* changes:
docs: linkify nix3-build mention in nix-build.md
build: make internal-api-docs PHONY
cleanup lookupFileArg
add docstring to lookupFileArg
add libcmd test for lookupFileArg
This breaks downstreams linking to us on purpose to make sure that if
someone is linking to Lix they're doing it on purpose and crucially not
mixing up Nix and Lix versions in compatibility code.
We still need to fix the internal includes to follow the same schema so
we can drop the single-level include system entirely. However, this
requires a little more effort.
This adds pkg-config for libfetchers and config.h.
Migration path:
expr.hh -> lix/libexpr/expr.hh
nix/config.h -> lix/config.h
To apply this migration automatically, remove all `<nix/>` from
includes, so: `#include <nix/expr.hh>` -> `#include <expr.hh>`. Then,
the correct paths will be resolved from the tangled mess, and the
clang-tidy automated fix will work.
Then run the following for out of tree projects:
```
lix_root=$HOME/lix
(cd $lix_root/clang-tidy && nix develop -c 'meson setup build && ninja -C build')
run-clang-tidy -checks='-*,lix-fixincludes' -load=$lix_root/clang-tidy/build/liblix-clang-tidy.so -p build/ -fix src
```
Related: lix-project/nix-eval-jobs#5
Fixes: lix-project/lix#279
Change-Id: I7498e903afa6850a731ef8ce77a70da6b2b46966
Fixes#183, #110, #116.
The default flake-registry option becomes 'vendored', and refers
to a vendored flake-registry.json file in the install path.
Vendored copy of the flake-registry is from github:NixOS/flake-registry
at commit 9c69f7bd2363e71fe5cd7f608113290c7614dcdd.
Change-Id: I752b81c85ebeaab4e582ac01c239d69d65580f37
Example: /nix/store/dr53sp25hyfsnzjpm8mh3r3y36vrw3ng-neovim-0.9.5^out
This is nonsensical since selecting outputs can only be done for a
buildable derivation, not for a realised store path. The build worker
side of things ends up crashing with an assertion when trying to handle
such malformed paths.
Change-Id: Ia3587c71fe3da5bea45d4e506e1be4dd62291ddf
Basically I'd expect the same behavior as with `nix-build`, i.e.
with `--keep-going` the hash-mismatch error of each failing
fixed-output derivation is shown.
The approach is derived from `Store::buildPaths` (`entry-point.cc`):
instead of throwing the first build-result, check if there are any build
errors and if so, display all of them and throw after that.
Unfortunately, the BuildResult struct doesn't have an `ErrorInfo`
(there's a FIXME for that at least), so I have to construct my own here.
This is a rather cheap bugfix and I decided against touching too many
parts of libstore for that (also I don't know if that's in line with the
ongoing refactoring work).
Closes lix-project/lix#302
Change-Id: I378ab984fa271e6808c6897c45e0f070eb4c6fac
Very basic behavior test to ensure that gzip data gets internally
decompressed by the file transfer pipeline.
Change a std::string_view return value in the test harness to
std::string. I wouldn't call myself a C++ beginner and I still managed
to shoot myself in the foot like three times with the lifetime
managements there (e.g. [&] { return an_std_string; } ends up with a
dangling string_view!).
Change-Id: I1360750d4181ce1ca2a3aa4dc0e97e131351c469
also add a few more tests for exception propagation behavior. using
packaged_tasks and futures (which only allow a single call to a few
of their methods) introduces error paths that weren't there before.
Change-Id: I42ca5236f156fefec17df972f6e9be45989cf805
The fix for the Darwin vulnerability in ecdbc3b207
also broke setting `__sandboxProfile` when `sandbox=relaxed` or
`sandbox=false`. This cppnix change fixes `sandbox=relaxed` and
adds a suitable test.
Co-Authored-By: Artemis Tosini <lix@artem.ist>
Co-Authored-By: Eelco Dolstra <edolstra@gmail.com>
Change-Id: I40190f44f3e1d61846df1c7b89677c20a1488522
only two users of this function exist. only one used it in a way that
even bears resemblance to asynchronicity, and even that one didn't do
it right. fully async and parallel computation would have only worked
if any getEdgesAsync never calls the continuation it receives itself,
only from more derived callbacks running on other threads. calling it
directly would cause the decoupling promise to be awaited immediately
*on the original thread*, completely negating all nice async effects.
Change-Id: I0aa640950cf327533a32dee410105efdabb448df
Some tests were failing on darwin,
if the auto-allocate-uids featrure was enabled.
