mirror of
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41298a0dff
* doc: actually document `lib.customisation.makeScope`
524 lines
19 KiB
Nix
524 lines
19 KiB
Nix
{ lib }:
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let
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inherit (builtins)
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intersectAttrs;
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inherit (lib)
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functionArgs isFunction mirrorFunctionArgs isAttrs setFunctionArgs
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optionalAttrs attrNames filter elemAt concatStringsSep sortOn take length
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filterAttrs optionalString flip pathIsDirectory head pipe isDerivation listToAttrs
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mapAttrs seq flatten deepSeq warnIf isInOldestRelease extends
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;
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inherit (lib.strings) levenshtein levenshteinAtMost;
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in
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rec {
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/* `overrideDerivation drv f` takes a derivation (i.e., the result
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of a call to the builtin function `derivation`) and returns a new
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derivation in which the attributes of the original are overridden
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according to the function `f`. The function `f` is called with
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the original derivation attributes.
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`overrideDerivation` allows certain "ad-hoc" customisation
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scenarios (e.g. in ~/.config/nixpkgs/config.nix). For instance,
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if you want to "patch" the derivation returned by a package
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function in Nixpkgs to build another version than what the
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function itself provides.
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For another application, see build-support/vm, where this
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function is used to build arbitrary derivations inside a QEMU
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virtual machine.
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Note that in order to preserve evaluation errors, the new derivation's
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outPath depends on the old one's, which means that this function cannot
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be used in circular situations when the old derivation also depends on the
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new one.
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You should in general prefer `drv.overrideAttrs` over this function;
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see the nixpkgs manual for more information on overriding.
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Example:
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mySed = overrideDerivation pkgs.gnused (oldAttrs: {
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name = "sed-4.2.2-pre";
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src = fetchurl {
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url = ftp://alpha.gnu.org/gnu/sed/sed-4.2.2-pre.tar.bz2;
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hash = "sha256-MxBJRcM2rYzQYwJ5XKxhXTQByvSg5jZc5cSHEZoB2IY=";
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};
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patches = [];
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});
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Type:
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overrideDerivation :: Derivation -> ( Derivation -> AttrSet ) -> Derivation
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*/
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overrideDerivation = drv: f:
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let
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newDrv = derivation (drv.drvAttrs // (f drv));
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in flip (extendDerivation (seq drv.drvPath true)) newDrv (
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{ meta = drv.meta or {};
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passthru = if drv ? passthru then drv.passthru else {};
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}
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//
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(drv.passthru or {})
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//
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optionalAttrs (drv ? __spliced) {
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__spliced = {} // (mapAttrs (_: sDrv: overrideDerivation sDrv f) drv.__spliced);
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});
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/* `makeOverridable` takes a function from attribute set to attribute set and
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injects `override` attribute which can be used to override arguments of
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the function.
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Please refer to documentation on [`<pkg>.overrideDerivation`](#sec-pkg-overrideDerivation) to learn about `overrideDerivation` and caveats
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related to its use.
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Example:
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nix-repl> x = {a, b}: { result = a + b; }
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nix-repl> y = lib.makeOverridable x { a = 1; b = 2; }
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nix-repl> y
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{ override = «lambda»; overrideDerivation = «lambda»; result = 3; }
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nix-repl> y.override { a = 10; }
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{ override = «lambda»; overrideDerivation = «lambda»; result = 12; }
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Type:
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makeOverridable :: (AttrSet -> a) -> AttrSet -> a
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*/
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makeOverridable = f:
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let
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# Creates a functor with the same arguments as f
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mirrorArgs = mirrorFunctionArgs f;
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in
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mirrorArgs (origArgs:
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let
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result = f origArgs;
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# Changes the original arguments with (potentially a function that returns) a set of new attributes
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overrideWith = newArgs: origArgs // (if isFunction newArgs then newArgs origArgs else newArgs);
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# Re-call the function but with different arguments
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overrideArgs = mirrorArgs (newArgs: makeOverridable f (overrideWith newArgs));
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# Change the result of the function call by applying g to it
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overrideResult = g: makeOverridable (mirrorArgs (args: g (f args))) origArgs;
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in
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if isAttrs result then
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result // {
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override = overrideArgs;
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overrideDerivation = fdrv: overrideResult (x: overrideDerivation x fdrv);
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${if result ? overrideAttrs then "overrideAttrs" else null} = fdrv:
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overrideResult (x: x.overrideAttrs fdrv);
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}
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else if isFunction result then
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# Transform the result into a functor while propagating its arguments
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setFunctionArgs result (functionArgs result) // {
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override = overrideArgs;
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}
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else result);
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/* Call the package function in the file `fn` with the required
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arguments automatically. The function is called with the
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arguments `args`, but any missing arguments are obtained from
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`autoArgs`. This function is intended to be partially
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parameterised, e.g.,
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```nix
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callPackage = callPackageWith pkgs;
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pkgs = {
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libfoo = callPackage ./foo.nix { };
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libbar = callPackage ./bar.nix { };
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};
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```
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If the `libbar` function expects an argument named `libfoo`, it is
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automatically passed as an argument. Overrides or missing
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arguments can be supplied in `args`, e.g.
