What if you could find memory bugs in Lix without really trying very
hard? I've had variously scuffed patches to do this, but this is
blocked on boost coroutines removal at this point tbh.
Change-Id: Id762af076aa06ad51e77a6c17ed10275929ed578
When the configured maximum depth has been reached, attribute sets and lists
are printed with ellipsis to indicate the elision of nested items. Previously,
this happened even in case the structure being printed is empty, so that such
items do not in fact exist. This is confusing, so stop doing it.
Change-Id: I0016970dad3e42625e085dc896e6f476b21226c9
The repeated value detection logic exists so that the occurrence of large
common substructures does not fill up the screen or the computer's memory.
However, empty attribute sets and derivations (when their detection is enabled)
are always cheap to print, and in practice I have observed them to make up a
significant majority of the cases where I was annoyed by the repeated value
detection kicking in. Furthermore, `nix-instantiate --eval` already disables
this logic for empty attribute sets, and empty lists are already exempted
everywhere. For these reasons, always print empty attribute sets and
derivations as what they are.
Change-Id: I5dac8e7739f9d726b76fd0521ec46f38af94463f
this is cursed. deeply and profoundly cursed. under NO CIRCUMSTANCES
must protocol serializer helpers be applied to temporaries! doing so
will inevitably cause dangling references and cause the entire thing
to crash. we need to do this even so to get rid of boost coroutines,
and likewise to encapsulate the serializers we suffer today at least
a little bit to allow a gradual migration to an actual IPC protocol.
(this isn't a problem that's unique to generators. c++ coroutines in
general cannot safely take references to arbitrary temporaries since
c++ does not have a lifetime system that can make this safe. -sigh-)
Change-Id: I2921ba451e04d86798752d140885d3c5cc08e146
This also bans various sneaking of negative numbers from the language
into unsuspecting builtins as was exposed while auditing the
consequences of changing the Nix language integer type to a newtype.
It's unlikely that this change comprehensively ensures correctness when
passing integers out of the Nix language and we should probably add a
checked-narrowing function or something similar, but that's out of scope
for the immediate change.
During the development of this I found a few fun facts about the
language:
- You could overflow integers by converting from unsigned JSON values.
- You could overflow unsigned integers by converting negative numbers
into them when going into Nix config, into fetchTree, and into flake
inputs.
The flake inputs and Nix config cannot actually be tested properly
since they both ban thunks, however, we put in checks anyway because
it's possible these could somehow be used to do such shenanigans some
other way.
Note that Lix has banned Nix language integer overflows since the very
first public beta, but threw a SIGILL about them because we run with
-fsanitize=signed-overflow -fsanitize-undefined-trap-on-error in
production builds. Since the Nix language uses signed integers, overflow
was simply undefined behaviour, and since we defined that to trap, it
did.
Trapping on it was a bad UX, but we didn't even entirely notice
that we had done this at all until it was reported as a bug a couple of
months later (which is, to be fair, that flag working as intended), and
it's got enough production time that, aside from code that is IMHO buggy
(and which is, in any case, not in nixpkgs) such as
#445, we don't think
anyone doing anything reasonable actually depends on wrapping overflow.
Even for weird use cases such as doing funny bit crimes, it doesn't make
sense IMO to have wrapping behaviour, since two's complement arithmetic
overflow behaviour is so *aggressively* not what you want for *any* kind
of mathematics/algorithms. The Nix language exists for package
management, a domain where bit crimes are already only dubiously in
scope to begin with, and it makes a lot more sense for that domain for
the integers to never lose precision, either by throwing errors if they
would, or by being arbitrary-precision.
This change will be ported to CppNix as well, to maintain language
consistency.
Fixes: #423
Change-Id: I51f253840c4af2ea5422b8a420aa5fafbf8fae75
the rewriting sink was just broken. when given a rewrite set that
contained a key that is also a proper infix of another key it was
possible to produce an incorrectly rewritten result if the writer
used the wrong block size. fixing this duplicates rewriteStrings,
to avoid this we'll rewrite rewriteStrings to use RewritingSource
in a new mode that'll allow rewrites we had previously forbidden.