This was because AAU on darwin works by setuid-ing as a non-existent
user, so the tests that were relying on `whoami` were failing.
In the case of trusted-users we fall back to printing the user id,
which is already handled gracefully in the daemon code - i.e. when
a user does not exist or for some other reason looking up their
username is not possible, the daemon falls back to searching for their
uid inside the trusted-users list.
When whoami is used to print the username for other purpose,
we default to printing nixbld.
Change-Id: Ib61615677565098cb5fbf5e26a946ef427c58caf
not doing this will cause transfers that had their readers disappear to
linger. with lingering transfers the curl thread can't shut down, which
will cause nix itself to not shut down until the transfer finishes some
other way (most likely network timeouts). also add a new test for this.
Change-Id: Id2401b3ac85731c824db05918d4079125be25b57
This was found when `logrotate.conf` failed to build in a NixOS system
with:
/nix/store/26zdl4pyw5qazppj8if5lm8bjzxlc07l-coreutils-9.3/bin/id: cannot find name for group ID 30000
This was surprising because it seemed to mean that /etc/group was busted
in the sandbox. Indeed it was:
root❌0:
nixbld:!💯
nogroup❌65534:
We diagnosed this to sandboxUid() being called before
usingUserNamespace() was called, in setting up /etc/group inside the
sandbox. This code desperately needs refactoring.
We also moved the /etc/group code to be with the /etc/passwd code, but
honestly this code is all spaghetti'd all over the place and needs some
more serious tidying than we did here.
We also moved some checks to be earlier to improve locality with where
the things they are checking come from.
Change-Id: Ie29798771f3593c46ec313a32960fa955054aceb
This reverts commit a8b3d777fb.
This undoes the revert of PR#6621, which allows nested `follows`, i.e.
{
inputs = {
foo.url = "github:bar/foo";
foo.inputs.bar.inputs.nixpkgs = "nixpkgs";
};
}
does the expected thing now. This is useful to avoid the 1000 instances
of nixpkgs problem without having each flake in the dependency tree to
expose all of its transitive dependencies for modification.
This was in fact part of Nix before and the C++ changes applied w/o
conflicts. However, it got reverted then because people didn't want to
merge lazy-trees against it which was supposed to be merged soon back in
October 2022.
Fixes: lix-project/lix#201
Change-Id: I5ddef914135b695717b2ef88862d57ced5e7aa3c
With Linux kernel >=6.6 & glibc 2.39 a `fchmodat2(2)` is available that
isn't filtered away by the libseccomp sandbox.
Being able to use this to bypass that restriction has surprising results
for some builds such as lxc[1]:
> With kernel ≥6.6 and glibc 2.39, lxc's install phase uses fchmodat2,
> which slips through 9b88e52846/src/libstore/build/local-derivation-goal.cc (L1650-L1663).
> The fixupPhase then uses fchmodat, which fails.
> With older kernel or glibc, setting the suid bit fails in the
> install phase, which is not treated as fatal, and then the
> fixup phase does not try to set it again.
Please note that there are still ways to bypass this sandbox[2] and this is
mostly a fix for the breaking builds.
This change works by creating a syscall filter for the `fchmodat2`
syscall (number 452 on most systems). The problem is that glibc 2.39
is needed to have the correct syscall number available via
`__NR_fchmodat2` / `__SNR_fchmodat2`, but this flake is still on
nixpkgs 23.11. To have this change everywhere and not dependent on the
glibc this package is built against, I added a header
"fchmodat2-compat.hh" that sets the syscall number based on the
architecture. On most platforms its 452 according to glibc with a few
exceptions:
$ rg --pcre2 'define __NR_fchmodat2 (?!452)'
sysdeps/unix/sysv/linux/x86_64/x32/arch-syscall.h
58:#define __NR_fchmodat2 1073742276
sysdeps/unix/sysv/linux/mips/mips64/n32/arch-syscall.h
67:#define __NR_fchmodat2 6452
sysdeps/unix/sysv/linux/mips/mips64/n64/arch-syscall.h
62:#define __NR_fchmodat2 5452
sysdeps/unix/sysv/linux/mips/mips32/arch-syscall.h
70:#define __NR_fchmodat2 4452
sysdeps/unix/sysv/linux/alpha/arch-syscall.h
59:#define __NR_fchmodat2 562
I added a small regression-test to the setuid integration-test that
attempts to set the suid bit on a file using the fchmodat2 syscall.
I confirmed that the test fails without the change in
local-derivation-goal.
