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1994 commits

Author SHA1 Message Date
Qyriad b913a939b0 meson: flip the switch!!
This commit makes Meson the default buildsystem for Lix.
The Make buildsystem is now deprecated and will be removed soon, but has
not yet, which will be done in a later commit when all seems good. The
mesonBuild jobs have been removed, and have not been replaced with
equivalent jobs to ensure the Make buildsystem still works.

The full, new commands in a development shell are:

$ meson setup ./build "--prefix=$out" $mesonFlags

(A simple `meson setup ./build` will also build, but will do a different
thing, not having the settings from package.nix applied.)

$ meson compile -C build
$ meson test -C build --suite=check
$ meson install -C build
$ meson test -C build --suite=installcheck

(Check and installcheck may both be done after install, allowing you to
omit the --suite argument entirely, but this is the order package.nix
runs them in.)

If tests fail and Meson helpfully has no output for why, use the
`--print-error-logs` option to `meson test`. Why this is not the default
I cannot explain.

If you change a setting in the buildsystem, most cases will
automatically regenerate the Meson configuration, but some cases, like
trying to build a specific target whose name is new to the buildsystem
(e.g. `meson compile -C build src/libmelt/libmelt.dylib`, when
`libmelt.dylib` did not exist as a target the last time the buildsystem
was generated), then you can reconfigure using new settings but
existing options, and only recompiling stuff affected by the changes:

$ meson setup --reconfigure build

Note that changes to the default values in `meson.options` or in the
`default_options :` argument to project() are NOT propagated with
`--reconfigure`.

If you want a totally clean build, you can use:

$ meson setup --wipe build

That will work regardless of if `./build` exists or not.

Specific, named targets may be addressed in
`meson build -C build <target>` with the "target ID" if there is one,
which is the first string argument passed to target functions that
have one, and unrelated to the variable name, e.g.:

libexpr_dylib = library('nixexpr', …)

can be addressed with:

$ meson compile -C build nixexpr

All targets may be addressed as their output, relative to the build
directory, e.g.:

$ meson compile -C build src/libexpr/libnixexpr.so

But Meson does not consider intermediate files like object files
targets. To build a specific object file, use Ninja directly and
specify the output file relative to the build directory:

$ ninja -C build src/libexpr/libnixexpr.so.p/nixexpr.cc.o

To inspect the canonical source of truth on what the state of the
buildsystem configuration is, use:

$ meson introspect

Have fun!

Change-Id: Ia3e7b1e6fae26daf3162e655b4ded611a5cd57ad
2024-04-22 21:41:58 -06:00
eldritch horrors adab839c98 manual: build docs with dummy envs
this was previously used because the macOS docs build would otherwise
pull files out of the host nix store. or something. not sure about it

Change-Id: I76b51eac1ebc5de5f00e2e4be086dd8db3eeb8e6
2024-04-11 13:36:04 +00:00
eldritch horrors 725f5cd358 docs: redo content generation for mdbook and manual
manpages can be rendered using the markdown output of mdbook, the rest
of the manual can generated out of the main doc/manual source tree. we
still use lowdown to actually render manpages instead of eg mdbook-man
because lowdown does generate reasonably good manpages (though that is
also somewhat debatable, but they're a lot better than mdbook-man).

doing this not only lets us drastically simplify the lowdown pipeline,
but also remove all custom {{#include}} handling since now mdbook does
all of it, even for the manpage builds. even the lowdown wrapper isn't
entirely necessary because lowdown can take all wrapper arguments with
command line flags rather than bits of input file content.

This also implements running mdbook in Meson, in order to generate the
manpages. The mdbook outputs are also installed in the usual location.

Co-authored-by: Qyriad <qyriad@qyriad.me>

Change-Id: I60193f9fd0f15d48872f071af35855cda2a0f40b
2024-04-11 13:32:06 +00:00
Rebecca Turner 99845e0e01 Merge "Print top-level errors normally in nix repl" into main 2024-04-10 15:40:03 +00:00
Qyriad 723ddadf92 docs: generalize manpage generation script as json-to-tree.py
This should be capable of replacing every invocation of
nix eval --write-to.

