On Tue, Apr 25, 2017 at 7:51 PM, Junio C Hamano <gitster@xxxxxxxxx> wrote:
> "Philip Oakley" <philipoakley@xxxxxxx> writes:
>
>> As I recall Christoph was using checkout to copy a file (e.g. a
>> template file) from an older commit/revision into his worktree, and
>> was suprised that this (git checkout <tree> <path>) also _staged_ the
>> file, rather than simply letting it be in a modified/untracked state.
>
> This probably is taking it even further than the original topic, but
> I raise this weather-balloon to see if anybody is interested.
>
> In the modern day, it might be useful if the "--working-tree-only"
> mode added a new file as an intent-to-add entry to the index, but
> that is not what "git apply (no other options)" (which is the gold
> standard for command that operates on the working tree and/or on the
> index) does, so it is not done in this patch. IOW, if you grab a
> path that does not exist in your index out of <tree-ish>, you will
> write out an untracked file to the working tree.
>
> -- >8 --
> Subject: [PATCH] checkout: add --working-tree-only option
>
> "git checkout <tree-ish> <pathspec>" has always copied the blob from
> the tree-ish to the index before checking them out to the working tree.
>
> Some users may want to grab a blob out of a tree-ish directly to the
> working tree, without updating the index, so that "git diff" can be
> used to assess the damage and adjust the file contents taken from a
> different branch to be more appropriate for the current branch.
That makes sense for the in-repo-point-of-view.
I assumed a use case like this:
A user may want to extract a file from a given tree-ish via
GIT_WORK_TREE=/tmp/place git checkout <tree> -- <file>
without modifying the repository (i.e. index) at all. For this
we'd need an option to modify the working tree only.
> The new option "--working-tree-only" allows exactly that.
>
> In the hindsight, when a command works on the working tree and/or
s/the// ?
> the index, the usual convention is:
>
> - with no other option, the command works only on the working tree;
>
> - with "--cached" option, the command works only on the index; and
>
> - with "--index" option, the command works on both the working tree
> and the index.
I never realized this as a usual convention explicitly. Thanks for pointing
it out.
> So we probably should have triggered the default behaviour under the
> "--index" option, and triggered this "--working-tree-only" mode of
> behaviour when "--index" option is not given. From the same point
> of view, "git checkout --cached <tree-ish> <pathspec>" would have
> done the same as "git reset <tree-ish> <pathspec>" would do. And
> that may have made the command set a bit more consistent.
>
> But that is merely a hindsight being 20/20, oh well.
>
> Signed-off-by: Junio C Hamano <gitster@xxxxxxxxx>
> ---
> Documentation/git-checkout.txt | 22 +++++++++++++++-------
> builtin/checkout.c | 10 +++++++++-
> t/t2022-checkout-paths.sh | 21 +++++++++++++++++++++
> 3 files changed, 45 insertions(+), 8 deletions(-)
>
> diff --git a/Documentation/git-checkout.txt b/Documentation/git-checkout.txt
> index 8e2c0662dd..201677752e 100644
> --- a/Documentation/git-checkout.txt
> +++ b/Documentation/git-checkout.txt
> @@ -14,6 +14,7 @@ SYNOPSIS
> 'git checkout' [-q] [-f] [-m] [[-b|-B|--orphan] <new_branch>] [<start_point>]
> 'git checkout' [-f|--ours|--theirs|-m|--conflict=<style>] [<tree-ish>] [--] <paths>...
> 'git checkout' [-p|--patch] [<tree-ish>] [--] [<paths>...]
> +'git checkout' --working-tree-only <tree-ish> [--] [<paths>...]
>
> DESCRIPTION
> -----------
> @@ -81,13 +82,14 @@ Omitting <branch> detaches HEAD at the tip of the current branch.
> 'git checkout' [-p|--patch] [<tree-ish>] [--] <pathspec>...::
>
> When <paths> or `--patch` are given, 'git checkout' does *not*
> - switch branches. It updates the named paths in the working tree
> - from the index file or from a named <tree-ish> (most often a
> - commit). In this case, the `-b` and `--track` options are
> - meaningless and giving either of them results in an error. The
> - <tree-ish> argument can be used to specify a specific tree-ish
> - (i.e. commit, tag or tree) to update the index for the given
> - paths before updating the working tree.
