1. `DerivationOutput` now as the `std::variant` as a base class. And the
variants are given hierarchical names under `DerivationOutput`.
In 8e0d0689be @matthewbauer and I
didn't know a better idiom, and so we made it a field. But this sort
of "newtype" is anoying for literals downstream.
Since then we leaned the base class, inherit the constructors trick,
e.g. used in `DerivedPath`. Switching to use that makes this more
ergonomic, and consistent.
2. `store-api.hh` and `derivations.hh` are now independent.
In bcde5456cc I swapped the dependency,
but I now know it is better to just keep on using incomplete types as
much as possible for faster compilation and good separation of
concerns.
The current `--out-path` flag has two disadvantages when one is only
concerned with querying the names of outputs:
- it requires evaluating every output's `outPath`, which takes
significantly more resources and runs into more failures
- it destroys the information of the order of outputs so we can't tell
which one is the main output
This patch makes the output names always present (replacing paths with
`null` in JSON if `--out-path` isn't given), and adds an `outputName`
field.
This is useful whenever we want to evaluate something to a store path
(e.g. in get-drvs.cc).
Extracted from the lazy-trees branch (where we can require that a
store path must come from a store source tree accessor).
- Make passing the position to `forceValue` mandatory,
this way we remember people that the position is
important for better error messages
- Add pos to all `forceValue` calls
Previously you had to remember to call value->attrs->sort() after
populating value->attrs. Now there is a BindingsBuilder helper that
wraps Bindings and ensures that sort() is called before you can use
it.
This avoids an ambiguity where the `StorePathWithOutputs { drvPath, {}
}` could mean "build `brvPath`" or "substitute `drvPath`" depending on
context.
It also brings the internals closer in line to the new CLI, by
generalizing the `Buildable` type is used there and makes that
distinction already.
In doing so, relegate `StorePathWithOutputs` to being a type just for
backwards compatibility (CLI and RPC).
These are by no means part of the notion of a store, but rather are
things that happen to use stores. (Or put another way, there's no way
we'd make them virtual methods any time soon.) It's better to move them
out of that too-big class then.
Also, this helps us remove StorePathWithOutputs from the Store interface
altogether next commit.
Most functions now take a StorePath argument rather than a Path (which
is just an alias for std::string). The StorePath constructor ensures
that the path is syntactically correct (i.e. it looks like
<store-dir>/<base32-hash>-<name>). Similarly, functions like
buildPaths() now take a StorePathWithOutputs, rather than abusing Path
by adding a '!<outputs>' suffix.
Note that the StorePath type is implemented in Rust. This involves
some hackery to allow Rust values to be used directly in C++, via a
helper type whose destructor calls the Rust type's drop()
function. The main issue is the dynamic nature of C++ move semantics:
after we have moved a Rust value, we should not call the drop function
on the original value. So when we move a value, we set the original
value to bitwise zero, and the destructor only calls drop() if the
value is not bitwise zero. This should be sufficient for most types.
Also lots of minor cleanups to the C++ API to make it more modern
(e.g. using std::optional and std::string_view in some places).
In particular, this disallows attribute names containing dots or
starting with dots. Hydra already disallowed these. This affects the
following packages in Nixpkgs master:
2048-in-terminal
2bwm
389-ds-base
90secondportraits
lispPackages.3bmd
lispPackages.hu.dwim.asdf
lispPackages.hu.dwim.def
Closes#1342.
The value pointers of lists with 1 or 2 elements are now stored in the
list value itself. In particular, this makes the "concatMap (x: if
cond then [(f x)] else [])" idiom cheaper.