Change-Id: I60387bc9b0fc54a91244eddb639beaa64d705878
2024-04-10 15:04:34 +02:00
Rebecca Turner 9e7e927837 Print top-level errors normally in nix repl
Previously, errors while printing values in `nix repl` would be printed
in `«error: ...»` brackets rather than displayed normally:

```
nix-repl> legacyPackages.aarch64-darwin.pythonPackages.APScheduler
«error: Package ‘python-2.7.18.7’ in /nix/store/6s0m1qc31zw3l3kq0q4wd5cp3lqpkq0q-source/pkgs/development/interpreters/python/cpython/2.7/default.nix:335 is marked as insecure, refusing to evaluate.»
```

Now, errors will be displayed normally if they're emitted at the
top-level of an expression:

```
nix-repl> legacyPackages.aarch64-darwin.pythonPackages.APScheduler
error:
       … in the condition of the assert statement
         at /nix/store/6s0m1qc31zw3l3kq0q4wd5cp3lqpkq0q-source/lib/customisation.nix:268:17:
          267|     in commonAttrs // {
          268|       drvPath = assert condition; drv.drvPath;
             |                 ^
          269|       outPath = assert condition; drv.outPath;

       … in the left operand of the OR (||) operator
         at /nix/store/6s0m1qc31zw3l3kq0q4wd5cp3lqpkq0q-source/pkgs/development/interpreters/python/passthrufun.nix:28:45:
           27|         if lib.isDerivation value then
           28|           lib.extendDerivation (valid value || throw "${name} should use `buildPythonPackage` or `toPythonModule` if it is to be part of the Python packages set.") {} value
             |                                             ^
           29|         else

       (stack trace truncated; use '--show-trace' to show the full trace)

       error: Package ‘python-2.7.18.7’ in /nix/store/6s0m1qc31zw3l3kq0q4wd5cp3lqpkq0q-source/pkgs/development/interpreters/python/cpython/2.7/default.nix:335 is marked as insecure, refusing to evaluate.
```

Errors emitted in nested structures (like e.g. when printing `nixpkgs`)
will still be printed in brackets.

Change-Id: I25aeddf08c017582718cb9772a677bf51b9fc2ad
2024-04-09 08:34:40 -07:00
Rebecca Turner a95c62673b Merge "Add repl-overlays" into main 2024-04-09 05:29:48 +00:00
eldritch horrors e6aab36d60 docs: put the manual build into a known tmpdir
this isn't strictly necessary, but it'll make it a lot easier to put the
generated files used by the autoconf build system in this directory too.
doing this now already will make the meson transition a lot easier later

Change-Id: I5fb39eade2ff88b6093c9ee436c9e8db793e9448
2024-04-09 02:09:36 +00:00
eldritch horrors c1ae35d34a docs: don't compute SUMMARY.md during build
this would make meson build compatibility unnecessarily hard and
the cli does not change often enough to justify this complexity.

Change-Id: I17b1870cdf8538feeaa01a9945db97af2175a642
2024-04-09 02:09:36 +00:00
eldritch horrors d9bc197ff4 docs: don't compute rl-next.md during build
not sure why this was done the way it was considering that includes are
a feature the doc toolchain had previously. let's just always have some
kind of entry for the upcoming release in the dev manual builds even if
that means having a completely empty release notes chapter.

the release notes generation script isn't entirely functional right now
due to pre-commit hooks, but it's good enough for time being. we need a
better release process for notes anyway.

Change-Id: Ifda6912cf5233db013f72a30247a62d6f22b1565

Change-Id: I9eb347ec4aabc5be2b816ff0fd3e4be45f93b934
2024-04-09 02:09:36 +00:00
eldritch horrors 07ef9f9f5d docs: skip do custom include processing for mdbook
mdbook already does include processing of its own, and the custom
processing code has always admitted as much. we don't need it for
the mdbook build at this point if we run our preprocessors in the
right order, and maybe we can even have mdbook to return complete
pages to us that we only have to pass to lowdown without any more
preprocessing of our own.

Change-Id: Icd978acbc3b1e215fee8f062c53ab2cb2a222ab1
2024-04-09 02:09:36 +00:00
eldritch horrors 14088e1ec5 docs: remove many link-to-self
for some reason these three were anchors, not links, but had they been
links they wouldn't've worked because they're not defined anywhere but
here. in the print version of the manual they're duplicated many times
over (creating id collisions), so we should better remove them anyway.

