Fixes fj#940.
When running `nix-shell`, the `$NIX_BUILD_TOP` environment variable is
set to `$TMPDIR` or `/tmp`.
nixpkgs stdenv uses $NIX_BUILD_TOP to create `$NIX_BUILD_TOP/env-vars`
which contains all the environment variables set by stdenv. This is used
for debugging purposes in combination with `--keep-failed` to reload the
bash environment of a derivation.
`$TMPDIR` is often unset, therefore, `/tmp/env-vars` was constantly
being created. On a multi-user system or, when you run Lix as root, you
might create a `/tmp/env-vars` with different permission bits.
As a result, `nix-shell` can cease to function because that file will
fail creation for an unprivileged user for example.
fj#940 rightfully remark that the code is not consistent between
nix3-develop and nix-shell and it should be reworked.
Change-Id: Iddf15945385d8bd497b2800b37fee5e1f97689b7
Signed-off-by: Raito Bezarius <raito@lix.systems>
This avoids mangling debug gdb scripts and breaking them resulting in no
script loading at all.
Change-Id: Ib5e7034c37a1e41d1a1c9bd8442b8b8b8758e350
Signed-off-by: Raito Bezarius <raito@lix.systems>
UnsafeValueList held pointers from Value which were not necessarily GC
allocated, causing mayhem when evaluating something with genericClosure
(texlive environments).
We get rid of storing pointers and we let comparison take places on
const references.
We keep `gc_allocator<Value>` so that GC can scan things it allocates
inside the `res` list.
Co-authored-by: eldritch horrors <pennae@lix.systems>
Reported-by: qbit
Change-Id: I4fed3a3d9e18a2ef2d751f32d81801540e196f92
Signed-off-by: Raito Bezarius <raito@lix.systems>
thunk values are shareable, and we can represent invalid/uninitialized
values with a special bit pattern that makes no sense otherwise. there
is no need to keep allocating values on the heap, instead we can treat
values like reference-counted smart pointers to heap objects, which in
turn lets us save a lot of allocations and, ultimately, gc heap space.
compared to our baseline (main of 2025-09-27) we save 15%+ memory on a
system rebuild and 17% on nix search. eval time regresses by ~3% for a
system rebuild, while nix search is 7% faster. further optimization is
probably possible (but for now this will just have to be good enough).
Change-Id: Ib6c47acdbe2fac4f76a83c2269f16f30ef66b2e1
with thunk state being shareable we no longer need to worry about value
uniqueness, only about value lifetime. this means we can liberally drop
indirections and allocations, passing references instead of pointers or
using stack memory instead of gc-managed memory for some intermediates.
Change-Id: I2d48a6fd57a376d544bd9bd2d05e5420611986d1
there's no measurable performance gain in real-world testing to abusing
our list value storage like this. we haven't tested how much storage we
actually need on the stack to offset most of the temporary storage cost
and used 128 as a "good enough" value instead, reserving 1 kiB of stack
space on 64 bit platforms in a leaf function. this should do for a bit.
Change-Id: Ie98519b1da3e6fe685da88d1c44ffb4580fb592a
Value is already tagged. Value::Acb blocks are allocated for lambdas (so
we can fit the value tag into the three bits we have available), but the
current layout is rather wasteful for this purpose. the type bits can be
stored together with parts of pointers, which in the lambda case will be
the scope the lambda captures. the expr could also be used, but Env is a
gc-allocated item and thus guaranteed to be aligned properly for tagging
Change-Id: Ia685875387c7795bc4a00d73d1ce3cfea84e7297
this is a strong prerequisite for making values themselves copyable
without duplicating evaluation side effects. with this we can treat
`Value` the way we treated `Value *` to date and drop indirections.