Additionally, we require libseccomp 2.5.5 or greater now: as it turns
out, libseccomp maintains an internal syscall table and
validates each rule against it. This means that when using libseccomp
2.5.4 or older, one may pass `452` as syscall number against it, but
since it doesn't exist in the internal structure, `libseccomp` will refuse
to create a filter for that. This happens with nixpkgs-23.11, i.e. on
stable NixOS and when building Lix against the project's flake.
To work around that
* a backport of libseccomp 2.5.5 on upstream nixpkgs has been
scheduled[3].
* the package now uses libseccomp 2.5.5 on its own already. This is to
provide a quick fix since the correct fix for 23.11 is still a staging cycle
away.
We still need the compat header though since `SCMP_SYS(fchmodat2)`
internally transforms this into `__SNR_fchmodat2` which points to
`__NR_fchmodat2` from glibc 2.39, so it wouldn't build on glibc 2.38.
The updated syscall table from libseccomp 2.5.5 is NOT used for that
step, but used later, so we need both, our compat header and their
syscall table 🤷
Relevant PRs in CppNix:
* https://github.com/NixOS/nix/pull/10591
* https://github.com/NixOS/nix/pull/10501
[1] https://github.com/NixOS/nixpkgs/issues/300635#issuecomment-2031073804
[2] https://github.com/NixOS/nixpkgs/issues/300635#issuecomment-2030844251
[3] https://github.com/NixOS/nixpkgs/pull/306070
(cherry picked from commit ba6804518772e6afb403dd55478365d4b863c854)
Change-Id: I6921ab5a363188c6bff617750d00bb517276b7fe
Part of #7672
My main motivation is to be able to use `nix.checkConfig`[1]. This
doesn't work with Lix currently since the module uses `nix show-config`
if the Nix version is <2.20pre and `nix config show` otherwise. I think
this is the only instance where nixpkgs checks for which Nix commands
exist that affects us now, so I figured we could just perform the rename
here as well[2] and still provide the current version number[3].
I don't have a strong opinion on whether to deprecate `nix show-config`,
the warning is added there automatically.
(cherry picked from commit f300e11b056dea414d7d77bbc6e5a7dc5d9ddd41)
[1] https://nixos.org/manual/nixos/stable/options.html#opt-nix.checkConfig
[2] I should add that I don't use the "official" ways of installing Lix
because using the flake directly and callPackaging it seemed to fit
better into my workflow: I already have a little mess to make
sure Hydra from the flake uses the correct pkgs.nix and I didn't
want to complicate it further while keeping a single package-set I
can build in CI. Don't get me wrong, I think such a module for a
quick-start is very important, just giving context on why I bother
in the first place :)
[3] When we go public, I think it's worth considering to add support in
nixpkgs itself for Lix.
Change-Id: I47b4239b05cbeda3c370d2fa56ea768b768768ac
this is used in CA rewriting, replacement of placeholders in
derivations, generating scripts for devShells, and some more
places. in all of these transitive replacements are unsound,
and overlapping replacements would be as well. there even is
a test that transitive replacements do not happen (in the CA
RewriteSink suite), but none for overlapping replacements. a
minimally surprising binary rewriter surely would not do any
of these replacements, the only reason we have not seen this
break yet is probably that rewriteStrings is only called for
store paths and things that look like store paths (and those
should never overlap nor admit such transitive replacements)
Change-Id: I6fc29f939d5061d9f56c752624a823ece8437c07
* changes:
nix3-profile: remove check "name" attr in manifests
Add profile migration test
nix3-profile: make element names stable
getNameFromURL(): Support uppercase characters in attribute names
nix3-profile: remove indices
nix3-profile: allow using human-readable names to select packages
implement parsing human-readable names from URLs
As discussed in the maintainer meeting on 2024-01-29.
Mainly this is to avoid a situation where the name is parsed and
treated as a file name, mostly to protect users.
.-* and ..-* are also considered invalid because they might strip
on that separator to remove versions. Doesn't really work, but that's
what we decided, and I won't argue with it, because .-* probably
doesn't seem to have a real world application anyway.
We do still permit a 1-character name that's just "-", which still
poses a similar risk in such a situation. We can't start disallowing
trailing -, because a non-zero number of users will need it and we've
seen how annoying and painful such a change is.
What matters most is preventing a situation where . or .. can be
injected, and to just get this done.
(cherry picked from commit f1b4663805a9dbcb1ace64ec110092d17c9155e0)
Change-Id: I900a8509933cee662f888c3c76fa8986b0058839
Gen::just is the constant generator. Don't just return that!
