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402 commits

Author SHA1 Message Date
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
John Ericson 3d065192c0 Overhaul completions, redo #6693 (#8131)
As I complained in
https://github.com/NixOS/nix/pull/6784#issuecomment-1421777030 (a
comment on the wrong PR, sorry again!), #6693 introduced a second
completions mechanism to fix a bug. Having two completion mechanisms
isn't so nice.

As @thufschmitt also pointed out, it was a bummer to go from `FlakeRef`
to `std::string` when collecting flake refs. Now it is `FlakeRefs`
again.

The underlying issue that sought to work around was that completion of
arguments not at the end can still benefit from the information from
latter arguments.

To fix this better, we rip out that change and simply defer all
completion processing until after all the (regular, already-complete)
arguments have been passed.

In addition, I noticed the original completion logic used some global
variables. I do not like global variables, because even if they save
lines of code, they also obfuscate the architecture of the code.

I got rid of them  moved them to a new `RootArgs` class, which now has
`parseCmdline` instead of `Args`. The idea is that we have many argument
parsers from subcommands and what-not, but only one root args that owns
the other per actual parsing invocation. The state that was global is
now part of the root args instead.

This did, admittedly, add a bunch of new code. And I do feel bad about
that. So I went and added a lot of API docs to try to at least make the
current state of things clear to the next person.

--

This is needed for RFC 134 (tracking issue #7868). It was very hard to
modularize `Installable` parsing when there were two completion
arguments. I wouldn't go as far as to say it is *easy* now, but at least
it is less hard (and the completions test finally passed).

Co-authored-by: Valentin Gagarin <valentin.gagarin@tweag.io>
Change-Id: If18cd5be78da4a70635e3fdcac6326dbfeea71a5
(cherry picked from commit 67eb37c1d0de28160cd25376e51d1ec1b1c8305b)
2024-03-25 15:30:36 +00:00
Tom Bereknyei 4494f9097f feat: notation to refer to no attribute search prefix
An attrPath prefix of "." indicates no need to try default attrPath prefixes. For example `nixpkgs#legacyPackages.x86_64-linux.ERROR` searches through

```
trying flake output attribute 'packages.x86_64-linux.legacyPackages.x86_64-linux.ERROR'
using cached attrset attribute ''
trying flake output attribute 'legacyPackages.x86_64-linux.legacyPackages.x86_64-linux.ERROR'
using cached attrset attribute 'legacyPackages.x86_64-linux'
trying flake output attribute 'legacyPackages.x86_64-linux.ERROR'
using cached attrset attribute 'legacyPackages.x86_64-linux'
```

And there is no way to specify that one does not want the automatic
search behavior. Now one can specify
`nixpkgs#.legacyPackages.x86_64-linux.ERROR` to only refer to the rooted
attribute path without any default injection of attribute search path or
system.

Change-Id: Iac1334e1470137b7ce11dcf845513810230638ec
(cherry picked from commit d4aed18883b361133607296fb6cd789c47427a38)
2024-03-25 15:30:36 +00:00
Lunaphied d3d7489571 Merge "Improve new CLI UX by supporting short -E flag for --expr" into main 2024-03-25 14:13:44 +00:00
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 946fc12e4e Revert "Merge pull request #9476 from alois31/restore-progress-bar"
Observed to regress nix repl attrset printing with narrow windows.

This reverts commit a2d5e803cf.

Fixes: lix-project/lix#168

Change-Id: I8e0031475b4ec26d6a71014357d973578b70815c
2024-03-23 18:04:29 -07:00
Qyriad b4d07656ff build: optionally build and install with meson
This commit adds several meson.build, which successfully build and
install Lix executables, libraries, and headers. Meson does not yet
build docs, Perl bindings, or run tests, which will be added in
following commits. As such, this commit does not remove the existing
build system, or make it the default, and also as such, this commit has
several FIXMEs and TODOs as notes for what should be done before the
existing autoconf + make buildsystem can be removed and Meson made the
default. This commit does not modify any source files.

A Meson-enabled build is also added as a Hydra job, and to
`nix flake check`.

