This patch change the behaviour or overridePackages:
- Before, overridePackages was based on top of the set of packages
overriden by `~/.nixpkgs/config.nix` file.
- After, overridePackages should when given a function f, behave almost¹
the same as-if the packageOverrides attribute of `~/.nixpkgs/config.nix`
file attribute was set to f, assuming that we ignore the extra `self`
argument.
¹ It is not yet exactly the same because we have many paths which are
re-entering nixpkgs while taking the default attributes, such as the
bootstrap phase of stdenv. Thus if the nixpkgs configuration overrides any
of the dependencies need for the bootstrap, then we might get different sha.
Extract stdenvDefault from the set of all packages. As this set of
attributes are inter-dependant, probably due to stdenvOverrides, we have to
keep them in a close set of inter-dependent options.
I guess I will have to investigate more ...
While evaluating the derivation of xbursttools:
the condition `pkgs.stdenv ? overrides` causes the evaluation of
`stdenvCross`. This evaluation comes too early during the execution, as
it prevents the resolution of names such as `pkgs.lib`, and
`stdenvAdapaters.makeStdenvCross`, which we want to take from `pkgs`
instead of `self` in following patches.
By swapping the conditions, we effectively make the resolution of `pkgs.lib`
and `stdenvAdapaters.makeStdenvCross` possible through the pkgs attribute.
Note, the aliases are now computed against the set of packages defined in
the set of all packages, and no longer apply to any overriden package.
I think this is better as this reduces the amount of surprizes.
This modification change the names bound to the `helperFunctions` attribute
set, to be bound to `self` which is constructed by merging the same
`helperFunctions` set with the set of all packages.
This patch works as expected because none of the helperFunction names is
aliased by the name of a package.
The `helperFunctions` and `stdenvAdapters` both use the `pkgs` attribute as
input, either to inherit some properties, either to use it as argument.
The `pkgs` binding used in both expressions of the `helperFunctions` and
`stdenvAdapters` is no longer the result of the `applyGlobalOverrides`
function, but the argument of the `pkgsFun` function.
The `pkgsFun` functions is called twice under `applyGlobalOverrides`, and in
both cases, the first argument of `pkgsFun` correspond to the result of
`applyGlobalOverrides`.
Thus, this modification will change the bindings, but the evaluation of
`<nixpkgs>`.
A third call the `pkgsFun` exists under `overridePackages` in the set of all
packages. Previously, the `helperFunctions` and `stdenvAdapaters` would use
the functions defined as part of the default `<nixpkgs>` set. With this
modification, the `helperFunctions` and the `stdenvAdapters` are now using
the fix-point of the newly evaluated package set.
This implies that this modification allow the user to use
`overridePackages`, which is already not recommended for performance
reasons, to override the inputs of the `helperFucntions` and
`stdenvAdapaters` too, where this was not possible before.
This move idioms which were used in `evalOptionValue` and in the `merge`
functions of `listOf` and `attrsOf` types, such that we can use a names such
as `isDefined` and `optionalValue` instead or repeating identical
comparisons of `defsFinal == []`.
The current implementation of the ApplyIfFunction is looking at the
arguments of a module to decide which arguments should be given to each
module. This patch make sure that we do not wrap a submodule function in
order to keep functionArgs working as expected.
With the new evaluation of arguments, pkgs is now defined by the
configuration, which implies that option declaration with pkgs.lib
will cause an infinite loop.
Add a script to add git branches for each channel.
To create / update references to remote / local channels, you have to run `./maintainers/scripts/update-channel-branches.sh` while you are at the top-level of nixpkgs work directory. To make this convenient for Nixpkgs / NixOS developer, one can run the following command:
```
$ git config --add alias.fetch-channels '!sh -c "$(git rev-parse --show-cdup)maintainers/scripts/update-channel-branches.sh"'
```
Which will register the alias fetch-channels such that the script can used from sub-directory of nixpkgs by running `git fetch-channels`.
Nicolas B. Pierron