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modules/nixpkgs: Make customizable & support multiple evaluations
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‎modules/nixpkgs.nix

+202-8
Original file line numberDiff line numberDiff line change
@@ -1,7 +1,7 @@
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#
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# Nixpkgs module. The only exception to the rule.
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#
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# Provides a `pkgs` argument in `perSystem`.
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# Provides customizable `nixpkgs` and `pkgs` arguments in `perSystem`.
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#
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# Arguably, this shouldn't be in flake-parts, but in nixpkgs.
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# Nixpkgs could define its own module that does this, which would be
@@ -11,16 +11,210 @@
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# will be accepted into flake-parts, because it's against the
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# spirit of Flakes.
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#
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{ config, flake-parts-lib, inputs, lib, options, ... }:
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let
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inherit (lib)
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last
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literalExpression
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mapAttrs
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mdDoc
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mkDefault
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mkOption
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mkOptionDefault
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mkOverride
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toList
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types
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;
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inherit (flake-parts-lib)
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mkPerSystemOption
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mkSubmoduleOptions
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;
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extendSubModules = type: modules:
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type.substSubModules (type.getSubModules ++ modules);
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getOptionSubOptions = locSuffix: opt:
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let
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loc = opt.loc ++ locSuffix;
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type = extendSubModules opt.type [{ _module.args.name = last loc; }];
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in
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type.getSubOptions loc;
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mkSubmoduleOptionsWithShorthand =
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options: mkOption {
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type = types.submoduleWith {
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modules = [{ inherit options; }];
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shorthandOnlyDefinesConfig = true;
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};
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};
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# Shorthand for `types.submoduleWith`.
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submoduleWithModules =
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{ ... }@attrs:
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modules:
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types.submoduleWith (attrs // { modules = toList modules; });
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rootConfig = config;
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rootOptions = options;
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in
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{
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options = {
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nixpkgs = {
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evals = mkOption {
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default = { default = { }; };
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description = ''
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Configuration for Nixpkgs evaluations of {option}`perSystem.nixpkgs.evals`.
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'';
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type = types.lazyAttrsOf (submoduleWithModules { } ({ config, name, options, ... }: {
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_file = ./nixpkgs.nix;
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options = {
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input = mkOption {
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description = mdDoc ''
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Nixpkgs function for evaluation.
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'';
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default = inputs.nixpkgs or (throw
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"flake-parts: The flake does not have a `nixpkgs` input. Please add it, or set `${options.input}` yourself."
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);
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defaultText = literalExpression ''inputs.nixpkgs'';
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type = types.coercedTo types.path import (types.functionTo types.unspecified);
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};
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settings = mkOption {
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default = { };
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description = mdDoc ''
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Settings argument for the Nixpkgs evaluations of {option}`perSystem.nixpkgs.evals.<name>`.
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'';
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type = rootOptions.nixpkgs.settings.type;
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};
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};
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config = {
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settings = mkDefault rootConfig.nixpkgs.settings;
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};
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}));
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};
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settings = mkOption {
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default = { };
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description = mdDoc ''
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Default settings argument for each Nixpkgs evaluations of {option}`nixpkgs.evals`.
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'';
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# This submodule uses `shorthandOnlyDefinesConfig` because of the top-level `config`
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# attribute and to make future upstreaming of this module to Nixpkgs easier.
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type = submoduleWithModules { shorthandOnlyDefinesConfig = true; } ({ config, name, options, ... }: {
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_file = ./nixpkgs.nix;
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freeformType = types.lazyAttrsOf types.raw;
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options = {
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config = mkOption {
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default = { };
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description = mdDoc ''
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Config for this Nixpkgs evaluation.
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'';
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type = submoduleWithModules { } {
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_file = ./nixpkgs.nix;
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freeformType = types.lazyAttrsOf types.raw;
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};
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};
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crossOverlays = mkOption {
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default = [ ];
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description = mdDoc ''
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List of Nixpkgs overlays to apply to target packages only for this Nixpkgs evaluation.
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'';
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type = types.listOf (types.uniq (types.functionTo (types.functionTo (types.lazyAttrsOf types.unspecified))));
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};
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overlays = mkOption {
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default = [ ];
