Re: Pull without fetch

[Damien Robert <damien.olivier.robert@gmail.com>]

From Damien Robert, Mon 08 Apr 2019 at 16:53:40 (+0200) :
> > Others may have a better idea, but I do not immediately see any
> > solution better than inventing a new option to "git pull".

So here is a RFC patch that implements --no-fetch. (I am not sure about
the wording of the documentation, and what's the best way to test that
fetch was not called).

-- >8 --

From: Damien Robert <damien.olivier.robert+git@gmail.com>
Date: Mon, 8 Apr 2019 17:51:51 +0200
Subject: [PATCH 1/1] pull: add --no-fetch

A common workflow is to do a fetch, review the changes, and then
integrate the changes via an explicit merge or rebase.

In the good old days `git pull` was essentially `git fetch` followed by
`git merge FETCH_HEAD` so it was easy to separate the fetching part from
the integrating part.

But nowadays there are no easy way to do the integrating part of `git
pull`. Indeed, `git pull` learnt to read the config values of
`branch.<current>.rebase` and `pull.rebase`, whose possible values are
growing. At the time of this commit, they can be 'true', 'merges',
'preserve' and 'interactive'.

To remedy this, add a new --no-fetch option to `git pull`.

Signed-off-by: Damien Robert <damien.olivier.robert+git@gmail.com>
---
 Documentation/git-pull.txt |  9 +++++++++
 builtin/pull.c             |  8 ++++++--
 t/t5520-pull.sh            | 14 ++++++++++++++
 3 files changed, 29 insertions(+), 2 deletions(-)

diff --git a/Documentation/git-pull.txt b/Documentation/git-pull.txt
index 118d9d86f7..cec06bf6e3 100644
--- a/Documentation/git-pull.txt
+++ b/Documentation/git-pull.txt
@@ -144,6 +144,15 @@ This option is only valid when "--rebase" is used.
 Options related to fetching
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
+--fetch::
+--no-fetch::
+	Perform a fetch first. This option can be used to override
+	--no-fetch.
++
+With --no-fetch don't fetch before updating the branch via a merge or a
+rebase. This can be used to review changes by doing a fetch first before
+pulling.
+
 include::fetch-options.txt[]
 
 include::pull-fetch-param.txt[]
diff --git a/builtin/pull.c b/builtin/pull.c
index 33db889955..0c14701abe 100644
--- a/builtin/pull.c
+++ b/builtin/pull.c
@@ -111,6 +111,7 @@ static char *opt_gpg_sign;
 static int opt_allow_unrelated_histories;
 
 /* Options passed to git-fetch */
+static int opt_fetch = 1;
 static char *opt_all;
 static char *opt_append;
 static char *opt_upload_pack;
@@ -195,6 +196,8 @@ static struct option pull_options[] = {
 
 	/* Options passed to git-fetch */
 	OPT_GROUP(N_("Options related to fetching")),
+	OPT_BOOL(0, "fetch", &opt_fetch,
+		N_("fetch before merging / rebasing (default)")),
 	OPT_PASSTHRU(0, "all", &opt_all, NULL,
 		N_("fetch from all remotes"),
 		PARSE_OPT_NOARG),
@@ -912,8 +915,9 @@ int cmd_pull(int argc, const char **argv, const char *prefix)
 			oidclr(&rebase_fork_point);
 	}
 
-	if (run_fetch(repo, refspecs))
-		return 1;
+	if (opt_fetch)
+		if (run_fetch(repo, refspecs))
+			return 1;
 
 	if (opt_dry_run)
 		return 0;
diff --git a/t/t5520-pull.sh b/t/t5520-pull.sh
index cf4cc32fd0..058c85e6a4 100755
--- a/t/t5520-pull.sh
+++ b/t/t5520-pull.sh
@@ -134,6 +134,20 @@ test_expect_success 'the default remote . should not break explicit pull' '
 	test_cmp reflog.expected reflog.fuzzy
 '
 
+test_expect_success 'With --no-fetch will not fetch but still merge pending changes' '
+	git checkout -b nofetch master^ &&
+	echo modified >file &&
+	git commit -a -m modified &&
+	git checkout copy &&
+	git reset --hard HEAD^ &&
+	test "$(cat file)" = file &&
+	stat --format %Y .git/FETCH_HEAD > fetch_head_before &&
+	git pull --no-fetch . nofetch &&
+	stat --format %Y .git/FETCH_HEAD > fetch_head_after &&
+	test "$(cat file)" = modified &&
+	test_cmp fetch_head_before fetch_head_after
+'
+
 test_expect_success 'fail if wildcard spec does not match any refs' '
 	git checkout -b test copy^ &&
 	test_when_finished "git checkout -f copy && git branch -D test" &&
-- 
Patched on top of v2.21.0-196-g041f5ea1cf (git version 2.21.0)