[PATCH v4 4/6] push doc: correct lies about how push refspecs work
- From
Ævar Arnfjörð Bjarmason <avarab@gmail.com>
- Date
- Aug 30, 2018, 20:12 UTC
- Message-ID
- <20180830201244.25759-5-avarab@gmail.com>
- In-Reply-To
- <20180813192249.27585-1-avarab@gmail.com>
There's complex rules governing whether a push is allowed to take place depending on whether we're pushing to refs/heads/*, refs/tags/* or refs/not-that/*. See is_branch() in refs.c, and the various assertions in refs/files-backend.c. (e.g. "trying to write non-commit object %s to branch '%s'").
This documentation has never been quite correct, but went downhill after dbfeddb12e ("push: require force for refs under refs/tags/", 2012-11-29) when we started claiming that <dst> couldn't be a tag object, which is incorrect. After some of the logic in that patch was changed in 256b9d70a4 ("push: fix "refs/tags/ hierarchy cannot be updated without --force"", 2013-01-16) the docs weren't updated, and we've had some version of documentation that confused whether <src> was a tag or not with whether <dst> would accept either an annotated tag object or the commit it points to.
This makes the intro somewhat more verbose & complex, perhaps we should have a shorter description here and split the full complexity into a dedicated section. Very few users will find themselves needing to e.g. push blobs or trees to refs/custom-namespace/* (or blobs or trees at all), and that could be covered separately as an advanced topic.
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> --- Documentation/git-push.txt | 41 +++++++++++++++++++++++++++++----- Documentation/gitrevisions.txt | 7 +++--- 2 files changed, 39 insertions(+), 9 deletions(-)
diff --git a/Documentation/git-push.txt b/Documentation/git-push.txt index 55277a9781..0f03d36f1e 100644 --- a/Documentation/git-push.txt +++ b/Documentation/git-push.txt @@ -74,12 +74,41 @@ without any `<refspec>` on the command line. Otherwise, missing `:<dst>` means to update the same ref as the `<src>`. + The object referenced by <src> is used to update the <dst> reference -on the remote side. By default this is only allowed if <dst> is not -a tag (annotated or lightweight), and then only if it can fast-forward -<dst>. By having the optional leading `+`, you can tell Git to update -the <dst> ref even if it is not allowed by default (e.g., it is not a -fast-forward.) This does *not* attempt to merge <src> into <dst>. See -EXAMPLES below for details. +on the remote side. Whether this is allowed depends on where in +`refs/*` the <dst> reference lives as described in detail below. Any +such update does *not* attempt to merge <src> into <dst>. See EXAMPLES +below for details. ++ +The `refs/heads/*` namespace will only accept commit objects, and only +if they can be fast-forwarded. ++ +The `refs/tags/*` namespace will accept any kind of object (as +commits, trees and blobs can be tagged), and any changes to them will +be rejected. ++ +It's possible to push any type of object to any namespace outside of +`refs/{tags,heads}/*`. In the case of tags and commits, these will be +treated as if they were the commits inside `refs/heads/*` for the +purposes of whether the update is allowed. ++ +I.e. a fast-forward of commits and tags outside `refs/{tags,heads}/*` +is allowed, even in cases where what's being fast-forwarded is not a +commit, but a tag object which happens to point to a new commit which +is a fast-forward of the commit the last tag (or commit) it's +replacing. Replacing a tag with an entirely different tag is also +allowed, if it points to the same commit, as well as pushing a peeled +tag, i.e. pushing the commit that existing tag object points to, or a +new tag object which an existing commit points to. ++ +Tree and blob objects outside of `refs/{tags,heads}/*` will be treated +the same way as if they were inside `refs/tags/*`, any modification of +them will be rejected. ++ +All of the rules described above about what's not allowed as an update +can be overridden by adding an the optional leading `+` to a refspec +(or using `--force` command line option). The only exception to this +is that no amount of forcing will make the `refs/heads/*` namespace +accept a non-commit object. + `tag <tag>` means the same as `refs/tags/<tag>:refs/tags/<tag>`. + diff --git a/Documentation/gitrevisions.txt b/Documentation/gitrevisions.txt index 1f6cceaefb..d407b7dee1 100644 --- a/Documentation/gitrevisions.txt +++ b/Documentation/gitrevisions.txt @@ -19,9 +19,10 @@ walk the revision graph (such as linkgit:git-log[1]), all commits which are reachable from that commit. For commands that walk the revision graph one can also specify a range of revisions explicitly. -In addition, some Git commands (such as linkgit:git-show[1]) also take -revision parameters which denote other objects than commits, e.g. blobs -("files") or trees ("directories of files"). +In addition, some Git commands (such as linkgit:git-show[1] and +linkgit:git-push[1]) can also take revision parameters which denote +other objects than commits, e.g. blobs ("files") or trees +("directories of files"). include::revisions.txt[]
-- 2.19.0.rc1.350.ge57e33dbd1