> + switch branches. In this case, the `-b` and `--track` options
> + are meaningless and giving either of them results in an error.
> ++
> +The command checks out blobs for paths that match the given
> +<pathspec> from the index to the working tree. When an optional
> +<tree-ish> is given, the blobs for paths that match the given
> +<pathspec> are copied from the <tree-ish> to the index before
> +they are checked out of the index.
> +
> 'git checkout' with <paths> or `--patch` is used to restore modified or
> deleted paths to their original contents from the index or replace paths
> @@ -101,6 +103,12 @@ specific side of the merge can be checked out of the index by
> using `--ours` or `--theirs`. With `-m`, changes made to the working tree
> file can be discarded to re-create the original conflicted merge result.
>
> +'git checkout' --working-tree-only <tree-ish> [--] <pathspec>...::
> + Similar to `git checkout <tree-ish> [--] <pathspec>`, but
> + the index file is left in the same state as it was before
> + running this command.
Adding this as a new mode seems like a "patch after the fact",
whereas the wording hints that this may be included in the prior
part, but I find it hard to come up with a good description there.
> diff --git a/builtin/checkout.c b/builtin/checkout.c
> index 9b2a5b31d4..d214e99521 100644
> --- a/builtin/checkout.c
> +++ b/builtin/checkout.c
> @@ -37,6 +37,7 @@ struct checkout_opts {
> int overwrite_ignore;
> int ignore_skipworktree;
> int ignore_other_worktrees;
> + int no_index;
> int show_progress;
>
> const char *new_branch;
> @@ -268,6 +269,9 @@ static int checkout_paths(const struct checkout_opts *opts,
> die(_("Cannot update paths and switch to branch '%s' at the same time."),
> opts->new_branch);
>
> + if (opts->no_index && !opts->source_tree)
> + die(_("'--working-tree-only' cannot be used without tree-ish"));
double negation, maybe:
"--working-tree-only requires tree-ish"
> @@ -370,7 +374,9 @@ static int checkout_paths(const struct checkout_opts *opts,
> }
> }
>
> - if (write_locked_index(&the_index, lock_file, COMMIT_LOCK))
> + if (opts->no_index)
> + ; /* discard the in-core index */
> + else if (write_locked_index(&the_index, lock_file, COMMIT_LOCK))
> die(_("unable to write new index file"));
>
> read_ref_full("HEAD", 0, rev.hash, NULL);
> @@ -1161,6 +1167,8 @@ int cmd_checkout(int argc, const char **argv, const char *prefix)
> OPT_BOOL(0, "ignore-other-worktrees", &opts.ignore_other_worktrees,
> N_("do not check if another worktree is holding the given ref")),
> OPT_BOOL(0, "progress", &opts.show_progress, N_("force progress reporting")),
> + OPT_BOOL(0, "working-tree-only", &opts.no_index, N_("checkout to working tree only without touching the index")),
> +
nit: no need for extra empty line here.
> +test_expect_success 'working-tree-only option leaves checked out files unadded' '
> + git reset --hard &&
> + git checkout -b pu next &&
> + echo another >>file1 &&
> + echo exists >file3 &&
> + git add file3 &&
> + git commit -a -m another &&
> + git checkout next &&
Up to here it is all preparation; I started to give an argument
on why using "another" for both the commit message and the file content
was suboptimal, but I was wrong. This seems to be best after some consideration.
The next paragraph checks for
'working-tree-only option populates the working tree, but doesn't touch index'
> + ! grep another file1 &&
> + git checkout --working-tree-only pu file1 file3 &&
> + grep another file1 &&
> + test_must_fail git grep --cached another file1 &&
but only for file1, whereas the next paragraph checks it for file3.
> + grep exists file3 &&
> + git ls-files file3 >actual &&
> + >expect &&
> + test_cmp expect actual
Thanks,
Stefan