(cherry picked from commit 8406da28773f050e00a006e4812e3ecbf919a2a9)
Change-Id: Ibfd0bd40f90942077a4720086ce0cd3bfabef79d
Gen: :just is the constant generator. Don't just return that!
(cherry picked from commit 69bbd5852af9b2f0b794162bd1debcdf64fc6648)
Change-Id: Id6e58141f5a42a1f67bd11d48c87b32a3ebd0500
This commit adds a new NixOS VM test, which tests that `nix upgrade-nix`
works on both kinds of profiles (manifest.nix and manifest.json).
Done as a separate commit from 831d18a13, since it relies on the
--store-path argument from 026c90e5f as well.
Change-Id: I5fc94b751d252862cb6cffb541a4c072faad9f3b
That's expected by `build-remote` and makes sure that errors are
correctly forwarded to the user. For instance, let's say that the
host-key of `example.org` is unknown and
nix-build ../nixpkgs -A hello -j0 --builders 'ssh-ng://example.org'
is issued, then you get the following output:
cannot build on 'ssh-ng://example.org?&': error: failed to start SSH connection to 'example.org'
Failed to find a machine for remote build!
derivation: yh46gakxq3kchrbihwxvpn5bmadcw90b-hello-2.12.1.drv
required (system, features): (x86_64-linux, [])
2 available machines:
[...]
The relevant information (`Host key verification failed`) ends up in the
daemon's log, but that's not very obvious considering that the daemon
isn't very chatty normally.
This can be fixed - the same way as its done for legacy-ssh - by passing
fd 4 to the SSH wrapper. Now you'd get the following error:
cannot build on 'ssh-ng://example.org': error: failed to start SSH connection to 'example.org': Host key verification failed.
Failed to find a machine for remote build!
[...]
...and now it's clear what's wrong.
Please note that this is won't end up in the derivation's log.
For previous discussion about this change see
https://github.com/NixOS/nix/pull/7659.
Change-Id: I5790856dbf58e53ea3e63238b015ea06c347cf92
Previously, the garbage collector found runtime roots on Darwin by
shelling out to `lsof -n -w -F n` then parsing the result.
However, this requires an lsof binary and can be extremely slow.
The official Apple lsof returns in a reasonable amount of time,
about 250ms in my tests, but the lsof packaged in nixpkgs is quite slow,
taking about 40 seconds to run the command.
Using libproc directly is about the same speed as Apple lsof,
and allows us to reënable several tests that were disabled on Darwin.
Change-Id: Ifa0adda7984e13c15535693baba835aae79a3577
In hopes of avoiding opaque error messages like the one in
https://buildbot.lix.systems/#/builders/49/builds/1054/steps/1/logs/stdio
Traceback (most recent call last):
File "/nix/store/wj6wh89jhd2492r781qsr09r9wydfs6m-nixos-test-driver-1.1/bin/.nixos-test-driver-wrapped", line 9, in <module>
sys.exit(main())
^^^^^^
File "/nix/store/wj6wh89jhd2492r781qsr09r9wydfs6m-nixos-test-driver-1.1/lib/python3.11/site-packages/test_driver/__init__.py", line 126, in main
driver.run_tests()
File "/nix/store/wj6wh89jhd2492r781qsr09r9wydfs6m-nixos-test-driver-1.1/lib/python3.11/site-packages/test_driver/driver.py", line 159, in run_tests
self.test_script()
File "/nix/store/wj6wh89jhd2492r781qsr09r9wydfs6m-nixos-test-driver-1.1/lib/python3.11/site-packages/test_driver/driver.py", line 151, in test_script
exec(self.tests, symbols, None)
File "<string>", line 13, in <module>
AssertionError
Change-Id: Idd2212a1c3714ce58c7c3a9f34c2ca4313eb6d55
Saves us a bunch of thinking about how to handle symlinks, and prevents
the DNS config from changing on the fly under the build, which may or may
not be a good thing?
Change-Id: I071e6ae7e220884690b788d94f480866f428db71
Previously, errors while printing values in `nix repl` would be printed
in `«error: ...»` brackets rather than displayed normally:
```
nix-repl> legacyPackages.aarch64-darwin.pythonPackages.APScheduler
«error: Package ‘python-2.7.18.7’ in /nix/store/6s0m1qc31zw3l3kq0q4wd5cp3lqpkq0q-source/pkgs/development/interpreters/python/cpython/2.7/default.nix:335 is marked as insecure, refusing to evaluate.»