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```nix
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libbar = callPackage ./bar.nix {
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libfoo = null;
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enableX11 = true;
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};
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```
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<!-- TODO: Apply "Example:" tag to the examples above -->
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Type:
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callPackageWith :: AttrSet -> ((AttrSet -> a) | Path) -> AttrSet -> a
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*/
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callPackageWith = autoArgs: fn: args:
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let
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f = if isFunction fn then fn else import fn;
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fargs = functionArgs f;
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# All arguments that will be passed to the function
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# This includes automatic ones and ones passed explicitly
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allArgs = intersectAttrs fargs autoArgs // args;
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# a list of argument names that the function requires, but
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# wouldn't be passed to it
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missingArgs =
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# Filter out arguments that have a default value
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(filterAttrs (name: value: ! value)
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# Filter out arguments that would be passed
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(removeAttrs fargs (attrNames allArgs)));
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# Get a list of suggested argument names for a given missing one
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getSuggestions = arg: pipe (autoArgs // args) [
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attrNames
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# Only use ones that are at most 2 edits away. While mork would work,
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# levenshteinAtMost is only fast for 2 or less.
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(filter (levenshteinAtMost 2 arg))
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# Put strings with shorter distance first
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(sortOn (levenshtein arg))
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# Only take the first couple results
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(take 3)
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# Quote all entries
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(map (x: "\"" + x + "\""))
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];
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prettySuggestions = suggestions:
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if suggestions == [] then ""
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else if length suggestions == 1 then ", did you mean ${elemAt suggestions 0}?"
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else ", did you mean ${concatStringsSep ", " (lib.init suggestions)} or ${lib.last suggestions}?";
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errorForArg = arg:
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let
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loc = builtins.unsafeGetAttrPos arg fargs;
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# loc' can be removed once lib/minver.nix is >2.3.4, since that includes
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# https://github.com/NixOS/nix/pull/3468 which makes loc be non-null
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loc' = if loc != null then loc.file + ":" + toString loc.line
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else if ! isFunction fn then
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toString fn + optionalString (pathIsDirectory fn) "/default.nix"
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else "<unknown location>";
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in "Function called without required argument \"${arg}\" at "
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+ "${loc'}${prettySuggestions (getSuggestions arg)}";
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# Only show the error for the first missing argument
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error = errorForArg (head (attrNames missingArgs));
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in if missingArgs == {}
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then makeOverridable f allArgs
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# This needs to be an abort so it can't be caught with `builtins.tryEval`,
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# which is used by nix-env and ofborg to filter out packages that don't evaluate.
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# This way we're forced to fix such errors in Nixpkgs,
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# which is especially relevant with allowAliases = false
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else abort "lib.customisation.callPackageWith: ${error}";
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/* Like callPackage, but for a function that returns an attribute
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set of derivations. The override function is added to the
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individual attributes.
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Type:
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callPackagesWith :: AttrSet -> ((AttrSet -> AttrSet) | Path) -> AttrSet -> AttrSet
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*/
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callPackagesWith = autoArgs: fn: args:
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let
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f = if isFunction fn then fn else import fn;
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auto = intersectAttrs (functionArgs f) autoArgs;
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mirrorArgs = mirrorFunctionArgs f;
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origArgs = auto // args;
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pkgs = f origArgs;
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mkAttrOverridable = name: _: makeOverridable (mirrorArgs (newArgs: (f newArgs).${name})) origArgs;
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in
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if isDerivation pkgs then throw
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("function `callPackages` was called on a *single* derivation "
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+ ''"${pkgs.name or "<unknown-name>"}";''
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+ " did you mean to use `callPackage` instead?")
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else mapAttrs mkAttrOverridable pkgs;
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/* Add attributes to each output of a derivation without changing
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the derivation itself and check a given condition when evaluating.
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Type:
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extendDerivation :: Bool -> Any -> Derivation -> Derivation
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*/
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extendDerivation = condition: passthru: drv:
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let
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outputs = drv.outputs or [ "out" ];
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commonAttrs = drv // (listToAttrs outputsList) //
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({ all = map (x: x.value) outputsList; }) // passthru;
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outputToAttrListElement = outputName:
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{ name = outputName;
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value = commonAttrs // {
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inherit (drv.${outputName}) type outputName;
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outputSpecified = true;
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drvPath = assert condition; drv.${outputName}.drvPath;
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outPath = assert condition; drv.${outputName}.outPath;
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} //
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# TODO: give the derivation control over the outputs.
