release: 2.90.0 "Vanilla Ice Cream"

Release produced with releng/create_release.xsh Change-Id: Ice53891cdeafff04bd6537be66e8cd6b7dd9678c
doc/release-notes: add date for major release
2024-07-10 08:40:42 -07:00 · 2024-07-10 15:35:00 +00:00 · 2024-07-10 15:32:19 +02:00 · 2024-06-16 19:06:45 -07:00
299 changed files with 3260 additions and 6901 deletions
@@ -1,5 +1,9 @@
 # shellcheck shell=bash
 source_env_if_exists .envrc.local
-# Use native-clangStdenvPackages to get clangd by default.
-use flake ".#${LIX_SHELL_VARIANT:-native-clangStdenvPackages}" "${LIX_SHELL_EXTRA_ARGS[@]}"
+# TODO: `use flake .#native-clangStdenvPackages` on macOS?
+use flake ".#${LIX_SHELL_VARIANT:-default}" "${LIX_SHELL_EXTRA_ARGS[@]}"
+export MAKEFLAGS="$MAKEFLAGS -e"
+if [[ -n "$NIX_BUILD_CORES" ]]; then
+    export MAKEFLAGS="$MAKEFLAGS -j $NIX_BUILD_CORES"
+fi
 export GTEST_BRIEF=1
@@ -1 +0,0 @@
-This is a file used by the dev shell shellHook in package.nix to check that this is actually a Lix repo before installing git hooks. Its contents have no meaning.
@@ -3,10 +3,6 @@
 #
 # It's used for crediting people accurately in release notes. The release notes
 # script will link to forgejo, then to GitHub if forgejo is not present.
-#
-# When adding someone from outside the Lix project, you generally want to simply link their GitHub profile without adding a display name unless they are well-known in the community by that display name.
-#
-# See doc/manual/src/contributing/hacking.md for more documentation on this file's format and typical usage.
 9999years:
  display_name: wiggles
  forgejo: rbt
@@ -44,11 +40,6 @@ cole-h:
  display_name: Cole Helbling
  github: cole-h

-delan:
-  display_name: delan
-  forgejo: delan
-  github: delan
-
 edolstra:
  display_name: Eelco Dolstra
  github: edolstra
@@ -69,10 +60,6 @@ jade:
  forgejo: jade
  github: lf-

-kloenk:
-  forgejo: kloenk
-  github: kloenk
-
 lovesegfault:
  github: lovesegfault

@@ -96,10 +83,6 @@ puck:
  forgejo: puck
  github: puckipedia

-quantumjump:
-  display_name: Quantum Jump
-  github: QuantumBJump
-
 r-vdp:
  github: r-vdp

@@ -110,7 +110,6 @@ manual = custom_target(
    builtins_md,
    builtin_constants_md,
    rl_next_generated,
-    nix,
  ],
  output : [
    'manual',
@@ -187,7 +186,6 @@ foreach command : nix_nested_manpages
      ],
      input : [
        manual_md,
-        nix,
      ],
      output : command[0] + '-' + page + '.1',
      install : true,
@@ -300,7 +298,6 @@ foreach page : nix3_manpages
    input : [
      'render-manpage.sh',
      manual_md,
-      nix,
    ],
    output : page + '.1',
    install : true,
@@ -344,7 +341,6 @@ foreach entry : nix_manpages
      'render-manpage.sh',
      manual_md,
      entry.get(3, []),
-      nix,
    ],
    output : '@0@.@1@'.format(entry[0], entry[1]),
    install : true,
@@ -1,4 +1,4 @@
-#!/usr/bin/env bash
+#!/bin/sh

 set -euo pipefail

@@ -1,4 +1,4 @@
-#!/usr/bin/env bash
+#!/bin/sh

 set -euo pipefail

@@ -1,90 +0,0 @@
---
-synopsis: "Trace which part of a `foo.bar.baz` expression errors"
-cls: 1505, 1506
-credits: Qyriad
-category: Improvements
---
-
-Previously, if an attribute path selection expression like `linux_4_9.meta.description` it wouldn't show you which one of those parts in the attribute path, or even that that line of code is what caused evaluation of the failing expression.
-The previous error looks like this:
-
-```
-pkgs.linuxKernel.kernels.linux_4_9.meta.description
-
-error:
-       … while evaluating the attribute 'linuxKernel.kernels.linux_4_9.meta.description'
-         at /nix/store/dk2rpyb6ndvfbf19bkb2plcz5y3k8i5v-source/pkgs/top-level/linux-kernels.nix:278:5:
-          277|   } // lib.optionalAttrs config.allowAliases {
-          278|     linux_4_9 = throw "linux 4.9 was removed because it will reach its end of life within 22.11";
-             |     ^
-          279|     linux_4_14 = throw "linux 4.14 was removed because it will reach its end of life within 23.11";
-
-       … while calling the 'throw' builtin
-         at /nix/store/dk2rpyb6ndvfbf19bkb2plcz5y3k8i5v-source/pkgs/top-level/linux-kernels.nix:278:17:
-          277|   } // lib.optionalAttrs config.allowAliases {
-          278|     linux_4_9 = throw "linux 4.9 was removed because it will reach its end of life within 22.11";
-             |                 ^
-          279|     linux_4_14 = throw "linux 4.14 was removed because it will reach its end of life within 23.11";
-
-       error: linux 4.9 was removed because it will reach its end of life within 22.11
-```
-
-Now, the error will look like this:
-
-```
-pkgs.linuxKernel.kernels.linux_4_9.meta.description
-
-error:
-       … while evaluating the attribute 'linuxKernel.kernels.linux_4_9.meta.description'
-         at /nix/store/dk2rpyb6ndvfbf19bkb2plcz5y3k8i5v-source/pkgs/top-level/linux-kernels.nix:278:5:
-          277|   } // lib.optionalAttrs config.allowAliases {
-          278|     linux_4_9 = throw "linux 4.9 was removed because it will reach its end of life within 22.11";
-             |     ^
-          279|     linux_4_14 = throw "linux 4.14 was removed because it will reach its end of life within 23.11";
-
-       … while evaluating 'pkgs.linuxKernel.kernels.linux_4_9' to select 'meta' on it
-         at «string»:1:1:
-            1| pkgs.linuxKernel.kernels.linux_4_9.meta.description
-             | ^
-
-       … caused by explicit throw
-         at /nix/store/dk2rpyb6ndvfbf19bkb2plcz5y3k8i5v-source/pkgs/top-level/linux-kernels.nix:278:17:
-          277|   } // lib.optionalAttrs config.allowAliases {
-          278|     linux_4_9 = throw "linux 4.9 was removed because it will reach its end of life within 22.11";
-             |                 ^
-          279|     linux_4_14 = throw "linux 4.14 was removed because it will reach its end of life within 23.11";
-
-       error: linux 4.9 was removed because it will reach its end of life within 22.11
-```
-
-Not only does the line of code that referenced the failing attribute show up in the trace, it also tells you that it was specifically the `linux_4_9` part that failed.
-
-This includes if the failing part is a top-level binding:
-
-```
-let
-  inherit (pkgs.linuxKernel.kernels) linux_4_9;
-in linux_4_9.meta.description
-error:
-       … while evaluating 'linux_4_9' to select 'meta.description' on it
-         at «string»:3:4:
-            2|   inherit (pkgs.linuxKernel.kernels) linux_4_9;
-            3| in linux_4_9.meta.description
-             |    ^
-
-       … while evaluating the attribute 'linux_4_9'
-         at /nix/store/dk2rpyb6ndvfbf19bkb2plcz5y3k8i5v-source/pkgs/top-level/linux-kernels.nix:278:5:
-          277|   } // lib.optionalAttrs config.allowAliases {
-          278|     linux_4_9 = throw "linux 4.9 was removed because it will reach its end of life within 22.11";
-             |     ^
-          279|     linux_4_14 = throw "linux 4.14 was removed because it will reach its end of life within 23.11";
-
-       … caused by explicit throw
-         at /nix/store/dk2rpyb6ndvfbf19bkb2plcz5y3k8i5v-source/pkgs/top-level/linux-kernels.nix:278:17:
-          277|   } // lib.optionalAttrs config.allowAliases {
-          278|     linux_4_9 = throw "linux 4.9 was removed because it will reach its end of life within 22.11";
-             |                 ^
-          279|     linux_4_14 = throw "linux 4.14 was removed because it will reach its end of life within 23.11";
-
-       error: linux 4.9 was removed because it will reach its end of life within 22.11
-```
@@ -1,12 +0,0 @@
---
-synopsis: "Add a `build-dir` setting to set the backing directory for builds"
-cls: 1514
-credits: [roberth, tomberek]
-category: Improvements
---
-
-`build-dir` can now be set in the Nix configuration to choose the backing directory for the build sandbox.
-This can be useful on systems with `/tmp` on tmpfs, or simply to relocate large builds to another disk.
-
-Also, `XDG_RUNTIME_DIR` is no longer considered when selecting the default temporary directory,
-as it's not intended to be used for large amounts of data.
@@ -1,70 +0,0 @@
---
-synopsis: "Distinguish between explicit throws and errors that happened while evaluating a throw"
-cls: 1511
-credits: Qyriad
-category: Improvements
---
-
-Previously, errors caused by an expression like `throw "invalid argument"` were treated like an error that happened simply while some builtin function was being called:
-
-```
-let
-  throwMsg = p: throw "${p} isn't the right package";
-in throwMsg "linuz"
-
-error:
-       … while calling the 'throw' builtin
-         at «string»:2:17:
-            1| let
-            2|   throwMsg = p: throw "${p} isn't the right package";
-             |                 ^
-            3| in throwMsg "linuz"
-
-       error: linuz isn't the right package
-```
-
-But the error didn't just happen "while" calling the `throw` builtin — it's a throw error!
-Now it looks like this:
-
-```
-let
-  throwMsg = p: throw "${p} isn't the right package";
-in throwMsg "linuz"
-
-error:
-       … caused by explicit throw
-         at «string»:2:17:
-            1| let
-            2|   throwMsg = p: throw "${p} isn't the right package";
-             |                 ^
-            3| in throwMsg "linuz"
-
-       error: linuz isn't the right package
-```
-
-This also means that incorrect usage of `throw` or errors evaluating its arguments are easily distinguishable from explicit throws:
-
-```
-let
-  throwMsg = p: throw "${p} isn't the right package";
-in throwMsg { attrs = "error when coerced in string interpolation"; }
-
-error:
-       … while calling the 'throw' builtin
-         at «string»:2:17:
-            1| let
-            2|   throwMsg = p: throw "${p} isn't the right package";
-             |                 ^
-            3| in throwMsg { attrs = "error when coerced in string interpolation"; }
-
-       … while evaluating a path segment
-         at «string»:2:24:
-            1| let
-            2|   throwMsg = p: throw "${p} isn't the right package";
-             |                        ^
-            3| in throwMsg { attrs = "error when coerced in string interpolation"; }
-
-       error: cannot coerce a set to a string: { attrs = "error when coerced in string interpolation"; }
-```
-
-Here, instead of an actual thrown error, a type error happens first (trying to coerce an attribute set to a string), but that type error happened *while* calling `throw`.
@@ -1,29 +0,0 @@
---
-synopsis: Fix nix-collect-garbage --dry-run
-issues: [fj#432]
-cls: [1566]
-category: Fixes
-credits: [quantumjump]
---
-
-`nix-collect-garbage --dry-run` did not previously give any output - it simply
-exited without even checking to see what paths would be deleted.
-
-```
-$ nix-collect-garbage --dry-run
-$
-```
-
-We updated the behaviour of the flag such that instead it prints out how many
-paths it *would* delete, but doesn't actually delete them.
-
-```
-$ nix-collect-garbage --dry-run
-finding garbage collector roots...
-determining live/dead paths...
-...
-<nix store paths>
-...
-2670 store paths deleted, 0.00MiB freed
-$
-```
@@ -1,16 +0,0 @@
---
-synopsis: "Hash mismatch diagnostics for fixed-output derivations include the URL"
-cls: [1536]
-credits: [jade]
-category: Improvements
---
-
-Now, when building fixed-output derivations, Lix will guess the URL that was used in the derivation using the `url` or `urls` properties in the derivation environment.
-This is a layering violation but making these diagnostics tractable when there are multiple instances of the `AAAA` hash is too significant of an improvement to pass it up.
-
-```
-error: hash mismatch in fixed-output derivation '/nix/store/sjfw324j4533lwnpmr5z4icpb85r63ai-x1.drv':
-        likely URL: https://meow.puppy.forge/puppy.tar.gz
-         specified: sha256-AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA=
-            got:    sha256-a1Qvp3FOOkWpL9kFHgugU1ok5UtRPSu+NwCZKbbaEro=
-```
@@ -1,14 +0,0 @@
---
-synopsis: Add log formats `multiline` and `multiline-with-logs`
-cls: [1369]
-credits: [kloenk]
-category: Improvements
---
-
-Added two new log formats (`multiline` and `multiline-with-logs`) that display
-current activities below each other for better visibility.
-
-These formats attempt to use the maximum available lines
-(defaulting to 25 if unable to determine) and print up to that many lines.
-The status bar is displayed as the first line, with each subsequent
-activity on its own line.
@@ -1,12 +0,0 @@
---
-synopsis: "`nix copy` is now several times faster at `querying info about /nix/store/...`"
-cls: [1462]
-issues: [fj#366]
-credits: [jade]
-category: Fixes
---
-
-We fixed a locking bug that serialized `querying info about /nix/store/...`
-onto just one thread such that it was eating `O(paths to copy * latency)` time
-while setting up to copy paths to s3 and other stores. It is now `nproc` times
-faster.
@@ -1,21 +0,0 @@
---
-synopsis: "Lix no longer speaks the Nix remote-build worker protocol to clients or servers older than CppNix 2.3"
-cls: [1207, 1208, 1206, 1205, 1204, 1203, 1479]
-issues: [fj#325]
-credits: [jade]
-category: Breaking Changes
---
-
-CppNix 2.3 was released in 2019, and is the new oldest supported version. We
-will increase our support baseline in the future up to a final version of CppNix
-2.18 (which may happen soon given that it is the only still-packaged and thus
-still-tested >2.3 version), but this step already removes a significant amount
-of dead, untested, code paths.
-
-Lix speaks the same version of the protocol as CppNix 2.18 and that fact will
-never change in the future; the Lix plans to replace the protocol for evolution
-will entail a complete incompatible replacement that will be supported in
-parallel with the old protocol. Lix will thus retain remote build compatibility
-with CppNix as long as CppNix maintains protocol compatibility with 2.18, and
-as long as Lix retains legacy protocol support (which will likely be a long
-time given that we plan to convert it to a frozen-in-time shim).
@@ -1,10 +0,0 @@
---
-synopsis: "`nix registry add` now requires a shorthand flakeref on the 'from' side"
-cls: 1494
-credits: delan
-category: Improvements
---
-
-The 'from' argument must now be a shorthand flakeref like `nixpkgs` or `nixpkgs/nixos-20.03`, making it harder to accidentally swap the 'from' and 'to' arguments.
-
-Registry entries that map from other flake URLs can still be specified in registry.json, the `nix.registry` option in NixOS, or the `--override-flake` option in the CLI, but they are not guaranteed to work correctly.
@@ -1,9 +0,0 @@
---
-synopsis: Allow automatic rejection of configuration options from flakes
-cls: [1541]
-credits: [alois31]
-category: Improvements
---
-
-Setting `accept-flake-config` to `false` now respects user choice by automatically rejecting configuration options set by flakes.
-The old behaviour of asking each time is still available (and default) by setting it to the special value `ask`.
@@ -1,8 +0,0 @@
---
-synopsis: "`nix repl` now allows tab-completing the special repl :colon commands"
-cls: 1367
-credits: Qyriad
-category: Improvements
---
-
-The REPL (`nix repl`) supports pressing `<TAB>` to complete a partial expression, but now also supports completing the special :colon commands as well (`:b`, `:edit`, `:doc`, etc), if the line starts with a colon.
@@ -1,10 +0,0 @@
---
-synopsis: "Lix now supports building with UndefinedBehaviorSanitizer"
-cls: [1483]
-credits: [jade]
-category: Development
---
-
-You can now build Lix with the configuration option `-Db_sanitize=undefined` and it will both work and pass tests. AddressSanitizer support is also coming soon.
-
-For a list of undefined behaviour fixed by sanitizer usage, see [the gerrit topic "undefined-behaviour"](https://gerrit.lix.systems/q/topic:%22undefined-behaviour%22).
@@ -197,7 +197,7 @@
 - [Release Notes](release-notes/release-notes.md)
  - [Upcoming release](release-notes/rl-next.md)
  <!-- RELENG-AUTO-INSERTION-MARKER (see releng/release_notes.py) -->
-  - [Lix 2.90 (FIXME date)](release-notes/rl-2.90.md)
+  - [Lix 2.90 (2024-07-10)](release-notes/rl-2.90.md)
  - [Nix 2.18 (2023-09-20)](release-notes/rl-2.18.md)
  - [Nix 2.17 (2023-07-24)](release-notes/rl-2.17.md)
  - [Nix 2.16 (2023-05-31)](release-notes/rl-2.16.md)
@@ -78,16 +78,6 @@ Most commands in Lix accept the following command-line options:

    Display the raw logs, with the progress bar at the bottom.

