The Determinate Nix Installer has set nosuid and noatime in https://github.com/DeterminateSystems/nix-installer/pull/1338, and figured this perf and security improvement is worthy of upstreaming.
The /nix volume shouldn't have setuid binaries anyway, and filesystems seem to generally be noatime on macOS.
Further, the garbage collector doesn't use atime.
We *could* use a "native" manual instead - ie reusing a native
`nixpkgsFor.${buildPlatform}`, but this works, and also
works for possible cases where we have a custom or patched build tool.
Without the change `meson setup` fails on `Gentoo or Debian as those
don't use multicall binary:
$ meson setup ..
...
Executing subproject nix-functional-tests
...
../src/nix-functional-tests/meson.build:24:14: ERROR: Program 'coreutils' not found or not executable
The change always uses `ls` to look `coreutils` up.
Closes: https://github.com/NixOS/nix/issues/11975
Upstream `bzip2` does not provide `pkg-config` files. As a result an
attempt to build `nix` on some distributions like Gentoo failos the
configure as:
$ meson setup ..
...
Executing subproject perl
...
perl| Run-time dependency bzip2 found: NO (tried pkgconfig and cmake)
../src/perl/meson.build:68:12: ERROR: Dependency "bzip2" not found, tried pkgconfig and cmake
The change falls back to `bz2` library for such cases.
This prevents any potential cases of deletion through base pointer and its
non-virtual dtor, which might leak memory. Also gets rid of the warning:
/nix/store/fg7ass3a5m5pgl26qzfdniicbwbgzccy-gcc-13.2.0/include/c++/13.2.0/bits/stl_construct.h:88:2: warning: destructor called on non-final 'nix::flake::Settings' that has virtual functions but non-virtual destructor [-Wdelete-non-abstract-non-virtual-dtor]
88 | __location->~_Tp();
....
../src/libflake-c/nix_api_flake.cc:10:30: note: in instantiation of function template specialization 'nix::make_ref<nix::flake::Settings>' requested here
10 | auto settings = nix::make_ref<nix::flake::Settings>();
This gets rid of unnecessary copies in range-based-for loops and
local variables, when they are used solely as `const &`.
Also added a fixme comment about a suspicious move out of const,
which might not be intended.
This shuts up a 300-line warning that includes
/nix/store/fg7ass3a5m5pgl26qzfdniicbwbgzccy-gcc-13.2.0/include/c++/13.2.0/bits/stl_tree.h:182:25: warning: ‘*(std::_Rb_tree_header*)((char*)&<unnamed> + offsetof(nix::value_type, nix::DerivedPath::<unnamed>.std::variant<nix::DerivedPathOpaque, nix::DerivedPathBuilt>::<unnamed>.std::__detail::__variant::_Variant_base<nix::DerivedPathOpaque, nix::DerivedPathBuilt>::<unnamed>.std::__detail::__variant::_Move_assign_base<false, nix::DerivedPathOpaque, nix::DerivedPathBuilt>::<unnamed>.std::__detail::__variant::_Copy_assign_base<false, nix::DerivedPathOpaque, nix::DerivedPathBuilt>::<unnamed>.std::__detail::__variant::_Move_ctor_base<false, nix::DerivedPathOpaque, nix::DerivedPathBuilt>::<unnamed>.std::__detail::__variant::_Copy_ctor_base<false, nix::DerivedPathOpaque, nix::DerivedPathBuilt>::<unnamed>.std::__detail::__variant::_Variant_storage<false, nix::DerivedPathOpaque, nix::DerivedPathBuilt>::_M_u) + 24).std::_Rb_tree_header::_M_header.std::_Rb_tree_node_base::_M_parent’ may be used uninitialized [-Wmaybe-uninitialized]
182 | if (__x._M_header._M_parent != nullptr)
| ~~~~~~~~~~~~~~^~~~~~~~~