```
Now, errors will be displayed normally if they're emitted at the
top-level of an expression:
```
nix-repl> legacyPackages.aarch64-darwin.pythonPackages.APScheduler
error:
… in the condition of the assert statement
at /nix/store/6s0m1qc31zw3l3kq0q4wd5cp3lqpkq0q-source/lib/customisation.nix:268:17:
267| in commonAttrs // {
268| drvPath = assert condition; drv.drvPath;
| ^
269| outPath = assert condition; drv.outPath;
… in the left operand of the OR (||) operator
at /nix/store/6s0m1qc31zw3l3kq0q4wd5cp3lqpkq0q-source/pkgs/development/interpreters/python/passthrufun.nix:28:45:
27| if lib.isDerivation value then
28| lib.extendDerivation (valid value || throw "${name} should use `buildPythonPackage` or `toPythonModule` if it is to be part of the Python packages set.") {} value
| ^
29| else
(stack trace truncated; use '--show-trace' to show the full trace)
error: Package ‘python-2.7.18.7’ in /nix/store/6s0m1qc31zw3l3kq0q4wd5cp3lqpkq0q-source/pkgs/development/interpreters/python/cpython/2.7/default.nix:335 is marked as insecure, refusing to evaluate.
```
Errors emitted in nested structures (like e.g. when printing `nixpkgs`)
will still be printed in brackets.
Change-Id: I25aeddf08c017582718cb9772a677bf51b9fc2ad
Adds a `repl-overlays` option, which specifies files that can overlay
and modify the top-level bindings in `nix repl`. For example, with the
following contents in `~/.config/nix/repl.nix`:
info: final: prev: let
optionalAttrs = predicate: attrs:
if predicate
then attrs
else {};
in
optionalAttrs (prev ? legacyPackages && prev.legacyPackages ? ${info.currentSystem})
{
pkgs = prev.legacyPackages.${info.currentSystem};
}
We can run `nix repl` and use `pkgs` to refer to `legacyPackages.${currentSystem}`:
$ nix repl --repl-overlays ~/.config/nix/repl.nix nixpkgs
Lix 2.90.0
Type :? for help.
Loading installable 'flake:nixpkgs#'...
Added 5 variables.
Loading 'repl-overlays'...
Added 6 variables.
nix-repl> pkgs.bash
«derivation /nix/store/g08b5vkwwh0j8ic9rkmd8mpj878rk62z-bash-5.2p26.drv»
Change-Id: Ic12e0f2f210b2f46e920c33088dfe1083f42391a
This probably snuck in in a refactor using truthiness or so. The
trustedness flag was having the optional fullness checked, rather than
the actual contained trust level.
Also adds some tests.
```
m1@6876551b-255d-4cb0-af02-8a4f17b27e2e ~ % nix store ping
warning: 'nix store ping' is a deprecated alias for 'nix store info'
Store URL: daemon
Version: 2.20.4
Trusted: 0
m1@6876551b-255d-4cb0-af02-8a4f17b27e2e ~ % nix doctor
warning: 'doctor' is a deprecated alias for 'config check'
[PASS] PATH contains only one nix version.
[PASS] All profiles are gcroots.
[PASS] Client protocol matches store protocol.
[INFO] You are trusted by store uri: daemon
```
Fixes: lix-project/lix#232
Change-Id: I21576e2a0a755036edf8814133345987617ba3d0
* changes:
Revert "libutil: drop Pool resources on exceptional free"
Revert "libutil: remove Pool::Handle::bad"
Revert "libstore: remove one Resource::good flag"
Revert "libstore: using throwing finally in withFramedSink"
Revert "libutil: allow graceful dropping of Pool::Handle"
Revert "libutil: drop Fs{Source,Sink}::good"
libutil: guard Finally against invalid exception throws
- Use a recursive descent parser so that it's easy to extend.
- Add `@args` to enable customizing command-line arguments
- Add `@should-start` to enable `nix repl` tests that error before
entering the REPL
- Make sure to read all stdout output before comparing. This catches
some extra output we were tossing out before!
Change-Id: I5522555df4c313024ab15cd10f9f04e7293bda3a
These were mistakenly labeled `eval-fail-*`.
Note that the `lang.sh` runner passes `parse-fail-*` tests on stdin, so
filenames are removed from error messages.
Change-Id: I7f3a0d78b6cfa87af29aaa1b7af19d5a57fd4ade
this was never actually used, and bad design in the first place—why
should a bad resource be put back into the idle pool? just drop it.