-  - `multiline`
-
-    Display a progress bar during the builds and in the lines below that one line per activity.
-
-
-  - `multiline-with-logs`
-
-    Displayes the raw logs, with a progress bar and activities each in a new line at the bottom.
-
-
 - <span id="opt-no-build-output">[`--no-build-output`](#opt-no-build-output)</span> / `-Q`

  By default, output written by builders to standard output and standard error is echoed to the Lix command's standard error.
@@ -39,19 +39,17 @@ $ nix-shell -A native-clangStdenvPackages

 ### Building from the development shell

-You can build and test Lix with just:
+As always you may run [stdenv's phases by name](https://nixos.org/manual/nixpkgs/unstable/#sec-building-stdenv-package-in-nix-shell), e.g.:

 ```bash
-$ just setup
-$ just build
-$ just test --suite=check
-$ just install
-$ just test --suite=installcheck
+$ configurePhase
+$ buildPhase
+$ checkPhase
+$ installPhase
+$ installCheckPhase
 ```

-(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.)
-
-You can also build Lix manually:
+To build manually, however, use the following:

 ```bash
 $ meson setup ./build "--prefix=$out" $mesonFlags
@@ -66,7 +64,9 @@ $ meson install -C build
 $ meson test -C build --suite=installcheck
 ```

-In both cases, Lix will be installed to `$PWD/outputs`, the `/bin` of which is prepended to PATH in the development shells.
+(Check and installcheck may both be done after install, allowing you to omit the --suite argument entirely, but this is the order package.nix runs them in.)
+
+This will install Lix to `$PWD/outputs`, the `/bin` of which is prepended to PATH in the development shells.

 If the tests fail and Meson helpfully has no output for why, use the `--print-error-logs` option to `meson test`.

@@ -168,26 +168,8 @@ or for Nix with the [`flakes`] and [`nix-command`] experimental features enabled
 $ nix build .#packages.aarch64-linux.default
 ```

-### Cross compiling using the Lix flake
-
-Lix can also be easily cross compiled to the following arbitrarily-chosen system doubles, which can be useful for bootstrapping Lix on new platforms.
-These are specified in `crossSystems` in `flake.nix`; feel free to submit changes to add new ones if they are useful to you.
-
- `armv6l-linux`
- `armv7l-linux`
- `riscv64-linux`
-
-For example, to cross-compile Lix for `armv6l-linux` from another Linux, use the following:
-
-```console
-$ nix build .#nix-armv6l-linux
-```
-
-It's also possible to cross-compile a tarball of binaries suitable for the Lix installer, for example, for `riscv64-linux`:
-
-```console
-$ nix build .#nix-riscv64-linux.passthru.binaryTarball
-```
+Cross-compiled builds are available for ARMv6 (`armv6l-linux`) and ARMv7 (`armv7l-linux`).
+Add more [system types](#system-type) to `crossSystems` in `flake.nix` to bootstrap Nix on unsupported platforms.

 ### Building for multiple platforms at once

@@ -300,8 +282,9 @@ Regular markdown files used for the manual have a base path of their own and the

 ## API documentation

-Doxygen API documentation will be available online in the future ([tracking issue](https://git.lix.systems/lix-project/lix/issues/422)).
-You can also build and view it yourself:
+Doxygen API documentation is [available
+online](https://hydra.nixos.org/job/nix/master/internal-api-docs/latest/download-by-type/doc/internal-api-docs). You
+can also build and view it yourself:

 ```console
 # nix build .#hydraJobs.internal-api-docs
@@ -311,50 +294,44 @@ You can also build and view it yourself:
 or inside a `nix develop` shell by running:

 ```bash
-$ meson configure build -Dinternal-api-docs=enabled
 $ meson compile -C build internal-api-docs
 $ xdg-open ./outputs/doc/share/doc/nix/internal-api/html/index.html
 ```

 ## Coverage analysis

-A coverage analysis report will be available online in the future (FIXME(lix-hydra)).
-You can build it yourself:
+A coverage analysis report is [available
+online](https://hydra.nixos.org/job/nix/master/coverage/latest/download-by-type/report/coverage). You
+can build it yourself:

 ```
 # nix build .#hydraJobs.coverage
 # xdg-open ./result/coverage/index.html
 ```

-Metrics about the change in line/function coverage over time will be available in the future (FIXME(lix-hydra)).
+Metrics about the change in line/function coverage over time are also
+[available](https://hydra.nixos.org/job/nix/master/coverage#tabs-charts).

 ## Add a release note

 `doc/manual/rl-next` contains release notes entries for all unreleased changes.

 User-visible changes should come with a release note.
-Developer-facing changes should have a release note in the Development category if they are significant and if developers should know about them.

 ### Add an entry

-Here's what a complete entry looks like.
-The file name is not incorporated in the final document, and is generally a super brief summary of the change synopsis.
+Here's what a complete entry looks like. The file name is not incorporated in the document.

-```markdown
+```
 ---
 synopsis: Basically a title
 # 1234 or gh#1234 will refer to CppNix GitHub, fj#1234 will refer to a Lix forgejo issue.
 issues: [1234, fj#1234]
-# Use this *only* if there is a CppNix pull request associated with this change.
+# Use this *only* if there is a CppNix pull request associated with this change
 prs: 1238
-# List of Lix Gerrit changelist numbers.
-# If there is an associated Lix GitHub PR, just put in the Gerrit CL number.
+# List of Lix Gerrit changelist numbers; if there is an associated Lix GitHub
+# PR, just put in the Gerrit CL number.
 cls: [123]
-# Heading that this release note will appear under.
-category: Breaking Changes
-# Add a credit mention in the bottom of the release note.
-# your-name is used as a key into doc/manual/change-authors.yml for metadata
-credits: [your-name]
 ---