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# `overrideAttrs` may not be the only attribute that needs
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# updating when switching outputs.
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optionalAttrs (passthru?overrideAttrs) {
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# TODO: also add overrideAttrs when overrideAttrs is not custom, e.g. when not splicing.
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overrideAttrs = f: (passthru.overrideAttrs f).${outputName};
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};
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};
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outputsList = map outputToAttrListElement outputs;
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in commonAttrs // {
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drvPath = assert condition; drv.drvPath;
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outPath = assert condition; drv.outPath;
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};
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/* Strip a derivation of all non-essential attributes, returning
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only those needed by hydra-eval-jobs. Also strictly evaluate the
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result to ensure that there are no thunks kept alive to prevent
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garbage collection.
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Type:
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hydraJob :: (Derivation | Null) -> (Derivation | Null)
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*/
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hydraJob = drv:
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let
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outputs = drv.outputs or ["out"];
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commonAttrs =
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{ inherit (drv) name system meta; inherit outputs; }
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// optionalAttrs (drv._hydraAggregate or false) {
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_hydraAggregate = true;
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constituents = map hydraJob (flatten drv.constituents);
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}
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// (listToAttrs outputsList);
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makeOutput = outputName:
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let output = drv.${outputName}; in
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{ name = outputName;
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value = commonAttrs // {
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outPath = output.outPath;
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drvPath = output.drvPath;
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type = "derivation";
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inherit outputName;
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};
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};
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outputsList = map makeOutput outputs;
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drv' = (head outputsList).value;
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in if drv == null then null else
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deepSeq drv' drv';
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/**
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Make an attribute set (a "scope") from functions that take arguments from that same attribute set.
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See [](#ex-makeScope) for how to use it.
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# Inputs
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1. `newScope` (`AttrSet -> ((AttrSet -> a) | Path) -> AttrSet -> a`)
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A function that takes an attribute set `attrs` and returns what ends up as `callPackage` in the output.
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Typical values are `callPackageWith` or the output attribute `newScope`.
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2. `f` (`AttrSet -> AttrSet`)
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A function that takes an attribute set as returned by `makeScope newScope f` (a "scope") and returns any attribute set.
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This function is used to compute the fixpoint of the resulting scope using `callPackage`.
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Its argument is the lazily evaluated reference to the value of that fixpoint, and is typically called `self` or `final`.
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See [](#ex-makeScope) for how to use it.
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See [](#sec-functions-library-fixedPoints) for details on fixpoint computation.
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# Output
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`makeScope` returns an attribute set of a form called `scope`, which also contains the final attributes produced by `f`:
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```
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scope :: {
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callPackage :: ((AttrSet -> a) | Path) -> AttrSet -> a
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newScope = AttrSet -> scope
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overrideScope = (scope -> scope -> AttrSet) -> scope
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packages :: AttrSet -> AttrSet
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}
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```
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- `callPackage` (`((AttrSet -> a) | Path) -> AttrSet -> a`)
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A function that
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1. Takes a function `p`, or a path to a Nix file that contains a function `p`, which takes an attribute set and returns value of arbitrary type `a`,
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2. Takes an attribute set `args` with explicit attributes to pass to `p`,
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3. Calls `f` with attributes from the original attribute set `attrs` passed to `newScope` updated with `args, i.e. `attrs // args`, if they match the attributes in the argument of `p`.
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All such functions `p` will be called with the same value for `attrs`.
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See [](#ex-makeScope-callPackage) for how to use it.
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- `newScope` (`AttrSet -> scope`)
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Takes an attribute set `attrs` and returns a scope that extends the original scope.
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- `overrideScope` (`(scope -> scope -> AttrSet) -> scope`)
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Takes a function `g` of the form `final: prev: { # attributes }` to act as an overlay on `f`, and returns a new scope with values determined by `extends g f`.
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See [](https://nixos.org/manual/nixpkgs/unstable/#function-library-lib.fixedPoints.extends) for details.
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This allows subsequent modification of the final attribute set in a consistent way, i.e. all functions `p` invoked with `callPackage` will be called with the modified values.
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- `packages` (`AttrSet -> AttrSet`)
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The value of the argument `f` to `makeScope`.
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- final attributes
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The final values returned by `f`.
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# Examples
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:::{#ex-makeScope .example}
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# Create an interdependent package set on top of `pkgs`
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The functions in `foo.nix` and `bar.nix` can depend on each other, in the sense that `foo.nix` can contain a function that expects `bar` as an attribute in its argument.
