Running parallel nix in nix can lead to multiple instances trying to
create the state directories and failing on the `createSymlink` step,
because the link already exists.
`replaceSymlink` is already idempotent, so let's use that.
Resolves#2706
This prevents C++ level undefined behavior from affecting
the evaluator. Stdlib implementation details should not affect
eval, regardless of the build platform. Even erroneous usage
of `builtins.sort` should not make it possible to crash the
evaluator or produce results that depend on the host platform.
Unlike std::sort and std::stable_sort, this implementation
does not lead to out-of-bounds memory reads or other undefined
behavior when the predicate is not strict weak ordering.
This makes it possible to use this function in libexpr for
builtins.sort, where an incorrectly implemented comparator
in the user nix code currently can crash and burn the evaluator
by invoking C++ UB.
Instead of parsing a structured attrs at some later point, we parsed it
right away when parsing the A-Term format, and likewise serialize it to
`__json = <JSON dump>` when serializing a derivation to A-Term.
The JSON format can directly contain the JSON structured attrs without
so encoding it, so we just do that.
Makes the behavoral change of #13263 without the underlying refactor.
Hopefully this clearly safe from a perf and GC perspective, and will
make it easier to benchmark #13263.
This overload isn't actually necessary anywhere and
doesn't make much sense. The pointers to `Value`s are
themselves const, but the `Value`s are mutable.
A non-const member function implies that the object itself
can be modified but this doesn't make much sense considering
the return type: `Value * const * `, which is a pointer
to a constant array of pointers to mutable values.
This adds a meson.format file that mostly mirrors the projects
meson style and a pre-commit hook to enforce this style.
Some low-diff files are formatted.
Invoking `:ll` will start a pager with all variables which have just
been loaded by `:lf`, `:l`, or by a flake provided to `nix repl` as an
argument.
https://github.com/NixOS/nix/issues/11404
When we run `nix repl nixpkgs` we get "Added 6 variables". This is not
useful as it doesn't tell us which variables the flake has exported to
our global repl scope.
This patch prints the name of each variable that was just loaded. We
currently cap printing to 20 variables in order to avoid excessive
prints.
https://github.com/NixOS/nix/issues/11404
`getPrimOp` function was basically identical to existing
`Value::primOpAppPrimOp` modulo some trivial differences.
Makes sense to reuse existing code for that.