Change-Id: I667c8685b13b7bab91e281053f807a11616ae3d4
2024-03-22 08:36:50 -06:00
jade 30233d87f9 un-nixes ur lix, a little
I didn't really go attack the docs because we need to pull a bunch of
PRs. I went looking for strings in the code that called lix nix.

Change-Id: I2138bb4dd239096bc530946b281db7f875195b39
2024-03-18 18:20:24 -07:00
jade 61e21b2557 Delete hasPrefix and hasSuffix from the codebase
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
2024-03-17 20:17:19 -07:00
jade be2b87ed4d add automated usage mode to the repl
This is definitely not a stable thing, but it does feel slightly crimes
to put it as an experimental feature. Shrug, up for bikeshedding.

Change-Id: I6ef176e3dee6fb1cac9c0a7a60d553a2c63ea728
2024-03-11 14:14:43 -07:00
jade 1758a6ef25 refactor: repl prompts are now the job of the interacter
Change-Id: I17c2873dfbbff303cdbdc7a8903deb8409ce3026
2024-03-11 01:04:52 -07:00
jade 95a87f2c2a refactor: move readline stuff into its own file
This is in direct preparation for an automation mode of nix repl.

Change-Id: I26e6ca88ef1c48aab11a2d1e939ff769f1770caa
2024-03-11 01:04:52 -07:00
jade 8be7030299 util.hh: split out signals stuff
Copies part of the changes of ac89bb064aeea85a62b82a6daf0ecca7190a28b7

Change-Id: I9ce601875cd6d4db5eb1132d7835c5bab9f126d8
2024-03-11 00:52:09 -07:00
eldritch horrors 030c8aa833 Rename ProcessLineResult variants
(cherry picked from commit 8e71883e3f59100479e96aa1883ef52dbaa03fd3)
Change-Id: If7d8b75eaec623dac106ce2363fa148af37d150c
2024-03-09 10:17:26 -07:00
eldritch horrors 992d99592f :quit in the debugger should quit the whole program
(cherry picked from commit 2a8fe9a93837733e9dd9ed5c078734a35b203e14)
Change-Id: I71dadfef6b24d9272b206e9e2c408040559d8a1c
2024-03-09 10:17:26 -07:00
eldritch horrors 1958152d14 Pretty-print values in the REPL
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
2024-03-09 07:20:23 -07:00
eldritch horrors 08252967a8 libexpr: Support structured error classes
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
2024-03-09 04:47:05 -07:00
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 89e99d94e4 Merge pull request #9634 from 9999years/combine-abstract-pos-and-pos
Combine `AbstractPos`, `PosAdapter`, and `Pos`

(cherry picked from commit 113499d16fc87d53b73fb62fe6242154909756ed)

===

this is a bit cursed because originally it was based on InputAccessor
code that we don't have and moved/patched features we likewise don't
have (fetchToStore caching, all the individual accessors,
ContentAddressMethod). the commit is adjusted accordingly to
match (remove caching, ignore accessors, use FileIngestionMethod).

note that `state.rootPath . CanonPath == abs` and
computeStorePathForPath works relative to cwd, so the slight rewrite in
the moved fetchToStore is legal.

Change-Id: I05fd340c273f0bcc8ffabfebdc4a88b98083bce5
2024-03-05 23:46:18 -07:00
eldritch horrors 4551dd0f2c Merge pull request #10010 from 9999years/fix-9941
Fix "Failed tcsetattr(TCSADRAIN)" when `nix repl` is not a TTY

(cherry picked from commit 864fc85fc88ff092725ba99907611b2b8d2205fb)
Change-Id: I8198674b935fabd741a349cc74544e61c53ea7b3
2024-03-04 09:25:17 +01:00
eldritch horrors 43cedec6c5 Merge pull request #9919 from 9999years/reduce-debugger-clutter
Reduce visual clutter in the debugger

(cherry picked from commit f388a6148dae0fc999f1a67d0b96d76788f9b97f)
Change-Id: I21bfe3e9f75816484b0f46dbe09e0ff40b22c6d9
2024-03-04 08:52:57 +01:00
eldritch horrors 625df32afc Merge pull request #9913 from 9999years/debugger-positions
Print positions in `--debugger`, instead of pointers

