Currently when 'git stash push -- <pathspec>' is used, untracked files
that match the pathspec will be deleted, even though they do not end up
in a stash anywhere.
This is because the original commit introducing the pathspec feature in
git stash push (df6bba0937 ("stash: teach 'push' (and 'create_stash') to
honor pathspec", 2017-02-28)) used the sequence of 'git reset <pathspec>
&& git ls-files --modified <pathspec> | git checkout-index && git clean
<pathspec>'.
The intention was to emulate what 'git reset --hard -- <pathspec>' would
do. The call to 'git clean' was supposed to clean up the files that
were unstaged by 'git reset'. This would work fine if the pathspec
doesn't match any files that were untracked before 'git stash push --
<pathspec>'. However if <pathspec> matches a file that was untracked
before invoking the 'stash' command, all untracked files matching the
pathspec would inadvertently be deleted as well, even though they
wouldn't end up in the stash, and are therefore lost.
This behaviour was never what was intended, only blobs that also end up
in the stash should be reset to their state in HEAD, previously
untracked files should be left alone.
To achieve this, first match what's in the index and what's in the
working tree by adding all changes to the index, ask diff-index what
changed between HEAD and the current index, and then apply that patch in
reverse to get rid of the changes, which includes removal of added
files and resurrection of removed files.
Reported-by: Reid Price <reid.price@gmail.com>
Helped-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Thomas Gummerer <t.gummerer@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
`git stash push -m foo` uses "foo" as the message for the stash. But
`git stash push -m"foo"` does not parse successfully. Similarly
`git stash push --message="My stash message"` also fails. The stash
documentation doesn't suggest this syntax should work, but gitcli
does and my fingers have learned this pattern long ago for `commit`.
Teach `git stash` to parse -mFoo and --message=Foo the same as `git
commit` would do. Even though it's an internal function, add
similar support to create_stash() for consistency.
Signed-off-by: Phil Hord <phil.hord@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
With the 'git stash save' interface, it was easily possible for users to
try to add a message which would start with "-", which 'git stash save'
would interpret as a command line argument, and fail. For this case we
added some extra help on how to create a stash with a message starting
with "-".
For 'stash push', messages are passed with the -m flag, avoiding this
potential pitfall. Now only pathspecs starting with "-" would have to
be distinguished from command line parameters by using
"-- --<pathspec>". This is fairly common in the git command line
interface, and we don't try to guess what the users wanted in the other
cases.
Because this way of passing pathspecs is quite common in other git
commands, and we don't provide any extra help there, do the same in the
error message for 'git stash push'.
Signed-off-by: Thomas Gummerer <t.gummerer@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
"git stash push" is the newer interface for creating a stash. While we
are still keeping "git stash save" around for the time being, it's better
to point new users of "git stash" to the more modern (and more feature
rich) interface, instead of teaching them the older version that we
might want to phase out in the future.
Signed-off-by: Thomas Gummerer <t.gummerer@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The `no_changes` function calls the `untracked_files` function through
command substitution. `untracked_files` will return null bytes because it
runs ls-files with the '-z' option.
Bash since version 4.4 warns about these null bytes. As they are not
required for the test that is being done, make sure `untracked_files`
does not output null bytes when not required.
This is achieved by adding a parameter to the `untracked_files` function to
specify wither `-z` should be passed to ls-files or not.
This warning is triggered when running git stash save -u resulting in
two warnings:
git-stash: line 43: warning: command substitution: ignored null byte
in input
Signed-off-by: Kevin Daudt <me@ikke.info>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
If calling git stash -u on a repo that contains a file that is not
ignored any more due to a current modification of the gitignore file,
this file is stashed but not remove from the working tree.
This is due to git-stash first doing a reset --hard which clears the
.gitignore file modification and the call git clean, leaving the file
untouched.
This causes git stash pop to fail due to the file existing.
This patch simply switches the order between cleaning and resetting
and adds a test for this usecase.
Reported-by: Sam Partington <sam@whiteoctober.co.uk>
Signed-off-by: Nicolas Morey-Chaisemartin <nicolas@morey-chaisemartin.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
We want to make sure that people who copy & paste code would see
fewer instances of "git-foo". The use of these dashed forms have
been discouraged since v1.6.0 days.
Signed-off-by: Michael Forney <mforney@mforney.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Most of the time, a 'stash entry' is called a 'stash'. Lets try to make
this more consistent and use 'stash entry' instead.