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description = mdDoc ''
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List of Nixpkgs overlays for this Nixpkgs evaluation.
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'';
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type = types.listOf (types.uniq (types.functionTo (types.functionTo (types.lazyAttrsOf types.unspecified))));
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};
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};
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});
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};
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};
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perSystem = mkPerSystemOption ({ config, system, ... }: {
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_file = ./nixpkgs.nix;
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options = {
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nixpkgs = {
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evals = mkOption {
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default = { };
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description = ''
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Configuration for Nixpkgs evaluations.
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'';
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type = types.lazyAttrsOf (submoduleWithModules { } [
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({ config, name, options, ... }: {
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_file = ./nixpkgs.nix;
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options = {
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output = mkOption {
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default = rootConfig.nixpkgs.evals.${name}.input config.settings;
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defaultText = literalExpression
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''config.nixpkgs.evals.''${name}.input config.perSystem.nixpkgs.''${name}.settings'';
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description = mdDoc ''
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Evaluated Nixpkgs.
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'';
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type = types.raw;
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};
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settings = mkOption {
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default = { };
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description = mdDoc ''
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Settings argument for the Nixpkgs evaluations of {option}`perSystem.nixpkgs.evals.<name>`.
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'';
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type = (getOptionSubOptions [ name ] rootOptions.nixpkgs.evals).settings.type;
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};
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};
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config = {
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settings = mkDefault rootConfig.nixpkgs.evals.${name}.settings;
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};
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})
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# Separate module, for type merging
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({ config, name, options, ... }: {
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_file = ./nixpkgs.nix;
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options = {
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# `mkSubmoduleOptions` can't be used here due to `shorthandOnlyDefinesConfig`.
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settings = mkSubmoduleOptionsWithShorthand {
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localSystem = mkOption {
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apply = lib.systems.elaborate;
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default = config.settings.crossSystem;
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defaultText = literalExpression ''config.perSystem.nixpkgs.evals.''${name}.crossSystem'';
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description = mdDoc ''
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Specifies the platform on which Nixpkgs packages should be built.
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Also known as `buildPlatform`.
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By default, Nixpkgs packages are built on the system where they run, but
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you can change where it's built. Setting this option will cause NixOS to
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be cross-compiled.
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For instance, if you're doing distributed multi-platform deployment,
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or if you're building for machines, you can set this to match your
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development system and/or build farm.
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'';
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type = types.either types.str types.attrs;
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};
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crossSystem = mkOption {
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apply = lib.systems.elaborate;
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default = system;
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defaultText = literalExpression ''system'';
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description = mdDoc ''
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Specifies the system where packages from this Nixpkgs evaluation will run.
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Also known as `hostPlatform`.
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193+
To cross-compile, see also {option}`config.perSystem.nixpkgs.evals.<name>.localSystem`.
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'';
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type = types.either types.str types.attrs;
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};
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};
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};
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})
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]);
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};
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};
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};
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config = {
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nixpkgs = {
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evals = mapAttrs (name: genericConfig: { }) rootConfig.nixpkgs.evals;
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};
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};
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});
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};
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config = {
16-
perSystem = { inputs', lib, options, ... }: {
212+
perSystem = { config, nixpkgs, options, ... }: {
213+
_file = ./nixpkgs.nix;
17214
config = {
18-
_module.args.pkgs = lib.mkOptionDefault (
19-
builtins.seq
20-
inputs'.nixpkgs or (throw
21-
"flake-parts: The flake does not have a `nixpkgs` input. Please add it, or set `${options._module.args}.pkgs` yourself."
22-
)
23-
inputs'.nixpkgs.legacyPackages
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_module.args.nixpkgs = mkOptionDefault (mapAttrs (name: nixpkgs: nixpkgs.output) config.nixpkgs.evals);
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_module.args.pkgs = mkOptionDefault (
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nixpkgs.default or (throw "flake-parts: The `perSystem` argument `nixpkgs` does not have a default attribute. Please configure `${options._module.args}.nixpkgs.default`, or set `${options._module.args}.nixpkgs` or `${options._module.args}.pkgs` yourself.")
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);
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};
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};

‎template/unfree/flake.nix

+3-7
Original file line numberDiff line numberDiff line change
@@ -3,16 +3,12 @@
33

44
inputs.nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
55

6-
outputs = inputs@{ flake-parts, nixpkgs, ... }:
6+
outputs = inputs@{ flake-parts, ... }:
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flake-parts.lib.mkFlake { inherit inputs; } {
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systems = [ "x86_64-linux" "aarch64-darwin" ];
9+
# This sets `pkgs` to a Nixpkgs with the `allowUnfree` option set.
10+
nixpkgs.settings.config.allowUnfree = true;
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perSystem = { pkgs, system, ... }: {
10-
# This sets `pkgs` to a nixpkgs with allowUnfree option set.
11-
_module.args.pkgs = import nixpkgs {
12-
inherit system;
13-
config.allowUnfree = true;
14-
};
15-
1612
packages.default = pkgs.hello-unfree;
1713
};
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};

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