forked from mirrors/nixpkgs
863d79b364
Each bootstrapping stage ought to just depend on the previous stage, but poorly-written compilers break this elegence. This provides an easy-enough way to depend on the next stage: targetPackages. PLEASE DO NOT USE IT UNLESS YOU MUST! I'm hoping someday in a pleasant future I can revert this commit :)
86 lines
3.9 KiB
Nix
86 lines
3.9 KiB
Nix
# The `splicedPackages' package set, and its use by `callPackage`
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#
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# The `buildPackages` pkg set is a new concept, and the vast majority package
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# expression (the other *.nix files) are not designed with it in mind. This
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# presents us with a problem with how to get the right version (build-time vs
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# run-time) of a package to a consumer that isn't used to thinking so cleverly.
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#
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# The solution is to splice the package sets together as we do below, so every
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# `callPackage`d expression in fact gets both versions. Each# derivation (and
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# each derivation's outputs) consists of the run-time version, augmented with a
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# `nativeDrv` field for the build-time version, and `crossDrv` field for the
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# run-time version.
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#
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# We could have used any names we want for the disambiguated versions, but
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# `crossDrv` and `nativeDrv` were somewhat similarly used for the old
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# cross-compiling infrastructure. The names are mostly invisible as
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# `mkDerivation` knows how to pull out the right ones for `buildDepends` and
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# friends, but a few packages use them directly, so it seemed efficient (to
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# @Ericson2314) to reuse those names, at least initially, to minimize breakage.
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#
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# For performance reasons, rather than uniformally splice in all cases, we only
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# do so when `pkgs` and `buildPackages` are distinct. The `actuallySplice`
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# parameter there the boolean value of that equality check.
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lib: pkgs: actuallySplice:
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let
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defaultBuildScope = pkgs.buildPackages // pkgs.buildPackages.xorg;
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# TODO(@Ericson2314): we shouldn't preclude run-time fetching by removing
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# these attributes. We should have a more general solution for selecting
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# whether `nativeDrv` or `crossDrv` is the default in `defaultScope`.
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pkgsWithoutFetchers = lib.filterAttrs (n: _: !lib.hasPrefix "fetch" n) pkgs;
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defaultRunScope = pkgsWithoutFetchers // pkgs.xorg;
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splicer = buildPkgs: runPkgs: let
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mash = buildPkgs // runPkgs;
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merge = name: {
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inherit name;
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value = let
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defaultValue = mash.${name};
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buildValue = buildPkgs.${name} or {};
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runValue = runPkgs.${name} or {};
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augmentedValue = defaultValue
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// (lib.optionalAttrs (buildPkgs ? ${name}) { nativeDrv = buildValue; })
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// (lib.optionalAttrs (runPkgs ? ${name}) { crossDrv = runValue; });
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# Get the set of outputs of a derivation
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getOutputs = value:
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lib.genAttrs (value.outputs or []) (output: value.${output});
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in
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# Certain *Cross derivations will fail assertions, but we need their
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# nativeDrv. We are assuming anything that fails to evaluate is an
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# attrset (including derivation) and thus can be unioned.
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if !(builtins.tryEval defaultValue).success then augmentedValue
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# The derivation along with its outputs, which we recur
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# on to splice them together.
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else if lib.isDerivation defaultValue then augmentedValue
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// splicer (getOutputs buildValue) (getOutputs runValue)
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# Just recur on plain attrsets
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else if lib.isAttrs defaultValue then splicer buildValue runValue
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# Don't be fancy about non-derivations. But we could have used used
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# `__functor__` for functions instead.
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else defaultValue;
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};
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in lib.listToAttrs (map merge (lib.attrNames mash));
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splicedPackages =
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if actuallySplice
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then splicer defaultBuildScope defaultRunScope // {
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# These should never be spliced under any circumstances
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inherit (pkgs) pkgs buildPackages __targetPackages
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buildPlatform targetPlatform hostPlatform;
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}
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else pkgs // pkgs.xorg;
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in
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{
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# We use `callPackage' to be able to omit function arguments that can be
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# obtained `pkgs` or `buildPackages` and their `xorg` package sets. Use
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# `newScope' for sets of packages in `pkgs' (see e.g. `gnome' below).
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callPackage = pkgs.newScope {};
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callPackages = lib.callPackagesWith splicedPackages;
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newScope = extra: lib.callPackageWith (splicedPackages // extra);
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}
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