		if ($rmode ne $null_mode) {
>  			my ($use, $wt_sha1) = use_wt_file($repo, $workdir,
> -							  $dst_path, $rsha1,
> -							  $symlinks);
> +							  $dst_path, $rsha1);
>  			if ($use) {
>  				push @working_tree, $dst_path;
>  				$wtindex .= "$rmode $wt_sha1\t$dst_path\0";
> diff --git a/t/t7800-difftool.sh b/t/t7800-difftool.sh
> index d46f041..2418528 100755
> --- a/t/t7800-difftool.sh
> +++ b/t/t7800-difftool.sh
> @@ -385,6 +385,25 @@ test_expect_success PERL,SYMLINKS 'difftool --dir-diff --symlink without unstage
>  	test_cmp actual expect
>  '
>  
> +write_script modify-right-file <<\EOF
> +echo "new content" >"$2/file"
> +EOF
> +
> +run_dir_diff_test 'difftool --dir-diff syncs worktree with unstaged change' '
> +	test_when_finished git reset --hard &&
> +	echo "orig content" >file &&
> +	git difftool -d $symlinks --extcmd "$(pwd)/modify-right-file" branch &&
> +	echo "new content" >expect &&
> +	test_cmp expect file
> +'
> +
> +run_dir_diff_test 'difftool --dir-diff syncs worktree without unstaged change' '
> +	test_when_finished git reset --hard &&
> +	git difftool -d $symlinks --extcmd "$(pwd)/modify-right-file" branch &&
> +	echo "new content" >expect &&
> +	test_cmp expect file
> +'
> +
>  write_script modify-file <<\EOF
>  echo "new content" >file
>  EOF