Signed-off-by: Liam Beguin <liambeguin@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The `git stash push` command recently gained the ability to get a
pathspec as its argument to only stash matching files. Calling this
command from a subdirectory does not work, though, as one of the first
things we do is changing to the top level directory without keeping
track of the prefix from which the command is being run.
Fix the shortcoming by storing the prefix previous to the call to
`cd_to_toplevel` and then subsequently using `git rev-parse --prefix` to
correctly resolve the pathspec. Add a test to catch future breakage of
this usecase.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Currently when there are untracked changes in a file "one" and in a file
"two" in the repository and the user uses:
git stash push -k one
all changes in "two" are wiped out completely. That is clearly not the
intended result. Make sure that only the files given in the pathspec
are changed when git stash push -k <pathspec> is used.
Reported-by: Jeff King <peff@peff.net>
Signed-off-by: Thomas Gummerer <t.gummerer@gmail.com>
Reviewed-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
For "git stash -p --no-keep-index", the pathspec argument is currently
not passed to "git reset". This means that changes that are staged but
that are excluded from the pathspec still get unstaged by git stash -p.
Make sure that doesn't happen by passing the pathspec argument to the
git reset in question, bringing the behaviour in line with "git stash --
<pathspec>".
Signed-off-by: Thomas Gummerer <t.gummerer@gmail.com>
Reviewed-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
git stash push uses other git commands internally. Currently it only
passes the -q flag to those if the -q flag is passed to git stash. when
using 'git stash push -p -q --no-keep-index', it doesn't even pass the
flag on to the internal reset at all.
It really is enough for the user to know that the stash is created,
without bothering them with the internal details of what's happening.
Always pass the -q flag to the internal git clean and git reset
commands, to avoid unnecessary and potentially confusing output.
Reported-by: Jeff King <peff@peff.net>
Signed-off-by: Thomas Gummerer <t.gummerer@gmail.com>
Reviewed-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Now that stash_push is used in the no verb form of stash, allow
specifying the command line for this form as well. Always use -- to
disambiguate pathspecs from other non-option arguments.
Also make git stash -p an alias for git stash push -p. This allows
users to use git stash -p <pathspec>.
Signed-off-by: Thomas Gummerer <t.gummerer@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Now that we have stash_push, which accepts pathspec arguments, use
it instead of stash_save in git stash without any additional verbs.
Previously we allowed git stash -- -message, which is no longer allowed
after this patch. Messages starting with a hyphen was allowed since
3c2eb80f, ("stash: simplify defaulting to "save" and reject unknown
options"). However it was never the intent to allow that, but rather it
was allowed accidentally.
Signed-off-by: Thomas Gummerer <t.gummerer@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
While working on a repository, it's often helpful to stash the changes
of a single or multiple files, and leave others alone. Unfortunately
git currently offers no such option. git stash -p can be used to work
around this, but it's often impractical when there are a lot of changes
over multiple files.
Allow 'git stash push' to take pathspec to specify which paths to stash.
Helped-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Thomas Gummerer <t.gummerer@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Refactor the internal stash_create function to use a -m flag for
specifying the message and -u flag to indicate whether untracked files
should be added to the stash.
This makes it easier to pass a pathspec argument to stash_create in the
next patch.
The user interface for git stash create stays the same.
Signed-off-by: Thomas Gummerer <t.gummerer@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Introduce a new git stash push verb in addition to git stash save. The
push verb is used to transition from the current command line arguments
to a more conventional way, in which the message is given as an argument
to the -m option.
This allows us to have pathspecs at the end of the command line
arguments like other Git commands do, so that the user can say which
subset of paths to stash (and leave others behind).
Helped-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Thomas Gummerer <t.gummerer@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When creating a stash, we need to look at the diff between
the working tree and HEAD, and do so using the git-diff
porcelain. Because git-diff enables porcelain config like
renames by default, this causes at least one problem. The
--name-only format will not mention the source side of a
rename, meaning we will fail to stash a deletion that is
part of a rename.
We could fix that case by passing --no-renames, but this is
a symptom of a larger problem. We should be using the
diff-index plumbing here, which does not have renames
enabled by default, and also does not respect any
potentially confusing config options.
