It is very typical for Git newcomers to inadvertently create merges and worst, inadvertently pushing them. This is one of the reasons many experienced users prefer to avoid 'git pull', and recommend newcomers to avoid it as well.
To avoid these problems and keep 'git pull' useful it has been suggested that 'git pull' barfs by default if the merge is non-fast-forward, which unfortunately would break backwards compatibility. This patch leaves everything in place to enable this new mode, but it only gets enabled if the user specifically configures it; pull.mode = merge-ff-only. Later on this mode can be enabled by default (e.g. in v2.0). For the full discussion you can read: http://thread.gmane.org/gmane.comp.version-control.git/225146/focus=225305 Signed-off-by: Felipe Contreras <felipe.contre...@gmail.com> --- Documentation/config.txt | 8 +++++--- builtin/merge.c | 9 ++++++++- git-pull.sh | 7 +++++++ t/t5520-pull.sh | 36 ++++++++++++++++++++++++++++++++++++ 4 files changed, 56 insertions(+), 4 deletions(-) diff --git a/Documentation/config.txt b/Documentation/config.txt index 9489a59..13635e0 100644 --- a/Documentation/config.txt +++ b/Documentation/config.txt @@ -1822,9 +1822,11 @@ pretty.<name>:: pull.mode:: When "git pull" is run, this determines if it would either merge or - rebase the fetched branch. The possible values are 'merge' and - 'rebase'. See "branch.<name>.pullmode" for doing this in a non - branch-specific manner. + rebase the fetched branch. The possible values are 'merge', + 'rebase', and 'merge-ff-only'. If 'merge-ff-only' is specified, the + merge will only succeed if it's fast-forward. See + "branch.<name>.pullmode" for doing this in a non branch-specific + manner. + *NOTE*: this is a possibly dangerous operation; do *not* use it unless you understand the implications (see linkgit:git-rebase[1] diff --git a/builtin/merge.c b/builtin/merge.c index da9fc08..97b4205 100644 --- a/builtin/merge.c +++ b/builtin/merge.c @@ -1437,8 +1437,15 @@ int cmd_merge(int argc, const char **argv, const char *prefix) } } - if (fast_forward == FF_ONLY) + if (fast_forward == FF_ONLY) { + const char *msg = getenv("GIT_MERGE_FF_ONLY_HELP"); + if (msg) { + fprintf(stderr, "%s\n", msg); + ret = 1; + goto done; + } die(_("Not possible to fast-forward, aborting.")); + } /* We are going to make a new commit. */ git_committer_info(IDENT_STRICT); diff --git a/git-pull.sh b/git-pull.sh index fbb8a9b..a9cf7ac 100755 --- a/git-pull.sh +++ b/git-pull.sh @@ -62,6 +62,7 @@ then echo "Please use pull.mode and branch.<name>.pullmode instead." fi fi +test -z "$mode" && mode=merge dry_run= while : do @@ -307,6 +308,12 @@ then fi fi +if test "$mode" = merge-ff-only -a -z "$no_ff$ff_only${squash#--no-squash}" +then + ff_only=--ff-only + export GIT_MERGE_FF_ONLY_HELP="The pull was not fast-forward, please either merge or rebase." +fi + merge_name=$(git fmt-merge-msg $log_arg <"$GIT_DIR/FETCH_HEAD") || exit case "$mode" in rebase) diff --git a/t/t5520-pull.sh b/t/t5520-pull.sh index 978a3c1..798ae2f 100755 --- a/t/t5520-pull.sh +++ b/t/t5520-pull.sh @@ -310,4 +310,40 @@ test_expect_success 'branch.to-rebase.pullmode should override pull.mode' ' test new = $(git show HEAD:file2) ' +test_expect_success 'git pull fast-forward' ' + test_when_finished "git checkout master && git branch -D other test" && + test_config pull.mode merge-ff-only && + git checkout -b other master && + >new && + git add new && + git commit -m new && + git checkout -b test -t other && + git reset --hard master && + git pull +' + +test_expect_success 'git pull non-fast-forward' ' + test_when_finished "git checkout master && git branch -D other test" && + test_config pull.mode merge-ff-only && + git checkout -b other master^ && + >new && + git add new && + git commit -m new && + git checkout -b test -t other && + git reset --hard master && + test_must_fail git pull +' + +test_expect_success 'git pull non-fast-forward (merge)' ' + test_when_finished "git checkout master && git branch -D other test" && + test_config pull.mode merge-ff-only && + git checkout -b other master^ && + >new && + git add new && + git commit -m new && + git checkout -b test -t other && + git reset --hard master && + git pull --merge +' + test_done -- 1.8.4-338-gefd7fa6 -- To unsubscribe from this list: send the line "unsubscribe git" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