(cherry picked from commit 49cf090cb2f51d6935756a6cf94d568cab063f81)
Change-Id: Ic27917b2aab3657c28d599898377bf0c14753f8a
2024-03-04 08:51:02 +01:00
eldritch horrors 180984178d Merge pull request #9648 from cole-h/nix-shell-ordering
nix shell: reflect command line order in PATH order

(cherry picked from commit b91c935c2faf08ced2c763dcd2a831f26d84fa86)
Change-Id: If16c120bb74857c2817366e74e5b0877eb997260
2024-03-04 07:50:55 +01:00
eldritch horrors 6b279cd10e Merge pull request #9658 from pennae/env-diet
reduce the size of Env by one pointer

(cherry picked from commit 83f5622545a2fc31eb7e7d5105f64ed6dd3058b3)
Change-Id: I5636290526d0165cfc61aee1e7a5b94db4a26cef
2024-03-04 07:37:45 +01:00
eldritch horrors dd180911d8 Merge pull request #9582 from pennae/misc-opts
a packet of small optimizations

(cherry picked from commit ee439734e924eb337a869ff2e48aff8b989198bc)
Change-Id: I125d870710750a32a0dece48f39a3e9132b0d023
2024-03-04 07:32:31 +01:00
eldritch horrors a2d5e803cf Merge pull request #9476 from alois31/restore-progress-bar
nix repl: Only hide the progress bar while waiting for user input

(cherry picked from commit 3bebaefcd0c5d650f7edcd39f397bb45c4382f41)
Change-Id: Ie7c0db46f7c2cf5f938e66bdd3c31f0b62bdb104
2024-03-04 07:11:25 +01:00
eldritch horrors a089d8f5f6 Merge pull request #9465 from obsidiansystems/build-dir
Use `buildprefix` in a few more places

(cherry picked from commit b6a3fde6b7a416929553e6be36fc991680ddf9ef)
Change-Id: I2790663fa9f8242ac2db6582b7e421d2fdf42942
2024-03-04 07:11:25 +01:00
eldritch horrors 6e0dd9f673 Merge pull request #9289 from edolstra/fix-warnings
Fix gcc warnings

(cherry picked from commit 66cb364f581486e0c426b35149ac13d19f7842bc)
Change-Id: I1474dbc18a4beaaf1bce16d4abbcc99806b79ff1
2024-03-04 05:27:35 +01:00
eldritch horrors d28a6618a8 Merge pull request #9167 from obsidiansystems/pre-overhaul-completions
Improve tests and docs prior to refactoring completions

(cherry picked from commit 5442d9b47298389918d1f38d20f768a80ffc2369)
Change-Id: Ief99ac2cd9c92981a9a522d15b9c3daf99182c9d
2024-03-04 04:38:33 +01:00
eldritch horrors 6feba52008 Merge pull request #8895 from hercules-ci/gc-before-stats
eval: Run a full GC before printing stats

(cherry picked from commit aeea49609be014b1928c95b7ec28dbedeb4f032a)
Change-Id: I47a23d3a7a47ea61d9a2b5727b638f879f3aaf1e
2024-03-04 04:36:47 +01:00
Théophane Hufschmitt 2a52ec4e92
Merge pull request #7661 from henrik-ch/repl-doc
improved help command listing.
2023-09-14 16:43:02 +02:00
John Ericson 7ad66cb3ef Allow dynamic derivation deps in inputDrvs
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>
2023-09-07 10:39:37 -04:00
John Ericson 9121fed4b4 Fixing #7479
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>
2023-08-18 11:44:00 -04:00
John Ericson 60b7121d2c Make the Derived Path family of types inductive for dynamic derivations
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>
2023-08-10 00:08:32 -04:00
John Ericson 1570e80219 Move evaluator settings (type and global) to separate file/header 2023-07-31 10:14:15 -04:00
John Ericson 7b30293d38 Tighten #includes: DerivedPath doesn't care about Realisation 2023-07-20 15:42:06 -04:00
John Ericson 2c3fb0eb33 Move BuiltPath to its own header/C++ file in libcmd
It is less important, and used less widely, than `DerivedPath`.
2023-07-12 23:01:10 -04:00
John Ericson be518e73ae Clean up SearchPath
- 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>
2023-07-09 23:22:22 -04:00
Eelco Dolstra b8e8f27159 Rename 'resolvedRef' to 'lockedRef'
'resolvedRef' was incorrect, since a resolved ref is one after
registry resolution, which may still be unlocked (e.g. 'nixpkgs' ->
'github:NixOS/nixpkgs').
2023-07-03 12:23:57 +02:00
John Ericson c404623a1d
Clean up a few things related to profiles (#8526)
- Greatly expand API docs