 Here's one or more paragraphs that describe the change.
@@ -369,31 +346,6 @@ Significant changes should add the following header, which moves them to the top
 significance: significant
 ```

-The following categories of release notes are supported (see `maintainers/build-release-notes.py`):
- Breaking Changes
- Features
- Improvements
- Fixes
- Packaging
- Development
- Miscellany
-
-The `credits` field, if present, gives credit to the author of the patch in the release notes with a message like "Many thanks to (your-name) for this" and linking to GitHub or Forgejo profiles if listed.
-
-If you are forward-porting a change from CppNix, please credit the original author, and optionally credit yourself.
-When adding credits metadata for people external to the project and deciding whether to put in a `display_name`, consider what they are generally known as in the community; even if you know their full name (e.g. from their GitHub profile), we suggest only adding it as a display name if that is what they go by in the community.
-There are multiple reasons we follow this practice, but it boils down to privacy and consent: we would rather not capture full names that are not widely used in the community without the consent of the parties involved, even if they are publicly available.
-As of this writing, the entries with full names as `display_name` are either members of the CppNix team or people who added them themselves.
-
-The names specified in `credits` are used as keys to look up the authorship info in `doc/manual/change-authors.yml`.
-The only mandatory part is that every key appearing in `credits` has an entry present in `change-authors.yml`.
-All of the following properties are optional; you can specify `{}` as the metadata if you want a simple non-hyperlinked mention.
-The following properties are supported:
-
- `display_name`: display name used in place of the key when showing names, if present.
- `forgejo`: Forgejo username. The name in the release notes will be a link to this, if present.
- `github`: GitHub username, used if `forgejo` is not set, again making a link.
-
 ### Build process

 Releases have a precomputed `rl-MAJOR.MINOR.md`, and no `rl-next.md`.
@@ -433,6 +433,9 @@ I grepped `src/` for `get[eE]nv\("` to find the mentions in Lix code.
 - `NIX_PROFILE` - Selects which profile `nix-env` will operate on. Documented elsewhere.
 - `NIX_SSHOPTS` - Options passed to `ssh(1)` when using a ssh remote store.
  Incorrectly documented on `nix-copy-closure` which is *surely* not the only place they are used??
+- `_NIX_TEST_NO_LSOF` - Used on non-Linux, non-macOS platforms to disable using `lsof` when finding gc roots.
+
+  Since https://git.lix.systems/lix-project/lix/issues/156 was fixed, this should probably just be removed as it was a bad workaround for a macOS issue.
 - `_NIX_TEST_GC_SYNC_1` - Path to a pipe that is used to block the GC briefly to validate invariants from the test suite.
 - `_NIX_TEST_GC_SYNC_2` - Path to a pipe that is used to block the GC briefly to validate invariants from the test suite.
 - `_NIX_TEST_FREE_SPACE_FILE` - Path to a file containing a decimal number with the free space that the GC is to believe it has.
@@ -1,7 +1,7 @@
-# Lix 2.90 "Vanilla Ice Cream" (FIXME date)
+# Lix 2.90 "Vanilla Ice Cream" (2024-07-10)


-# Lix 2.90.0 (FIXME date)
+# Lix 2.90.0 (2024-07-10)

 ## Breaking Changes
 - Deprecate the online flake registries and vendor the default registry [fj#183](https://git.lix.systems/lix-project/lix/issues/183) [fj#110](https://git.lix.systems/lix-project/lix/issues/110) [fj#116](https://git.lix.systems/lix-project/lix/issues/116) [#8953](https://github.com/NixOS/nix/issues/8953) [#9087](https://github.com/NixOS/nix/issues/9087) [cl/1127](https://gerrit.lix.systems/c/lix/+/1127)
@@ -59,7 +59,7 @@
        (Run `touch .nocontribmsg` to hide this message.)
      '';

-      officialRelease = false;
+      officialRelease = true;

      # Set to true to build the release notes for the next release.
      buildUnreleasedNotes = true;
@@ -84,8 +84,6 @@
      ];
      systems = linuxSystems ++ darwinSystems;

-      # If you add something here, please update the list in doc/manual/src/contributing/hacking.md.
-      # Thanks~
      crossSystems = [
        "armv6l-linux"
        "armv7l-linux"
@@ -197,19 +195,14 @@
            busybox-sandbox-shell = final.busybox-sandbox-shell or final.default-busybox-sandbox-shell;
          };

-          pegtl = final.nix.passthru.pegtl;
-
          # Export the patched version of boehmgc that Lix uses into the overlay
          # for consumers of this flake.
-          boehmgc-nix = final.nix.passthru.boehmgc-nix;
+          boehmgc-nix = final.nix.boehmgc-nix;
          # And same thing for our build-release-notes package.
-          build-release-notes = final.nix.passthru.build-release-notes;
+          build-release-notes = final.nix.build-release-notes;
        };
    in
    {
-      # for repl debugging
-      inherit self;
-
      # A Nixpkgs overlay that overrides the 'nix' and
      # 'nix.perl-bindings' packages.
      overlays.default = overlayFor (p: p.stdenv);
@@ -240,11 +233,6 @@
          }
        );

-        # Completion tests for the Nix REPL.
-        repl-completion = forAllSystems (
-          system: nixpkgsFor.${system}.native.callPackage ./tests/repl-completion.nix { }
-        );
-
        # Perl bindings for various platforms.
        perlBindings = forAllSystems (system: nixpkgsFor.${system}.native.nix.passthru.perl-bindings);

@@ -342,7 +330,6 @@
          rl-next = self.hydraJobs.rl-next.${system}.user;
          # Will be empty attr set on i686-linux, and filtered out by forAvailableSystems.
          pre-commit = self.hydraJobs.pre-commit.${system};
-          repl-completion = self.hydraJobs.repl-completion.${system};
        }
        // (lib.optionalAttrs (builtins.elem system linux64BitSystems)) {
          dockerImage = self.hydraJobs.dockerImage.${system};
@@ -392,7 +379,7 @@
              nix = pkgs.callPackage ./package.nix {
                inherit stdenv officialRelease versionSuffix;
                busybox-sandbox-shell = pkgs.busybox-sandbox-shell or pkgs.default-busybox-sandbox;
-                internalApiDocs = false;
+                internalApiDocs = true;
              };
              pre-commit = self.hydraJobs.pre-commit.${pkgs.system} or { };
            in
@@ -9,8 +9,8 @@ clean:
    rm -rf build

 # Prepare meson for building
-setup *OPTIONS:
-    meson setup build --prefix="$PWD/outputs/out" $mesonFlags {{ OPTIONS }}
+setup:
+    meson setup build --prefix="$PWD/outputs/out"

 # Build lix
 build *OPTIONS:
@@ -20,8 +20,6 @@ SIGNIFICANCECES = {

 # This is just hardcoded for better validation. If you think there should be
 # more of them, feel free to add more.
-#
-# Please update doc/manual/src/contributing/hacking.md if you do. Thanks~
 CATEGORIES = [
    'Breaking Changes',
    'Features',
@@ -1,4 +1,4 @@
-#!/usr/bin/env bash
+#!/bin/sh

 # Generates a report of build time based on a meson build using -ftime-trace in
 # Clang.
@@ -142,16 +142,6 @@ else
  cpp_pch = []
 endif

-# gcc 12 is known to miscompile some coroutine-based code quite horribly,
-# causing (among other things) copies of move-only objects and the double
-# frees one would expect when the objects are unique_ptrs. these problems
-# often show up as memory corruption when nesting generators (since we do
-# treat generators like owned memory) and will cause inexplicable crashs.
-assert(
-  cxx.get_id() != 'gcc' or cxx.version().version_compare('>=13'),
-  'GCC 12 and earlier are known to miscompile lix coroutines, use GCC 13 or clang.'
-)
-

 # Translate some historical and Mesony CPU names to Lixy CPU names.
 # FIXME(Qyriad): the 32-bit x86 code is not tested right now, because cross compilation for Lix
@@ -177,7 +167,6 @@ message('canonical Nix system name:', host_system)

 is_linux = host_machine.system() == 'linux'
 is_darwin = host_machine.system() == 'darwin'
-is_freebsd = host_machine.system() == 'freebsd'
 is_x64 = host_machine.cpu_family() == 'x86_64'

 # Per-platform arguments that you should probably pass to shared_module() invocations.
@@ -233,8 +222,7 @@ brotli = [

 openssl = dependency('libcrypto', 'openssl', required : true)

-# FIXME: confirm we actually support such old versions of aws-sdk-cpp
-aws_sdk = dependency('aws-cpp-sdk-core', required : false, version : '>=1.8')
+aws_sdk = dependency('aws-cpp-sdk-core', required : false)
 aws_sdk_transfer = dependency('aws-cpp-sdk-transfer', required : aws_sdk.found(), fallback : ['aws_sdk', 'aws_cpp_sdk_transfer_dep'])
 if aws_sdk.found()
  # The AWS pkg-config adds -std=c++11.
@@ -246,6 +234,12 @@ if aws_sdk.found()
    links : true,
    sources : true,
  )
+  s = aws_sdk.version().split('.')
+  configdata += {
+    'AWS_VERSION_MAJOR': s[0].to_int(),
+    'AWS_VERSION_MINOR': s[1].to_int(),
+    'AWS_VERSION_PATCH': s[2].to_int(),
+  }
  aws_sdk_transfer = aws_sdk_transfer.partial_dependency(
    compile_args : false,
    includes : true,
@@ -297,14 +291,6 @@ gtest = [

 toml11 = dependency('toml11', version : '>=3.7.0', required : true, method : 'cmake')

-pegtl = dependency(
-  'pegtl',
-  version : '>=3.2.7',
-  required : true,
-  method : 'cmake',
-  modules : [ 'taocpp::pegtl' ],
-)
-
 nlohmann_json = dependency('nlohmann_json', required : true)

 # lix-doc is a Rust project provided via buildInputs and unfortunately doesn't have any way to be detected.
@@ -353,6 +339,8 @@ endif
 # that busybox sh won't run busybox applets as builtins (which would break our sandbox).

 lsof = find_program('lsof', native : true)
+bison = find_program('bison', native : true)
+flex = find_program('flex', native : true)

 # This is how Nix does generated headers...
 # other instances of header generation use a very similar command.
@@ -442,7 +430,6 @@ add_project_arguments(
  '-Wimplicit-fallthrough',
  '-Werror=switch',
  '-Werror=switch-enum',
-  '-Werror=unused-result',
  '-Wdeprecated-copy',
  '-Wignored-qualifiers',
  # Enable assertions in libstdc++ by default. Harmless on libc++. Benchmarked
@@ -454,9 +441,7 @@ add_project_arguments(
  language : 'cpp',
 )

-# We turn off the production UBSan if the slower dev UBSan is requested, to
-# give better diagnostics.
-if cxx.get_id() in ['gcc', 'clang'] and 'undefined' not in get_option('b_sanitize')
+if cxx.get_id() in ['gcc', 'clang']
  # 2024-03-24: jade benchmarked the default sanitize reporting in clang and got
  # a regression of about 10% on hackage-packages.nix with clang. So we are trapping instead.
  #
@@ -471,23 +456,12 @@ if cxx.get_id() in ['gcc', 'clang'] and 'undefined' not in get_option('b_sanitiz
  add_project_arguments(sanitize_args, language: 'cpp')
  add_project_link_arguments(sanitize_args, language: 'cpp')
 endif
-# Clang's default of -no-shared-libsan on Linux causes link errors; on macOS it defaults to shared.
-# GCC defaults to shared libsan so is fine.
-if cxx.get_id() == 'clang' and get_option('b_sanitize') != ''
-  add_project_link_arguments('-shared-libsan', language : 'cpp')
-endif

 add_project_link_arguments('-pthread', language : 'cpp')
 if cxx.get_linker_id() in ['ld.bfd', 'ld.gold']
  add_project_link_arguments('-Wl,--no-copy-dt-needed-entries', language : 'cpp')
 endif

-if is_freebsd
-  # FreeBSD's `environ` is defined in `crt1.o`, not `libc.so`,
-  # so the linker thinks it's undefined
-  add_project_link_arguments('-Wl,-z,undefs', language: 'cpp')
-endif
-
 # Generate Chromium tracing files for each compiled file, which enables
 # maintainers/buildtime_report.sh BUILD-DIR to simply work in clang builds.
 #
@@ -0,0 +1,50 @@
+#!/usr/bin/env bash
+# Meson will call this with an absolute path to Bash.
+# The shebang is just for convenience.
+
+# The parser and lexer tab are generated via custom Meson targets in src/libexpr/meson.build,
+# but Meson doesn't support marking only part of a target for install. The generation creates
+# both headers (parser-tab.hh, lexer-tab.hh) and source files (parser-tab.cc, lexer-tab.cc),
+# and we definitely want the former installed, but not the latter. This script is added to
+# Meson's install steps to correct this, as the logic for it is just complex enough to
+# warrant separate and careful handling, because both Meson's configured include directory
+# may or may not be an absolute path, and DESTDIR may or may not be set at all, but can't be
+# manipulated in Meson logic.
+
+set -euo pipefail
+
+echo "cleanup-install: removing Meson-placed C++ sources from dest includedir"
+
+if [[ "${1/--help/}" != "$1" ]]; then
+	echo "cleanup-install: this script should only be called from the Meson build system"
+	exit 1
+fi
+
+# Ensure the includedir was passed as the first argument
+# (set -u will make this fail otherwise).
+includedir="$1"
+# And then ensure that first argument is a directory that exists.
+if ! [[ -d "$1" ]]; then
+	echo "cleanup-install: this script should only be called from the Meson build system"
+	echo "argv[1] (${1@Q}) is not a directory"
+	exit 2
+fi
+
+# If DESTDIR environment variable is set, prepend it to the include dir.
+# Unfortunately, we cannot do this on the Meson side. We do have an environment variable
+# `MESON_INSTALL_DESTDIR_PREFIX`, but that will not refer to the include directory if
+# includedir has been set separately, which Lix's split-output derivation does.
+# We also cannot simply do an inline bash conditional like "${DESTDIR:=}" or similar,
+# because we need to specifically *join* DESTDIR and includedir with a slash, and *not*
+# have a slash if DESTDIR isn't set at all, since $includedir could be a relative directory.
+# Finally, DESTDIR is only available to us as an environment variable in these install scripts,
+# not in Meson logic.
+# Therefore, our best option is to have Meson pass this script the configured includedir,
+# and perform this dance with it and $DESTDIR.
+if [[ -n "${DESTDIR:-}" ]]; then
+	includedir="$DESTDIR/$includedir"
+fi
+
+# Intentionally not using -f.
+# If these files don't exist then our assumptions have been violated and we should fail.
+rm -v "$includedir/lix/libexpr/parser-tab.cc" "$includedir/lix/libexpr/lexer-tab.cc"
@@ -1,23 +0,0 @@
-{
-  stdenv,
-  cmake,
-  ninja,
-  fetchFromGitHub,
-}:
-
-stdenv.mkDerivation {
-  pname = "pegtl";
-  version = "3.2.7";
-
-  src = fetchFromGitHub {
-    repo = "PEGTL";
-    owner = "taocpp";
-    rev = "refs/tags/3.2.7";
-    hash = "sha256-IV5YNGE4EWVrmg2Sia/rcU8jCuiBynQGJM6n3DCWTQU=";
-  };
-
-  nativeBuildInputs = [
-    cmake
-    ninja
-  ];
-}
@@ -10,16 +10,17 @@
  boehmgc-nix ? __forDefaults.boehmgc-nix,
  boehmgc,
  nlohmann_json,
+  bison,
  build-release-notes ? __forDefaults.build-release-notes,
  boost,
  brotli,
  bzip2,
-  callPackage,
  cmake,
  curl,
  doxygen,
  editline-lix ? __forDefaults.editline-lix,
  editline,
+  flex,
  git,
  gtest,
  jq,
@@ -35,7 +36,6 @@
  meson,
  ninja,
  openssl,
-  pegtl ? __forDefaults.pegtl,
  pkg-config,
  python3,
  rapidcheck,
@@ -76,10 +76,8 @@
      configureFlags = prev.configureFlags or [ ] ++ [ (lib.enableFeature true "sigstop") ];
    });

-    lix-doc = callPackage ./lix-doc/package.nix { };
-    build-release-notes = callPackage ./maintainers/build-release-notes.nix { };
-
-    pegtl = callPackage ./misc/pegtl.nix { };
+    lix-doc = pkgs.callPackage ./lix-doc/package.nix { };
+    build-release-notes = pkgs.callPackage ./maintainers/build-release-notes.nix { };
  },
 }:
 let
@@ -212,6 +210,8 @@ stdenv.mkDerivation (finalAttrs: {

  nativeBuildInputs =
    [
+      bison
+      flex
      python3
      meson
      ninja
@@ -250,7 +250,6 @@ stdenv.mkDerivation (finalAttrs: {
      libsodium
      toml11
      lix-doc
-      pegtl
    ]
    ++ lib.optionals hostPlatform.isLinux [
      libseccomp
@@ -305,9 +304,6 @@ stdenv.mkDerivation (finalAttrs: {
      else
        appendToVar configureFlags "--disable-tests"
      fi
-
-      # Fix up /usr/bin/env shebangs relied on by the build
-      patchShebangs --build tests/ doc/manual/
    '';

  mesonBuildType = "debugoptimized";
@@ -383,12 +379,7 @@ stdenv.mkDerivation (finalAttrs: {
  # Export the patched version of boehmgc.
  # flake.nix exports that into its overlay.
  passthru = {
-    inherit (__forDefaults)
-      boehmgc-nix
-      editline-lix
-      build-release-notes
-      pegtl
-      ;
+    inherit (__forDefaults) boehmgc-nix editline-lix build-release-notes;

    inherit officialRelease;

@@ -401,7 +392,6 @@ stdenv.mkDerivation (finalAttrs: {
