* doc: primops: add more info for foldl
From the existing doc it is not obvious whether the first or the
second argument is the accumulator. This is however relevant to
know, as for certain scenarios, this might change the behavior.
Co-authored-by: Valentin Gagarin <valentin.gagarin@tweag.io>
https://github.com/NixOS/nixpkgs/pull/269064 makes rapidcheck be build
as a shared lib, but that broke Nix because the `-lrapidcheck` was
missing. This fixes that (and doesn't break Nix what the library is a
static archive as today).
getFlake currently calls lstat (via isLink via canonPath) before it
performs the sanity check that a flake.nix exists in the first place.
This commit moves the check to before path canonicalization, so that
failed symlink check operations don't throw before the check does.
**`Value` and `const`**
These two deserve some explanation. We'll get to lists later.
Values can normally be thought of as immutable, except they are
are also the vehicle for call by need, which must be implemented
using mutation.
This circumstance makes a `const Value` a rather useless thing:
- If it's a thunk, you can't evaluate it, except by copying, but
that would not be call by need.
- If it's not a thunk, you know the type, so the method that
acquired it for you should have returned something more specific,
such as a `const Bindings &` (which actually does make sense
because that's an immutable span of pointers to mutable `Value`s.
- If you don't care about the type yet, you might establish the
convention that `const Value` means `deepSeq`-ed data, but
this is hardly useful and not actually as safe as you would
supposedly want to trust it to be - just convention.
**Lists**
`std::span` is a tuple of pointer and size - just what we need.
We don't return them as `const Value`, because considering the
first bullet point we discussed before, we'd have to force all
the list values, which isn't what we want.
So what we end up with is a nice representation of a list in
weak head normal form: the spine is immutable, but the
items may need some evaluation later.
Closes#9343
See that issue for motivation.
Installing these is disabled by default, but we enable it (and the
additional output we want isntall these too so as not to clutter the
existing ones) to use in cross builds and dev shells.
Try to stay away from stack overflows.
These small vectors use stack space. Most instances will not need
to allocate because in general most things are small, and large
things are worth heap allocating.
16 * 3 * word = 384 bytes is still quite a bit, but these functions
tend not to be part of deep recursions.
This makes stack usage significantly more compact, allowing larger
amounts of data to be processed on the same stack.
PrimOp functions with more than 8 positional (curried) arguments
should use an attrset instead.
VLAs are a dangerous feature, and their usage triggers an undefined
behavior since theire size can be zero in some cases.
So replace them with `boost::small_vector`s which fit the same goal but
are safer.
It's also incidentally consistently 1% faster on the benchmarks.
As discussed in our last meeting, we need a bit more time, but we are
"time boxing" the work left to do to ensure there is not unbounded
delay.
Rather than putting it back underneath `flakes`, though, put it
underneath its own `fetch-tree` experimental feature (which `flakes`
includes/implies). This signals our commitment to the plan to stabilize
it first without waiting to go through the rest of Flakes, and also will
give users a "release candidate" when we get closer to stabilization.
This reverts commit 4112dd1fc9.
Users may select specific outputs using the ^output syntax or selecting
any output using ^*.
URL parsing currently doesn't support these kinds of output references:
parsing will fail.
Currently `queryRegex` was reused for URL fragments, which didn't
include support for ^. Now queryRegex has been split from fragmentRegex,
where only the fragmentRegex supports ^.
* Fix boost::bad_format_string exception in builtins.addErrorContext
The message passed to addTrace was incorrectly being used as a format
string and this this would cause an exception when the string contained
a '%', which can be hit in places where arbitrary file paths are
interpolated.
* add test
All OS and IO operations should be moved out, leaving only some misc
portable pure functions.
This is useful to avoid copious CPP when doing things like Windows and
Emscripten ports.
Newly exposed functions to break cycles:
- `restoreSignals`
- `updateWindowSize`
This adds publicKeys as an optional fetcher input attribute to flakes
and builtins.fetchGit to provide a nix interface for the json-encoded
`publicKeys` attribute of the git fetcher.
Co-authored-by: Valentin Gagarin <valentin.gagarin@tweag.io>
Committing a lock file using markFileChanged() required the input to
be writable by the caller in the local filesystem (using the path
returned by getSourcePath()). putFile() abstracts over this.
End goal: make `(mkDerivation x).drvPath` behave like a non-DrvDeep
context.