Change-Id: I57fa0a9a994e654e11d07172b8e31d15f0b7e8c0
generators are a better basis for serializers than streaming into sinks
as we do currently for many reasons, such as being usable as sources if
one wishes to (without requiring an intermediate sink to serialize full
data sets into memory, or boost coroutines to turn sinks into sources),
composing more naturally (as one can just yield a sub-generator instead
of being forced to wrap entire substreams into clunky functions or even
more clunky custom types to implement operator<< on), allowing wrappers
to transform data with clear ownership semantics (removing the need for
explicit memory allocations and Source wrappers), and many other things
Change-Id: I361d89ff556354f6930d9204f55117565f2f7f20
this will be the basis of non-boost coroutines in lix. anything that is
a boost coroutine *should* be representable with a Generator coroutine,
and many things that are not currently boost coroutines but behave much
like one (such as, notably, serializers) should be as well. this allows
us to greatly simplify many things that look like iteration but aren't.
Change-Id: I2cebcefa0148b631fb30df4c8cfa92167a407e34
Previously, the progress bar had two subtly different states in which the bar
would not actually render, both with their own shortcomings: inactive (which
was irreversible) and paused (reversible, but swallowing logs). Furthermore,
there was no way of resetting the statistics, so a very bad solution was
implemented (243c0f18da) that would create a new
logger for each line of the repl, leaking the previous one and discarding the
value of printBuildLogs. Finally, if stderr was not attached to a TTY, the
update thread was started even though the logger was not active, violating the
invariant required by the destructor (which is not observed because the logger
is leaked).
In this commit, the two aforementioned states are unified into a single one,
which can be exited again, correctly upholds the invariant that the update
thread is only running while the progress bar is active, and does not swallow
logs. The latter change in behavior is not expected to be a problems in the
rare cases where the paused state was used before, since other loggers (like
the simple one) don't exhibit it anyway. The startProgressBar/stopProgressBar
API is removed due to being a footgun, and a new method for properly resetting
the progress is added.
Co-Authored-By: Qyriad <qyriad@qyriad.me>
Change-Id: I2b7c3eb17d439cd0c16f7b896cfb61239ac7ff3a
If we've consumed the entire input, that doesn't actually mean we're
done decompressing - there might be more output left. This worked (?)
in most cases because the input and output sizes are pretty comparable,
but sometimes they're not and then things get very funny.
Change-Id: I73435a654a911b8ce25119f713b80706c5783c1b
without this we will not be able to get rid of makeDecompressionSink,
which in turn will be necessary to get rid of sourceToSink (since the
libarchive archive wrapper *must* be a Source due to api limitations)
Change-Id: Iccd3d333ba2cbcab49cb5a1d3125624de16bce27
even the transfer function is not all that necessary since there aren't
that many users, but we'll keep it for now. we could've kept both names
but we also kind of want to use `download` for something else very soon
Change-Id: I005e403ee59de433e139e37aa2045c26a523ccbf
* changes:
libstore client: remove remaining dead code
libstore: refuse to serialise ancient protocols
libstore client: remove support for <2.3 clients
libstore daemon: remove very old protocol support (<2.3)
Delete old ValidPathInfo test, fix UnkeyedValidPathInfo
Set up minimum protocol version
with the prepatory work done this mostly means turning plain pointers
into unique_ptrs, with all the associated churn that necessitates. we
might want to change some of these to box_ptrs at some point as well,
but that would be a semantic change that isn't fully appropriate yet.
Change-Id: I0c238c118617420650432f4ed45569baa3e3f413
almost all places where Exprs are passed as pointers expect the pointers
to be non-null. pass them as references to encode this constraint in the
type system as well (and also communicate that Exprs must not be freed).
Change-Id: Ia98f166fec3c23151f906e13acb4a0954a5980a2
We don't want to deal with these at all, let's stop doing so.
