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It is a big no-no to have side-effects in an assertion, because if the assert() is compiled out, you don't get that side-effect, leading to the code behaving differently. That can be a large headache to debug. We have roughly 566 assert() calls in our codebase (my grep might have picked up things that aren't actually assert() calls, but most appeared to be). All but 9 of them can be determined by gcc to be free of side effects with a clever redefine of assert() provided by Bruno De Fraine (from https://stackoverflow.com/questions/10593492/catching-assert-with-side-effects), who upon request has graciously placed his two-liner into the public domain without warranty of any kind. The current 9 assert() calls flagged by this clever redefinition of assert() appear to me to be free of side effects as well, but are too complicated for a compiler/linker to figure that since each assertion involves some kind of function call. Add a CI job which will find and report these possibly problematic assertions, and have the job suggest to the user that they replace these with ASSERT() calls. Example output from running: ``` ERROR: The compiler could not verify the following assert() calls are free of side-effects. Please replace with ASSERT() calls. /home/newren/floss/git/diffcore-rename.c:1409 assert(!dir_rename_count || strmap_empty(dir_rename_count)); /home/newren/floss/git/merge-ort.c:1645 assert(renames->deferred[side].trivial_merges_okay && !strset_contains(&renames->deferred[side].target_dirs, path)); /home/newren/floss/git/merge-ort.c:794 assert(omittable_hint == (!starts_with(type_short_descriptions[type], "CONFLICT") && !starts_with(type_short_descriptions[type], "ERROR")) || type == CONFLICT_DIR_RENAME_SUGGESTED); /home/newren/floss/git/merge-recursive.c:1200 assert(!merge_remote_util(commit)); /home/newren/floss/git/object-file.c:2709 assert(would_convert_to_git_filter_fd(istate, path)); /home/newren/floss/git/parallel-checkout.c:280 assert(is_eligible_for_parallel_checkout(pc_item->ce, &pc_item->ca)); /home/newren/floss/git/scalar.c:244 assert(have_fsmonitor_support()); /home/newren/floss/git/scalar.c:254 assert(have_fsmonitor_support()); /home/newren/floss/git/sequencer.c:4968 assert(!(opts->signoff || opts->no_commit || opts->record_origin || should_edit(opts) || opts->committer_date_is_author_date || opts->ignore_date)); ``` Note that if there are possibly problematic assertions, not necessarily all of them will be shown in a single run, because the compiler errors may include something like "ld: ... more undefined references to `not_supposed_to_survive' follow" instead of listing each individually. But in such cases, once you clean up a few that are shown in your first run, subsequent runs will show (some of) the ones that remain, allowing you to iteratively remove them all. Helped-by: Bruno De Fraine <defraine@gmail.com> Signed-off-by: Elijah Newren <newren@gmail.com> Acked-by: Taylor Blau <me@ttaylorr.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Git - fast, scalable, distributed revision control system
Git is a fast, scalable, distributed revision control system with an unusually rich command set that provides both high-level operations and full access to internals.
Git is an Open Source project covered by the GNU General Public License version 2 (some parts of it are under different licenses, compatible with the GPLv2). It was originally written by Linus Torvalds with help of a group of hackers around the net.
Please read the file INSTALL for installation instructions.
Many Git online resources are accessible from https://git-scm.com/ including full documentation and Git related tools.
See Documentation/gittutorial.adoc to get started, then see
Documentation/giteveryday.adoc for a useful minimum set of commands, and
Documentation/git-<commandname>.adoc for documentation of each command.
If git has been correctly installed, then the tutorial can also be
read with man gittutorial or git help tutorial, and the
documentation of each command with man git-<commandname> or git help <commandname>.
CVS users may also want to read Documentation/gitcvs-migration.adoc
(man gitcvs-migration or git help cvs-migration if git is
installed).
The user discussion and development of Git take place on the Git mailing list -- everyone is welcome to post bug reports, feature requests, comments and patches to git@vger.kernel.org (read Documentation/SubmittingPatches for instructions on patch submission and Documentation/CodingGuidelines).
Those wishing to help with error message, usage and informational message
string translations (localization l10) should see po/README.md
(a po file is a Portable Object file that holds the translations).
To subscribe to the list, send an email to git+subscribe@vger.kernel.org (see https://subspace.kernel.org/subscribing.html for details). The mailing list archives are available at https://lore.kernel.org/git/, https://marc.info/?l=git and other archival sites.
Issues which are security relevant should be disclosed privately to the Git Security mailing list git-security@googlegroups.com.
The maintainer frequently sends the "What's cooking" reports that list the current status of various development topics to the mailing list. The discussion following them give a good reference for project status, development direction and remaining tasks.
The name "git" was given by Linus Torvalds when he wrote the very first version. He described the tool as "the stupid content tracker" and the name as (depending on your mood):
- random three-letter combination that is pronounceable, and not actually used by any common UNIX command. The fact that it is a mispronunciation of "get" may or may not be relevant.
- stupid. contemptible and despicable. simple. Take your pick from the dictionary of slang.
- "global information tracker": you're in a good mood, and it actually works for you. Angels sing, and a light suddenly fills the room.
- "goddamn idiotic truckload of sh*t": when it breaks