The `sparseCheckout` argument allows the user to specify directories or
patterns of files, which Git uses to filter files it should check-out.
Git expects a multi-line string on stdin ("newline-delimited list", see
`git-sparse-checkout(1)`), but within nixpkgs it is more consistent to
use a list of strings instead. The list elements are joined to a
multi-line string only before passing it to the builder script.
A deprecation warning is emitted if a (multi-line) string is passed to
`sparseCheckout`, but for the time being it is still accepted.
The fetchgit function in nixpkgs sets the leaveDotGit argument to true
if deepClone is set to true. nix-prefetch-git did behave differently. It
would not assume --leave-dotGit if --deepClone is specified. With this
change the inconsistency is addressed by assuming --leave-dotGit if
--deepClone is specified.
When maintainers override stages of `fetchgit' (e.g. `postPatch`) it
is very easy for them to accidentally leak the outpath-hash of their
current `stdenv` into `fetchgit''s output, and therefore into the
value they paste into `sha256`.
This is a problem, because the resulting expression will break
whenever any change is made to `stdenv` or when anybody attempts to
build the expression on a different platform than the one used by the
original maintainer.
Almost as much of a problem is the fact that CI **does not catch**
these problems. The `fetchgit` is run only once, then its output goes
into cachix, and all future builds (hydra, CI, ofborg) pull from
cachix.
Let's offer maintainers the option to check that they aren't making
this mistake, by passing through `allowedRequisites`. The default
value is `null`, but it might be worth changing that at some point in
the future.
It is also sometimes difficult to communicate to package maintainers
why their expression is problematic. Having `allowedRequisites`
passed through makes it easier to do this: "look, when I switch on
`allowedRequisites` your package breaks; are you sure you meant to
hardcode the hash today's `x86_64-linux.stdenv` into your expression?`
For an example use case, see https://github.com/NixOS/nixpkgs/pull/171223
The issue above is part of a larger problem with nixpkgs infra: there
large parts of cachix cannot be reproduced easily if they are lost.
Once something ends goes into cachix, we never ever again reverify the
procedure by which it was placed into cachix.
a67950f20b added `url` attribute
from `fetchurl` and therefore also from `fetchzip`.
We previously relied on `url` from fetchgit-based fetchers
to find the repo URL but now it will just return tarballs
in the case of `fetchFrom{GitHub,GitLab}`.
Let’s add an attribute to `fetch{git,FromGitHub,FromGitLab}`
to expose a repo URL consistently.
It's hugely inefficient as we can't use shallow cloning (--depth=1).
This has been tested and adapted for quite a few hosts fetchgit is used on in
Nixpkgs. For those where fetching the hash directly doesn't work (most notably
git.savannah.gnu.org), we simply fall back to the old method.
The reason for this change is simply to avoid the following messages
that are unnecessary and can be confusing (and these messages will be
repeated for each submodule):
hint: Using 'master' as the name for the initial branch. This default branch name
hint: is subject to change. To configure the initial branch name to use in all
hint: of your new repositories, which will suppress this warning, call:
hint:
hint: git config --global init.defaultBranch <name>
hint:
hint: Names commonly chosen instead of 'master' are 'main', 'trunk' and
hint: 'development'. The just-created branch can be renamed via this command:
hint:
hint: git branch -m <name>
With this change the behaviour remains unchanged (apart from the
suppressed "warning" in the console output of course) and therefore this
doesn't cause any hashes to change and by default nix-prefetch-git uses
the "fetchgit" branch anyway (branchName can be set to override the
default):
Switched to a new branch 'fetchgit'
For that reason the initial branch name doesn't matter anyway and since
we're not relying on / hardcoding "master" we could simply switch to
"main" (which seems most common nowadays). See [0] for more details on
why this wouldn't break anything.
However, since the initial branch name doesn't matter and to avoid any
additional risks it was "decided" to keep using "master" (s. #113313).
[0]: https://github.com/NixOS/nixpkgs/pull/113313#issuecomment-780589516
`git repack` and `git gc` sometimes print “Nothing new to pack.”
to stdout, which breaks redirecting output to JSON file.
Let’s move the stdout of all git calls where it is not used to stderr
so that we still receive the info but it does not pollute our output.
Especially as a new user it is a much better experience to receive a
proper help response to `-h`. Currently passing `-h` will cause some
runtime error with the `git remote` error help being shown. Not very
helpful.
It doesn't hurt to be a bit more user friendly in this case.