(marking this one as the fix commit since its immediate predecessors
aren't the complete fix)
Fixes: #325
Change-Id: Ieea1b0b8ac0f903d1e24e5b3e63cfe12eeec119d
The UnkeyedValidPathInfo test was testing an ancient version but not the
current version. Doesn't make much sense to me.
Change-Id: Ib476a4297d9075f2dcd31a073b3e7b149b2189af
The libcmd unit test creates files (more specifically, the fetcher cache) in
its home directory. In the single-user sandbox, this leads to the creation of
/homeless-shelter, since this is the default HOME and the root is writable.
Unfortunately, this conflicts with the assumption of the functional tests that
this directory does not exist. Use a different home directory to prevent these
test failures, and thus restore the ability to build inside the single-user
sandbox.
Fixes: #365
Change-Id: I4df8c53d043234b95a7c0ac45fc5ee89e8d46aff
They are enabled by default, and Meson will also prints whether or not
they're enabled at the bottom at the end of configuration.
Change-Id: I48db238510bf9e74340b86f243f4bbe360794281
This causes libstore, libexpr, libfetchers, and libutil to be linked
with -Wl,--whole-archive to executables, when building statically.
libstore for the store backends, libexpr for the primops, libfetchers
for the fetcher backends I assume(?), and libutil for the nix::logger
initializer (which notably shows in pre-main constructors when HOME is
not owned by the user. cursed.).
This workaround should be removed when #359 is fixed.
Fixes#306.
Change-Id: Ie9ef0154e09a6ed97920ee8ab23810ca5e2de84c
It seems like someone implemented precompiled headers a long time ago
and then it never got ported to meson or maybe didn't work at all.
This is, however, blessedly easy to simply implement. I went looking for
`#define` that could affect the result of precompiling the headers, and
as far as I can tell we aren't doing any of that, so this should truly
just be free build time savings.
Previous state:
Compilation (551 times):
Parsing (frontend): 1302.1 s
Codegen & opts (backend): 956.3 s
New state:
**** Time summary:
Compilation (567 times):
Parsing (frontend): 1123.0 s
Codegen & opts (backend): 1078.1 s
I wonder if the "regression" in codegen time is just doing the PCH
operation a few times, because meson does it per-target.
Change-Id: I664366b8069bab4851308b3a7571bea97ac64022
This reverts commit 285bc67318.
Reason for revert: #364
For some reason this broke `main` even though the change we are reverting passed CI! Mysterious, haunted, etc. Needs more debugging, let's turn it off for now.
Change-Id: Ica4819d61cd35b83eb52985bfcb657e858f025a9
* changes:
util.hh: Delete remaining file and clean up headers
util.hh: Move nativeSystem to local-derivation-goal.cc
util.hh: Move stuff to types.hh
util.cc: Delete remaining file
util.{hh,cc}: Move ignoreException to error.{hh,cc}
util.{hh,cc}: Split out namespaces.{hh,cc}
util.{hh,cc}: Split out users.{hh,cc}
util.{hh,cc}: Split out strings.{hh,cc}
util.{hh,cc}: Split out unix-domain-socket.{hh,cc}
util.{hh,cc}: Split out child.{hh,cc}
util.{hh,cc}: Split out current-process.{hh,cc}
util.{hh,cc}: Split out processes.{hh,cc}
util.{hh,cc}: Split out file-descriptor.{hh,cc}
util.{hh,cc}: Split out file-system.{hh,cc}
util.{hh,cc}: Split out terminal.{hh,cc}
util.{hh,cc}: Split out environment-variables.{hh,cc}
while refactoring the curl wrapper we inadvertently broken the immutable
flake protocol, because the immutable flake protocol accumulates headers
across the entire redirect chain instead of using only the headers given
in the final response of the chain. this is a problem because Some Known
Providers Of Flake Infrastructure set rel=immutable link headers only in
the penultimate entry of the redirect chain, and curl does not regard it
as worth returning to us via its response header enumeration mechanisms.
fixes #358
Change-Id: I645c3932b465cde848bd6a3565925a1e3cbcdda0
* changes:
docs: linkify nix3-build mention in nix-build.md
build: make internal-api-docs PHONY
cleanup lookupFileArg
add docstring to lookupFileArg
add libcmd test for lookupFileArg
This breaks downstreams linking to us on purpose to make sure that if
someone is linking to Lix they're doing it on purpose and crucially not
mixing up Nix and Lix versions in compatibility code.
