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 | 7 +++++-- git-pull.sh | 15 ++++++++++++++- t/t5520-pull.sh | 36 ++++++++++++++++++++++++++++++++++++ 3 files changed, 55 insertions(+), 3 deletions(-) diff --git a/Documentation/config.txt b/Documentation/config.txt index 5978d35..4ebd3b5 100644 --- a/Documentation/config.txt +++ b/Documentation/config.txt @@ -1884,8 +1884,11 @@ 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', - 'rebase', and 'rebase-preserve'. See "branch.<name>.pullmode" for doing - this in a non branch-specific manner. + 'rebase', 'merge-ff-only,' and 'rebase-preserve'. + 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. + When 'rebase-preserve', also pass `--preserve-merges` along to 'git rebase' so that locally committed merge commits will not be diff --git a/git-pull.sh b/git-pull.sh index 26e4e55..946cbbe 100755 --- a/git-pull.sh +++ b/git-pull.sh @@ -57,7 +57,7 @@ then mode=$(git config pull.mode) fi case "$mode" in -merge|rebase|'') +merge|rebase|merge-ff-only|'') ;; rebase-preserve) mode="rebase" @@ -83,6 +83,7 @@ then warn "$(gettext "Please use pull.mode and branch.<name>.pullmode instead.")" fi fi +test -z "$mode" && mode=merge dry_run= while : do @@ -318,6 +319,18 @@ case "$merge_head" in die "$(gettext "Cannot rebase onto multiple branches")" fi ;; +*) + # check if a non-fast-foward merge would be needed + merge_head=${merge_head% } + if test "$mode" = merge-ff-only -a -z "$no_ff$ff_only${squash#--no-squash}" && + test -n "$orig_head" && + ! git merge-base --is-ancestor "$orig_head" "$merge_head" && + ! git merge-base --is-ancestor "$merge_head" "$orig_head" + then + die "$(gettext "The pull was not fast-forward, please either merge or rebase. +If unsure, run 'git pull --merge'.")" + fi + ;; esac # Pulling into unborn branch: a shorthand for branching off diff --git a/t/t5520-pull.sh b/t/t5520-pull.sh index 01ad17a..2e2b476 100755 --- a/t/t5520-pull.sh +++ b/t/t5520-pull.sh @@ -365,4 +365,40 @@ test_expect_success 'git pull --rebase against local branch' ' test file = "$(cat 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 -- 1.9.2+fc1.3.gade8541 -- 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
