In _very_ rare cases (I had about 7 cases out of 32200 files!),
the order of how inherit-from bindings are printed when using
`nix-instantiate --parse` gets messed up.
The cause of this seems to be because the std::map the bindings are
placed in is keyed on a _pointer_, which then uses an
[implementation-defined strict total order](https://en.cppreference.com/w/cpp/language/operator_comparison#Pointer_total_order).
The fix here is to key the bindings on their displacement instead,
which maintains the same order as they appear in the file.
Unfortunately I wasn't able to make a reproducible test for this in the
source, there's something about the local environment that makes it
unreproducible for me.
However I was able to make a reproducible test in a Nix build on a Nix
version from a very recent master:
nix build github:infinisil/non-det-nix-parsing-repro
Co-authored-by: Robert Hensing <roberth@users.noreply.github.com>
Following what is outlined in #10766 refactor the uds-remote-store such
that the member variables (state) don't live in the store itself but in
the config object.
Additionally, the config object includes a new necessary constructor
that takes a scheme & authority.
Tests are commented out because of linking errors with the current config system.
When there is a new config system we can reenable them.
Co-authored-by: John Ericson <John.Ericson@Obsidian.Systems>
This generally gives a better experience with bindings generators,
possibly other tooling.
A possible risk is that some generators may not represent unknown
codes correctly.
Rust bindgen by default generates suitable code:
* a type alias nix_err = c_int
* individual constants for the known enum values
It does _not_ generate a closed type that can only hold the values
that were known at code generation time.
If this proves to be a problem, we could instead split the type:
`typedef int nix_err;` for return values
`enum nix_known_err` for code generation.
This would complicate the interface, so let's not do it unless it
is shown to be needed.
This was accidentally introduced
in f71b4da0b3. We didn't notice this
because the version got interpreted by the daemon as the obsolete "CPU
affinity will follow" field, and being non-zero, it would then read
another integer for the ignored CPU affinity.
The default value for the setting was evaluated by
calling a method on the object _being currently constructed_,
so we were using it before all fields were initialized.
This has been fixed by making the called method static,
and not using the previously used fields at all.
But functionality hasn't changed!
The fields were usually always zero (by chance?) anyway,
meaning the conditional path was always taken.
Thus the current logic has been kept, the code simplified,
and UB removed.
This was found with the helper of UBSan.
Splitting it out immediately answers questions like [this],
without increasing the number of compilation units.
I did consider using boost::hash_combine instead, but it doesn't seem
to be quite as capable, accepting only two arguments.
[this]: https://github.com/NixOS/nix/pull/11113#discussion_r1679991573