We still need to fix the internal includes to follow the same schema so
we can drop the single-level include system entirely. However, this
requires a little more effort.
This adds pkg-config for libfetchers and config.h.
Migration path:
expr.hh -> lix/libexpr/expr.hh
nix/config.h -> lix/config.h
To apply this migration automatically, remove all `<nix/>` from
includes, so: `#include <nix/expr.hh>` -> `#include <expr.hh>`. Then,
the correct paths will be resolved from the tangled mess, and the
clang-tidy automated fix will work.
Then run the following for out of tree projects:
```
lix_root=$HOME/lix
(cd $lix_root/clang-tidy && nix develop -c 'meson setup build && ninja -C build')
run-clang-tidy -checks='-*,lix-fixincludes' -load=$lix_root/clang-tidy/build/liblix-clang-tidy.so -p build/ -fix src
```
Related: lix-project/nix-eval-jobs#5
Fixes: #279
Change-Id: I7498e903afa6850a731ef8ce77a70da6b2b46966
Example: /nix/store/dr53sp25hyfsnzjpm8mh3r3y36vrw3ng-neovim-0.9.5^out
This is nonsensical since selecting outputs can only be done for a
buildable derivation, not for a realised store path. The build worker
side of things ends up crashing with an assertion when trying to handle
such malformed paths.
Change-Id: Ia3587c71fe3da5bea45d4e506e1be4dd62291ddf
Very basic behavior test to ensure that gzip data gets internally
decompressed by the file transfer pipeline.
Change a std::string_view return value in the test harness to
std::string. I wouldn't call myself a C++ beginner and I still managed
to shoot myself in the foot like three times with the lifetime
managements there (e.g. [&] { return an_std_string; } ends up with a
dangling string_view!).
Change-Id: I1360750d4181ce1ca2a3aa4dc0e97e131351c469
also add a few more tests for exception propagation behavior. using
packaged_tasks and futures (which only allow a single call to a few
of their methods) introduces error paths that weren't there before.
Change-Id: I42ca5236f156fefec17df972f6e9be45989cf805
only two users of this function exist. only one used it in a way that
even bears resemblance to asynchronicity, and even that one didn't do
it right. fully async and parallel computation would have only worked
if any getEdgesAsync never calls the continuation it receives itself,
only from more derived callbacks running on other threads. calling it
directly would cause the decoupling promise to be awaited immediately
*on the original thread*, completely negating all nice async effects.
Change-Id: I0aa640950cf327533a32dee410105efdabb448df
not doing this will cause transfers that had their readers disappear to
linger. with lingering transfers the curl thread can't shut down, which
will cause nix itself to not shut down until the transfer finishes some
other way (most likely network timeouts). also add a new test for this.
Change-Id: Id2401b3ac85731c824db05918d4079125be25b57
this is used in CA rewriting, replacement of placeholders in
derivations, generating scripts for devShells, and some more
places. in all of these transitive replacements are unsound,
and overlapping replacements would be as well. there even is
a test that transitive replacements do not happen (in the CA
RewriteSink suite), but none for overlapping replacements. a
minimally surprising binary rewriter surely would not do any
of these replacements, the only reason we have not seen this
break yet is probably that rewriteStrings is only called for
store paths and things that look like store paths (and those
should never overlap nor admit such transitive replacements)
Change-Id: I6fc29f939d5061d9f56c752624a823ece8437c07
* changes:
nix3-profile: remove check "name" attr in manifests
Add profile migration test
nix3-profile: make element names stable
getNameFromURL(): Support uppercase characters in attribute names
nix3-profile: remove indices
nix3-profile: allow using human-readable names to select packages
implement parsing human-readable names from URLs
As discussed in the maintainer meeting on 2024-01-29.
