I recently got fairly confused why the following expression didn't have
any effect
{
description = "Foobar";
inputs.sops-nix = {
url = github:mic92/sops-nix;
inputs.nixpkgs_22_05.follows = "nixpkgs";
};
}
until I found out that the input was called `nixpkgs-22_05` (please note
the dash vs. underscore).
IMHO it's not a good idea to not throw an error in that case and
probably leave end-users rather confused, so I implemented a small check
for that which basically checks whether `follows`-declaration from
overrides actually have corresponding inputs in the transitive flake.
In fact this was done by accident already in our own test-suite where
the removal of a `follows` was apparently forgotten[1].
Since the key of the `std::map` that holds the `overrides` is a vector
and we have to find the last element of each vector (i.e. the override)
this has to be done with a for loop in O(n) complexity with `n` being
the total amount of overrides (which shouldn't be that large though).
Please note that this doesn't work with nested expressions, i.e.
inputs.fenix.inputs.nixpkgs.follows = "...";
which is a known problem[2].
For the expression demonstrated above, an error like this will be
thrown:
error: sops-nix has a `follows'-declaration for a non-existant input nixpkgs_22_05!
[1] 2664a216e5
[2] https://github.com/NixOS/nix/issues/5790
Basically an attempt to resume fixing #5543 for a breakage introduced
earlier[1]. Basically, when evaluating an older `nixpkgs` with
`nix-shell` the following error occurs:
λ ma27 [~] → nix-shell -I nixpkgs=channel:nixos-18.03 -p nix
error: anonymous function at /nix/store/zakqwc529rb6xcj8pwixjsxscvlx9fbi-source/pkgs/top-level/default.nix:20:1 called with unexpected argument 'inNixShell'
at /nix/store/zakqwc529rb6xcj8pwixjsxscvlx9fbi-source/pkgs/top-level/impure.nix:82:1:
81|
82| import ./. (builtins.removeAttrs args [ "system" "platform" ] // {
| ^
83| inherit config overlays crossSystem;
This is a problem because one of the main selling points of Nix is that
you can evaluate any old Nix expression and still get the same result
(which also means that it *still evaluates*). In fact we're deprecating,
but not removing a lot of stuff for that reason such as unquoted URLs[2]
or `builtins.toPath`. However this property was essentially thrown away
here.
The change is rather simple: check if `inNixShell` is specified in the
formals of an auto-called function. This means that
{ inNixShell ? false }:
builtins.trace inNixShell
(with import <nixpkgs> { }; makeShell { name = "foo"; })
will show `trace: true` while
args@{ ... }:
builtins.trace args.inNixShell
(with import <nixpkgs> { }; makeShell { name = "foo"; })
will throw the following error:
error: attribute 'inNixShell' missing
This is explicitly needed because the function in
`pkgs/top-level/impure.nix` of e.g. NixOS 18.03 has an ellipsis[3], but
passes the attribute-set on to another lambda with formals that doesn't
have an ellipsis anymore (hence the error from above). This was perhaps
a mistake, but we can't fix it anymore. This also means that there's
AFAICS no proper way to check if the attr-set that's passed to the Nix
code via `EvalState::autoCallFunction` is eventually passed to a lambda
with formals where `inNixShell` is missing.
However, this fix comes with a certain price. Essentially every
`shell.nix` that assumes `inNixShell` to be passed to the formals even
without explicitly specifying it would break with this[4]. However I think
that this is ugly, but preferable:
* Nix 2.3 was declared stable by NixOS up until recently (well, it still
is as long as 21.11 is alive), so most people might not have even
noticed that feature.
* We're talking about a way shorter time-span with this change being
in the wild, so the fallout should be smaller IMHO.
[1] 9d612c393a
[2] https://github.com/NixOS/rfcs/pull/45#issuecomment-488232537
[3] https://github.com/NixOS/nixpkgs/blob/release-18.03/pkgs/top-level/impure.nix#L75
[4] See e.g. the second expression in this commit-message or the changes
for `tests/ca/nix-shell.sh`.
nixos/nix#6290 introduced a regex pattern to account for tags when
resolving sourcehut refs. nixos/nix#4638 reafactored the code,
accidentally treating the pattern as a regular string, causing all
non-HEAD ref resolving to break.
This fixes the regression and adds more test cases to avoid future
breakage.
Relative 'path:' flake inputs now use the containing flake's
InputAccessor. This has the following implications:
* They're no longer locked in the lock file.
* They don't cause an additional copy to the store.
* They can reference the containing directory (i.e. a subflake can
have an input '../foo', so long as it doesn't go outside the
top-level containing flake).
Note: this is not a complete fix for subflake handling, since the lock
file currently makes it ambiguous what the containing flake is. We'll
probably need to add another field to the lock file for that.
Fixes#6352.
To quote Eelco in #5867:
> Unfortunately we can't do
>
> evalSettings.pureEval.setDefault(false);
>
> because then we have to do the same in main.cc (where
> pureEval is set to true), and that would allow pure-eval
> to be disabled globally from nix.conf.
Instead, a command should specify that it should be impure by
default. Then, `evalSettings.pureEval` will be set to `false;` unless
it's overridden by e.g. a CLI flag.
In that case it's IMHO OK to be (theoretically) able to override
`pure-eval` via `nix.conf` because it doesn't have an effect on commands
where `forceImpureByDefault` returns `false` (i.e. everything where pure
eval actually matters).
Closes#5867
- Test that without the XP feature things work as before
- Test that with or without the XP feature `--file file` works
- Test that with XP feature passing a flakeref works
- Test `:reload` with a flake
Add a new `file` fetcher type, which will fetch a plain file over
http(s), or from the local file.
Because plain `http(s)://` or `file://` urls can already correspond to
`tarball` inputs (if the path ends-up with a know archive extension),
the URL parsing logic is a bit convuluted in that:
- {http,https,file}:// urls will be interpreted as either a tarball or a
file input, depending on the extensions of the path part (so
`https://foo.com/bar` will be a `file` input and
`https://foo.com/bar.tar.gz` as a `tarball` input)
- `file+{something}://` urls will be interpreted as `file` urls (with
the `file+` part removed)
- `tarball+{something}://` urls will be interpreted as `tarball` urls (with
the `tarball+` part removed)
Fix#3785
Co-Authored-By: Tony Olagbaiye <me@fron.io>