Change-Id: I8988a7c32c812dee0f0b6d4953faa7cd1255228d
2024-04-09 02:09:36 +00:00
Rebecca Turner 727b43478c Add repl-overlays
Adds a `repl-overlays` option, which specifies files that can overlay
and modify the top-level bindings in `nix repl`. For example, with the
following contents in `~/.config/nix/repl.nix`:

    info: final: prev: let
      optionalAttrs = predicate: attrs:
        if predicate
        then attrs
        else {};
    in
      optionalAttrs (prev ? legacyPackages && prev.legacyPackages ? ${info.currentSystem})
      {
        pkgs = prev.legacyPackages.${info.currentSystem};
      }

We can run `nix repl` and use `pkgs` to refer to `legacyPackages.${currentSystem}`:

    $ nix repl --repl-overlays ~/.config/nix/repl.nix nixpkgs
    Lix 2.90.0
    Type :? for help.
    Loading installable 'flake:nixpkgs#'...
    Added 5 variables.
    Loading 'repl-overlays'...
    Added 6 variables.
    nix-repl> pkgs.bash
    «derivation /nix/store/g08b5vkwwh0j8ic9rkmd8mpj878rk62z-bash-5.2p26.drv»

Change-Id: Ic12e0f2f210b2f46e920c33088dfe1083f42391a
2024-04-08 17:11:47 -07:00
jade 0d37b99a15 build: enable libstdc++ assertions
Benchmarks say that it does not regress performance by more than 1%
(which is where it gets really hard to measure accurately anyhow).

Meson appears to be planning to do this for us without asking us in a
release we will get in the future, and it seems good enough to ship
today:
https://mesonbuild.com/Release-notes-for-1-4-0.html#ndebug-setting-now-controls-c-stdlib-assertions

Benchmarks:

| Command | Mean [ms] | Min [ms] | Max [ms] | Relative |
|:---|---:|---:|---:|---:|
| `result-asserts/bin/nix --extra-experimental-features 'nix-command flakes' eval -f ../nixpkgs/pkgs/development/haskell-modules/hackage-packages.nix` | 418.4 ± 25.0 | 396.9 | 451.2 | 1.01 ± 0.08 |
| `result/bin/nix --extra-experimental-features 'nix-command flakes' eval -f ../nixpkgs/pkgs/development/haskell-modules/hackage-packages.nix` | 416.1 ± 23.9 | 397.1 | 445.4 | 1.00 |

| Command | Mean [s] | Min [s] | Max [s] | Relative |
|:---|---:|---:|---:|---:|
| `GC_INITIAL_HEAP_SIZE=10g result-asserts/bin/nix eval --extra-experimental-features 'nix-command flakes' --raw --impure --expr 'with import <nixpkgs/nixos> {}; system'` | 4.147 ± 0.021 | 4.123 | 4.195 | 1.00 |
| `GC_INITIAL_HEAP_SIZE=10g result/bin/nix eval --extra-experimental-features 'nix-command flakes' --raw --impure --expr 'with import <nixpkgs/nixos> {}; system'` | 4.149 ± 0.027 | 4.126 | 4.215 | 1.00 ± 0.01 |

| Command | Mean [s] | Min [s] | Max [s] | Relative |
|:---|---:|---:|---:|---:|
| `result-asserts/bin/nix --extra-experimental-features 'nix-command flakes' eval --raw --impure --expr 'with import <nixpkgs/nixos> {}; system'` | 5.838 ± 0.023 | 5.799 | 5.867 | 1.01 ± 0.01 |
| `result/bin/nix --extra-experimental-features 'nix-command flakes' eval --raw --impure --expr 'with import <nixpkgs/nixos> {}; system'` | 5.788 ± 0.044 | 5.715 | 5.876 | 1.00 |

| Command | Mean [s] | Min [s] | Max [s] | Relative |
|:---|---:|---:|---:|---:|
| `result-asserts/bin/nix --extra-experimental-features 'nix-command flakes' search --no-eval-cache github:nixos/nixpkgs/e1fa12d4f6c6fe19ccb59cac54b5b3f25e160870 hello` | 15.993 ± 0.081 | 15.829 | 16.096 | 1.01 ± 0.01 |
| `result/bin/nix --extra-experimental-features 'nix-command flakes' search --no-eval-cache github:nixos/nixpkgs/e1fa12d4f6c6fe19ccb59cac54b5b3f25e160870 hello` | 15.897 ± 0.075 | 15.807 | 16.047 | 1.00 |