Change-Id: I08f30d12697614a3ae7149615f6f1da83b13f52b
preserve type information of wrapped exception when constructing a
ForeignException. this requires using `std::current_exception` for
construction in all cases as passing the exception by reference to
any function erases dynamic type information: `throw` may copy the
thrown exception from its source expression; this only works as we
need it to if static and dynamic type of the expression are equal.
fixes#1000
Change-Id: I7167f298540de7c43c2566592bdb8d7a93c34d31
same as for null: we have few of them, they're statically allocated,
and they're not the largest contributor to the value population. not
storing them in Value itself frees up resources we *will* use later.
Change-Id: I521f9f243f48f56a78f7bffdf1dc1f0bc40a5c2d
we only need the one object for it. there's no need to waste precious
bits of the value internal type enum for this simple singleton datum.
Change-Id: Ie314b5bf429015e518798d9d65ad8ab2bb84a38e
floats are used very rarely, and our float support is bad enough to
strongly discourage using them on reproducibility grounds alone. we
can thus move them to more expensive storage without hurting folks.
Change-Id: I1086f612f85e294dd3fae4a2d334e09f52bbe4a8
external values very rarely appear during eval "normal" eval, and
creating them is pretty expensive. does *anything* even use them?
Change-Id: Id50fa3f76b7e1f551d550d99996a1ed5880b2531
despite not using allocation caches this does not have a statistically
significant performance impact, with less than 1% extra memory needed.
Change-Id: Ibe51a55ba986e471f217f3724977af17880fafff
using the same nodes as tApp is possible, and thanks to multi-arg app
nodes it can even be a bit faster than the linked lists used to date.
Change-Id: Idccb7c0b54c808e62da85d1c42ee09e6e92c4f7b
these behave like the old chains of app nodes, but they can store more
than one argument per node. for tApp values themselves this is not all
that useful, but if we could share tApp and tPrimOpApp backing storage
we could avoid creating and traversing the linked lists of values that
are currently needed to represent partially applied builtin functions.
Change-Id: I5a2a02d9733e1e0be5443459e2998d62fd3b9a5b
paths already are just strings with slightly magic semantics. the type
can mirror that at no perf cost, letting us drop one internalType tag.
Change-Id: I98acaa4fe3bedd28fc0841e1b81184d8dcddacc5
memory overhead is minimal and performance impact not measurable. once
we've done something like this for all value types that don't fit in a
single machine word we can cut a word from Value, offsetting the cost.
Change-Id: I9813bacd7e851957ad3426aed8f74033179a4212
we now use a single cache set for a number of sizes from one to eight
words. this also matches small attrsets, but perf impact seems small.
Change-Id: Icf16b329b98a20fcc9fe75e6395e148f0852c798
on its own this is not very useful, but having accessors for every value
kind is a prerequisite for doing smart things with Value than the union.
the net effect for now is only to add a few parentheses across the tree.
Change-Id: I88688ac09eb08495dad1eb221034ca540f094950
nix develop should ignore output checks in general.
This was done only for the old way of specifying output checks, the
structured attrs way requires rewriting the JSON and removing the output
checks pieces.
We take a brutal approach of removing as many as possible including
non-recommended ways of doing it.
Fixes#997.
Change-Id: Iaf83029016c71b5171e56e15d4eadc1a60a8be98
Signed-off-by: Raito Bezarius <raito@lix.systems>
In 7b37d5ea6a, aside from subdaemons getting
properly executed, they also lost the ability to outlive their parent, due to
now getting set the parent death signal like most other processes spawned by
Lix. This has annoying consequences like all concurrent builds being forcefully
terminated on system updates requiring a nix-daemon restart. As the behaviour
change was not documented and the systemd service file retained
`KillMode=process`, it seems to have been accidental. Restore the old behaviour
of letting the subdaemons outlive their parent.
Change-Id: I6a6a69645312a90dbce55495c2fef3825dd3c097
In preparations for a new representation of bindings that will make it
impossible to write an efficient `Bindings::find`.
