This way, the crates can be published without interfering with
potential future non-bindings `nix-` crates, if Nix proper wants to
have native rust code, for instance.
Fixes#106
The Nix settings system uses global mutable state without internal
synchronization. When multiple threads call settings::set concurrently
(as happens in parallel test execution), this causes a segfault in the
C++ std::set implementation.
Changes:
- Add mutex to serialize access through the Rust API
- Add documentation explaining thread safety limitations
- Add Once guard in nix-flake tests to minimize concurrent access
The mutex provides protection between Rust callers, though it cannot
completely prevent C++ Nix code from modifying settings concurrently.
(cherry picked from commit 203917657b60c4e1dcbaf442bec64c37c634abc4)
This spreads out transitively to many places and requires that
we use `check_call!` instead of `check_one_call` in a number of
places.
(cherry picked from commit 6bc31dcf206518a7be7f0ac6e773d5dfe25531ea)
The mutation-based methods had some pitfalls, and we don't really
need them.
We could re-add them if we need to.
(cherry picked from commit ca92b8491d87cebf54dd2468599168fc7a16c07f)
This is slightly easier to use than the previous pattern that was
always followed up by the same conversions.
(cherry picked from commit 756c080730cd4fa81d4c0e3a99688cbe8debe57f)