Reported-by: Matthew Patey <matthew.patey2167@gmail.com>
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Instead of referencing "stash@{n}" explicitly, make it possible to
simply reference as "n". Most users only reference stashes by their
position in the stash stack (what I refer to as the "index" here).
The syntax for the typical stash (stash@{n}) is slightly annoying and
easy to forget, and sometimes difficult to escape properly in a
script. Because of this the capability to do things with the stash by
simply referencing the index is desirable.
This patch includes the superior implementation provided by Øsse Walle
(thanks for that), with a slight change to fix a broken test in the test
suite. I also merged the test scripts as suggested by Jeff King, and
un-wrapped the documentation as suggested by Junio Hamano.
Signed-off-by: Aaron M Watson <watsona4@gmail.com>
Reviewed-by: Jeff King <peff@peff.net>
Positional arguments, such as $0, $1, etc, need to be stored on shell
variables for use in translatable strings, according to gettext manual
[1].
Add git-sh-setup.sh to LOCALIZED_SH variable in Makefile to enable
extraction of string marked for translation by xgettext.
Source git-sh-i18n in git-sh-setup.sh for gettext support.
git-sh-setup.sh is a shell library to be sourced by other shell scripts.
In order to avoid other scripts from sourcing git-sh-i18n twice, remove
line that sources it from them. Not sourcing git-sh-i18n in any script
that uses gettext would lead to failure due to, for instance, gettextln
not being found.
[1] http://www.gnu.org/software/gettext/manual/html_node/Preparing-Shell-Scripts.html
Signed-off-by: Vasco Almeida <vascomalmeida@sapo.pt>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
In shell code like:
test -z $foo
test -n $foo
that does not quote its arguments, it's easy to think that
it is actually looking at the contents of $foo in each case.
But if $foo is empty, then "test" does not see any argument
at all! The results are quite subtle.
POSIX specifies that test's behavior depends on the number
of arguments it sees, and if $foo is empty, it sees only
one. The behavior in this case is:
1 argument: Exit true (0) if $1 is not null; otherwise,
exit false.
So in the "-z $foo" case, if $foo is empty, then we check
that "-z" is non-null, and it returns success. Which happens
to match what we expected. But for "-n $foo", if $foo is
empty, we'll see that "-n" is non-null and still return
success. That's the opposite of what we intended!
Furthermore, if $foo contains whitespace, we'll end up with
more than 2 arguments. The results in this case are
generally unspecified (unless the first part of $foo happens
to be a valid binary operator, in which case the results are
specified but certainly not what we intended).
And on top of this, even though "test -z $foo" _should_ work
for the empty case, some older shells (reportedly ksh88)
complain about the missing argument.
So let's make sure we consistently quote our variable
arguments to "test". After this patch, the results of:
git grep 'test -[zn] [^"]'
are empty.
Reported-by: Armin Kunaschik <megabreit@googlemail.com>
Helped-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Some users might want to see diff (patch) output always rather than
diffstat when [s]he runs 'git stash show'. Although this can be
done with adding -p option, users are too lazy to type extra three
keys.
Add two variables that control to show diffstat and patch output
respectively. The stash.showStat is for diffstat and default is
true. The stat.showPatch is for the patch output and default is
false.
Signed-off-by: Namhyung Kim <namhyung@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This is in support of alternate ref backends which don't necessarily
store reflogs as files.
Signed-off-by: David Turner <dturner@twopensource.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This reverts commit ed178ef13a.
That commit was an attempt to improve the safety of applying
a stash, because the application process may create
conflicted index entries, after which it is hard to restore
the original index state.
Unfortunately, this hurts some common workflows around "git
stash -k", like:
git add -p ;# (1) stage set of proposed changes
git stash -k ;# (2) get rid of everything else
make test ;# (3) make sure proposal is reasonable
git stash apply ;# (4) restore original working tree
If you "git commit" between steps (3) and (4), then this
just works. However, if these steps are part of a pre-commit
hook, you don't have that opportunity (you have to restore
the original state regardless of whether the tests passed or
failed).
It's possible that we could provide better tools for this
sort of workflow. In particular, even before ed178ef, it
could fail with a conflict if there were conflicting hunks
in the working tree and index (since the "stash -k" puts the
index version into the working tree, and we then attempt to
apply the differences between HEAD and the old working tree
on top of that). But the fact remains that people have been
using it happily for a while, and the safety provided by
ed178ef is simply not that great. Let's revert it for now.