Problem: users won't be able to recover the DrvDeep behavior when
nixpkgs makes this change.
Solution: add this primop.
The new primop is fairly simple, and is supposed to complement other
existing ones (`builtins.storePath`, `builtins.outputOf`) so there are
simple ways to construct strings with every type of string context
element.
(It allows nothing we couldn't already do with `builtins.getContext` and `builtins.appendContext`, which is also true of those other two primops.)
This was originally in #8595, but then it was proposed to land some doc
changes separately. So now the code changes proper is just moved to
this, and the doc will be done in that.
Co-authored-by: Robert Hensing <roberth@users.noreply.github.com>
Co-authored-by: Théophane Hufschmitt <7226587+thufschmitt@users.nore
github.com>
Co-authored-by: Valentin Gagarin <valentin.gagarin@tweag.io
MemoryInputAccessor is an in-memory virtual filesystem that returns
files like <nix/fetchurl.nix>. This removes the need for special hacks
to handle those files.
Two changes:
* The (probably unintentional) hack to handle paths as tarballs has
been removed. This is almost certainly not what users expect and is
inconsistent with flakeref handling everywhere else.
* The hack to support scp-style Git URLs has been moved to the Git
fetcher, so it's now supported not just by fetchTree but by flake
inputs.
* document "Import From Derivation"
Co-authored-by: Robert Hensing <roberth@users.noreply.github.com>
Co-authored-by: John Ericson <git@JohnEricson.me>
Support using nix flakes in paths with spaces or abitrary unicode characters.
This introduces the convention that the path part of the URL should be
percent-encoded when dealing with `path:` urls and not when using
filepaths (following the convention of firefox).
Co-authored-by: Rendal <rasmus@rend.al>
We use the same nested map representation we used for goals, again in
order to save space. We might someday want to combine with `inputDrvs`,
by doing `V = bool` instead of `V = std::set<OutputName>`, but we are
not doing that yet for sake of a smaller diff.
The ATerm format for Derivations also needs to be extended, in addition
to the in-memory format. To accomodate this, we added a new basic
versioning scheme, so old versions of Nix will get nice errors. (And
going forward, if the ATerm format changes again the errors will be even
better.)
`parsedStrings`, an internal function used as part of parsing
derivations in A-Term format, used to consume the final `]` but expect
the initial `[` to already be consumed. This made for what looked like
unbalanced brackets at callsites, which was confusing. Now it consumes
both which is hopefully less confusing.
As part of testing, we also created a unit test for the A-Term format for
regular non-experimental derivations too.
Co-authored-by: Robert Hensing <roberth@users.noreply.github.com>
Co-authored-by: Valentin Gagarin <valentin.gagarin@tweag.io>
Apply suggestions from code review
Co-authored-by: Robert Hensing <roberth@users.noreply.github.com>
This function is now trivial enough that it doesn't need to exist.
`EvalState` can still be initialized with a custom search path, but we
don't have a need to mutate the search path after it has been
constructed, and I don't see why we would need to in the future.
Fixes#8229
Types converted:
- `NixStringContextElem`
- `OutputsSpec`
- `ExtendedOutputsSpec`
- `DerivationOutput`
- `DerivationType`
Existing ones mostly conforming the pattern cleaned up:
- `ContentAddressMethod`
- `ContentAddressWithReferences`
The `DerivationGoal::derivationType` field had a bogus initialization,
now caught, so I made it `std::optional`. I think #8829 can make it
non-optional again because it will ensure we always have the derivation
when we construct a `DerivationGoal`.
See that issue (#7479) for details on the general goal.
`git grep 'Raw::Raw'` indicates the two types I didn't yet convert
`DerivedPath` and `BuiltPath` (and their `Single` variants) . This is
because @roberth and I (can't find issue right now...) plan on reworking
them somewhat, so I didn't want to churn them more just yet.
Co-authored-by: Eelco Dolstra <edolstra@gmail.com>
Without the change build with `-D_GLIBCXX_ASSERTIONS` exposes testsuite
assertion:
$ gdb src/libexpr/tests/libnixexpr-tests
Reading symbols from src/libexpr/tests/libnixexpr-tests...
