The idea behind that is to enable users and developers of
downstream tools such as home-manager to test Nix master for several
reasons:
* Nix is currently trying to have a `master` branch that's always
releasable[1]. We're still on Nix 2.18 in nixpkgs due to too many
notable regressions. Enabling people to test latest master may help on
that end.
* This uses the most bleeding-edge Nix, but our packaging, so we can
identify issues with our packaging early.
* From what I've seen, most people are using the packages from nixpkgs
anyways instead of the upstream flake, this is far more convenient
anyways.
My plan is to update this once a week. Right now we rely on the
`installCheckPhase` here, but as soon as we have proper regression
testing[2], we may want to add `nixUnstable` there as well (however with
failures being allowed probably).
[1] https://discourse.nixos.org/t/nix-release-schedule-and-roadmap/14204
[2] https://github.com/NixOS/nixpkgs/pull/304332
makeOverridable is very careful to ensure the arguments to the
overridden function are the same as the input function. As a result,
the arguments of hello.override are exactly the same as the original
arguments of the hello function that produced the derivation.
However, callPackagesWith calls makeOverridable with a lambda that
does not propagate the arguments. The override function for a package
instantiated with callPackagesWith will not have the original
arguments.
For example:
nix-repl> lib.functionArgs hello.override
{ callPackage = false; fetchurl = false; hello = false; lib = false; nixos = false; stdenv = false; testers = false; }
nix-repl> lib.functionArgs openssl.override
{ }
By copying the arguments onto the inner lambda before passing it to
makeOverridable, we can make callPackage and callPackages behave the
same.
nix-repl> lib.functionArgs openssl.override
{ buildPackages = false; coreutils = false; cryptodev = false; enableSSL2 = true; enableSSL3 = true; fetchurl = false; lib = false; perl = false; removeReferencesTo = false; static = true; stdenv = false; withCryptodev = true; withPerl = true; }
This allows for adding new, conditionally set, derivation attributes
to an existing derivation without changing any output paths in the
case where the condition is not met.
It is useful that all (or almost all) .nix files in nixpkgs at least
parse since it allows for checking syntax in the repository
programmatically without evaluating anything.
This doesn't change uniq. Why not?
- In NixOS it seems that uniq is only used with
simple types that are fully checked by t.check.
- It exists for much longer and is used more widely.
- I believe we should deprecate it, because unique was
already better.
- unique can be a proving ground.
Type: either ints.positive (enum ["auto"])
Before: positive integer, meaning >0 or value "auto" (singular enum)
After: positive integer, meaning >0, or value "auto" (singular enum)