Change-Id: I4e5a25b8d37d01b5728f7fe43978ceda2ab1b9b6
Signed-off-by: Raito Bezarius <raito@lix.systems>
Co-authored-by: Sergei Zimmerman <sergei@zimmerman.foo>
The way zipAttrsWith works is to replace the attribute set value by a
call to a function (the argument of zipAttrsWith) over the list of
attributes sharing a common key.
Instead of that, we will insert into the resulting attribute set the
various lazy calls and return that.
Change-Id: I2aae054eb99b1d1f8b0e7c658cc8d3488e5cdb01
Signed-off-by: Raito Bezarius <raito@lix.systems>
C++ has the "spaceship" operator which can be auto-implemented and
generates efficiently a strong ordering.
Change-Id: Idfd1fd68039b395e54401cbe913454e0cbd80fb3
Signed-off-by: Raito Bezarius <raito@lix.systems>
Prior to this change, references or pointers could be mutated. In
practice, we do not require this capability in the codebase except in
zipAttrsWith.
This cleans up all easy sites in preparation to have a smarter
representation of attribute sets albeit one that requires constant
references.
Change-Id: I2be20cce040a9228bde9e5f7b42c0499fba9550b
Signed-off-by: Raito Bezarius <raito@lix.systems>
Co-authored-by: Sergei Zimmerman <sergei@zimmerman.foo>
The stdio stream identifiers (stdin, stdout, stderr) are allowed to be macros.
In musl libc they are, for example doing `#define stdout (stdout)`, breaking
compilation with an error when one of the clashing variables is attempted to be
initialized the "wrong" way:
../lix/libutil/processes.cc:272:7: error: expected class member or base class name
272 | , stdout(stdout ? std::make_unique<AsyncFdIoStream>(std::move(stdout)) : nullptr)
| ^
/nix/store/ziw42d7rvgnf3vkbfc8kry07kipwf1xm-musl-static-x86_64-unknown-linux-musl-1.2.5-dev/include/stdio.h:67:16: note: expanded from macro 'stdout'
67 | #define stdout (stdout)
| ^
Other places only cause warnings on musl:
../lix/libutil/processes.cc:254:17: warning: parentheses were disambiguated as redundant parentheses around declaration of variable named 'stdout' [-Wvexing-parse]
254 | std::string stdout;
| ^~~~~~
/nix/store/ziw42d7rvgnf3vkbfc8kry07kipwf1xm-musl-static-x86_64-unknown-linux-musl-1.2.5-dev/include/stdio.h:67:16: note: expanded from macro 'stdout'
67 | #define stdout (stdout)
| ^~~~~~~~
../lix/libutil/processes.cc:254:17: note: add a variable name to declare a 'std::string' (aka 'basic_string<char>') initialized with 'stdout'
254 | std::string stdout;
| ^
| varname
/nix/store/ziw42d7rvgnf3vkbfc8kry07kipwf1xm-musl-static-x86_64-unknown-linux-musl-1.2.5-dev/include/stdio.h:67:16: note: expanded from macro 'stdout'
67 | #define stdout (stdout)
| ^
../lix/libutil/processes.cc:254:5: note: add enclosing parentheses to perform a function-style cast
254 | std::string stdout;
| ^
| ( )
../lix/libutil/processes.cc:254:17: note: remove parentheses to silence this warning
254 | std::string stdout;
| ^
/nix/store/ziw42d7rvgnf3vkbfc8kry07kipwf1xm-musl-static-x86_64-unknown-linux-musl-1.2.5-dev/include/stdio.h:67:16: note: expanded from macro 'stdout'
67 | #define stdout (stdout)
| ^
However they are still wrong, since the macro could be more complicated. Fix
them as well.
Change-Id: I6a6a6964a50ef7dec8f05f0bd8fc8f13f3036d51
It was supposed to be removed in 480fdf146d, as
it is not needed any more with the prelinked library. Due to a mistake in
rebase conflict resolution it reappeared by accident. Actually remove it now.
Change-Id: I6a6a6964d175fdb0ba0ad9ac55d4d22d7b27ad3f
Raito Bezarius