Fixes: lix-project/lix#4

Change-Id: Id3a6f38274ba94d5d10b09edd19dfd96bc3e7d5f
2024-04-08 15:40:12 -07:00
Rebecca Turner cfbcf12276 Format Nix code with nixfmt
Change-Id: I61efeb666ff7481c05fcb247168290e86a250151
2024-04-08 13:00:00 -07:00
Qyriad 5bac308c7c meson: fix warm nix3 CLI manual generation
`nix eval --write-to` refuses to write to a directory that exists at
all, so now we generate in a temporary directory, and copy the generated
tree to the build directory. This is equivalent to what the Make
buildsystem did, actually, but hopefully more robust.

Future work: documenting the doc generation architecture in the
top-level meson.build outline comment.

Change-Id: Ic3eb6d26e3cc249a1c042fd3ced22d637ac66a69
2024-04-06 14:43:14 -06:00
Qyriad a4ef195a9f always re-eval cached failures
This is terrible UX, and frankly an eval failure should be a cache
invalidation anyway.

This removes the CachedEvalError type entirely.

Fixes #223.

Change-Id: I91f8003eabd0ea45003024e96d1de3c7ae8e49d8
2024-04-06 04:35:25 +00:00
Qyriad c355354772 docs: replace sed invocation with an mdbook preprocessor for @docroot@
We're not entirely clear on why the links preprocessor has to be done
*before* rather than after, but we assume it is probably that as a
builtin preprocessor it does some processing on the raw book source,
and not just the JSON data.

Also a real use for Python pattern matching? I know I was surprised too.

Change-Id: Ibe8b59e7b5bd5f357a655d8b4c5f0b0f58a67d6b
2024-04-04 21:43:19 +00:00
Qyriad 9166babbaf Revert "meson: move nix3 manpage generation into command-ref/"
This reverts commit 70954233743a233744787103d3211237a28ddbca.

This seems to have broken running ninja on warm build directories, which
is not what we want. Reverted until we figure out something better

Change-Id: I9623ae078917e7c59a930bf8044a216501d4bb20
2024-04-04 11:59:08 -06:00
Qyriad c263554ec6 Merge "meson: move nix3 manpage generation into command-ref/" into main 2024-04-03 21:34:27 +00:00
Qyriad c96c5db030 meson: move nix3 manpage generation into command-ref/
This puts the generated files where they are for the make system.
This is in preparation for further meson-mdbook stuff.

Change-Id: I934df6854a80af5ccf381cf1da0bda0187a8bcfc
2024-04-03 13:52:56 -06:00
Lunaphied 7a1054fa5f repl: improve :doc builtin repl command to support lambdas.
For a long time `nix repl` has supported displaying documentation set on
builtins, however, it has long been convention to use Markdown comments
on Nix functions themselves for documentation. This exposes that
information to `nix repl` users in a nice and formatted way.

NixOS/rfcs#145 doc-comments are primarily what this feature is intended
to consume, however, support for lambda documentation in the repl is
experimental. We do our best effort to support the RFC here.

These changes are based on [the nix-doc library](https://github.com/lf-/nix-doc) and
are licensed under the terms described in the relevant source files.

Change-Id: Ic6fe947d39a22540705d890737e336c4720b0a22
2024-04-03 13:47:22 -06:00
eldritch horrors d2aca15f31 doc: remove the -- unescaping hack
lowdown has an option to disable this behavior. use it.

Change-Id: I06d4201b7f528021ddb8e94ac6baff385402e080
2024-04-01 20:15:28 +00:00
Théophane Hufschmitt 6c29016a09 Merge pull request #9920 from 9999years/forbid-nested-debuggers
Forbid nested debuggers

(cherry picked from commit e164b39ee90fd655dbb7f479fdd4fbe38cc883bd)
Change-Id: Iff62f40fd251116516a63e2d3f9fb5b21480b16d
2024-03-31 17:28:25 +00:00
Rebecca Turner 4b730f328e Merge "Add pre-commit checks" into main 2024-03-30 22:26:59 +00:00
eldritch horrors 351c1a9c52 meson: build and install nix3 manpages
this notably does *not* install the `nix3-manpages` manpage the old
system generated, mostly because that page was empty and just a bug
with a coat of documentation paint.