Mainly this is to avoid a situation where the name is parsed and
treated as a file name, mostly to protect users.
.-* and ..-* are also considered invalid because they might strip
on that separator to remove versions. Doesn't really work, but that's
what we decided, and I won't argue with it, because .-* probably
doesn't seem to have a real world application anyway.
We do still permit a 1-character name that's just "-", which still
poses a similar risk in such a situation. We can't start disallowing
trailing -, because a non-zero number of users will need it and we've
seen how annoying and painful such a change is.
What matters most is preventing a situation where . or .. can be
injected, and to just get this done.
(cherry picked from commit f1b4663805a9dbcb1ace64ec110092d17c9155e0)
Change-Id: I900a8509933cee662f888c3c76fa8986b0058839
Gen::just is the constant generator. Don't just return that!
(cherry picked from commit 8406da28773f050e00a006e4812e3ecbf919a2a9)
Change-Id: Ibfd0bd40f90942077a4720086ce0cd3bfabef79d
Gen: :just is the constant generator. Don't just return that!
(cherry picked from commit 69bbd5852af9b2f0b794162bd1debcdf64fc6648)
Change-Id: Id6e58141f5a42a1f67bd11d48c87b32a3ebd0500
- Use a recursive descent parser so that it's easy to extend.
- Add `@args` to enable customizing command-line arguments
- Add `@should-start` to enable `nix repl` tests that error before
entering the REPL
- Make sure to read all stdout output before comparing. This catches
some extra output we were tossing out before!
Change-Id: I5522555df4c313024ab15cd10f9f04e7293bda3a
this was never actually used, and bad design in the first place—why
should a bad resource be put back into the idle pool? just drop it.
Change-Id: Idab8774bee19dadae0209d404c4fb86dd4aeba1e
if a scope owning a resource does not gracefully drop that resource
while handling exceptions from deeper down the call stack we should
assume the resource is invalid state and drop it. currently it *is*
true that such cases do not cause resources to be freed, but thanks
to validator misuses this has so far not caused any larger problem.
Change-Id: Ie4f91bcd60a64d05c5ff9d22cc97954816d13b97
The big ones here are `trim-trailing-whitespace` and `end-of-file-fixer`
(which makes sure that every file ends with exactly one newline
character).
Change-Id: Idca73b640883188f068f9903e013cf0d82aa1123
* some things that can throw are marked noexcept
yet the linter seems to think not. Maybe they can't throw in practice.
I would rather not have the UB possibility in pretty obvious cold
paths.
* various default-case-missing complaints
* a fair pile of casts from integer to character, which are in fact
deliberate.
* an instance of <https://clang.llvm.org/extra/clang-tidy/checks/bugprone/move-forwarding-reference.html>
* bugprone-not-null-terminated-result on handing a string to curl in
chunks of bytes. our usage is fine.
* reassigning a unique_ptr by CRIMES instead of using release(), then
using release() and ignoring the result. wild. let's use release() for
its intended purpose.
Change-Id: Ic3e7affef12383576213a8a7c8145c27e662513d
Without this, the Meson setup won't bail out if nlohmann_json is
missing, leading to subpar DX (and maybe worse, but I'm not entirely
sure).
Change-Id: I5913111060226b540dcf003257c99a08e84da0de
This was achieved by running maintainers/buildtime_report.sh on the
build directory of a meson build, then asking "why the heck is json
eating our build times", and strategically moving the json using bits
out of widely included headers.
It turns out that putting literally any metrics whatsoever into the
build had immediate and predictable results.
Results are 1382.5s frontend time -> 1175.4s frontend time, back end
time approximately invariant.