- Clean up code in misc ways

  - Instead of a complicated single loop on generations, do different
    operations in successive subsequent steps.

  - Avoid `ref` in one place where `&` is fine

  - Just return path instead of mutating an argument in `makeName`

Co-authored-by: Valentin Gagarin <valentin.gagarin@tweag.io>
2023-06-19 04:04:59 +00:00
Eelco Dolstra e503eadafc
Merge pull request #8477 from edolstra/tarball-flake-redirects
Tarball flake improvements
2023-06-16 18:03:50 +02:00
Eelco Dolstra 1ad3328c5e Allow tarball URLs to redirect to a lockable immutable URL
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.
2023-06-13 14:17:45 +02:00
Tom Bereknyei 0e3849dc65 test: add test for non-defaulting for stding installable input 2023-06-12 08:40:17 -04:00
Tom Bereknyei 08089fdd32 fix: Do not apply default installables when using --stdin 2023-06-11 13:33:38 -04:00
John Ericson d2162e7acd Make more string values work as installables
As discussed in #7417, it would be good to make more string values work
as installables. That is to say, if an installable refers to a value,
and the value is a string, it used to not work at all, since #7484, it
works somewhat, and this PR make it work some more.

The new cases that are added for `BuiltPath` contexts:

- Fixed input- or content-addressed derivation:

  ```
  nix-repl> hello.out.outPath
  "/nix/store/jppfl2bp1zhx8sgs2mgifmsx6dv16mv2-hello-2.12"

  nix-repl> :p builtins.getContext hello.out.outPath
  { "/nix/store/c7jrxqjhdda93lhbkanqfs07x2bzazbm-hello-2.12.drv" = { outputs = [ "out" ]; }; }

  The string matches the specified single output of that derivation, so
  it should also be valid.

- Floating content-addressed derivation:

  ```
  nix-repl> (hello.overrideAttrs (_: { __contentAddressed = true; })).out.outPath
  "/1a08j26xqc0zm8agps8anxpjji410yvsx4pcgyn4bfan1ddkx2g0"