        bashInteractive,
        clang-tools,
        clangbuildanalyzer,
-        doxygen,
        glibcLocales,
        just,
        llvmPackages,
@@ -467,10 +457,6 @@ stdenv.mkDerivation (finalAttrs: {
              skopeo
              just
              nixfmt
-              # Included above when internalApiDocs is true, but we set that to
-              # false intentionally to save dev build time.
-              # To build them in a dev shell, you can set -Dinternal-api-docs=enabled when configuring.
-              doxygen
              # Load-bearing order. Must come before clang-unwrapped below, but after clang_tools above.
              stdenv.cc
            ]
@@ -490,7 +476,7 @@ stdenv.mkDerivation (finalAttrs: {
              # https://git.lix.systems/lix-project/lix/src/commit/7575db522e9008685c4009423398f6900a16bcce/src/nix/develop.cc#L240-L241
              # this is, of course, absurd.
              if [[ $name != lix-shell-env && $name != lix-shell-env-env ]]; then
-                return
+                return;
              fi

              PATH=$prefix/bin:$PATH
@@ -500,11 +486,6 @@ stdenv.mkDerivation (finalAttrs: {
              # Make bash completion work.
              XDG_DATA_DIRS+=:$out/share

-              if [[ ! -f ./.this-is-lix ]]; then
-                echo "Dev shell not started from inside a Lix repo, skipping repo setup" >&2
-                return
-              fi
-
              ${lib.optionalString (pre-commit-checks ? shellHook) pre-commit-checks.shellHook}
              # Allow `touch .nocontribmsg` to turn this notice off.
              if ! [[ -f .nocontribmsg ]]; then
@@ -65,6 +65,5 @@ if cxx.get_linker_id() in ['ld.bfd', 'ld.gold']
 endif

 libstore = dependency('lixstore', 'lix-store', required : true)
-libutil = dependency('lixutil', 'lix-util', required : true)

 subdir('lib/Nix')
@@ -1,7 +1,3 @@
-// SPDX-FileCopyrightText: 2024 Nix and Lix Authors
-//
-// SPDX-License-Identifier: LGPL-2.1-only
-
 #include "built-path.hh"
 #include "derivations.hh"
 #include "store-api.hh"
@@ -1,7 +1,3 @@
-// SPDX-FileCopyrightText: 2024 Nix and Lix Authors
-//
-// SPDX-License-Identifier: LGPL-2.1-only
-
 #pragma once
 ///@file
 #include "derived-path.hh"
@@ -1,7 +1,3 @@
-// SPDX-FileCopyrightText: 2024 Nix and Lix Authors
-//
-// SPDX-License-Identifier: LGPL-2.1-only
-
 #include <set>

 #include "cmd-profiles.hh"
@@ -248,7 +244,7 @@ StorePath ProfileManifest::build(ref<Store> store)

    /* Add the symlink tree to the store. */
    StringSink sink;
-    sink << dumpPath(tempDir);
+    dumpPath(tempDir, sink);

    auto narHash = hashString(htSHA256, sink.s);

@@ -1,7 +1,3 @@
-// SPDX-FileCopyrightText: 2024 Nix and Lix Authors
-//
-// SPDX-License-Identifier: LGPL-2.1-only
-
 #pragma once
 ///@file

@@ -0,0 +1,11 @@
+#include "command-installable-value.hh"
+
+namespace nix {
+
+void InstallableValueCommand::run(ref<Store> store, ref<Installable> installable)
+{
+    auto installableValue = InstallableValue::require(installable);
+    run(store, installableValue);
+}
+
+}
@@ -0,0 +1,23 @@
+#pragma once
+///@file
+
+#include "installable-value.hh"
+#include "command.hh"
+
+namespace nix {
+
+/**
+ * An InstallableCommand where the single positional argument must be an
+ * InstallableValue in particular.
+ */
+struct InstallableValueCommand : InstallableCommand
+{
+    /**
+     * Entry point to this command
+     */
+    virtual void run(ref<Store> store, ref<InstallableValue> installable) = 0;
+
+    void run(ref<Store> store, ref<Installable> installable) override;
+};
+
+}
@@ -1,7 +1,3 @@
-// SPDX-FileCopyrightText: 2024 Nix and Lix Authors
-//
-// SPDX-License-Identifier: LGPL-2.1-only
-
 #include "command.hh"
 #include "store-api.hh"
 #include "local-fs-store.hh"
@@ -1,7 +1,3 @@
-// SPDX-FileCopyrightText: 2024 Nix and Lix Authors
-//
-// SPDX-License-Identifier: LGPL-2.1-only
-
 #pragma once
 ///@file

@@ -1,7 +1,3 @@
-// SPDX-FileCopyrightText: 2024 Nix and Lix Authors
-//
-// SPDX-License-Identifier: LGPL-2.1-only
-
 #include "eval-settings.hh"
 #include "common-eval-args.hh"
 #include "shared.hh"
@@ -1,7 +1,3 @@
-// SPDX-FileCopyrightText: 2024 Nix and Lix Authors
-//
-// SPDX-License-Identifier: LGPL-2.1-only
-
 #pragma once
 ///@file

@@ -1,7 +1,3 @@
-// SPDX-FileCopyrightText: 2024 Nix and Lix Authors
-//
-// SPDX-License-Identifier: LGPL-2.1-only
-
 #include "editor-for.hh"
 #include "environment-variables.hh"
 #include "source-path.hh"
@@ -1,7 +1,3 @@
-// SPDX-FileCopyrightText: 2024 Nix and Lix Authors
-//
-// SPDX-License-Identifier: LGPL-2.1-only
-
 #pragma once
 ///@file

@@ -1,7 +1,3 @@
-// SPDX-FileCopyrightText: 2024 Nix and Lix Authors
-//
-// SPDX-License-Identifier: LGPL-2.1-only
-
 #include "globals.hh"
 #include "installable-attr-path.hh"
 #include "outputs-spec.hh"
@@ -1,7 +1,3 @@
-// SPDX-FileCopyrightText: 2024 Nix and Lix Authors
-//
-// SPDX-License-Identifier: LGPL-2.1-only
-
 #pragma once
 ///@file

@@ -1,7 +1,3 @@
-// SPDX-FileCopyrightText: 2024 Nix and Lix Authors
-//
-// SPDX-License-Identifier: LGPL-2.1-only
-
 #include "installable-derived-path.hh"
 #include "derivations.hh"

@@ -1,7 +1,3 @@
-// SPDX-FileCopyrightText: 2024 Nix and Lix Authors
-//
-// SPDX-License-Identifier: LGPL-2.1-only
-
 #pragma once
 ///@file

@@ -1,7 +1,3 @@
-// SPDX-FileCopyrightText: 2024 Nix and Lix Authors
-//
-// SPDX-License-Identifier: LGPL-2.1-only
-
 #include "globals.hh"
 #include "installable-flake.hh"
 #include "installable-derived-path.hh"
@@ -1,7 +1,3 @@
-// SPDX-FileCopyrightText: 2024 Nix and Lix Authors
-//
-// SPDX-License-Identifier: LGPL-2.1-only
-
 #pragma once
 ///@file

@@ -1,7 +1,3 @@
-// SPDX-FileCopyrightText: 2024 Nix and Lix Authors
-//
-// SPDX-License-Identifier: LGPL-2.1-only
-
 #include "installable-value.hh"
 #include "eval-cache.hh"
 #include "fetch-to-store.hh"
@@ -1,7 +1,3 @@
-// SPDX-FileCopyrightText: 2024 Nix and Lix Authors
-//
-// SPDX-License-Identifier: LGPL-2.1-only
-
 #pragma once
 ///@file

@@ -1,7 +1,3 @@
-// SPDX-FileCopyrightText: 2024 Nix and Lix Authors
-//
-// SPDX-License-Identifier: LGPL-2.1-only
-
 #include "globals.hh"
 #include "installables.hh"
 #include "installable-derived-path.hh"
@@ -218,7 +214,7 @@ void SourceExprCommand::completeInstallable(AddCompletions & completions, std::s

            evalSettings.pureEval = false;
            auto state = getEvalState();
-            Expr & e = state->parseExprFromFile(
+            Expr *e = state->parseExprFromFile(
                resolveExprPath(state->checkSourcePath(lookupFileArg(*state, *file)))
                );

@@ -397,10 +393,13 @@ ref<eval_cache::EvalCache> openEvalCache(
    EvalState & state,
    std::shared_ptr<flake::LockedFlake> lockedFlake)
 {
-    auto fingerprint = evalSettings.useEvalCache && evalSettings.pureEval
-        ? std::make_optional(lockedFlake->getFingerprint())
-        : std::nullopt;
-    auto rootLoader = [&state, lockedFlake]()
+    auto fingerprint = lockedFlake->getFingerprint();
+    return make_ref<nix::eval_cache::EvalCache>(
+        evalSettings.useEvalCache && evalSettings.pureEval
+            ? std::optional { std::cref(fingerprint) }
+            : std::nullopt,
+        state,
+        [&state, lockedFlake]()
        {
            /* For testing whether the evaluation cache is
               complete. */
@@ -416,17 +415,7 @@ ref<eval_cache::EvalCache> openEvalCache(
            assert(aOutputs);

            return aOutputs->value;
-        };
-
-    if (fingerprint) {
-        auto search = state.evalCaches.find(fingerprint.value());
-        if (search == state.evalCaches.end()) {
-            search = state.evalCaches.emplace(fingerprint.value(), make_ref<nix::eval_cache::EvalCache>(fingerprint, state, rootLoader)).first;
-        }
-        return search->second;
-    } else {
-        return make_ref<nix::eval_cache::EvalCache>(std::nullopt, state, rootLoader);
-    }
+        });
 }

 Installables SourceExprCommand::parseInstallables(
@@ -445,13 +434,13 @@ Installables SourceExprCommand::parseInstallables(
        auto vFile = state->allocValue();

        if (file == "-") {
-            auto & e = state->parseStdin();
+            auto e = state->parseStdin();
            state->eval(e, *vFile);
        }
        else if (file)
            state->evalFile(lookupFileArg(*state, *file), *vFile);
        else {
-            auto & e = state->parseExprFromString(*expr, state->rootPath(CanonPath::fromCwd()));
+            auto e = state->parseExprFromString(*expr, state->rootPath(CanonPath::fromCwd()));
            state->eval(e, *vFile);
        }

@@ -1,7 +1,3 @@
-// SPDX-FileCopyrightText: 2024 Nix and Lix Authors
-//
-// SPDX-License-Identifier: LGPL-2.1-only
-
 #pragma once
 ///@file

@@ -1,7 +1,3 @@
-// SPDX-FileCopyrightText: 2024 Nix and Lix Authors
-//
-// SPDX-License-Identifier: LGPL-2.1-only
-
 #include "legacy.hh"

 namespace nix {
@@ -1,7 +1,3 @@
-// SPDX-FileCopyrightText: 2024 Nix and Lix Authors
-//
-// SPDX-License-Identifier: LGPL-2.1-only
-
 #pragma once
 ///@file

@@ -1,7 +1,3 @@
-// SPDX-FileCopyrightText: 2024 Nix and Lix Authors
-//
-// SPDX-License-Identifier: LGPL-2.1-only
-
 #include "markdown.hh"
 #include "error.hh"
 #include "finally.hh"
@@ -1,7 +1,3 @@
-// SPDX-FileCopyrightText: 2024 Nix and Lix Authors
-//
-// SPDX-License-Identifier: LGPL-2.1-only
-
 #pragma once
 ///@file

@@ -1,9 +1,6 @@
-# SPDX-FileCopyrightText: 2024 Nix and Lix Authors
-#
-# SPDX-License-Identifier: LGPL-2.1-only
-
 libcmd_sources = files(
  'built-path.cc',
+  'command-installable-value.cc',
  'cmd-profiles.cc',
  'command.cc',
  'common-eval-args.cc',
@@ -21,6 +18,7 @@ libcmd_sources = files(

 libcmd_headers = files(
  'built-path.hh',
+  'command-installable-value.hh',
  'cmd-profiles.hh',
  'command.hh',
  'common-eval-args.hh',
@@ -1,7 +1,3 @@
-// SPDX-FileCopyrightText: 2024 Nix and Lix Authors
-//
-// SPDX-License-Identifier: LGPL-2.1-only
-
 #include "error.hh"
 #include "file-system.hh"
 #include "logging.hh"
@@ -1,7 +1,3 @@
-// SPDX-FileCopyrightText: 2024 Nix and Lix Authors
-//
-// SPDX-License-Identifier: LGPL-2.1-only
-
 #pragma once
 /// @file

@@ -1,7 +1,3 @@
-# SPDX-FileCopyrightText: 2024 Nix and Lix Authors
-#
-# SPDX-License-Identifier: LGPL-2.1-only
-
 info: initial: functions:
 let
  final = builtins.foldl' (prev: function: prev // (function info final prev)) initial functions;
@@ -1,14 +1,7 @@
-// SPDX-FileCopyrightText: 2024 Nix and Lix Authors
-//
-// SPDX-License-Identifier: LGPL-2.1-only
-
-#include <cstdio>
-#include <editline.h>
 #include <iostream>
 #include <cstdlib>
 #include <cstring>
 #include <climits>
-#include <string_view>

 #include "box_ptr.hh"
 #include "repl-interacter.hh"
@@ -36,6 +29,7 @@
 #include "local-fs-store.hh"
 #include "signals.hh"
 #include "print.hh"
+#include "progress-bar.hh"
 #include "gc-small-vector.hh"
 #include "users.hh"

@@ -85,8 +79,6 @@ enum class ProcessLineResult {
    PromptAgain,
 };

-using namespace std::literals::string_view_literals;
-
 struct NixRepl
    : AbstractNixRepl
    , detail::ReplCompleterMixin
@@ -94,35 +86,6 @@ struct NixRepl
    , gc
    #endif
 {
-    /* clang-format: off */
-    static constexpr std::array COMMANDS = {
-        "add"sv, "a"sv,
-        "load"sv, "l"sv,
-        "load-flake"sv, "lf"sv,
-        "reload"sv, "r"sv,
-        "edit"sv, "e"sv,
-        "t"sv,
-        "u"sv,
-        "b"sv,
-        "bl"sv,
-        "i"sv,
-        "sh"sv,
-        "log"sv,
-        "print"sv, "p"sv,
-        "quit"sv, "q"sv,
-        "doc"sv,
-        "te"sv,
-    };
-
-    static constexpr std::array DEBUG_COMMANDS = {
-        "env"sv,
-        "bt"sv, "backtrace"sv,
-        "st"sv,
-        "c"sv, "continue"sv,
-        "s"sv, "step"sv,
-    };
-    /* clang-format: on */
-
    size_t debugTraceIndex;

    Strings loadedFiles;
@@ -159,7 +122,7 @@ struct NixRepl
    void reloadFiles();
    void addAttrsToScope(Value & attrs);
    void addVarToScope(const Symbol name, Value & v);
-    Expr & parseString(std::string s);
+    Expr * parseString(std::string s);
    void evalString(std::string s, Value & v);
    void loadDebugTraceEnv(DebugTrace & dt);

@@ -246,7 +209,8 @@ NixRepl::NixRepl(const SearchPath & searchPath, nix::ref<Store> store, ref<EvalS
 {
 }

-void runNix(Path program, const Strings & args)
+void runNix(Path program, const Strings & args,
+    const std::optional<std::string> & input = {})
 {
    auto subprocessEnv = getEnv();
    subprocessEnv["NIX_CONFIG"] = globalConfig.toKeyValue();
@@ -255,7 +219,8 @@ void runNix(Path program, const Strings & args)
        .program = settings.nixBinDir+ "/" + program,
        .args = args,
        .environment = subprocessEnv,
-    }).wait();
+        .input = input,
+    });

    return;
 }
@@ -303,7 +268,7 @@ ReplExitStatus NixRepl::mainLoop()

    /* Stop the progress bar because it interferes with the display of
       the repl. */
-    logger->pause();
+    stopProgressBar();

    std::string input;

@@ -358,36 +323,6 @@ StringSet NixRepl::completePrefix(const std::string & prefix)
 {
    StringSet completions;

-    // We should only complete colon commands if there's a colon at the beginning,
-    // but editline (for... whatever reason) doesn't *give* us the colon in the
-    // completion callback. If the user types :rel<TAB>, `prefix` will only be `rel`.
-    // Luckily, editline provides a global variable for its current buffer, so we can
-    // check for the presence of a colon there.
-    if (rl_line_buffer != nullptr && rl_line_buffer[0] == ':') {
-        for (auto const & colonCmd : this->COMMANDS) {
-            if (colonCmd.starts_with(prefix)) {
-                completions.insert(std::string(colonCmd));
-            }
-        }
-
-        if (state->debugRepl) {
-            for (auto const & colonCmd : this->DEBUG_COMMANDS) {
-                if (colonCmd.starts_with(prefix)) {
-                    completions.insert(std::string(colonCmd));
-                }
-            }
-        }
-
-        // If there were : command completions, then we should only return those,
-        // because otherwise this is not valid Nix syntax.
-        // However if we didn't get any completions, then this could be something
-        // like `:b pkgs.hel<TAB>`, in which case we should do expression completion
-        // as normal.
-        if (!completions.empty()) {
-            return completions;
-        }
-    }
-
    size_t start = prefix.find_last_of(" \n\r\t(){}[]");
    std::string prev, cur;
    if (start == std::string::npos) {
@@ -430,9 +365,9 @@ StringSet NixRepl::completePrefix(const std::string & prefix)
            auto expr = cur.substr(0, dot);
            auto cur2 = cur.substr(dot + 1);

-            Expr & e = parseString(expr);
+            Expr * e = parseString(expr);
            Value v;
-            e.eval(*state, *env, v);
+            e->eval(*state, *env, v);
            state->forceAttrs(v, noPos, "while evaluating an attrset for the purpose of completion (this error should not be displayed; file an issue?)");

            for (auto & i : *v.attrs) {
@@ -654,7 +589,7 @@ ProcessLineResult NixRepl::processLine(std::string line)

        // runProgram redirects stdout to a StringSink,
        // using runProgram2 to allow editors to display their UI
-        runProgram2(RunOptions { .program = editor, .searchPath = true, .args = args }).wait();
+        runProgram2(RunOptions { .program = editor, .searchPath = true, .args = args });

        // Reload right after exiting the editor
        state->resetFileCache();
@@ -687,10 +622,9 @@ ProcessLineResult NixRepl::processLine(std::string line)
            // TODO: this only shows a progress bar for explicitly initiated builds,
            // not eval-time fetching or builds performed for IFD.
            // But we can't just show it everywhere, since that would erase partial output from evaluation.
-            logger->resetProgress();
-            logger->resume();
+            startProgressBar();
            Finally stopLogger([&]() {
-                logger->pause();
+                stopProgressBar();
            });

            state->store->buildPaths({
@@ -824,7 +758,7 @@ ProcessLineResult NixRepl::processLine(std::string line)
            line[p + 1] != '=' &&
            isVarName(name = removeWhitespace(line.substr(0, p))))
        {
-            Expr & e = parseString(line.substr(p + 1));
+            Expr * e = parseString(line.substr(p + 1));
            Value & v(*state->allocValue());
            v.mkThunk(env, e);