Change-Id: I7a4248a72e7bb5e0cc925a6311a33b6b72589569
2024-03-30 14:26:47 +00:00
eldritch horrors bfbcc3352b meson: add manpages for old cli and config files
Change-Id: I93384ec774d1945a649f6aaf7cd967c3fb7197f9
2024-03-30 14:26:47 +00:00
eldritch horrors 65d544b1a6 build: extract make "functions" into scripts
we'll want to use these for the meson builds, and probably eventually
rewrite them in something that isn't plain shell. diffoscope confirms
that out/share and doc/share are equal before and after these changes

Change-Id: I49aa418fc8615cad86d67328e08c28a7405ec952
2024-03-30 14:26:47 +00:00
Rebecca Turner 2a98ba8b97 Add pre-commit checks
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
2024-03-29 22:57:40 -07:00
Winter Cute 80405d0626 Stop vendoring toml11
We don't apply any patches to it, and vendoring it locks users into
bugs (it hasn't been updated since its introduction in late 2021).

Closes lix-project/lix#164

Change-Id: Ied071c841fc30b0dfb575151afd1e7f66970fdb9
2024-03-27 21:04:00 -04:00
jade 412a9c9f67 Enable clang build timing analysis
I didn't enable this by default for clang due to making the build time
10% worse or so. Unfortunate, but tbh devs for whom 10% of build time is
not *that* bad should probably simply enable this.

Change-Id: I8d1e5b6f3f76c649a4e2f115f534f7f97cee46e6
2024-03-27 03:52:57 +00:00
eldritch horrors 279e30e7ef build: replace changelog-d with local script
hacking changelog-d to support not just github but also forgejo and
gerrit is a lot more complicated than it's worth, even moreso since
the entire thing can just as well be done with ~60 lines of python.
this new script is also much cheaper to instantiate (being python),
so having it enabled in all shells is far less of a hassle.

we've also adjusted existing release notes that referenced a gerrit
cl to auto-link to the cl in question, making the diff a bit bigger

closes lix-project/lix#176

Change-Id: I8ba7dd0070aad9ba4474401731215fcf5d9d2130
2024-03-27 03:09:14 +00:00
eldritch horrors 8fd02df90d manual: fix release notes
fix key spelling errors, type errors, things-should-not-be-comments errors

Change-Id: I3ce12873aa78002bca686bd88404771895b05d30
2024-03-27 03:09:14 +00:00
Théophane Hufschmitt 86881226b0 Merge pull request #8817 from iFreilicht/flake-update-lock-overhaul
Overhaul `nix flake update` and `nix flake lock` UX

(cherry picked from commit 12a0ae73dbb37becefa5a442eb4532ff0de9ce65)
Change-Id: Iff3b4f4235ebb1948ec612036b39ab29e4ca22b2
2024-03-25 17:36:24 -06:00
Lunaphied 185ecf1f45 Improve new CLI UX by supporting short -E flag for --expr
Change-Id: I55881c846da8416a92a14deedfa5bbbf09a122fb
2024-03-24 21:17:51 -06:00
jade 5a28d70d1e Merge "un-ups your start" into main 2024-03-19 14:29:57 -06:00
jade 985bd5eb9f un-ups your start
We do not need upstart, it is so thoroughly obsolete that we should not
care about supporting it.

Change-Id: Ie0ca084740845555fddffacc899cd129c9a4c1fe
2024-03-18 18:28:08 -07:00
jade 20b4a97af3 Release notes for builtins.nixVersion change
Change-Id: I72c945cab464d26d73f5594ef0a4bb2184545da4
2024-03-18 18:26:52 -07:00
eldritch horrors 9cf92c012d report inherit attr errors at the duplicate name
previously we reported the error at the beginning of the binding
block (for plain inherits) or the beginning of the attr list (for
inherit-from), effectively hiding where exactly the error happened.

this also carries over to runtime positions of attributes in sets as
reported by unsafeGetAttrPos. we're not worried about this changing
observable eval behavior because it *is* marked unsafe, and the new
behavior is much more useful.