Related: #159
Change-Id: I7edea95c8536203325c8bb4dae5f32d727a21b2d
Unit tests can be run with `meson test -C build --suite check`.
`--suite check` is optional, as right now that's the only test suite,
but when functional tests are added those will be in a separate suite.
Change-Id: I7f22f1cde4b489b3cdb5f9a36a544f0c409fcc1f
we now keep not a table of all positions, but a table of all origins and
their sizes. position indices are now direct pointers into the virtual
concatenation of all parsed contents. this slightly reduces memory usage
and time spent in the parser, at the cost of not being able to report
positions if the total input size exceeds 4GiB. this limit is not unique
to nix though, rustc and clang also limit their input to 4GiB (although
at least clang refuses to process inputs that are larger, we will not).
this new 4GiB limit probably will not cause any problems for quite a
while, all of nixpkgs together is less than 100MiB in size and already
needs over 700MiB of memory and multiple seconds just to parse. 4GiB
worth of input will easily take multiple minutes and over 30GiB of
memory without even evaluating anything. if problems *do* arise we can
probably recover the old table-based system by adding some tracking to
Pos::Origin (or increasing the size of PosIdx outright), but for time
being this looks like more complexity than it's worth.
since we now need to read the entire input again to determine the
line/column of a position we'll make unsafeGetAttrPos slightly lazy:
mostly the set it returns is only used to determine the file of origin
of an attribute, not its exact location. the thunks do not add
measurable runtime overhead.
notably this change is necessary to allow changing the parser since
apparently nothing supports nix's very idiosyncratic line ending choice
of "anything goes", making it very hard to calculate line/column
positions in the parser (while byte offsets are very easy).
(cherry picked from commit 5d9fdab3de0ee17c71369ad05806b9ea06dfceda)
Change-Id: Ie0b2430cb120c09097afa8c0101884d94f4bbf34
These now have equivalents in the standard lib in C++20. This change was
performed with a custom clang-tidy check which I will submit later.
Executed like so:
ninja -C build && run-clang-tidy -checks='-*,nix-*' -load=build/libnix-clang-tidy.so -p .. -fix ../tests | tee -a clang-tidy-result
Change-Id: I62679e315ff9e7ce72a40b91b79c3e9fc01b27e9
This builtin is only going to cause us problems because we are not Nix,
so let's just falsify being in the 2.18 series, since that is the
closest target that has any meaning.
In future we might want to have a better feature detection mechanism,
for when we actually add stuff to some builtin's attr set argument. But
builtins.nixVersion is just going to be hopelessly broken and it should
be stubbed out.
Fixes #144
Change-Id: Id7390b32a29c6147f2977737d81846320de5d67e
this lets us set per-test-program environment variables rather than only
a single, global default. this was supported in nix originally but
might've gone partially missing in the upstream backports process?
Change-Id: Iad0919841b1b6d11e0b7ebd3920449a62f544e77
This has some Flaws for sure (like, it is going to be a bit stretched to
use for repl characterization), but it is a start.
Change-Id: I258c8beb3aee236f45818a03be83bcda858120c9
Pretty-print values in the REPL by printing each item in a list or
attrset on a separate line. When possible, single-item lists and
attrsets are printed on one line, as long as they don't contain a nested
list, attrset, or thunk.
Before:
```
{ attrs = { a = { b = { c = { }; }; }; }; list = [ 1 ]; list' = [ 1 2 3 ]; }
```
After:
```
{
attrs = {
a = {
b = {
c = { };
};
};
};
list = [ 1 ];
list' = [
1
2
3
];
}
```
(cherry picked from commit c0a15fb7d03dfb8f53bc6726c414bc88aa362592)
Change-Id: Ia2b41849165a5ddb63f7a8c272a2476b3e4292df
While preparing PRs like #9753, I've had to change error messages in
dozens of code paths. It would be nice if instead of
EvalError("expected 'boolean' but found '%1%'", showType(v))
we could write
TypeError(v, "boolean")
or similar. Then, changing the error message could be a mechanical
refactor with the compiler pointing out places the constructor needs to
be changed, rather than the error-prone process of grepping through the
codebase. Structured errors would also help prevent the "same" error
from having multiple slightly different messages, and could be a first
step towards error codes / an error index.