            addVarToScope(state->symbols.create(name), v);
@@ -949,7 +883,7 @@ Value * NixRepl::getReplOverlaysEvalFunction()
    auto code =
        #include "repl-overlays.nix.gen.hh"
        ;
-    auto & expr = state->parseExprFromString(
+    auto expr = state->parseExprFromString(
        code,
        SourcePath(evalReplInitFilesPath),
        state->staticBaseEnv
@@ -1057,7 +991,7 @@ Value * NixRepl::bindingsToAttrs()
 }


-Expr & NixRepl::parseString(std::string s)
+Expr * NixRepl::parseString(std::string s)
 {
    return state->parseExprFromString(std::move(s), state->rootPath(CanonPath::fromCwd()), staticEnv);
 }
@@ -1065,16 +999,16 @@ Expr & NixRepl::parseString(std::string s)

 void NixRepl::evalString(std::string s, Value & v)
 {
-    Expr & e = parseString(s);
-    e.eval(*state, *env, v);
+    Expr * e = parseString(s);
+    e->eval(*state, *env, v);
    state->forceValue(v, v.determinePos(noPos));
 }

 Value * NixRepl::evalFile(SourcePath & path)
 {
-    auto & expr = state->parseExprFromFile(path, staticEnv);
+    auto expr = state->parseExprFromFile(path, staticEnv);
    Value * result(state->allocValue());
-    expr.eval(*state, *env, *result);
+    expr->eval(*state, *env, *result);
    state->forceValue(*result, result->determinePos(noPos));
    return result;
 }
@@ -1,7 +1,3 @@
-// SPDX-FileCopyrightText: 2024 Nix and Lix Authors
-//
-// SPDX-License-Identifier: LGPL-2.1-only
-
 #pragma once
 ///@file

@@ -1,7 +1,3 @@
-// SPDX-FileCopyrightText: 2024 Nix and Lix Authors
-//
-// SPDX-License-Identifier: LGPL-2.1-only
-
 #include "attr-path.hh"
 #include "eval-inline.hh"

@@ -1,7 +1,3 @@
-// SPDX-FileCopyrightText: 2024 Nix and Lix Authors
-//
-// SPDX-License-Identifier: LGPL-2.1-only
-
 #pragma once
 ///@file

@@ -1,7 +1,3 @@
-// SPDX-FileCopyrightText: 2024 Nix and Lix Authors
-//
-// SPDX-License-Identifier: LGPL-2.1-only
-
 #include "attr-set.hh"
 #include "eval-inline.hh"

@@ -1,7 +1,3 @@
-// SPDX-FileCopyrightText: 2024 Nix and Lix Authors
-//
-// SPDX-License-Identifier: LGPL-2.1-only
-
 #pragma once
 ///@file

@@ -1,7 +1,3 @@
-// SPDX-FileCopyrightText: 2024 Nix and Lix Authors
-//
-// SPDX-License-Identifier: LGPL-2.1-only
-
 #include "eval-cache.hh"
 #include "sqlite.hh"
 #include "eval.hh"
@@ -1,7 +1,3 @@
-// SPDX-FileCopyrightText: 2024 Nix and Lix Authors
-//
-// SPDX-License-Identifier: LGPL-2.1-only
-
 #pragma once
 ///@file

@@ -1,7 +1,3 @@
-// SPDX-FileCopyrightText: 2024 Nix and Lix Authors
-//
-// SPDX-License-Identifier: LGPL-2.1-only
-
 #include "eval-error.hh"
 #include "eval.hh"
 #include "value.hh"
@@ -1,7 +1,3 @@
-// SPDX-FileCopyrightText: 2024 Nix and Lix Authors
-//
-// SPDX-License-Identifier: LGPL-2.1-only
-
 #pragma once
 ///@file

@@ -51,16 +47,12 @@ MakeError(MissingArgumentError, EvalError);
 MakeError(RestrictedPathError, Error);
 MakeError(InfiniteRecursionError, EvalError);

-/**
- * Represents an exception due to an invalid path; that is, it does not exist.
- * It corresponds to `!Store::validPath()`.
- */
 struct InvalidPathError : public EvalError
 {
 public:
    Path path;
    InvalidPathError(EvalState & state, const Path & path)
-        : EvalError(state, "path '%s' did not exist in the store during evaluation", path)
+        : EvalError(state, "path '%s' is not valid", path)
    {
    }
 };
@@ -1,7 +1,3 @@
-// SPDX-FileCopyrightText: 2024 Nix and Lix Authors
-//
-// SPDX-License-Identifier: LGPL-2.1-only
-
 #pragma once
 ///@file

@@ -90,11 +86,11 @@ void EvalState::forceValue(Value & v, const PosIdx pos)
 {
    if (v.isThunk()) {
        Env * env = v.thunk.env;
-        Expr & expr = *v.thunk.expr;
+        Expr * expr = v.thunk.expr;
        try {
            v.mkBlackhole();
            //checkInterrupt();
-            expr.eval(*this, *env, v);
+            expr->eval(*this, *env, v);
        } catch (...) {
            v.mkThunk(env, expr);
            tryFixupBlackHolePos(v, pos);
@@ -1,7 +1,3 @@
-// SPDX-FileCopyrightText: 2024 Nix and Lix Authors
-//
-// SPDX-License-Identifier: LGPL-2.1-only
-
 #include "file-system.hh"
 #include "globals.hh"
 #include "profiles.hh"
@@ -67,9 +63,11 @@ Strings EvalSettings::getDefaultNixPath()
        }
    };

-    add(getNixDefExpr() + "/channels");
-    add(rootChannelsDir() + "/nixpkgs", "nixpkgs");
-    add(rootChannelsDir());
+    if (!evalSettings.restrictEval && !evalSettings.pureEval) {
+        add(getNixDefExpr() + "/channels");
+        add(rootChannelsDir() + "/nixpkgs", "nixpkgs");
+        add(rootChannelsDir());
+    }

    return res;
 }
@@ -1,7 +1,3 @@
-// SPDX-FileCopyrightText: 2024 Nix and Lix Authors
-//
-// SPDX-License-Identifier: LGPL-2.1-only
-
 #pragma once
 ///@file
 #include "config.hh"
@@ -19,21 +15,9 @@ struct EvalSettings : Config
    static std::string resolvePseudoUrl(std::string_view url);

    Setting<bool> enableNativeCode{this, false, "allow-unsafe-native-code-during-evaluation", R"(
-        Enable built-in functions that allow executing native code.
+        Whether builtin functions that allow executing native code should be enabled.

-        In particular, this adds:
-        - `builtins.importNative` *path* *symbol*
-
-          Runs function with *symbol* from a dynamic shared object (DSO) at *path*.
-          This may be used to add new builtins to the Nix language.
-          The procedure must have the following signature:
-          ```cpp
-          extern "C" typedef void (*ValueInitialiser) (EvalState & state, Value & v);
-          ```
-
-        - `builtins.exec` *arguments*
-
-          Execute a program, where *arguments* are specified as a list of strings, and parse its output as a Nix expression.
+        In particular, this adds the `importNative` and `exec` builtins.
    )"};

    Setting<Strings> nixPath{
@@ -79,17 +63,8 @@ struct EvalSettings : Config
        R"(
          Pure evaluation mode ensures that the result of Nix expressions is fully determined by explicitly declared inputs, and not influenced by external state:

-          - File system and network access is restricted to accesses to immutable data only:
-            - Path literals relative to the home directory like `~/lix` are rejected at parse time.
-            - Access to absolute paths that did not result from Nix language evaluation is rejected when such paths are given as parameters to builtins like, for example, [`builtins.readFile`](@docroot@/language/builtins.md#builtins-readFile).
-
-              Access is nonetheless allowed to (absolute) paths in the Nix store that are returned by builtins like [`builtins.filterSource`](@docroot@/language/builtins.md#builtins-filterSource), [`builtins.fetchTarball`](@docroot@/language/builtins.md#builtins-fetchTarball) and similar.
-            - Impure fetches such as not specifying a commit ID for `builtins.fetchGit` or not specifying a hash for `builtins.fetchTarball` are rejected.
-            - In flakes, access to relative paths outside of the root of the flake's source tree (often, a git repository) is rejected.
-          - The evaluator ignores `NIX_PATH`, `-I` and the `nix-path` setting. Thus, [`builtins.nixPath`](@docroot@/language/builtin-constants.md#builtins-nixPath) is an empty list.
-          - The builtins [`builtins.currentSystem`](@docroot@/language/builtin-constants.md#builtins-currentSystem) and [`builtins.currentTime`](@docroot@/language/builtin-constants.md#builtins-currentTime) are absent from `builtins`.
-          - [`builtins.getEnv`](@docroot@/language/builtin-constants.md#builtins-currentSystem) always returns empty string for any variable.
-          - [`builtins.storePath`](@docroot@/language/builtins.md#builtins-storePath) throws an error (Lix may change this, tracking issue: <https://git.lix.systems/lix-project/lix/issues/402>)
+          - Restrict file system and network access to files specified by cryptographic hash
+          - Disable [`builtins.currentSystem`](@docroot@/language/builtin-constants.md#builtins-currentSystem) and [`builtins.currentTime`](@docroot@/language/builtin-constants.md#builtins-currentTime)
        )"
        };

@@ -111,7 +86,6 @@ struct EvalSettings : Config
          allowed to access `https://github.com/NixOS/patchelf.git`.
        )"};

-
    Setting<bool> traceFunctionCalls{this, false, "trace-function-calls",
        R"(
          If set to `true`, the Nix evaluator will trace every function call.
@@ -1,14 +1,9 @@
-// SPDX-FileCopyrightText: 2024 Nix and Lix Authors
-//
-// SPDX-License-Identifier: LGPL-2.1-only
-
 #include "eval.hh"
 #include "eval-settings.hh"
 #include "hash.hh"
 #include "primops.hh"
 #include "print-options.hh"
 #include "shared.hh"
-#include "suggestions.hh"
 #include "types.hh"
 #include "store-api.hh"
 #include "derivations.hh"
@@ -22,6 +17,7 @@
 #include "gc-small-vector.hh"
 #include "fetch-to-store.hh"
 #include "flake/flakeref.hh"
+#include "parser-tab.hh"

 #include <algorithm>
 #include <chrono>
@@ -422,7 +418,7 @@ EvalState::EvalState(
    }

    if (evalSettings.restrictEval || evalSettings.pureEval) {
-        allowedPaths = std::optional(PathSet());
+        allowedPaths = PathSet();

        for (auto & i : searchPath.elements) {
            auto r = resolveSearchPathPath(i.path);
@@ -954,14 +950,14 @@ void EvalState::mkList(Value & v, size_t size)

 unsigned long nrThunks = 0;

-static inline void mkThunk(Value & v, Env & env, Expr & expr)
+static inline void mkThunk(Value & v, Env & env, Expr * expr)
 {
    v.mkThunk(&env, expr);
    nrThunks++;
 }


-void EvalState::mkThunk_(Value & v, Expr & expr)
+void EvalState::mkThunk_(Value & v, Expr * expr)
 {
    mkThunk(v, baseEnv, expr);
 }
@@ -1062,7 +1058,7 @@ void EvalState::mkSingleDerivedPathString(
 Value * Expr::maybeThunk(EvalState & state, Env & env)
 {
    Value * v = state.allocValue();
-    mkThunk(*v, env, *this);
+    mkThunk(*v, env, this);
    return v;
 }

@@ -1126,7 +1122,7 @@ void EvalState::evalFile(const SourcePath & path_, Value & v, bool mustBeTrivial
        e = j->second;

    if (!e)
-        e = &parseExprFromFile(checkSourcePath(resolvedPath));
+        e = parseExprFromFile(checkSourcePath(resolvedPath));

    cacheFile(path, resolvedPath, e, v, mustBeTrivial);
 }
@@ -1163,7 +1159,7 @@ void EvalState::cacheFile(
        if (mustBeTrivial &&
            !(dynamic_cast<ExprAttrs *>(e)))
            error<EvalError>("file '%s' must be an attribute set", path).debugThrow();
-        eval(*e, v);
+        eval(e, v);
    } catch (Error & e) {
        addErrorTrace(e, "while evaluating the file '%1%':", resolvedPath.to_string());
        throw;
@@ -1174,23 +1170,23 @@ void EvalState::cacheFile(
 }


-void EvalState::eval(Expr & e, Value & v)
+void EvalState::eval(Expr * e, Value & v)
 {
-    e.eval(*this, baseEnv, v);
+    e->eval(*this, baseEnv, v);
 }


-inline bool EvalState::evalBool(Env & env, Expr & e, const PosIdx pos, std::string_view errorCtx)
+inline bool EvalState::evalBool(Env & env, Expr * e, const PosIdx pos, std::string_view errorCtx)
 {
    try {
        Value v;
-        e.eval(*this, env, v);
+        e->eval(*this, env, v);
        if (v.type() != nBool)
            error<TypeError>(
                 "expected a Boolean but found %1%: %2%",
                 showType(v),
                 ValuePrinter(*this, v, errorPrintOptions)
-             ).atPos(pos).withFrame(env, e).debugThrow();
+             ).atPos(pos).withFrame(env, *e).debugThrow();
        return v.boolean;
    } catch (Error & e) {
        e.addTrace(positions[pos], errorCtx);
@@ -1199,16 +1195,16 @@ inline bool EvalState::evalBool(Env & env, Expr & e, const PosIdx pos, std::stri
 }


-inline void EvalState::evalAttrs(Env & env, Expr & e, Value & v, const PosIdx pos, std::string_view errorCtx)
+inline void EvalState::evalAttrs(Env & env, Expr * e, Value & v, const PosIdx pos, std::string_view errorCtx)
 {
    try {
-        e.eval(*this, env, v);
+        e->eval(*this, env, v);
        if (v.type() != nAttrs)
            error<TypeError>(
                "expected a set but found %1%: %2%",
                showType(v),
                ValuePrinter(*this, v, errorPrintOptions)
-            ).withFrame(env, e).debugThrow();
+            ).withFrame(env, *e).debugThrow();
    } catch (Error & e) {
        e.addTrace(positions[pos], errorCtx);
        throw;
@@ -1251,7 +1247,7 @@ Env * ExprAttrs::buildInheritFromEnv(EvalState & state, Env & up)
    inheritEnv.up = &up;

    Displacement displ = 0;
-    for (auto & from : *inheritFromExprs)
+    for (auto from : *inheritFromExprs)
        inheritEnv.values[displ++] = from->maybeThunk(state, up);

    return &inheritEnv;
@@ -1281,7 +1277,7 @@ void ExprAttrs::eval(EvalState & state, Env & env, Value & v)
            Value * vAttr;
            if (hasOverrides && i.second.kind != AttrDef::Kind::Inherited) {
                vAttr = state.allocValue();
-                mkThunk(*vAttr, *i.second.chooseByKind(&env2, &env, inheritEnv), *i.second.e);
+                mkThunk(*vAttr, *i.second.chooseByKind(&env2, &env, inheritEnv), i.second.e);
            } else
                vAttr = i.second.e->maybeThunk(state, *i.second.chooseByKind(&env2, &env, inheritEnv));
            env2.values[displ++] = vAttr;
@@ -1430,26 +1426,11 @@ static std::string showAttrPath(EvalState & state, Env & env, const AttrPath & a

 void ExprSelect::eval(EvalState & state, Env & env, Value & v)
 {
-    Value vFirst;
+    Value vTmp;
+    PosIdx pos2;
+    Value * vAttrs = &vTmp;

-    // Pointer to the current attrset Value in this select chain.
-    Value * vCurrent = &vFirst;
-    // Position for the current attrset Value in this select chain.
-    PosIdx posCurrent;
-
-    try {
-        e->eval(state, env, vFirst);
-    } catch (Error & e) {
-        assert(this->e != nullptr);
-        state.addErrorTrace(
-            e,
-            getPos(),
-            "while evaluating '%s' to select '%s' on it",
-            ExprPrinter(state, *this->e),
-            showAttrPath(state.symbols, this->attrPath)
-        );
-        throw;
-    }
+    e->eval(state, env, vTmp);

    try {
        auto dts = state.debugRepl
@@ -1462,112 +1443,48 @@ void ExprSelect::eval(EvalState & state, Env & env, Value & v)
                showAttrPath(state, env, attrPath))
            : nullptr;

-        for (auto const & [partIdx, currentAttrName] : enumerate(attrPath)) {
+        for (auto & i : attrPath) {
            state.nrLookups++;
-
-            Symbol const name = getName(currentAttrName, state, env);
-
-            // For formatting errors, which should be done only when needed.
-            auto partsSoFar = [&]() -> std::string {
-                std::stringstream ss;
-                // We start with the base thing this ExprSelect is selecting on.
-                assert(this->e != nullptr);
-                this->e->show(state.symbols, ss);
-
-                // Then grab each part of the attr path up to this one.
-                assert(partIdx < attrPath.size());
-                std::span<AttrName> const parts(
-                    attrPath.begin(),
-                    attrPath.begin() + partIdx
-                );
-
-                // And convert them to strings and join them.
-                for (auto const & part : parts) {
-                    auto const partName = getName(part, state, env);
-                    ss << "." << state.symbols[partName];
-                }
-
-                return ss.str();
-            };
-
-            try {
-                state.forceValue(*vCurrent, pos);
-            } catch (Error & e) {
-                state.addErrorTrace(
-                    e,
-                    getPos(),
-                    "while evaluating '%s' to select '%s' on it",
-                    partsSoFar(),
-                    state.symbols[name]
-                );
-                throw;
-            }
-
-            if (vCurrent->type() != nAttrs) {
-
-                // If we have an `or` provided default,
-                // then this is allowed to not be an attrset.
-                if (def != nullptr) {
-                    this->def->eval(state, env, v);
+            Bindings::iterator j;
+            auto name = getName(i, state, env);
+            if (def) {
+                state.forceValue(*vAttrs, pos);
+                if (vAttrs->type() != nAttrs ||
+                    (j = vAttrs->attrs->find(name)) == vAttrs->attrs->end())
+                {
+                    def->eval(state, env, v);
                    return;
                }
-
