We’re already allowing `/tmp` anyway, so this should be harmless,
and it fixes a regression in the default configuration caused by
moving the build directories out of `temp-dir`. (For instance, that
broke the Lix `guessOrInventPath.sockets` test.)
Note that removing `/tmp` breaks quite a few builds, so although it may
be a good idea in general it would require work on the Nixpkgs side.
Fixes: 749afbbe99fd7b45f828b72628252feba9241362
Change-Id: I6a6a69645f429bc50d4cb24283feda3d3091f534
(This is a cherry-pick of commit d1db3e5fa3faa43b3d2f2e2e843e9cfc1e6e1b71)
Lix patch: https://gerrit.lix.systems/c/lix/+/3500
c39cc00404 has added assertions for
all Value accesses and the following case has started failing with
an `unreachable`:
(/tmp/fun.nix):
```nix
{a}: a
```
```
$ nix eval --impure --expr 'import /tmp/fun.nix {a="a";b="b";}'
```
This would crash:
```
terminating due to unexpected unrecoverable internal error: Unexpected condition in getStorage at ../include/nix/expr/value.hh:844
```
This is not a regression, but rather surfaces an existing problem, which previously
was left undiagnosed. In the case of an import `fun` is the `import` primOp, so that read is invalid
and previously this resulted in an access into an inactive union member, which is UB.
The correct thing to use is `vCur`. Identical problem also affected the case of a missing argument.
Add previously failing test cases to the functional/lang test suite.
Fixes#13448.
Fixes:
[261/394] Linking target src/libexpr/libnixexpr.so
In function ‘copy’,
inlined from ‘__ct ’ at /nix/store/24sdvjs6rfqs69d21gdn437mb3vc0svh-gcc-14.2.1.20250322/include/c++/14.2.1.20250322/bits/basic_string.h:688:23,
inlined from ‘operator+’ at /nix/store/24sdvjs6rfqs69d21gdn437mb3vc0svh-gcc-14.2.1.20250322/include/c++/14.2.1.20250322/bits/basic_string.h:3735:43,
inlined from ‘operator()’ at ../src/libexpr/primops/fetchClosure.cc:127:58,
inlined from ‘prim_fetchClosure’ at ../src/libexpr/primops/fetchClosure.cc:132:88:
/nix/store/24sdvjs6rfqs69d21gdn437mb3vc0svh-gcc-14.2.1.20250322/include/c++/14.2.1.20250322/bits/char_traits.h:427:56: warning: ‘__builtin_memcpy’ writing 74 bytes into a region of size 16 overflows the destination [-Wstringop-overflow=]
427 | return static_cast<char_type*>(__builtin_memcpy(__s1, __s2, __n));
| ^
../src/libexpr/primops/fetchClosure.cc: In function ‘prim_fetchClosure’:
../src/libexpr/primops/fetchClosure.cc:132:88: note: at offset 16 into destination object ‘<anonymous>’ of size 32
132 | fromPath = state.coerceToStorePath(attr.pos, *attr.value, context, attrHint());
| ^
-p preserves xattrs and acls which can be incompatible between
filesystems
Unfortunately keep -p on darwin because the bsd coreutils do not
support --preserve.
Fixes#13426
This changes makes nix detect a machines available cores automatically whenever build-cores is set to 0.
So far, nix simply passed NIX_BUILD_CORES=0 whenever build-cores is set to 0. (only when build-cores is unset it was detecting cores automatically)
The behavior of passing NIX_BUILD_CORES=0 leads to a performance penalty when sourcing nixpkgs' generic builder's `setup.sh`, as setup.sh has to execute `nproc`. This significantly slows down sourcing of setup.sh
The use of R"(...)" added a bunch of unnecessary whitespace, e.g.
error:
Unable to start any build;
either increase '--max-jobs' or enable remote builds.
For more information run 'man nix.conf' and search for '/machines'.
Now we get
error: Unable to start any build; either increase '--max-jobs' or enable remote builds.
For more information run 'man nix.conf' and search for '/machines'.
This shaves off a very significand amount of memory used
for evaluation as well as reduces the GC-managed heap.
Previously the union discriminator (InternalType) was
stored as a separate field in the Value, which takes up
whole 8 bytes due to padding needed for member alignment.
This effectively wasted 7 whole bytes of memory. Instead
of doing that InternalType is instead packed into pointer
alignment niches. As it turns out, there's more than enough
unused bits there for the bit packing to be effective.
See the doxygen comment in the ValueStorage specialization
for more details.
This does not add any performance overhead, even though
we now consistently assert the InternalType in all getters.
This can also be made atomic with a double width compare-and-swap
instruction on x86_64 (CMPXCHG16B instruction) for parallel evaluation.