  nix-repl> :p builtins.getContext (hello.overrideAttrs (_: { __contentAddressed = true; })).out.outPath
  { "/nix/store/qc645pyf9wl37c6qvqzaqkwsm1gp48al-hello-2.12.drv" = { outputs = [ "out" ]; }; }
  ```

  The string is not a path but a placeholder, however it also matches
  the context, and because it is a CA derivation we have no better
  option. This should also be valid.

We may also want to think about richer attrset based values (also
discussed in that issue and #6507), but this change "completes" our
string-based building blocks, from which the others can be desugared
into or at least described/document/taught in terms of.

Progress towards #7417

Co-authored-by: Robert Hensing <roberth@users.noreply.github.com>
2023-05-15 09:03:38 -04:00
John Ericson a93110ab19 Fix nix print-dev-env & nix develop with drv paths
Fixes #8309

This regression was because both `CmdDevelop` and `CmdPrintDevEnv` were
switched to be `InstallableValueCommand` subclasses, but actually
neither should have been.

The `nixpkgsFlakeRef` method should indeed not be on the base
installable class, because "flake refs" and "nixpkgs" are not
installable-wide notions, but that doesn't mean these commands should
only accept installable values.
2023-05-10 11:29:45 -04:00
Eelco Dolstra 17e6b85d05 nix: Support the --repair flag 2023-04-28 17:03:04 +02:00
Eelco Dolstra 01232358ff Merge remote-tracking branch 'origin/master' into source-path 2023-04-24 13:20:36 +02:00
John Ericson 85f0cdc370 Use std::set<StringContextElem> not PathSet for string contexts
Motivation

`PathSet` is not correct because string contexts have other forms
(`Built` and `DrvDeep`) that are not rendered as plain store paths.
Instead of wrongly using `PathSet`, or "stringly typed" using
`StringSet`, use `std::std<StringContextElem>`.

-----

In support of this change, `NixStringContext` is now defined as
`std::std<StringContextElem>` not `std:vector<StringContextElem>`. The
old definition was just used by a `getContext` method which was only
used by the eval cache. It can be deleted altogether since the types are
now unified and the preexisting `copyContext` function already suffices.

Summarizing the previous paragraph:

Old:

  - `value/context.hh`: `NixStringContext = std::vector<StringContextElem>`
  - `value.hh`: `NixStringContext Value::getContext(...)`
  - `value.hh`: `copyContext(...)`

New:

  - `value/context.hh`: `NixStringContext = std::set<StringContextElem>`
  - `value.hh`: `copyContext(...)`
----

The string representation of string context elements no longer contains
the store dir. The diff of `src/libexpr/tests/value/context.cc` should
make clear what the new representation is, so we recommend reviewing
that file first. This was done for two reasons:

Less API churn:

`Value::mkString` and friends did not take a `Store` before. But if
`NixStringContextElem::{parse, to_string}` *do* take a store (as they
did before), then we cannot have the `Value` functions use them (in
order to work with the fully-structured `NixStringContext`) without
adding that argument.

That would have been a lot of churn of threading the store, and this
diff is already large enough, so the easier and less invasive thing to
do was simply make the element `parse` and `to_string` functions not
take the `Store` reference, and the easiest way to do that was to simply
drop the store dir.

Space usage:

Dropping the `/nix/store/` (or similar) from the internal representation
will safe space in the heap of the Nix programming being interpreted. If
the heap contains many strings with non-trivial contexts, the saving
could add up to something significant.

----

The eval cache version is bumped.

The eval cache serialization uses `NixStringContextElem::{parse,
to_string}`, and since those functions are changed per the above, that
means the on-disk representation is also changed.

This is simply done by changing the name of the used for the eval cache
from `eval-cache-v4` to eval-cache-v5`.

----

To avoid some duplication `EvalCache::mkPathString` is added to abstract
over the simple case of turning a store path to a string with just that
string in the context.

Context

This PR picks up where #7543 left off. That one introduced the fully
structured `NixStringContextElem` data type, but kept `PathSet context`
as an awkward middle ground between internal `char[][]` interpreter heap
string contexts and `NixStringContext` fully parsed string contexts.

The infelicity of `PathSet context` was specifically called out during
Nix team group review, but it was agreeing that fixing it could be left
as future work. This is that future work.

A possible follow-up step would be to get rid of the `char[][]`
evaluator heap representation, too, but it is not yet clear how to do
that. To use `NixStringContextElem` there we would need to get the STL
containers to GC pointers in the GC build, and I am not sure how to do
that.

----

PR #7543 effectively is writing the inverse of a `mkPathString`,
`mkOutputString`, and one more such function for the `DrvDeep` case. I
would like that PR to have property tests ensuring it is actually the
inverse as expected.

This PR sets things up nicely so that reworking that PR to be in that
more elegant and better tested way is possible.

Co-authored-by: Théophane Hufschmitt <7226587+thufschmitt@users.noreply.github.com>
2023-04-21 01:05:49 -04:00
Robert Hensing 3f9589f17e
Merge pull request #6312 from obsidiansystems/keyed-build-result
Shuffle `BuildResult` data definition, make state machine clearer, introduce `SingleDrvOutputs`
2023-04-17 18:08:05 +02:00