In the long run, people can work on improving stash for this
sort of workflow, but the safety tradeoff is not worth it in
the meantime.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
If you run "git stash --help", you get the help for stash
(this magic is done by the git wrapper itself). But if you
run "git stash drop --help", you get an error. We
cannot show help specific to "stash drop", of course, but we
can at least give the user the normal stash manpage.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The option parser for git-stash stuffs unknown flags into
the $FLAGS variable, where they can be accessed by the
individual commands. However, most commands do not even look
at these extra flags, leading to unexpected results like
this:
$ git stash drop --help
Dropped refs/stash@{0} (e6cf6d80faf92bb7828f7b60c47fc61c03bd30a1)
We should notice the extra flags and bail. Rather than
annotate each command to reject a non-empty $FLAGS variable,
we can notice that "stash show" is the only command that
actually _wants_ arbitrary flags. So we switch the default
mode to reject unknown flags, and let stash_show() opt into
the feature.
Reported-by: Vincent Legoll <vincent.legoll@gmail.com>
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
If you have staged contents in your index and run "stash
apply", we may hit a conflict and put new entries into the
index. Recovering to your original state is difficult at
that point, because tools like "git reset --keep" will blow
away anything staged. We can make this safer by refusing to
apply when there are staged changes.
It's possible we could provide better tooling here, as "git
stash apply" should be writing only conflicts to the index
(so we know that any stage-0 entries are potentially
precious). But it is the odd duck; most "mergy" commands
will update the index for cleanly merged entries, and it is
not worth updating our tooling to support this use case
which is unlikely to be of interest (besides which, we would
still need to block a dirty index for "stash apply --index",
since that case _would_ be ambiguous).
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Use `git rev-parse --verify --quiet` instead of redirecting
stderr to /dev/null.
Signed-off-by: David Aguilar <davvid@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When you list stashes, you can provide arbitrary git-log
options to change the display. However, adding just "-p"
does nothing, because each stash is actually a merge commit.
This implementation detail is easy to forget, leading to
confused users who think "-p" is not working. We can make
this easier by defaulting to "--first-parent -m", which will
show the diff against the working tree. This omits the
index portion of the stash entirely, but it's simple and it
matches what "git stash show" provides.
People who are more clueful about stash's true form can use
"--cc" to override the "-m", and the "--first-parent" will
then do nothing. For diffs, it only affects non-combined
diffs, so "--cc" overrides it. And for the traversal, we are
walking the linear reflog anyway, so we do not even care
about the parents.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Found by check-non-portable-shell.pl
Signed-off-by: Elia Pinto <gitter.spiros@gmail.com>
Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The Git CodingGuidelines prefer the $(...) construct for command
substitution instead of using the backquotes `...`.
The backquoted form is the traditional method for command
substitution, and is supported by POSIX. However, all but the
simplest uses become complicated quickly. In particular, embedded
command substitutions and/or the use of double quotes require
careful escaping with the backslash character.
The patch was generated by:
for _f in $(find . -name "*.sh")
do
sed -i 's@`\(.*\)`@$(\1)@g' ${_f}
done
and then carefully proof-read.
Signed-off-by: Elia Pinto <gitter.spiros@gmail.com>
Reviewed-by: Matthieu Moy <Matthieu.Moy@imag.fr>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When trying to pop/apply a stash specified with an argument
containing IFS whitespace, git-stash will throw an error:
$ git stash pop 'stash@{two hours ago}'
Too many revisions specified: stash@{two hours ago}
This happens because word splitting is used to count non-option
arguments. Make use of rev-parse's --sq option to quote the arguments
for us to ensure a correct count. Add quotes where necessary.
Also add a test that verifies correct behaviour.
Helped-by: Thomas Rast <tr@thomasrast.ch>
Signed-off-by: Øystein Walle <oystwa@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This reverts commit a73653130e, as it
has been reported that "ls-files --killed" is too time-consuming in
a deep directory with too many untracked crufts (e.g. $HOME/.git
tracking only a few files).
We'd need to revisit it later but "ls-files --killed" needs to be
optimized before it happens.
"stash save" is about saving the local change to the working tree,
but also about restoring the state of the last commit to the working
tree. When a local change is to turn a non-directory to a directory,
in order to restore the non-directory, everything in the directory
needs to be removed.