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```nix
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let
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pkgs = import <nixpkgs> { };
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in
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pkgs.lib.makeScope pkgs.newScope (self: {
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foo = self.callPackage ./foo.nix { };
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bar = self.callPackage ./bar.nix { };
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})
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```
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evaluates to
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```nix
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{
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callPackage = «lambda»;
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newScope = «lambda»;
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overrideScope = «lambda»;
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packages = «lambda»;
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foo = «derivation»;
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bar = «derivation»;
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}
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```
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:::
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:::{#ex-makeScope-callPackage .example}
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# Using `callPackage` from a scope
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```nix
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let
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pkgs = import <nixpkgs> { };
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inherit (pkgs) lib;
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scope = lib.makeScope lib.callPackageWith (self: { a = 1; b = 2; });
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three = scope.callPackage ({ a, b }: a + b) { };
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four = scope.callPackage ({ a, b }: a + b) { a = 2; };
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in
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[ three four ]
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```
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evaluates to
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```nix
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[ 3 4 ]
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```
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:::
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# Type
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```
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makeScope :: (AttrSet -> ((AttrSet -> a) | Path) -> AttrSet -> a) -> (AttrSet -> AttrSet) -> scope
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```
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*/
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makeScope = newScope: f:
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let self = f self // {
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newScope = scope: newScope (self // scope);
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callPackage = self.newScope {};
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overrideScope = g: makeScope newScope (extends g f);
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# Remove after 24.11 is released.
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overrideScope' = g: warnIf (isInOldestRelease 2311)
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"`overrideScope'` (from `lib.makeScope`) has been renamed to `overrideScope`."
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(makeScope newScope (extends g f));
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packages = f;
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};
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in self;
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/* backward compatibility with old uncurried form; deprecated */
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makeScopeWithSplicing =
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splicePackages: newScope: otherSplices: keep: extra: f:
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makeScopeWithSplicing'
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{ inherit splicePackages newScope; }
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{ inherit otherSplices keep extra f; };
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/* Like makeScope, but aims to support cross compilation. It's still ugly, but
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hopefully it helps a little bit.
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Type:
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makeScopeWithSplicing' ::
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{ splicePackages :: Splice -> AttrSet
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, newScope :: AttrSet -> ((AttrSet -> a) | Path) -> AttrSet -> a
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}
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-> { otherSplices :: Splice, keep :: AttrSet -> AttrSet, extra :: AttrSet -> AttrSet }
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-> AttrSet
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Splice ::
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{ pkgsBuildBuild :: AttrSet
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, pkgsBuildHost :: AttrSet
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, pkgsBuildTarget :: AttrSet
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, pkgsHostHost :: AttrSet
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, pkgsHostTarget :: AttrSet
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, pkgsTargetTarget :: AttrSet
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}
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*/
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makeScopeWithSplicing' =
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{ splicePackages
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, newScope
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}:
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{ otherSplices
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# Attrs from `self` which won't be spliced.
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# Avoid using keep, it's only used for a python hook workaround, added in PR #104201.
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# ex: `keep = (self: { inherit (self) aAttr; })`
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, keep ? (_self: {})
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# Additional attrs to add to the sets `callPackage`.
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# When the package is from a subset (but not a subset within a package IS #211340)
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# within `spliced0` it will be spliced.
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# When using an package outside the set but it's available from `pkgs`, use the package from `pkgs.__splicedPackages`.
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# If the package is not available within the set or in `pkgs`, such as a package in a let binding, it will not be spliced
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# ex:
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# ```
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# nix-repl> darwin.apple_sdk.frameworks.CoreFoundation
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# «derivation ...CoreFoundation-11.0.0.drv»
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# nix-repl> darwin.CoreFoundation
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# error: attribute 'CoreFoundation' missing
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# nix-repl> darwin.callPackage ({ CoreFoundation }: CoreFoundation) { }
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# «derivation ...CoreFoundation-11.0.0.drv»
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# ```
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, extra ? (_spliced0: {})
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, f
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}:
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let
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spliced0 = splicePackages {
|
|
pkgsBuildBuild = otherSplices.selfBuildBuild;
|
|
pkgsBuildHost = otherSplices.selfBuildHost;
|
|
pkgsBuildTarget = otherSplices.selfBuildTarget;
|
|
pkgsHostHost = otherSplices.selfHostHost;
|
|
pkgsHostTarget = self; # Not `otherSplices.selfHostTarget`;
|
|
pkgsTargetTarget = otherSplices.selfTargetTarget;
|
|
};
|
|
spliced = extra spliced0 // spliced0 // keep self;
|
|
self = f self // {
|
|
newScope = scope: newScope (spliced // scope);
|
|
callPackage = newScope spliced; # == self.newScope {};
|
|
# N.B. the other stages of the package set spliced in are *not*
|
|
# overridden.
|
|
overrideScope = g: (makeScopeWithSplicing'
|
|
{ inherit splicePackages newScope; }
|
|
{ inherit otherSplices keep extra;
|
|
f = extends g f;
|
|
});
|
|
packages = f;
|
|
};
|
|
in self;
|
|
|
|
}
|