-                // Otherwise, we must type error.
-                state.error<TypeError>(
-                    "expected a set but found %s: %s",
-                    showType(*vCurrent),
-                    ValuePrinter(state, *vCurrent, errorPrintOptions)
-                ).addTrace(
-                    pos,
-                    HintFmt("while selecting '%s' on '%s'", state.symbols[name], partsSoFar())
-                ).debugThrow();
-            }
-
-            // Now that we know this is actually an attrset, try to find an attr
-            // with the selected name.
-            Bindings::iterator attrIt = vCurrent->attrs->find(name);
-            if (attrIt == vCurrent->attrs->end()) {
-
-                // If we have an `or` provided default, then we'll use that.
-                if (def != nullptr) {
-                    this->def->eval(state, env, v);
-                    return;
+            } else {
+                state.forceAttrs(*vAttrs, pos, "while selecting an attribute");
+                if ((j = vAttrs->attrs->find(name)) == vAttrs->attrs->end()) {
+                    std::set<std::string> allAttrNames;
+                    for (auto & attr : *vAttrs->attrs)
+                        allAttrNames.insert(state.symbols[attr.name]);
+                    auto suggestions = Suggestions::bestMatches(allAttrNames, state.symbols[name]);
+                    state.error<EvalError>("attribute '%1%' missing", state.symbols[name])
+                        .atPos(pos).withSuggestions(suggestions).withFrame(env, *this).debugThrow();
                }
-
-                // Otherwise, missing attr error.
-                std::set<std::string> allAttrNames;
-                for (auto const & attr : *vCurrent->attrs) {
-                    allAttrNames.insert(state.symbols[attr.name]);
-                }
-                auto suggestions = Suggestions::bestMatches(allAttrNames, state.symbols[name]);
-                state.error<EvalError>("attribute '%s' missing", state.symbols[name])
-                    .atPos(pos)
-                    .withSuggestions(suggestions)
-                    .withFrame(env, *this)
-                    .debugThrow();
            }
-
-            // If we're here, then we successfully found the attribute.
-            // Set our currently operated-on attrset to this one, and keep going.
-            vCurrent = attrIt->value;
-            posCurrent = attrIt->pos;
-            if (state.countCalls) state.attrSelects[posCurrent]++;
+            vAttrs = j->value;
+            pos2 = j->pos;
+            if (state.countCalls) state.attrSelects[pos2]++;
        }

-        state.forceValue(*vCurrent, (posCurrent ? posCurrent : this->pos));
+        state.forceValue(*vAttrs, (pos2 ? pos2 : this->pos ) );

    } catch (Error & e) {
-        if (posCurrent) {
-            auto pos2r = state.positions[posCurrent];
+        if (pos2) {
+            auto pos2r = state.positions[pos2];
            auto origin = std::get_if<SourcePath>(&pos2r.origin);
            if (!(origin && *origin == state.derivationInternal))
-                state.addErrorTrace(e, posCurrent, "while evaluating the attribute '%1%'",
+                state.addErrorTrace(e, pos2, "while evaluating the attribute '%1%'",
                    showAttrPath(state, env, attrPath));
        }
        throw;
    }

-    v = *vCurrent;
+    v = *vAttrs;
 }


@@ -1616,66 +1533,6 @@ public:
 };
 };

-/** Currently these each just take one, but maybe in the future we could have diagnostics
- * for all unexpected and missing arguments?
- */
-struct FormalsMatch
-{
-    std::vector<Symbol> missing;
-    std::vector<Symbol> unexpected;
-};
-
-/** Matchup an attribute argument set to a lambda's formal arguments,
- * or return what arguments were required but not given, or given but not allowed.
- * (currently returns only one, for each).
- */
-FormalsMatch matchupFormals(EvalState & state, Env & env, Displacement & displ, ExprLambda const & lambda, Bindings & attrs)
-{
-    size_t attrsUsed = 0;
-
-    for (auto const & formal : lambda.formals->formals) {
-
-        // The attribute whose name matches the name of the formal we're matching up, if it exists.
-        Attr const * matchingArg = attrs.get(formal.name);
-        if (matchingArg) {
-            attrsUsed += 1;
-            env.values[displ] = matchingArg->value;
-            displ += 1;
-
-            // We're done here. Move on to the next formal.
-            continue;
-        }
-
-        // The argument for this formal wasn't given.
-        // If the formal has a default, use it.
-        if (formal.def) {
-            env.values[displ] = formal.def->maybeThunk(state, env);
-            displ += 1;
-        } else {
-            // Otherwise, let our caller know what was missing.
-            return FormalsMatch{
-                .missing = {formal.name},
-            };
-        }
-    }
-
-    // Check for unexpected extra arguments.
-    if (!lambda.formals->ellipsis && attrsUsed != attrs.size()) {
-        // Return the first unexpected argument.
-        for (Attr const & attr : attrs) {
-            if (!lambda.formals->has(attr.name)) {
-                return FormalsMatch{
-                    .unexpected = {attr.name},
-                };
-            }
-        }
-
-        abort(); // unreachable.
-    }
-
-    return FormalsMatch{};
-}
-
 void EvalState::callFunction(Value & fun, size_t nrArgs, Value * * args, Value & vRes, const PosIdx pos)
 {
    if (callDepth > evalSettings.maxCallDepth)
@@ -1729,42 +1586,53 @@ void EvalState::callFunction(Value & fun, size_t nrArgs, Value * * args, Value &
                if (lambda.arg)
                    env2.values[displ++] = args[0];

-                ///* For each formal argument, get the actual argument.  If
-                //   there is no matching actual argument but the formal
-                //   argument has a default, use the default. */
-                auto const formalsMatch = matchupFormals(
-                    *this,
-                    env2,
-                    displ,
-                    lambda,
-                    *args[0]->attrs
-                );
-                for (auto const & missingArg : formalsMatch.missing) {
-                    auto const missing = symbols[missingArg];
-                    error<TypeError>("function '%s' called without required argument '%s'", lambda.getName(symbols), missing)
-                        .atPos(lambda.pos)
-                        .withTrace(pos, "from call site")
-                        .withFrame(*fun.lambda.env, lambda)
-                        .debugThrow();
-                }
-                for (auto const & unexpectedArg : formalsMatch.unexpected) {
-                    auto const unex = symbols[unexpectedArg];
-                    std::set<std::string> formalNames;
-                    for (auto const & formal : lambda.formals->formals) {
-                        formalNames.insert(symbols[formal.name]);
+                /* For each formal argument, get the actual argument.  If
+                   there is no matching actual argument but the formal
+                   argument has a default, use the default. */
+                size_t attrsUsed = 0;
+                for (auto & i : lambda.formals->formals) {
+                    auto j = args[0]->attrs->get(i.name);
+                    if (!j) {
+                        if (!i.def) {
+                            error<TypeError>("function '%1%' called without required argument '%2%'",
+                                             (lambda.name ? std::string(symbols[lambda.name]) : "anonymous lambda"),
+                                             symbols[i.name])
+                                    .atPos(lambda.pos)
+                                    .withTrace(pos, "from call site")
+                                    .withFrame(*fun.lambda.env, lambda)
+                                    .debugThrow();
+                        }
+                        env2.values[displ++] = i.def->maybeThunk(*this, env2);
+                    } else {
+                        attrsUsed++;
+                        env2.values[displ++] = j->value;
                    }
-                    auto sug = Suggestions::bestMatches(formalNames, unex);
-                    error<TypeError>("function '%s' called with unexpected argument '%s'", lambda.getName(symbols), unex)
-                        .atPos(lambda.pos)
-                        .withTrace(pos, "from call site")
-                        .withSuggestions(sug)
-                        .withFrame(*fun.lambda.env, lambda)
-                        .debugThrow();
                }

+                /* Check that each actual argument is listed as a formal
+                   argument (unless the attribute match specifies a `...'). */
+                if (!lambda.formals->ellipsis && attrsUsed != args[0]->attrs->size()) {
+                    /* Nope, so show the first unexpected argument to the
+                       user. */
+                    for (auto & i : *args[0]->attrs)
+                        if (!lambda.formals->has(i.name)) {
+                            std::set<std::string> formalNames;
+                            for (auto & formal : lambda.formals->formals)
+                                formalNames.insert(symbols[formal.name]);
+                            auto suggestions = Suggestions::bestMatches(formalNames, symbols[i.name]);
+                            error<TypeError>("function '%1%' called with unexpected argument '%2%'",
+                                             (lambda.name ? std::string(symbols[lambda.name]) : "anonymous lambda"),
+                                             symbols[i.name])
+                                .atPos(lambda.pos)
+                                .withTrace(pos, "from call site")
+                                .withSuggestions(suggestions)
+                                .withFrame(*fun.lambda.env, lambda)
+                                .debugThrow();
+                        }
+                    abort(); // can't happen
+                }
            }

-
            nrFunctionCalls++;
            if (countCalls) incrFunctionCall(&lambda);

@@ -1774,7 +1642,9 @@ void EvalState::callFunction(Value & fun, size_t nrArgs, Value * * args, Value &
                    ? makeDebugTraceStacker(
                        *this, *lambda.body, env2, positions[lambda.pos],
                        "while calling %s",
-                        lambda.getQuotedName(symbols))
+                        lambda.name
+                        ? concatStrings("'", symbols[lambda.name], "'")
+                        : "anonymous lambda")
                    : nullptr;

                lambda.body->eval(*this, env2, vCur);
@@ -1784,7 +1654,9 @@ void EvalState::callFunction(Value & fun, size_t nrArgs, Value * * args, Value &
                        e,
                        lambda.pos,
                        "while calling %s",
-                        lambda.getQuotedName(symbols));
+                        lambda.name
+                        ? concatStrings("'", symbols[lambda.name], "'")
+                        : "anonymous lambda");
                    if (pos) addErrorTrace(e, pos, "from call site");
                }
                throw;
@@ -1811,15 +1683,6 @@ void EvalState::callFunction(Value & fun, size_t nrArgs, Value * * args, Value &

                try {
                    fn->fun(*this, vCur.determinePos(noPos), args, vCur);
-                } catch (ThrownError & e) {
-                    // Distinguish between an error that simply happened while "throw"
-                    // was being evaluated and an explicit thrown error.
-                    if (fn->name == "throw") {
-                        addErrorTrace(e, pos, "caused by explicit %s", "throw");
-                    } else {
-                        addErrorTrace(e, pos, "while calling the '%s' builtin", fn->name);
-                    }
-                    throw;
                } catch (Error & e) {
                    addErrorTrace(e, pos, "while calling the '%1%' builtin", fn->name);
                    throw;
@@ -2009,13 +1872,13 @@ void ExprWith::eval(EvalState & state, Env & env, Value & v)
 void ExprIf::eval(EvalState & state, Env & env, Value & v)
 {
    // We cheat in the parser, and pass the position of the condition as the position of the if itself.
-    (state.evalBool(env, *cond, pos, "while evaluating a branch condition") ? *then : *else_).eval(state, env, v);
+    (state.evalBool(env, cond, pos, "while evaluating a branch condition") ? then : else_)->eval(state, env, v);
 }


 void ExprAssert::eval(EvalState & state, Env & env, Value & v)
 {
-    if (!state.evalBool(env, *cond, pos, "in the condition of the assert statement")) {
+    if (!state.evalBool(env, cond, pos, "in the condition of the assert statement")) {
        std::ostringstream out;
        cond->show(state.symbols, out);
        state.error<AssertionError>("assertion '%1%' failed", out.str()).atPos(pos).withFrame(env, *this).debugThrow();
@@ -2026,7 +1889,7 @@ void ExprAssert::eval(EvalState & state, Env & env, Value & v)

 void ExprOpNot::eval(EvalState & state, Env & env, Value & v)
 {
-    v.mkBool(!state.evalBool(env, *e, getPos(), "in the argument of the not operator")); // XXX: FIXME: !
+    v.mkBool(!state.evalBool(env, e, getPos(), "in the argument of the not operator")); // XXX: FIXME: !
 }


@@ -2048,27 +1911,27 @@ void ExprOpNEq::eval(EvalState & state, Env & env, Value & v)

 void ExprOpAnd::eval(EvalState & state, Env & env, Value & v)
 {
-    v.mkBool(state.evalBool(env, *e1, pos, "in the left operand of the AND (&&) operator") && state.evalBool(env, *e2, pos, "in the right operand of the AND (&&) operator"));
+    v.mkBool(state.evalBool(env, e1, pos, "in the left operand of the AND (&&) operator") && state.evalBool(env, e2, pos, "in the right operand of the AND (&&) operator"));
 }


 void ExprOpOr::eval(EvalState & state, Env & env, Value & v)
 {
-    v.mkBool(state.evalBool(env, *e1, pos, "in the left operand of the OR (||) operator") || state.evalBool(env, *e2, pos, "in the right operand of the OR (||) operator"));
+    v.mkBool(state.evalBool(env, e1, pos, "in the left operand of the OR (||) operator") || state.evalBool(env, e2, pos, "in the right operand of the OR (||) operator"));
 }


 void ExprOpImpl::eval(EvalState & state, Env & env, Value & v)
 {
-    v.mkBool(!state.evalBool(env, *e1, pos, "in the left operand of the IMPL (->) operator") || state.evalBool(env, *e2, pos, "in the right operand of the IMPL (->) operator"));
+    v.mkBool(!state.evalBool(env, e1, pos, "in the left operand of the IMPL (->) operator") || state.evalBool(env, e2, pos, "in the right operand of the IMPL (->) operator"));
 }


 void ExprOpUpdate::eval(EvalState & state, Env & env, Value & v)
 {
    Value v1, v2;
-    state.evalAttrs(env, *e1, v1, pos, "in the left operand of the update (//) operator");
-    state.evalAttrs(env, *e2, v2, pos, "in the right operand of the update (//) operator");
+    state.evalAttrs(env, e1, v1, pos, "in the left operand of the update (//) operator");
+    state.evalAttrs(env, e2, v2, pos, "in the right operand of the update (//) operator");

    state.nrOpUpdates++;

@@ -2172,10 +2035,10 @@ void ExprConcatStrings::eval(EvalState & state, Env & env, Value & v)
    };

    // List of returned strings. References to these Values must NOT be persisted.
-    SmallTemporaryValueVector<conservativeStackReservation> values(es.size());
+    SmallTemporaryValueVector<conservativeStackReservation> values(es->size());
    Value * vTmpP = values.data();

-    for (auto & [i_pos, i] : es) {
+    for (auto & [i_pos, i] : *es) {
        Value & vTmp = *vTmpP++;
        i->eval(state, env, vTmp);

@@ -2205,7 +2068,7 @@ void ExprConcatStrings::eval(EvalState & state, Env & env, Value & v)
            } else
                state.error<EvalError>("cannot add %1% to a float", showType(vTmp)).atPos(i_pos).withFrame(env, *this).debugThrow();
        } else {
-            if (s.empty()) s.reserve(es.size());
+            if (s.empty()) s.reserve(es->size());
            /* skip canonization of first path, which would only be not
            canonized in the first place if it's coming from a ./${foo} type
            path */
@@ -2889,39 +2752,39 @@ SourcePath resolveExprPath(SourcePath path)
 }


-Expr & EvalState::parseExprFromFile(const SourcePath & path)
