Re: 'git pull --dry-run' accepted, but moves HEAD and changes working tree
- From
Jeff King <peff@peff.net>
- Date
- May 25, 2010, 06:07 UTC
- Message-ID
- <20100525060725.GA10898@coredump.intra.peff.net>
- In-Reply-To
- <20100524135823.GC19861@unpythonic.net>
On Mon, May 24, 2010 at 08:58:23AM -0500, Jeff Epler wrote:
> I don't recall why I initially typed it, I was surprised to discover > that 'git pull --dry-run' moves HEAD and modifies the working tree.
Yeah, that's bad.
> (I assume it's passing --dry-run to fetch, which does accept it, but > that doesn't ensure that there's nothing at all to merge)
That is exactly what is happening.
> Maybe 'git pull --dry-run' should just be forbidden, or maybe it could > tell the user whether the result of the pull would be a merge, FF, or no > change.
We can't tell what would have happened, because the dry-run fetch doesn't write anything into FETCH_HEAD (which is where we would look to see what was merge-able or not). But we can at least stop at the fetch dry-run to prevent any further damage.
I have no problem with simply reporting an error, but it is easy enough to also just have it stop after doing the fetch dry-run, as below.
-- >8 -- Subject: [PATCH] pull: do nothing on --dry-run
Pull was never meant to take --dry-run at all. However, it passes unknown arguments to git-fetch, which does do a dry-run. Unfortunately, pull then attempts to merge whatever cruft was in FETCH_HEAD (which the dry-run fetch will not have written to).
Even though we never advertise --dry-run as something that should work, it is still worth being defensive because:
1. Other commands (including fetch) take --dry-run, so a
user might try it. 2. Rather than simply producing an error, it actually
changes the repository in totally unexpected ways.This patch makes "pull --dry-run" equivalent to "fetch --dry-run".
Signed-off-by: Jeff King <peff@peff.net> --- git-pull.sh | 7 ++++++- 1 files changed, 6 insertions(+), 1 deletions(-)
diff --git a/git-pull.sh b/git-pull.sh index 1a4729f..a09a44e 100755 --- a/git-pull.sh +++ b/git-pull.sh @@ -43,6 +43,7 @@ merge_args= curr_branch=$(git symbolic-ref -q HEAD) curr_branch_short="${curr_branch#refs/heads/}" rebase=$(git config --bool branch.$curr_branch_short.rebase) +dry_run= while : do case "$1" in @@ -104,6 +105,9 @@ do --no-r|--no-re|--no-reb|--no-reba|--no-rebas|--no-rebase) rebase=false ;; + --d|--dr|--dry|--dry-|--dry-r|--dry-ru|--dry-run) + dry_run=--dry-run + ;; -h|--h|--he|--hel|--help) usage ;; @@ -216,7 +220,8 @@ test true = "$rebase" && { done } orig_head=$(git rev-parse -q --verify HEAD) -git fetch $verbosity $progress --update-head-ok "$@" || exit 1 +git fetch $verbosity $progress $dry_run --update-head-ok "$@" || exit 1 +test -z "$dry_run" || exit 0 curr_head=$(git rev-parse -q --verify HEAD) if test -n "$orig_head" && test "$curr_head" != "$orig_head"
-- 1.7.1.226.g770c5.dirty