(gdb) break __glibcxx_assert_fail
(gdb) run
(gdb) bt
in std::__glibcxx_assert_fail(char const*, int, char const*, char const*)@plt () from /mnt/archive/big/git/nix/src/libexpr/libnixexpr.so
in std::basic_string_view<char, std::char_traits<char> >::operator[] (this=0x7fffffff56c0, __pos=4)
at /nix/store/r74fw2j8rx5idb0w8s1s6ynwwgs0qmh9-gcc-14.0.0/include/c++/14.0.0/string_view:258
in nix::SearchPath::Prefix::suffixIfPotentialMatch (this=0x7fffffff5780, path=...) at src/libexpr/search-path.cc:15
in nix::SearchPathElem_suffixIfPotentialMatch_partialPrefix_Test::TestBody (this=0x555555a17540) at src/libexpr/tests/search-path.cc:62
As string sizes are usigned types `(a - b) > 0` effectively means
`a != b`. While the intention should be `a > b`.
The change fixes test suite pass.
In the Nix language, given a drv path, we should be able to construct
another string referencing to one of its output. We can do this today
with `(import drvPath).output`, but this only works for derivations we
already have.
With dynamic derivations, however, that doesn't work well because the
`drvPath` isn't yet built: importing it like would need to trigger IFD,
when the whole point of this feature is to do "dynamic build graph"
without IFD!
Instead, what we want to do is create a placeholder value with the right
string context to refer to the output of the as-yet unbuilt derivation.
A new primop in the language, analogous to `builtins.placeholder` can be
used to create one. This will achieve all the right properties. The
placeholder machinery also will match out the `outPath` attribute for CA
derivations works.
In 60b7121d2c we added that type of
placeholder, and the derived path and string holder changes necessary to
support it. Then in the previous commit we cleaned up the code
(inspiration finally hit me!) to deduplicate the code and expose exactly
what we need. Now, we can wire up the primop trivally!
Part of RFC 92: dynamic derivations (tracking issue #6316)
Co-authored-by: Robert Hensing <roberth@users.noreply.github.com>
`EvalState::mkSingleDerivedPathString` previously contained its own
inverse (printing, rather than parsing) in order to validate what was
parsed. Now that is pulled out into its own separate function:
`EvalState::coerceToSingleDerivedPath`.
In additional that pulled out logic is deduplicated with
`EvalState::mkOutputString` via `EvalState::mkOutputStringRaw`, which is
itself deduplicated (and generalized) with
`DownstreamPlaceholder::mkOutputStringRaw`.
All these changes make the unit tests simpler.
(We would ideally write more unit tests for `mkSingleDerivedPathString`
`coerceToSingleDerivedPath` directly, but we cannot yet do that because
the IO in reading the store path won't work when the dummy store cannot
hold anything. Someday we'll have a proper in-memory store which will
work for this.)
Co-authored-by: Robert Hensing <roberth@users.noreply.github.com>
We want to be able to write down `foo.drv^bar.drv^baz`:
`foo.drv^bar.drv` is the dynamic derivation (since it is itself a
derivation output, `bar.drv` from `foo.drv`).
To that end, we create `Single{Derivation,BuiltPath}` types, that are
very similar except instead of having multiple outputs (in a set or
map), they have a single one. This is for everything to the left of the
rightmost `^`.
`NixStringContextElem` has an analogous change, and now can reuse
`SingleDerivedPath` at the top level. In fact, if we ever get rid of
`DrvDeep`, `NixStringContextElem` could be replaced with
`SingleDerivedPath` entirely!
Important note: some JSON formats have changed.
We already can *produce* dynamic derivations, but we can't refer to them
directly. Today, we can merely express building or example at the top
imperatively over time by building `foo.drv^bar.drv`, and then with a
second nix invocation doing `<result-from-first>^baz`, but this is not
declarative. The ethos of Nix of being able to write down the full plan
everything you want to do, and then execute than plan with a single
command, and for that we need the new inductive form of these types.
Co-authored-by: Robert Hensing <roberth@users.noreply.github.com>
Co-authored-by: Valentin Gagarin <valentin.gagarin@tweag.io>
Avoid duplicated code, and also avoid "on the fly" path construction
(which makes it harder to keep track of which paths we use).
The factored out code doesn't create the Nix state dir anymore, but this
is fine because other in nix-env and nix-channel does:
- nix-channel: Line 158 in this commit
- nix-env: Line 1407 in this commit
Special-casing the file name is rather ugly, so we shouldn't do
that. So now any {file,http,https} URL is handled by
TarballInputScheme, except for non-flake inputs (i.e. inputs that have
the attribute `flake = false`).