+Expr * EvalState::parseExprFromFile(const SourcePath & path)
 {
    return parseExprFromFile(path, staticBaseEnv);
 }


-Expr & EvalState::parseExprFromFile(const SourcePath & path, std::shared_ptr<StaticEnv> & staticEnv)
+Expr * EvalState::parseExprFromFile(const SourcePath & path, std::shared_ptr<StaticEnv> & staticEnv)
 {
    auto buffer = path.readFile();
    // readFile hopefully have left some extra space for terminators
    buffer.append("\0\0", 2);
-    return *parse(buffer.data(), buffer.size(), Pos::Origin(path), path.parent(), staticEnv);
+    return parse(buffer.data(), buffer.size(), Pos::Origin(path), path.parent(), staticEnv);
 }


-Expr & EvalState::parseExprFromString(std::string s_, const SourcePath & basePath, std::shared_ptr<StaticEnv> & staticEnv)
+Expr * EvalState::parseExprFromString(std::string s_, const SourcePath & basePath, std::shared_ptr<StaticEnv> & staticEnv)
 {
    // NOTE this method (and parseStdin) must take care to *fully copy* their input
    // into their respective Pos::Origin until the parser stops overwriting its input
    // data.
    auto s = make_ref<std::string>(s_);
    s_.append("\0\0", 2);
-    return *parse(s_.data(), s_.size(), Pos::String{.source = s}, basePath, staticEnv);
+    return parse(s_.data(), s_.size(), Pos::String{.source = s}, basePath, staticEnv);
 }


-Expr & EvalState::parseExprFromString(std::string s, const SourcePath & basePath)
+Expr * EvalState::parseExprFromString(std::string s, const SourcePath & basePath)
 {
    return parseExprFromString(std::move(s), basePath, staticBaseEnv);
 }


-Expr & EvalState::parseStdin()
+Expr * EvalState::parseStdin()
 {
    // NOTE this method (and parseExprFromString) must take care to *fully copy* their
    // input into their respective Pos::Origin until the parser stops overwriting its
@@ -2931,7 +2794,7 @@ Expr & EvalState::parseStdin()
    // drainFD should have left some extra space for terminators
    auto s = make_ref<std::string>(buffer);
    buffer.append("\0\0", 2);
-    return *parse(buffer.data(), buffer.size(), Pos::Stdin{.source = s}, rootPath(CanonPath::fromCwd()), staticBaseEnv);
+    return parse(buffer.data(), buffer.size(), Pos::Stdin{.source = s}, rootPath(CanonPath::fromCwd()), staticBaseEnv);
 }


@@ -3020,6 +2883,21 @@ std::optional<std::string> EvalState::resolveSearchPathPath(const SearchPath::Pa
 }


+Expr * EvalState::parse(
+    char * text,
+    size_t length,
+    Pos::Origin origin,
+    const SourcePath & basePath,
+    std::shared_ptr<StaticEnv> & staticEnv)
+{
+    auto result = parseExprFromBuf(text, length, origin, basePath, symbols, positions, exprSymbols);
+
+    result->bindVars(*this, staticEnv);
+
+    return result;
+}
+
+
 std::string ExternalValueBase::coerceToString(EvalState & state, const PosIdx & pos, NixStringContext & context, bool copyMore, bool copyToStore) const
 {
    state.error<TypeError>(
@@ -1,7 +1,3 @@
-// SPDX-FileCopyrightText: 2024 Nix and Lix Authors
-//
-// SPDX-License-Identifier: LGPL-2.1-only
-
 #pragma once
 ///@file

@@ -13,13 +9,14 @@
 #include "symbol-table.hh"
 #include "config.hh"
 #include "experimental-features.hh"
+#include "input-accessor.hh"
 #include "search-path.hh"
 #include "repl-exit-status.hh"

-#include <gc/gc_allocator.h>
 #include <map>
 #include <optional>
 #include <unordered_map>
+#include <mutex>
 #include <functional>

 namespace nix {
@@ -36,31 +33,12 @@ class EvalState;
 class StorePath;
 struct SingleDerivedPath;
 enum RepairFlag : bool;
-struct MemoryInputAccessor;
-namespace eval_cache {
-    class EvalCache;
-}
-
-/** Alias for std::map which uses boehmgc's allocator conditional on us actually
- * using boehmgc in this build.
- */
-#if HAVE_BOEHMGC
-    template<typename KeyT, typename ValueT>
-    using GcMap = std::map<
-        KeyT,
-        ValueT,
-        std::less<KeyT>,
-        traceable_allocator<std::pair<KeyT const, ValueT>>
-    >;
-#else
-    using GcMap = std::map<KeyT, ValueT>
-#endif


 /**
 * Function that implements a primop.
 */
-using PrimOpImpl = void(EvalState & state, PosIdx pos, Value ** args, Value & v);
+typedef void (* PrimOpFun) (EvalState & state, const PosIdx pos, Value * * args, Value & v);

 /**
 * Info about a primitive operation, and its implementation
@@ -94,7 +72,7 @@ struct PrimOp
    /**
     * Implementation of the primop.
     */
-    std::function<PrimOpImpl> fun;
+    std::function<std::remove_pointer<PrimOpFun>::type> fun;

    /**
     * Optional experimental for this to be gated on.
@@ -133,7 +111,11 @@ struct Constant
    bool impureOnly = false;
 };

-using ValMap = GcMap<std::string, Value *>;
+#if HAVE_BOEHMGC
+    typedef std::map<std::string, Value *, std::less<std::string>, traceable_allocator<std::pair<const std::string, Value *> > > ValMap;
+#else
+    typedef std::map<std::string, Value *> ValMap;
+#endif

 struct Env
 {
@@ -228,7 +210,7 @@ public:
    /**
     * Debugger
     */
-    std::function<ReplExitStatus(ref<EvalState> es, ValMap const & extraEnv)> debugRepl;
+    ReplExitStatus (* debugRepl)(ref<EvalState> es, const ValMap & extraEnv);
    bool debugStop;
    bool inDebugger = false;
    int trylevel;
@@ -252,11 +234,6 @@ public:
        return *new EvalErrorBuilder<T>(*this, args...);
    }

-    /**
-     * A cache for evaluation caches, so as to reuse the same root value if possible
-     */
-    std::map<const Hash, ref<eval_cache::EvalCache>> evalCaches;
-
 private:

    /* Cache for calls to addToStore(); maps source paths to the store
@@ -266,13 +243,21 @@ private:
    /**
     * A cache from path names to parse trees.
     */
-    using FileParseCache = GcMap<SourcePath, Expr *>;
+#if HAVE_BOEHMGC
+    typedef std::map<SourcePath, Expr *, std::less<SourcePath>, traceable_allocator<std::pair<const SourcePath, Expr *>>> FileParseCache;
+#else
+    typedef std::map<SourcePath, Expr *> FileParseCache;
+#endif
    FileParseCache fileParseCache;

    /**
     * A cache from path names to values.
     */
-    using FileEvalCache = GcMap<SourcePath, Value>;
+#if HAVE_BOEHMGC
+    typedef std::map<SourcePath, Value, std::less<SourcePath>, traceable_allocator<std::pair<const SourcePath, Value>>> FileEvalCache;
+#else
+    typedef std::map<SourcePath, Value> FileEvalCache;
+#endif
    FileEvalCache fileEvalCache;

    SearchPath searchPath;
@@ -355,16 +340,16 @@ public:
    /**
     * Parse a Nix expression from the specified file.
     */
-    Expr & parseExprFromFile(const SourcePath & path);
-    Expr & parseExprFromFile(const SourcePath & path, std::shared_ptr<StaticEnv> & staticEnv);
+    Expr * parseExprFromFile(const SourcePath & path);
+    Expr * parseExprFromFile(const SourcePath & path, std::shared_ptr<StaticEnv> & staticEnv);

    /**
     * Parse a Nix expression from the specified string.
     */
-    Expr & parseExprFromString(std::string s, const SourcePath & basePath, std::shared_ptr<StaticEnv> & staticEnv);
-    Expr & parseExprFromString(std::string s, const SourcePath & basePath);
+    Expr * parseExprFromString(std::string s, const SourcePath & basePath, std::shared_ptr<StaticEnv> & staticEnv);
+    Expr * parseExprFromString(std::string s, const SourcePath & basePath);

-    Expr & parseStdin();
+    Expr * parseStdin();

    /**
     * Evaluate an expression read from the given file to normal
@@ -405,15 +390,15 @@ public:
     *
     * @param [out] v The resulting is stored here.
     */
-    void eval(Expr & e, Value & v);
+    void eval(Expr * e, Value & v);

    /**
     * Evaluation the expression, then verify that it has the expected
     * type.
     */
-    inline bool evalBool(Env & env, Expr & e);
-    inline bool evalBool(Env & env, Expr & e, const PosIdx pos, std::string_view errorCtx);
-    inline void evalAttrs(Env & env, Expr & e, Value & v, const PosIdx pos, std::string_view errorCtx);
+    inline bool evalBool(Env & env, Expr * e);
+    inline bool evalBool(Env & env, Expr * e, const PosIdx pos, std::string_view errorCtx);
+    inline void evalAttrs(Env & env, Expr * e, Value & v, const PosIdx pos, std::string_view errorCtx);

    /**
     * If `v` is a thunk, enter it and overwrite `v` with the result
@@ -634,7 +619,7 @@ public:
    }

    void mkList(Value & v, size_t length);
-    void mkThunk_(Value & v, Expr & expr);
+    void mkThunk_(Value & v, Expr * expr);
    void mkPos(Value & v, PosIdx pos);

    /**
@@ -743,15 +728,15 @@ private:

    bool countCalls;

-    using PrimOpCalls = std::map<std::string, size_t>;
+    typedef std::map<std::string, size_t> PrimOpCalls;
    PrimOpCalls primOpCalls;

-    using FunctionCalls = std::map<ExprLambda *, size_t>;
+    typedef std::map<ExprLambda *, size_t> FunctionCalls;
    FunctionCalls functionCalls;

    void incrFunctionCall(ExprLambda * fun);

-    using AttrSelects = std::map<PosIdx, size_t>;
+    typedef std::map<PosIdx, size_t> AttrSelects;
    AttrSelects attrSelects;

    friend struct ExprOpUpdate;
@@ -793,7 +778,7 @@ std::string showType(const Value & v);
 */
 SourcePath resolveExprPath(SourcePath path);

-static constexpr std::string_view corepkgsPrefix{"/__corepkgs__/"};
+static const std::string corepkgsPrefix{"/__corepkgs__/"};


 }
@@ -1,7 +1,3 @@
-# SPDX-FileCopyrightText: 2024 Nix and Lix Authors
-#
-# SPDX-License-Identifier: LGPL-2.1-only
-
 {
  system ? "", # obsolete
  url,
@@ -1,7 +1,3 @@
-# SPDX-FileCopyrightText: 2024 Nix and Lix Authors
-#
-# SPDX-License-Identifier: LGPL-2.1-only
-
 lockFileStr: rootSrc: rootSubdir:

 let
@@ -1,7 +1,3 @@
-// SPDX-FileCopyrightText: 2024 Nix and Lix Authors
-//
-// SPDX-License-Identifier: LGPL-2.1-only
-
 #include "flake.hh"
 #include "logging.hh"
 #include "users.hh"
@@ -55,46 +51,30 @@ void ConfigFile::apply()
        else
            assert(false);

-        bool trusted = whitelist.count(baseName);
-        if (!trusted) {
-            switch (nix::fetchSettings.acceptFlakeConfig) {
-            case AcceptFlakeConfig::True: {
-                trusted = true;
-                break;
-            }
-            case AcceptFlakeConfig::Ask: {
-                auto trustedList = readTrustedList();
-                auto tlname = get(trustedList, name);
-                if (auto saved = tlname ? get(*tlname, valueS) : nullptr) {
-                    trusted = *saved;
-                    printInfo("Using saved setting for '%s = %s' from ~/.local/share/nix/trusted-settings.json.", name, valueS);
-                } else {
-                    // FIXME: filter ANSI escapes, newlines, \r, etc.
-                    if (std::tolower(logger->ask(fmt("Do you want to allow configuration setting '%s' to be set to '" ANSI_RED "%s" ANSI_NORMAL "' (y/N)? This may allow the flake to gain root, see the nix.conf manual page.", name, valueS)).value_or('n')) == 'y') {
-                        trusted = true;
-                    } else {
-                        warn("you can set '%s' to '%b' to automatically reject configuration options supplied by flakes", "accept-flake-config", false);
-                    }
-                    if (std::tolower(logger->ask(fmt("do you want to permanently mark this value as %s (y/N)?",  trusted ? "trusted": "untrusted" )).value_or('n')) == 'y') {
-                        trustedList[name][valueS] = trusted;
-                        writeTrustedList(trustedList);
-                    }
+        if (!whitelist.count(baseName) && !nix::fetchSettings.acceptFlakeConfig) {
+            bool trusted = false;
+            auto trustedList = readTrustedList();
+            auto tlname = get(trustedList, name);
+            if (auto saved = tlname ? get(*tlname, valueS) : nullptr) {
+                trusted = *saved;
+                printInfo("Using saved setting for '%s = %s' from ~/.local/share/nix/trusted-settings.json.", name, valueS);
+            } else {
+                // FIXME: filter ANSI escapes, newlines, \r, etc.
+                if (std::tolower(logger->ask(fmt("do you want to allow configuration setting '%s' to be set to '" ANSI_RED "%s" ANSI_NORMAL "' (y/N)?", name, valueS)).value_or('n')) == 'y') {
+                    trusted = true;
+                }
+                if (std::tolower(logger->ask(fmt("do you want to permanently mark this value as %s (y/N)?",  trusted ? "trusted": "untrusted" )).value_or('n')) == 'y') {
+                    trustedList[name][valueS] = trusted;
+                    writeTrustedList(trustedList);
                }
-                break;
            }
-            case nix::AcceptFlakeConfig::False: {
-                trusted = false;
-                break;
-            };
+            if (!trusted) {
+                warn("ignoring untrusted flake configuration setting '%s'.\nPass '%s' to trust it", name, "--accept-flake-config");
+                continue;
            }
        }

-        if (trusted) {
-            debug("accepting trusted flake configuration setting '%s'", name);
-            globalConfig.set(name, valueS);
-        } else {
-            warn("ignoring untrusted flake configuration setting '%s', pass '%s' to trust it (may allow the flake to gain root, see the nix.conf manual page)", name, "--accept-flake-config");
-        }
+        globalConfig.set(name, valueS);
    }
 }

@@ -1,7 +1,3 @@
-// SPDX-FileCopyrightText: 2024 Nix and Lix Authors
-//
-// SPDX-License-Identifier: LGPL-2.1-only
-
 #include "flake.hh"
 #include "eval.hh"
 #include "eval-settings.hh"
@@ -1,7 +1,3 @@
-// SPDX-FileCopyrightText: 2024 Nix and Lix Authors
-//
-// SPDX-License-Identifier: LGPL-2.1-only
-
 #pragma once
 ///@file

@@ -1,7 +1,3 @@
-// SPDX-FileCopyrightText: 2024 Nix and Lix Authors
-//
-// SPDX-License-Identifier: LGPL-2.1-only
-
 #include "flakeref.hh"
 #include "store-api.hh"
 #include "url.hh"
@@ -89,8 +85,8 @@ std::pair<FlakeRef, std::string> parseFlakeRefWithFragment(
        + "(?:#(" + queryRegex + "))?",
        std::regex::ECMAScript);

-    static std::regex flakeShorthandRegex(
-        flakeShorthandRegexS
+    static std::regex flakeRegex(
+        "((" + flakeIdRegexS + ")(?:/(?:" + refAndOrRevRegex + "))?)"
        + "(?:#(" + queryRegex + "))?",
        std::regex::ECMAScript);

@@ -99,7 +95,7 @@ std::pair<FlakeRef, std::string> parseFlakeRefWithFragment(
    /* Check if 'url' is a flake ID. This is an abbreviated syntax for
       'flake:<flake-id>?ref=<ref>&rev=<rev>'. */

-    if (std::regex_match(url, match, flakeShorthandRegex)) {
+    if (std::regex_match(url, match, flakeRegex)) {
        auto parsedURL = ParsedURL{
            .url = url,
            .base = "flake:" + match.str(1),
@@ -1,7 +1,3 @@
-// SPDX-FileCopyrightText: 2024 Nix and Lix Authors
-//
-// SPDX-License-Identifier: LGPL-2.1-only
-
 #pragma once
 ///@file

@@ -1,7 +1,3 @@
-// SPDX-FileCopyrightText: 2024 Nix and Lix Authors
-//
-// SPDX-License-Identifier: LGPL-2.1-only
-
 #include "lockfile.hh"
 #include "store-api.hh"
 #include "url-parts.hh"
@@ -1,7 +1,3 @@
-// SPDX-FileCopyrightText: 2024 Nix and Lix Authors
-//
-// SPDX-License-Identifier: LGPL-2.1-only
-
 #pragma once
 ///@file

@@ -1,7 +1,3 @@
-# SPDX-FileCopyrightText: 2024 Nix and Lix Authors
-#
-# SPDX-License-Identifier: LGPL-2.1-only
-
 libexpr_generated_headers += custom_target(
  command : [ 'bash', '-c', 'echo \'R"__NIX_STR(\' | cat - @INPUT@ && echo \')__NIX_STR"\'' ],
  input : 'call-flake.nix',
@@ -1,7 +1,3 @@
-// SPDX-FileCopyrightText: 2024 Nix and Lix Authors
-//
-// SPDX-License-Identifier: LGPL-2.1-only
-
 #include "function-trace.hh"
 #include "logging.hh"

@@ -1,7 +1,3 @@
-// SPDX-FileCopyrightText: 2024 Nix and Lix Authors
-//
-// SPDX-License-Identifier: LGPL-2.1-only
-
 #pragma once
 ///@file

@@ -1,7 +1,3 @@
-// SPDX-FileCopyrightText: 2024 Nix and Lix Authors
-//
-// SPDX-License-Identifier: LGPL-2.1-only
-
 #pragma once
 ///@file

@@ -1,7 +1,3 @@
-// SPDX-FileCopyrightText: 2024 Nix and Lix Authors
-//
-// SPDX-License-Identifier: LGPL-2.1-only
-
 #include "get-drvs.hh"
 #include "eval-inline.hh"
 #include "derivations.hh"
@@ -49,7 +45,7 @@ DrvInfo::DrvInfo(EvalState & state, ref<Store> store, const std::string & drvPat
 }


-std::string DrvInfo::queryName()
+std::string DrvInfo::queryName() const
 {
    if (name == "" && attrs) {
        auto i = attrs->find(state->sName);
@@ -60,7 +56,7 @@ std::string DrvInfo::queryName()
 }


-std::string DrvInfo::querySystem()
+std::string DrvInfo::querySystem() const
 {
    if (system == "" && attrs) {
        auto i = attrs->find(state->sSystem);
@@ -70,7 +66,7 @@ std::string DrvInfo::querySystem()
 }


-std::optional<StorePath> DrvInfo::queryDrvPath()
+std::optional<StorePath> DrvInfo::queryDrvPath() const