(cherry picked from commit 1edd6fada53553b89847ac3981ac28025857ca02)
Change-Id: I2f50eb9f3dc3977db4eb3e3da96f1cb37ccd5174
2024-03-18 16:12:45 +01:00
eldritch horrors d826427f02 normalize formal order on ExprLambda::show
we already normalize attr order to lexicographic, doing the same for
formals makes sense. doubly so because the order of formals would
otherwise depend on the context of the expression, which is not quite as
useful as one might expect.

(cherry picked from commit 4147ecfb1c51f3fe3b4adcbd4e753fd487dab645)
Change-Id: I3fd0dbdef3ac7447a3a03ff20bb514a0d0f23fb1
2024-03-18 07:56:34 -06:00
eldritch horrors 11f35afa6f diagnose duplicated attrs at correct path
diagnose attr duplication at the path the duplication was detected, not
at the path the current attribute wanted to place. doing the latter is
only correct if a leaf attribute was duplicated, not if an attrpath was
set to a non-attrset in one binding and a (potentially implied) attrset
in another binding.

fixes #124

Change-Id: Ic4aa9cc12a9874d4e7897c6f64408f10aa36fc82
2024-03-16 22:12:49 +01:00
eldritch horrors b667b4cded evaluate inherit (from) exprs only once per directive
desugaring inherit-from to syntactic duplication of the source expr also
duplicates side effects of the source expr (such as trace calls) and
expensive computations (such as derivationStrict).

(cherry picked from commit cefd0302b55b3360dbca59cfcb4bf6a750d6cdcf)
Change-Id: Iff519f991adef2e51683ba2c552d37a3df7a179e
2024-03-10 03:18:32 -06:00
eldritch horrors f2e11ddce1 Merge pull request #9914 from 9999years/debugger-on-trace
Enter debugger on `builtins.trace` with an option

(cherry picked from commit 774e7ca5847ebc392eac2a124a8f12b24da4f65a)
Change-Id: If01e2110b3a128e639b05143227e365227d149f1
2024-03-09 10:17:26 -07:00
eldritch horrors 7673312ccc Merge pull request #9928 from 9999years/error-messages-in-nix-repl
Improve error printing in `nix repl`

(cherry picked from commit a8050d9b83052e4b5c52bf2d116381aedec3a93e)
Change-Id: I588f92d1dd4c546c98788b71403cc034f5e7129a
2024-03-09 03:37:35 -07:00
eldritch horrors 3e1be9c530 Merge pull request #9917 from 9999years/enter-debugger-more-reliably
Enter debugger more reliably in `let` expressions and function calls

(cherry picked from commit c4ed92fa6f836d3d8eb354a48c37a2f9eeecc3aa)
Change-Id: I16d0cad7e898feecd2399723b92ba8df67222fb4
2024-03-09 03:37:35 -07:00
eldritch horrors 609a8e0d94 Merge pull request #9754 from 9999years/print-value-when-coercion-fails
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
2024-03-09 00:05:41 -07:00
eldritch horrors 87e6ac5eb7 Merge pull request #9753 from 9999years/print-value-on-type-error
Print the value in `value is X while a Y is expected` error

(cherry picked from commit 5f72a97092da6af28a7d2b2a50d74e9d34fae7e1)
Change-Id: Idb4bc903ae59a0f5b6fb3b1da4d47970fe0a6efe
2024-03-09 00:05:41 -07:00
eldritch horrors 7e1f8b09a4 Merge pull request #9755 from 9999years/printer-followup
Printer followup

(cherry picked from commit 51f524c629b778b75cb62a9e0c85bae655984abc)
Change-Id: I29214cc86c5e846cbcfec382022293a70011b316
2024-03-09 04:04:46 +01:00
eldritch horrors 512c1f05c3 Unify and refactor value printing
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
2024-03-09 03:50:06 +01:00
eldritch horrors d76125747f Merge changes I03bbff94,I778edad1,Iaa80073b,Ib1d58fe4 into main
* changes:
  Add release notes
  Print how many checks are run
  Print derivation paths
  Log what `nix flake check` does
2024-03-07 18:48:17 -07:00