This PR reworks the exception infrastructure in `libexpr` to
support exception types with different constructor signatures than
`BaseError`. Actually refactoring the exceptions to use structured data
will come in a future PR (this one is big enough already, as it has to
touch every exception in `libexpr`).
The core design is in `eval-error.hh`. Generally, errors like this:
state.error("'%s' is not a string", getAttrPathStr())
.debugThrow<TypeError>()
are transformed like this:
state.error<TypeError>("'%s' is not a string", getAttrPathStr())
.debugThrow()
The type annotation has moved from `ErrorBuilder::debugThrow` to
`EvalState::error`.
(cherry picked from commit c6a89c1a1659b31694c0fbcd21d78a6dd521c732)
Change-Id: Iced91ba4e00ca9e801518071fb43798936cbd05a
Don't print the first bracket in values in magenta in error messages
(cherry picked from commit 46a0625a40aef6946a35f92fdacf0e6b4a14414f)
Change-Id: I8435565c87db182116140eaeea9df1243e67ea94
Print the value in `error: cannot coerce` messages
(cherry picked from commit 5b7bfd2d6b89d7dd5f54c1ca6c8072358d31a84e)
===
test taken from 6e8d5983143ae576e3f4b1d2954a5267f2943a49; it was added
previously (and not backported because its pr was a mostly-revert), but
it's useful to have around.
Change-Id: Icbd14b55e3610ce7b774667bf14b82e6dc717982
libexpr: print value of what is attempted to be called as function
(cherry picked from commit 50e5d7b883042852538371237e32a66bb22f0485)
Change-Id: I7cb6290bd8f244e83bfce3b2eed2a4c8b4f16a83
Print the value in `value is X while a Y is expected` error
(cherry picked from commit 5f72a97092da6af28a7d2b2a50d74e9d34fae7e1)
Change-Id: Idb4bc903ae59a0f5b6fb3b1da4d47970fe0a6efe
Previously, there were two mostly-identical value printers -- one in
`libexpr/eval.cc` (which didn't force values) and one in
`libcmd/repl.cc` (which did force values and also printed ANSI color
codes).
This PR unifies both of these printers into `print.cc` and provides a
`PrintOptions` struct for controlling the output, which allows for
toggling whether values are forced, whether repeated values are tracked,
and whether ANSI color codes are displayed.
Additionally, `PrintOptions` allows tuning the maximum number of
attributes, list items, and bytes in a string that will be displayed;
this makes it ideal for contexts where printing too much output (e.g.
all of Nixpkgs) is distracting. (As requested by @roberth in
https://github.com/NixOS/nix/pull/9554#issuecomment-1845095735)
Please read the tests for example output.
Future work:
- It would be nice to provide this function as a builtin, perhaps
`builtins.toStringDebug` -- a printing function that never fails would
be useful when debugging Nix code.
- It would be nice to support customizing `PrintOptions` members on the
command line, e.g. `--option to-string-max-attrs 1000`.
(cherry picked from commit 0fa08b451682fb3311fe58112ff05c4fe5bee3a4, )
===
Restore ambiguous value printer for `nix-instantiate`
The Nix team has requested that this output format remain unchanged.
I've added a warning to the man page explaining that `nix-instantiate
--eval` output will not parse correctly in many situations.
(cherry picked from commit df84dd4d8dd3fd6381ac2ca3064432ab31a16b79)
Change-Id: I7cca6b4b53cd0642f2d49af657d5676a8554c9f8
Factor out `ServeProto::Serialiser<UnkeyedValidPathInfo>` and test
(cherry picked from commit 139982997eec493a0f74105c427953f6be77da6d)
Change-Id: I28e4ba5a681a90d81915a56e6dbaa5456d64f96d
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