Which is fine when running "git stash save --include-untracked",
but without that option, untracked, newly created files in the
directory will have to be discarded, if the state you are restoring
to has a non-directory at the same path as the directory.
Introduce a safety valve to fail the operation in such case, using
the "ls-files --killed" which was designed for this exact purpose.
The "stash save" is stopped when untracked files need to be
discarded because their leading path ceased to be a directory, and
the user is required to pass --force to really have the data
removed.
Signed-off-by: Petr Baudis <pasky@ucw.cz>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
save_stash() contains the logic for doing two potentially independent
operations; the first is preparing the stash merge commit, and the
second is updating the stash ref/ reflog accordingly. While the first
operation is abstracted out into a create_stash() for callers to access
via 'git stash create', the second one is not. Fix this by factoring
out the logic for storing the stash into a store_stash() that callers
can access via 'git stash store'.
Like create, store is not intended for end user interactive use, but for
callers in other scripts. We can simplify the logic in the
rebase.autostash feature using this new subcommand.
Signed-off-by: Ramkumar Ramachandra <artagnon@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The option parser for create unnecessarily checks "$1" inside a case
statement that matches "$1" in the first place.
Signed-off-by: Ramkumar Ramachandra <artagnon@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
"stash apply" directly calls a backend merge function which does not
automatically invoke rerere. This confuses mergetool when leftover
rerere state is left behind from previous merges.
Invoke rerere explicitly when we encounter a conflict during stash
apply. This turns the test introduced by the previous commit to
succeed.
Signed-off-by: Phil Hord <hordp@cisco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Otherwise, passing an invalid option, git stash -v, gave:
git-stash: line 204: $'error: unknown option for \'stash save\':
$option\n To provide a message, use git stash save -- \'$option\'':
command not found
Signed-off-by: Ross Lagerwall <rosslagerwall@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When performing a plain "git stash" (without --patch), git-diff would fail
with "fatal: ambiguous argument 'HEAD': both revision and filename". The
output was piped into git-update-index, masking the failed exit status.
The output is now sent to a temporary file (which is cleaned up by
existing code), and the exit status is checked. The "HEAD" arg to the
git-diff invocation has been disambiguated too, of course.
In patch mode, "git stash -p" would fail harmlessly, leaving the working
dir untouched. Interactive adding is fine, but the resulting tree was
diffed with an ambiguous 'HEAD' argument.
Use >foo (no space) when redirecting output.
In t3904, checks and operations on each file are in the order they'll
appear when interactively staging.
In t3905, fix a bug in "stash save --include-untracked -q is quiet": The
redirected stdout file was considered untracked, and so was removed from
the working directory. Use test path helper functions where appropriate.
Signed-off-by: Jonathon Mah <me@JonathonMah.com>
Acked-by: Thomas Rast <trast@student.ethz.ch>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The two new stash options --include-untracked and --all do not remove the
untracked and/or ignored files that are stashed if those files reside in
a subdirectory. e.g. the following sequence fails:
mkdir untracked &&
echo hello >untracked/file.txt &&
git stash --include-untracked &&
test ! -f untracked/file.txt
Within the git-stash script, git-clean is used to remove the
untracked/ignored files, but since the -d option was not supplied, it does
not remove directories.
So, add -d to the git-clean arguments, and update the tests to test this
functionality.
Reported-by: Hilco Wijbenga <hilco.wijbenga@gmail.com>
Signed-off-by: Brandon Casey <drafnel@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The --include-untracked option acts like the normal "git stash save" but
also adds all untracked files in the working directory to the stash and then
calls "git clean --force --quiet" to restore the working directory to a
pristine state.
This is useful for projects that need to run release scripts. With this
option, the release scripts can be from the main working directory so one
does not have to maintain a "clean" directory in parallel just for
releasing. Basically the work-flow becomes:
$ git tag release-1.0
$ git stash --include-untracked
$ make release
$ git clean -f
$ git stash pop
"git stash" alone is not enough in this case--it leaves untracked files
lying around that might mess up a release process that expects everything to
be very clean or might let a release succeed that should actually fail (due
to a new source file being created that hasn't been committed yet).
Signed-off-by: David Caldwell <david@porkrind.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Gettextize the say/die eval_gettext messages in the drop_stash
function. Since making these translatable would result in a long line
I've wrapped this into two lines.
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Thomas Gummerer