Over the last year or so I've run into several use cases where I need to
parse and/or serialize URLs for use by `builtins.fetchTree` or
`builtins.getFlake`, largely in order to produce _lockfile-like_ files
for lang2nix frameworks or tools which use `nix` internally to drive
builds.
I've gone through the painstaking process of emulating
`nix::FlakeRef::fromAttrs` and `nix::parseFlakeRef` several times with
mixed success; but these are difficult to create and even harder to
maintain if I hope to stay aligned with changes to the real
parser/serializer.
I understand why adding new `builtins` isn't something we want to do
flagrantly. I'm recommending this addition simply because I keep
encountering use cases where I need to parse/serialize these URIs in
`nix` expressions, and I want a reliable solution.
Co-authored-by: Eelco Dolstra <edolstra@gmail.com>
Co-authored-by: John Ericson <git@JohnEricson.me>
the original change broke many pre-existing anchor links.
also change formatting of the constants listing slightly:
- the type should not be part of the anchor
- add highlight to the "impure only" note
- Better types
- Own header / C++ file pair
- Test factored out methods
- Pass parsed thing around more than strings
Co-authored-by: Robert Hensing <roberth@users.noreply.github.com>
Whereas `ContentAddressWithReferences` is a sum type complex because different
varieties support different notions of reference, and
`ContentAddressMethod` is a nested enum to support that,
`ContentAddress` can be a simple pair of a method and hash.
`ContentAddress` does not need to be a sum type on the outside because
the choice of method doesn't effect what type of hashes we can use.
Co-Authored-By: Cale Gibbard <cgibbard@gmail.com>
If we call `adjustLoc`, the global variable `prev_yylloc` is shared
between threads and racy.
Currently, nix itself does not concurrently parsing files, but this is
helpful for libexpr users. (The parser is thread-safe except this.)
When explicitly requested by the caller, as suggested in the meeting
(https://github.com/NixOS/nix/pull/8090#issuecomment-1531139324)
> @edolstra: { toPath } vs { fromPath } is too implicit
I've opted for the `inputAddressed = true` requirement, because it
we did not agree on renaming the path attributes.
> @roberth: more explicit
> @edolstra: except for the direction; not immediately clear in which direction the rewriting happens
This is in fact the most explicit syntax and a bit redundant, which is
good, because that redundancy lets us deliver an error message that
reminds expression authors that CA provides a better experience to
their users.
This is done in roughly the same way builtin functions are documented.
Also auto-link experimental features for primops, subsuming PR #8371.
Co-authored-by: Eelco Dolstra <edolstra@gmail.com>
Co-authored-by: Robert Hensing <roberth@users.noreply.github.com>
Co-authored-by: Valentin Gagarin <valentin.gagarin@tweag.io>
I got very confused trying to keep all the `first` and `second` straight
reading the code, *especially* as there is also another `(boolean,
string)` pair type also being used.
Named fields is much better.
There are other cleanups that we can do (for example, the existing
TODO), but we can do them later. Doing them now would just make this
harder to review.
The remaining constructor RegisterPrimOp::RegisterPrimOp(Info && info)
allows specifying the documentation in .args and .doc members of the
Info structure.
Commit 8ec1ba0210 removed all uses of the removed constructor in the
nix binary. Here, we remove the constructor completely as well as its
use in a plugin test. According to #8515, we didn't promis to maintain
compatibility with external plugins.
Fixes#8515
Previously, for tarball flakes, we recorded the original URL of the
tarball flake, rather than the URL to which it ultimately
redirects. Thus, a flake URL like
http://example.org/patchelf-latest.tar that redirects to
http://example.org/patchelf-<revision>.tar was not really usable. We
couldn't record the redirected URL, because sites like GitHub redirect
to CDN URLs that we can't rely on to be stable.
So now we use the redirected URL only if the server returns the
`x-nix-is-immutable` or `x-amz-meta-nix-is-immutable` headers in its
response.
This will allow documenting them (in later commits).
Note that we keep the old constructor even if it is no longer used by
Nix code, because it is used in tests/plugins/plugintest.cc, which
suggests that it might be used by some external plugin.
Currently `fromTOML` throws an exception when encountering a timestamp
since the Nix language lacks a way to represent them.
This patch changes this beaviour and makes `fromTOML` parse timestamps as
attrsets of the format
{ _type = "timestamp"; value = "1979-05-27T07:32:00Z"; }
This is guarded by an experimental feature flag to leave room for iterating on the representation.
