This is useful whenever we want to evaluate something to a store path
(e.g. in get-drvs.cc).
Extracted from the lazy-trees branch (where we can require that a
store path must come from a store source tree accessor).
At this point, we don’t know if the input is a flake or not. So, we
should allow the user to override the input with a directory without a
flake.nix.
Ideally, we could figure whether the input was originally a flake or
not, but that would require instantiating the whole flake. So just
allow it to be missing here, and rely on checks later on to verify the
input for us.
- Make passing the position to `forceValue` mandatory,
this way we remember people that the position is
important for better error messages
- Add pos to all `forceValue` calls
This is needed to get the path of a derivation that might not exist
(e.g. for 'nix store copy-log').
InstallableStorePath::toDerivedPaths() cannot be used for this because
it calls readDerivation(), so it fails if the store doesn't have the
derivation.
Rather than having them plain strings scattered through the whole
codebase, create an enum containing all the known experimental features.
This means that
- Nix can now `warn` when an unkwown experimental feature is passed
(making it much nicer to spot typos and spot deprecated features)
- It’s now easy to remove a feature altogether (once the feature isn’t
experimental anymore or is dropped) by just removing the field for the
enum and letting the compiler point us to all the now invalid usages
of it.
I had started the trend of doing `std::visit` by value (because a type
error once mislead me into thinking that was the only form that
existed). While the optomizer in principle should be able to deal with
extra coppying or extra indirection once the lambdas inlined, sticking
with by reference is the conventional default. I hope this might even
improve performance.
In dry run mode, new derivations can't be create, so running the command on anything that has not been evaluated before results in an error message of the form `don't know how to build these paths (may be caused by read-only store access)`.
For comparison, the classical `nix-build --dry-run` doesn't use read-only mode.
Closes#1795
(cherry picked from commit 54525682df707742e58311c32e9c9cb18de1e31f)
If the store path contains a flake, this means that a command like
"nix path-info /path" will show info about /path, not about the
default output of the flake in /path. If you want the latter, you can
explicitly ask for it by doing "nix path-info path:/path".
Fixes#4568.
With this, we don't have to copy the entire .drv closure to the
destination store ahead of time (or at all). Instead, buildPaths()
reads .drv files from the eval store and copies inputSrcs to the
destination store if it needs to build a derivation.
Issue #5025.
In particular, this now works:
$ nix path-info --eval-store auto --store https://cache.nixos.org nixpkgs#hello
Previously this would fail as it would try to upload the hello .drv to
cache.nixos.org. Now the .drv is instantiated in the local store, and
then we check for the existence of the outputs in cache.nixos.org.
Some people want to avoid using registries at all on their system; Instead
of having to add --no-registries to every command, this commit allows to
set use-registries = false in the config. --no-registries is still allowed
everywhere it was allowed previously, but is now deprecated.
Co-authored-by: Eelco Dolstra <edolstra@gmail.com>
Before this commit, nixConfig.flake-registry didn't have any real effect
on the evaluation, since config was applied after inputs were evaluated.
Change this behavior: apply the config in the beginning of flake::lockFile.
This makes Nix look up paths derivations when they are passed as a
store paths. So:
$ nix path-info --derivation /nix/store/0pisd259nldh8yfjvw663mspm60cn5v8-hello-2.10
now gives
/nix/store/qp724w90516n4bk5r9gfb37vzmqdh3z7-hello-2.10.drv
instead of "".
If no deriver is available, Nix now errors instead of silently
ignoring that argument.
In case of pure input-addressed derivations, the build loop doesn't
guaranty that the realisations are stored in the db (if the output paths
are already there or can be substituted, the realisations won't be
registered). This caused `nix shell` to fail in some cases because it
was assuming that the realisations were always existing.
A better (but more involved) fix would probably to ensure that we always
register the realisations, but in the meantime this patches the surface
issue.
Fix#4721
I think that it's not very helpful to get "cached failures" in a wrong
`flake.nix`. This can be very confusing when debugging a Nix expression.
See for instance NixOS/nixpkgs#118115.
In fact, the eval cache allows a forced reevaluation which is used for
e.g. `nix eval`.
This change makes sure that this is the case for `nix build` as well. So
rather than
λ ma27 [~/Projects/exp] → ../nix/outputs/out/bin/nix build -L --rebuild --experimental-features 'nix-command flakes'
error: cached failure of attribute 'defaultPackage.x86_64-linux'
the evaluation of already-evaluated (and failed) attributes looks like
this now:
λ ma27 [~/Projects/exp] → ../nix/outputs/out/bin/nix build -L --rebuild --experimental-features 'nix-command flakes'
error: attribute 'hell' missing
at /nix/store/mrnvi9ss8zn5wj6gpn4bcd68vbh42mfh-source/flake.nix:6:35:
5|
6| packages.x86_64-linux.hello = nixpkgs.legacyPackages.x86_64-linux.hell;
| ^
7|
(use '--show-trace' to show detailed location information)
This avoids an ambiguity where the `StorePathWithOutputs { drvPath, {}
}` could mean "build `brvPath`" or "substitute `drvPath`" depending on
context.
It also brings the internals closer in line to the new CLI, by
generalizing the `Buildable` type is used there and makes that
distinction already.
In doing so, relegate `StorePathWithOutputs` to being a type just for
backwards compatibility (CLI and RPC).
Jörg Thalheim
Maximilian Bosch