Change-Id: Idab8774bee19dadae0209d404c4fb86dd4aeba1e
if a scope owning a resource does not gracefully drop that resource
while handling exceptions from deeper down the call stack we should
assume the resource is invalid state and drop it. currently it *is*
true that such cases do not cause resources to be freed, but thanks
to validator misuses this has so far not caused any larger problem.
Change-Id: Ie4f91bcd60a64d05c5ff9d22cc97954816d13b97
The big ones here are `trim-trailing-whitespace` and `end-of-file-fixer`
(which makes sure that every file ends with exactly one newline
character).
Change-Id: Idca73b640883188f068f9903e013cf0d82aa1123
* some things that can throw are marked noexcept
yet the linter seems to think not. Maybe they can't throw in practice.
I would rather not have the UB possibility in pretty obvious cold
paths.
* various default-case-missing complaints
* a fair pile of casts from integer to character, which are in fact
deliberate.
* an instance of <https://clang.llvm.org/extra/clang-tidy/checks/bugprone/move-forwarding-reference.html>
* bugprone-not-null-terminated-result on handing a string to curl in
chunks of bytes. our usage is fine.
* reassigning a unique_ptr by CRIMES instead of using release(), then
using release() and ignoring the result. wild. let's use release() for
its intended purpose.
Change-Id: Ic3e7affef12383576213a8a7c8145c27e662513d
Without this, the Meson setup won't bail out if nlohmann_json is
missing, leading to subpar DX (and maybe worse, but I'm not entirely
sure).
Change-Id: I5913111060226b540dcf003257c99a08e84da0de
sometimes these fail with timeouts on loaded machines. let's up the
timeouts until we can pull the tests apart to more reasonable sizes
Change-Id: I2dfff2183cc1f3ff5e6107f43748ac046fe00d05
Functional tests can be run with
`meson test -C build --suite installcheck`.
Notably, functional tests must be run *after* running `meson install`
(Lix's derivation runs the installcheck suite in installCheckPhase so it
does this correctly), due to some quirks between Meson and the testing
system.
As far as I can tell the functional tests are meant to be run after
installing anyway, but unfortunately I can't transparently make
`meson test --suite installcheck` depend on the install targets.
The script that runs the functional tests, meson/run-test.py, checks
that `meson install` has happened and fails fast with a (hopefully)
helpful error message if any of the functional tests are run before
installing.
TODO: this change needs reflection in developer documentation
Change-Id: I8dcb5fdfc0b6cb17580973d24ad930abd57018f6
This was achieved by running maintainers/buildtime_report.sh on the
build directory of a meson build, then asking "why the heck is json
eating our build times", and strategically moving the json using bits
out of widely included headers.
It turns out that putting literally any metrics whatsoever into the
build had immediate and predictable results.
Results are 1382.5s frontend time -> 1175.4s frontend time, back end
time approximately invariant.
Related: lix-project/lix#159
Change-Id: I7edea95c8536203325c8bb4dae5f32d727a21b2d
Unit tests can be run with `meson test -C build --suite check`.
`--suite check` is optional, as right now that's the only test suite,
but when functional tests are added those will be in a separate suite.
Change-Id: I7f22f1cde4b489b3cdb5f9a36a544f0c409fcc1f
An attrPath prefix of "." indicates no need to try default attrPath prefixes. For example `nixpkgs#legacyPackages.x86_64-linux.ERROR` searches through
```
trying flake output attribute 'packages.x86_64-linux.legacyPackages.x86_64-linux.ERROR'
using cached attrset attribute ''
trying flake output attribute 'legacyPackages.x86_64-linux.legacyPackages.x86_64-linux.ERROR'
using cached attrset attribute 'legacyPackages.x86_64-linux'
trying flake output attribute 'legacyPackages.x86_64-linux.ERROR'
using cached attrset attribute 'legacyPackages.x86_64-linux'
```
And there is no way to specify that one does not want the automatic
search behavior. Now one can specify
`nixpkgs#.legacyPackages.x86_64-linux.ERROR` to only refer to the rooted
attribute path without any default injection of attribute search path or
system.
Change-Id: Iac1334e1470137b7ce11dcf845513810230638ec
(cherry picked from commit d4aed18883b361133607296fb6cd789c47427a38)
Pierre Bourdon
Qyriad
jade
julia
Maximilian Bosch
Artemis Tosini
eldritch horrors
Nikodem Rabuliński
Robert Hensing
puck
Ilya K
Rebecca Turner
Winter Cute