While it makes sense to allow merging unrelated histories of two
projects that started independently into one, in the way "gitk" was
merged to "git" itself aka "the coolest merge ever", such a merge is
still an unusual event. Worse, if somebody creates an independent
history by starting from a tarball of an established project and
sends a pull request to the original project, "git merge" however
happily creates such a merge without any sign of something unusual
is happening.
Teach "git merge" to refuse to create such a merge by default,
unless the user passes a new "--allow-unrelated-histories" option to
tell it that the user is aware that two unrelated projects are
merged.
Because such a "two project merge" is a rare event, a configuration
option to always allow such a merge is not added.
We could add the same option to "git pull" and have it passed
through to underlying "git merge". I do not have a fundamental
opposition against such a feature, but this commit does not do so
and instead leaves it as low-hanging fruit for others, because such
a "two project merge" would be done after fetching the other project
into some location in the working tree of an existing project and
making sure how well they fit together, it is sufficient to allow a
local merge without such an option pass-through from "git pull" to
"git merge". Many tests that are updated by this patch does the
pass-through manually by turning:
git pull something
into its equivalent:
git fetch something &&
git merge --allow-unrelated-histories FETCH_HEAD
If somebody is inclined to add such an option, updated tests in this
change need to be adjusted back to:
git pull --allow-unrelated-histories something
Signed-off-by: Junio C Hamano <gitster@pobox.com>
"git merge-base --octopus" used to leave cleaning up suboptimal
result to the caller, but now it does the clean-up itself.
* bm/merge-base-octopus-dedup:
merge-base --octopus: reduce the result from get_octopus_merge_bases()
merge-base: separate "--independent" codepath into its own helper
Scripts that use "merge-base --octopus" could do the reducing
themselves, but most of them are expected to want to get the reduced
results without having to do any work themselves.
Tests are taken from a message by Василий Макаров
<einmalfel@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
We might want to vet the existing callers of the underlying
get_octopus_merge_bases() and find out if _all_ of them are doing
anything extra (like deduping) because the machinery can return
duplicate results. And if that is the case, then we may want to
move the dedupling down the callchain instead of having it here.
The "git pull --rebase" command computes the fork point of the
branch being rebased using the reflog entries of the "base" branch
(typically a remote-tracking branch) the branch's work was based on,
in order to cope with the case in which the "base" branch has been
rewound and rebuilt. For example, if the history looked like this:
o---B1
/
---o---o---B2--o---o---o---Base
\
B3
\
Derived
where the current tip of the "base" branch is at Base, but earlier
fetch observed that its tip used to be B3 and then B2 and then B1
before getting to the current commit, and the branch being rebased
on top of the latest "base" is based on commit B3, it tries to find
B3 by going through the output of "git rev-list --reflog base" (i.e.
Base, B1, B2, B3) until it finds a commit that is an ancestor of the
current tip "Derived".
Internally, we have get_merge_bases_many() that can compute this
with one-go. We would want a merge-base between Derived and a
fictitious merge commit that would result by merging all the
historical tips of "base". When such a commit exist, we should get
a single result, which exactly match one of the reflog entries of
"base".
Teach "git merge-base" a new mode, "--fork-point", to compute
exactly that.
Helped-by: Martin von Zweigbergk <martinvonz@gmail.com>
Helped-by: John Keeping <john@keeping.me.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Most of git's tests write files and define shell functions and
variables that will last throughout a test script at the top of
the script, before all test assertions:
. ./test-lib.sh
VAR='some value'
export VAR
>empty
fn () {
do something
}
test_expect_success 'setup' '
... nontrivial commands go here ...
'
Two scripts use a different style with this kind of trivial code
enclosed by a test assertion; fix them. The usual style is easier to
read since there is less indentation to keep track of and no need to
worry about nested quotes; and on the other hand, because the commands
in question are trivial, it should not make the test suite any worse
at catching future bugs in git.
While at it, make some other small tweaks:
- spell function definitions with a space before () for consistency
with other scripts;
- use the self-contained command "git mktree </dev/null" in
preference to "git write-tree" which looks at the index when
writing an empty tree.
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Breaks in a test assertion's && chain can potentially hide
failures from earlier commands in the chain.
Commands intended to fail should be marked with !, test_must_fail, or
test_might_fail. The examples in this patch do not require that.
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
While show-branch --independent does not support more than MAX_REVS
revs, git internally supports more with a different algorithm.
Expose that functionality as "git merge-base --independent".
This should help scripts to catch up with builtin merge in supporting
dodecapus.
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
While show-branch --merge-base does not support more than MAX_REVS
revs, git supports more with a different algorithm
(v1.6.0-rc0~51^2~13, Introduce get_octopus_merge_bases() in commit.c,
2008-06-27). Expose that functionality.
This should help scripts to catch up with builtin merge in supporting
dodecapus.
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Guard setup with test_expect_success, put the opening quote
starting each test on the same line as the test_expect_* invocation,
and combine related actions into single tests.
While at it:
- use test_cmp instead of expr or test $foo = $bar, for more helpful
output with -v when tests fail;
- use test_commit for brevity.
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Currently, the documentation suggests that 'git merge-base -a' and 'git
show-branch --merge-base' are equivalent (in fact it claims that the
former cannot handle more than two revs).
Alas, the handling of more than two revs is very different. Document
this by tests and correct the documentation to reflect this.
Signed-off-by: Michael J Gruber <git@drmicha.warpmail.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
...so that it is easier to reuse it for other tests.
Signed-off-by: Michael J Gruber <git@drmicha.warpmail.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This form is not portable across all shells, so replace instances of:
export FOO=bar
with:
FOO=bar
export FOO
Signed-off-by: Bryan Donlan <bdonlan@fushizen.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Add a picture, and keep the setup and the tests together.
Signed-off-by: Sam Vilain <sam.vilain@catalyst.net.nz>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
In a repository with mainto/1.0 (to keep maintaining the 1.0.X
series) and fixo/1.0 (to keep fixes that apply to both 1.0.X
series and upwards) branches, "git-name-rev mainto/1.0" answered
just "1.0" making things ambiguous. Show refnames unambiguously
like show-branch does.
Signed-off-by: Junio C Hamano <junkio@cox.net>
Although it was shown that the "full contamination" was not really full
during the list discussion, the series improves things without incurring
extra parsing cost, and here is a test to check that.
Signed-off-by: Junio C Hamano <junkio@cox.net>
