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.
The boolean is only used to determine if the formals are set to a
non-null pointer in all our cases. We can get rid of that allocation and
instead just compare the pointer value with NULL. Saving up to
sizeof(bool) + platform specific alignment per ExprLambda instace.
Probably not a lot of memory but perhaps a few kilobyte with nixpkgs?
This also gets rid of a potential issue with dereferencing formals based on
the value of the boolean that didn't have to be aligned with the formals
pointer but was in all our cases.
I found it somewhat confusing to have an error like
error: attribute 'getFlake' missing
if the required experimental-feature (`flakes`) is not enabled. Instead,
I'd expect Nix to throw an error just like it's the case when using e.g. `nix
flake` without `flakes` being enabled.
With this change, the error looks like this:
$ nix-instantiate -E 'builtins.getFlake "nixpkgs"'
error: Cannot call 'builtins.getFlake' because experimental Nix feature 'flakes' is disabled. You can enable it via '--extra-experimental-features flakes'.
at «string»:1:1:
1| builtins.getFlake "nixpkgs"
| ^
I didn't use `settings.requireExperimentalFeature` here on purpose
because this doesn't contain a position. Also, it doesn't seem as if we
need to catch the error and check for the missing feature here since
this already happens at evaluation time.
Without this, flakes within the same tree and same lock data will have
the same fingerprint and the eval cache for one flake will be
incorrectly used for another.
Alternative to #4639. You can still read flake.lock, but at least in
reproducible workflows like NixOS configurations where you require a
non-dirty tree, evaluation will fail because there is no rev.
This fixes a use-after-free bug:
1. s = new EvalState();
2. callFlake()
3. static vCallFlake now references s
4. delete s;
5. s2 = new EvalState();
6. callFlake()
7. static vCallFlake still references s
8. crash
Nix 2.3 did not have a problem with recreating EvalState.
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 it possible to have per-project configuration in flake.nix,
e.g. binary caches and other stuff:
nixConfig.bash-prompt-suffix = "[1;35mngi# [0m";
nixConfig.substituters = [ "https://cache.ngi0.nixos.org/" ];
The registry targets generally follow a URL formatting schema with
support for a query parameter of "?dir=subpath" to specify a sub-path
location below the URL root.
Alternatively, an absolute path can be specified. This specification
mode accepts the query parameter but ignores/drops it. It would
probably be better to either (a) disallow the query parameter for the
path form, or (b) recognize the query parameter and add to the path.
This patch implements (b) for consistency, and to make it easier for
tooling that might switch between a remote git reference and a local
path reference.
See also issue #4050.
std::optional had redundant checks for whether it had a value.
An object is emplaced either way so it can be dereferenced
without repeating a value check
Maximilian Bosch
Robert Hensing