 {
    if (!drvPath && attrs) {
        Bindings::iterator i = attrs->find(state->sDrvPath);
@@ -84,7 +80,7 @@ std::optional<StorePath> DrvInfo::queryDrvPath()
 }


-StorePath DrvInfo::requireDrvPath()
+StorePath DrvInfo::requireDrvPath() const
 {
    if (auto drvPath = queryDrvPath())
        return *drvPath;
@@ -92,7 +88,7 @@ StorePath DrvInfo::requireDrvPath()
 }


-StorePath DrvInfo::queryOutPath()
+StorePath DrvInfo::queryOutPath() const
 {
    if (!outPath && attrs) {
        Bindings::iterator i = attrs->find(state->sOutPath);
@@ -168,7 +164,7 @@ DrvInfo::Outputs DrvInfo::queryOutputs(bool withPaths, bool onlyOutputsToInstall
 }


-std::string DrvInfo::queryOutputName()
+std::string DrvInfo::queryOutputName() const
 {
    if (outputName == "" && attrs) {
        Bindings::iterator i = attrs->find(state->sOutputName);
@@ -1,7 +1,3 @@
-// SPDX-FileCopyrightText: 2024 Nix and Lix Authors
-//
-// SPDX-License-Identifier: LGPL-2.1-only
-
 #pragma once
 ///@file

@@ -23,11 +19,11 @@ public:
 private:
    EvalState * state;

-    std::string name;
-    std::string system;
-    std::optional<std::optional<StorePath>> drvPath;
-    std::optional<StorePath> outPath;
-    std::string outputName;
+    mutable std::string name;
+    mutable std::string system;
+    mutable std::optional<std::optional<StorePath>> drvPath;
+    mutable std::optional<StorePath> outPath;
+    mutable std::string outputName;
    Outputs outputs;

    /**
@@ -51,12 +47,12 @@ public:
    DrvInfo(EvalState & state, std::string attrPath, Bindings * attrs);
    DrvInfo(EvalState & state, ref<Store> store, const std::string & drvPathWithOutputs);

-    std::string queryName();
-    std::string querySystem();
-    std::optional<StorePath> queryDrvPath();
-    StorePath requireDrvPath();
-    StorePath queryOutPath();
-    std::string queryOutputName();
+    std::string queryName() const;
+    std::string querySystem() const;
+    std::optional<StorePath> queryDrvPath() const;
+    StorePath requireDrvPath() const;
+    StorePath queryOutPath() const;
+    std::string queryOutputName() const;
    /**
     * Return the unordered map of output names to (optional) output paths.
     * The "outputs to install" are determined by `meta.outputsToInstall`.
@@ -1,7 +1,3 @@
-# SPDX-FileCopyrightText: 2024 Nix and Lix Authors
-#
-# SPDX-License-Identifier: LGPL-2.1-only
-
 attrs@{
  drvPath,
  outputs,
@@ -1,7 +1,3 @@
-// SPDX-FileCopyrightText: 2024 Nix and Lix Authors
-//
-// SPDX-License-Identifier: LGPL-2.1-only
-
 #include "json-to-value.hh"
 #include "value.hh"
 #include "eval.hh"
@@ -1,7 +1,3 @@
-// SPDX-FileCopyrightText: 2024 Nix and Lix Authors
-//
-// SPDX-License-Identifier: LGPL-2.1-only
-
 #pragma once
 ///@file

@@ -0,0 +1,296 @@
+%option reentrant bison-bridge bison-locations
+%option align
+%option noyywrap
+%option never-interactive
+%option stack
+%option nodefault
+%option nounput noyy_top_state
+
+
+%s DEFAULT
+%x STRING
+%x IND_STRING
+%x INPATH
+%x INPATH_SLASH
+%x PATH_START
+
+
+%{
+#ifdef __clang__
+#pragma clang diagnostic ignored "-Wunneeded-internal-declaration"
+#endif
+
+// yacc generates code that uses unannotated fallthrough.
+#pragma GCC diagnostic ignored "-Wimplicit-fallthrough"
+#ifdef __clang__
+#pragma clang diagnostic ignored "-Wimplicit-fallthrough"
+#endif
+
+#include "nixexpr.hh"
+#include "parser-tab.hh"
+#include "strings.hh"
+
+using namespace nix;
+
+namespace nix {
+
+#define CUR_POS state->at(*yylloc)
+
+static void initLoc(YYLTYPE * loc)
+{
+    loc->first_line = loc->last_line = 0;
+    loc->first_column = loc->last_column = 0;
+}
+
+static void adjustLoc(YYLTYPE * loc, const char * s, size_t len)
+{
+    loc->stash();
+
+    loc->first_column = loc->last_column;
+    loc->last_column += len;
+}
+
+
+// we make use of the fact that the parser receives a private copy of the input
+// string and can munge around in it.
+static StringToken unescapeStr(SymbolTable & symbols, char * s, size_t length)
+{
+    char * result = s;
+    char * t = s;
+    char c;
+    // the input string is terminated with *two* NULs, so we can safely take
+    // *one* character after the one being checked against.
+    while ((c = *s++)) {
+        if (c == '\\') {
+            c = *s++;
+            if (c == 'n') *t = '\n';
+            else if (c == 'r') *t = '\r';
+            else if (c == 't') *t = '\t';
+            else *t = c;
+        }
+        else if (c == '\r') {
+            /* Normalise CR and CR/LF into LF. */
+            *t = '\n';
+            if (*s == '\n') s++; /* cr/lf */
+        }
+        else *t = c;
+        t++;
+    }
+    return {result, size_t(t - result)};
+}
+
+
+}
+
+#define YY_USER_INIT initLoc(yylloc)
+#define YY_USER_ACTION adjustLoc(yylloc, yytext, yyleng);
+
+#define PUSH_STATE(state) yy_push_state(state, yyscanner)
+#define POP_STATE() yy_pop_state(yyscanner)
+
+%}
+
+
+ANY         .|\n
+ID          [a-zA-Z\_][a-zA-Z0-9\_\'\-]*
+INT         [0-9]+
+FLOAT       (([1-9][0-9]*\.[0-9]*)|(0?\.[0-9]+))([Ee][+-]?[0-9]+)?
+PATH_CHAR   [a-zA-Z0-9\.\_\-\+]
+PATH        {PATH_CHAR}*(\/{PATH_CHAR}+)+\/?
+PATH_SEG    {PATH_CHAR}*\/
+HPATH       \~(\/{PATH_CHAR}+)+\/?
+HPATH_START \~\/
+SPATH       \<{PATH_CHAR}+(\/{PATH_CHAR}+)*\>
+URI         [a-zA-Z][a-zA-Z0-9\+\-\.]*\:[a-zA-Z0-9\%\/\?\:\@\&\=\+\$\,\-\_\.\!\~\*\']+
+
+
+%%
+
+
+if          { return IF; }
+then        { return THEN; }
+else        { return ELSE; }
+assert      { return ASSERT; }
+with        { return WITH; }
+let         { return LET; }
+in          { return IN; }
+rec         { return REC; }
+inherit     { return INHERIT; }
+or          { return OR_KW; }
+\.\.\.      { return ELLIPSIS; }
+
+\=\=        { return EQ; }
+\!\=        { return NEQ; }
+\<\=        { return LEQ; }
+\>\=        { return GEQ; }
+\&\&        { return AND; }
+\|\|        { return OR; }
+\-\>        { return IMPL; }
+\/\/        { return UPDATE; }
+\+\+        { return CONCAT; }
+
+{ID}        { yylval->id = {yytext, (size_t) yyleng}; return ID; }
+{INT}       { errno = 0;
+              std::optional<int64_t> numMay = string2Int<int64_t>(yytext);
+              if (numMay.has_value()) {
+                  yylval->n = *numMay;
+              } else {
+                  throw ParseError(ErrorInfo{
+                      .msg = HintFmt("invalid integer '%1%'", yytext),
+                      .pos = state->positions[CUR_POS],
+                  });
+              }
+              return INT;
+            }
+{FLOAT}     { errno = 0;
+              yylval->nf = strtod(yytext, 0);
+              if (errno != 0)
+                  throw ParseError(ErrorInfo{
+                      .msg = HintFmt("invalid float '%1%'", yytext),
+                      .pos = state->positions[CUR_POS],
+                  });
+              return FLOAT;
+            }
+
+\$\{        { PUSH_STATE(DEFAULT); return DOLLAR_CURLY; }
+
+\}          { /* State INITIAL only exists at the bottom of the stack and is
+                 used as a marker. DEFAULT replaces it everywhere else.
+                 Popping when in INITIAL state causes an empty stack exception,
+                 so don't */
+              if (YYSTATE != INITIAL)
+                POP_STATE();
+              return '}';
+            }
+\{          { PUSH_STATE(DEFAULT); return '{'; }
+
+\"          { PUSH_STATE(STRING); return '"'; }
+<STRING>([^\$\"\\]|\$[^\{\"\\]|\\{ANY}|\$\\{ANY})*\$/\" |
+<STRING>([^\$\"\\]|\$[^\{\"\\]|\\{ANY}|\$\\{ANY})+ {
+                /* It is impossible to match strings ending with '$' with one
+                   regex because trailing contexts are only valid at the end
+                   of a rule. (A sane but undocumented limitation.) */
+                yylval->str = unescapeStr(state->symbols, yytext, yyleng);
+                return STR;
+              }
+<STRING>\$\{  { PUSH_STATE(DEFAULT); return DOLLAR_CURLY; }
+<STRING>\"    { POP_STATE(); return '"'; }
+<STRING>\$|\\|\$\\ {
+                /* This can only occur when we reach EOF, otherwise the above
+                   (...|\$[^\{\"\\]|\\.|\$\\.)+ would have triggered.
+                   This is technically invalid, but we leave the problem to the
+                   parser who fails with exact location. */
+                return EOF;
+              }
+
+\'\'(\ *\n)?     { PUSH_STATE(IND_STRING); return IND_STRING_OPEN; }
+<IND_STRING>([^\$\']|\$[^\{\']|\'[^\'\$])+ {
+                   yylval->str = {yytext, (size_t) yyleng, true};
+                   return IND_STR;
+                 }
+<IND_STRING>\'\'\$ |
+<IND_STRING>\$   {
+                   yylval->str = {"$", 1};
+                   return IND_STR;
+                 }
+<IND_STRING>\'\'\' {
+                   yylval->str = {"''", 2};
+                   return IND_STR;
+                 }
+<IND_STRING>\'\'\\{ANY} {
+                   yylval->str = unescapeStr(state->symbols, yytext + 2, yyleng - 2);
+                   return IND_STR;
+                 }
+<IND_STRING>\$\{ { PUSH_STATE(DEFAULT); return DOLLAR_CURLY; }
+<IND_STRING>\'\' { POP_STATE(); return IND_STRING_CLOSE; }
+<IND_STRING>\'   {
+                   yylval->str = {"'", 1};
+                   return IND_STR;
+                 }
+
+{PATH_SEG}\$\{ |
+{HPATH_START}\$\{ {
+  PUSH_STATE(PATH_START);
+  yyless(0);
+  yylloc->unstash();
+}
+
+<PATH_START>{PATH_SEG} {
+  POP_STATE();
+  PUSH_STATE(INPATH_SLASH);
+  yylval->path = {yytext, (size_t) yyleng};
+  return PATH;
+}
+
+<PATH_START>{HPATH_START} {
+  POP_STATE();
+  PUSH_STATE(INPATH_SLASH);
+  yylval->path = {yytext, (size_t) yyleng};
+  return HPATH;
+}
+
+{PATH} {
+  if (yytext[yyleng-1] == '/')
+    PUSH_STATE(INPATH_SLASH);
+  else
+    PUSH_STATE(INPATH);
+  yylval->path = {yytext, (size_t) yyleng};
+  return PATH;
+}
+{HPATH} {
+  if (yytext[yyleng-1] == '/')
+    PUSH_STATE(INPATH_SLASH);
+  else
+    PUSH_STATE(INPATH);
+  yylval->path = {yytext, (size_t) yyleng};
+  return HPATH;
+}
+
+<INPATH,INPATH_SLASH>\$\{ {
+  POP_STATE();
+  PUSH_STATE(INPATH);
+  PUSH_STATE(DEFAULT);
+  return DOLLAR_CURLY;
+}
+<INPATH,INPATH_SLASH>{PATH}|{PATH_SEG}|{PATH_CHAR}+ {
+  POP_STATE();
+  if (yytext[yyleng-1] == '/')
+      PUSH_STATE(INPATH_SLASH);
+  else
+      PUSH_STATE(INPATH);
+  yylval->str = {yytext, (size_t) yyleng};
+  return STR;
+}
+<INPATH>{ANY} |
+<INPATH><<EOF>> {
+  /* if we encounter a non-path character we inform the parser that the path has
+     ended with a PATH_END token and re-parse this character in the default
+     context (it may be ')', ';', or something of that sort) */
+  POP_STATE();
+  yyless(0);
+  yylloc->unstash();
+  return PATH_END;
+}
+
+<INPATH_SLASH>{ANY} |
+<INPATH_SLASH><<EOF>> {
+  throw ParseError(ErrorInfo{
+      .msg = HintFmt("path has a trailing slash"),
+      .pos = state->positions[CUR_POS],
+  });
+}
+
+{SPATH}     { yylval->path = {yytext, (size_t) yyleng}; return SPATH; }
+{URI}       { yylval->uri = {yytext, (size_t) yyleng}; return URI; }
+
+[ \t\r\n]+    /* eat up whitespace */
+\#[^\r\n]*    /* single-line comments */
+\/\*([^*]|\*+[^*/])*\*+\/  /* long comments */
+
+{ANY}       {
+              /* Don't return a negative number, as this will cause
+                 Bison to stop parsing without an error. */
+              return (unsigned char) yytext[0];
+            }
+
+%%
@@ -1,6 +1,53 @@
-# SPDX-FileCopyrightText: 2024 Nix and Lix Authors
-#
-# SPDX-License-Identifier: LGPL-2.1-only
+parser_tab = custom_target(
+  input : 'parser.y',
+  output : [
+    'parser-tab.cc',
+    'parser-tab.hh',
+  ],
+  command : [
+    'bison',
+    '-v',
+    '-o',
+    '@OUTPUT0@',
+    '@INPUT@',
+    '-d',
+  ],
+  # NOTE(Qyriad): Meson doesn't support installing only part of a custom target, so we add
+  # an install script below which removes parser-tab.cc.
+  install : true,
+  install_dir : includedir / 'lix/libexpr',
+)
+
+lexer_tab = custom_target(
+  input : [
+    'lexer.l',
+    parser_tab,
+  ],
+  output : [
+    'lexer-tab.cc',
+    'lexer-tab.hh',
+  ],
+  command : [
+    'flex',
+    '--outfile',
+    '@OUTPUT0@',
+    '--header-file=' + '@OUTPUT1@',
+    '@INPUT0@',
+  ],
+  # NOTE(Qyriad): Meson doesn't support installing only part of a custom target, so we add
+  # an install script below which removes lexer-tab.cc.
+  install : true,
+  install_dir : includedir / 'lix/libexpr',
+)
+
+# TODO(Qyriad): When the parser and lexer are rewritten this should be removed.
+# NOTE(Qyriad): We do this this way instead of an inline bash or rm command
+# due to subtleties in Meson. Check the comments in cleanup-install.bash for details.
+meson.add_install_script(
+  bash,
+  meson.project_source_root() / 'meson/cleanup-install.bash',
+  '@0@'.format(includedir),
+)

 libexpr_generated_headers = [
  gen_header.process('primops/derivation.nix', preserve_path_from : meson.current_source_dir()),
@@ -28,7 +75,6 @@ libexpr_sources = files(
  'get-drvs.cc',
  'json-to-value.cc',
  'nixexpr.cc',
-  'parser/parser.cc',
  'paths.cc',
  'primops.cc',
  'print-ambiguous.cc',
@@ -64,9 +110,7 @@ libexpr_headers = files(
  'get-drvs.hh',
  'json-to-value.hh',
  'nixexpr.hh',
-  'parser/change_head.hh',
-  'parser/grammar.hh',
-  'parser/state.hh',
+  'parser-state.hh',
  'pos-idx.hh',
  'pos-table.hh',
  'primops.hh',
@@ -85,6 +129,8 @@ libexpr_headers = files(
 libexpr = library(
  'lixexpr',
  libexpr_sources,
+  parser_tab,
+  lexer_tab,
  libexpr_generated_headers,
  dependencies : [
    liblixutil,
@@ -1,7 +1,3 @@
-// SPDX-FileCopyrightText: 2024 Nix and Lix Authors
-//
-// SPDX-License-Identifier: LGPL-2.1-only
-
 #include "nixexpr.hh"
 #include "derivations.hh"
 #include "eval.hh"
@@ -54,13 +50,6 @@ void ExprVar::show(const SymbolTable & symbols, std::ostream & str) const
    str << symbols[name];
 }

-void ExprInheritFrom::show(SymbolTable const & symbols, std::ostream & str) const
-{
-    str << "(/* expanded inherit (expr) */ ";
-    fromExpr->show(symbols, str);
-    str << ")";
-}
-
 void ExprSelect::show(const SymbolTable & symbols, std::ostream & str) const
 {
    str << "(";
@@ -90,7 +79,7 @@ void ExprAttrs::showBindings(const SymbolTable & symbols, std::ostream & str) co
        return sa < sb;
    });
    std::vector<Symbol> inherits;
-    std::map<Displacement, std::vector<Symbol>> inheritsFrom;
+    std::map<ExprInheritFrom *, std::vector<Symbol>> inheritsFrom;
    for (auto & i : sorted) {
        switch (i->second.kind) {
        case AttrDef::Kind::Plain:
@@ -101,7 +90,7 @@ void ExprAttrs::showBindings(const SymbolTable & symbols, std::ostream & str) co
        case AttrDef::Kind::InheritedFrom: {
            auto & select = dynamic_cast<ExprSelect &>(*i->second.e);
            auto & from = dynamic_cast<ExprInheritFrom &>(*select.e);
-            inheritsFrom[from.displ].push_back(i->first);
+            inheritsFrom[&from].push_back(i->first);
            break;
        }
        }
@@ -113,7 +102,7 @@ void ExprAttrs::showBindings(const SymbolTable & symbols, std::ostream & str) co
    }
    for (const auto & [from, syms] : inheritsFrom) {
        str << "inherit (";
-        (*inheritFromExprs)[from]->show(symbols, str);
+        (*inheritFromExprs)[from->displ]->show(symbols, str);
        str << ")";
        for (auto sym : syms) str << " " << symbols[sym];
        str << "; ";
@@ -162,7 +151,7 @@ void ExprLambda::show(const SymbolTable & symbols, std::ostream & str) const
        // the natural Symbol ordering is by creation time, which can lead to the
        // same expression being printed in two different ways depending on its
        // context. always use lexicographic ordering to avoid this.
-        for (const Formal & i : formals->lexicographicOrder(symbols)) {
+        for (auto & i : formals->lexicographicOrder(symbols)) {
            if (first) first = false; else str << ", ";
            str << symbols[i.name];
            if (i.def) {
@@ -187,7 +176,7 @@ void ExprCall::show(const SymbolTable & symbols, std::ostream & str) const
 {
    str << '(';
    fun->show(symbols, str);
-    for (auto & e : args) {
+    for (auto e : args) {
        str <<  ' ';
        e->show(symbols, str);
    }
@@ -242,7 +231,7 @@ void ExprConcatStrings::show(const SymbolTable & symbols, std::ostream & str) co
 {
    bool first = true;
    str << "(";
-    for (auto & i : es) {
+    for (auto & i : *es) {
        if (first) first = false; else str << " + ";
        i.second->show(symbols, str);
    }
@@ -386,7 +375,7 @@ std::shared_ptr<const StaticEnv> ExprAttrs::bindInheritSources(
    // not even *have* an expr that grabs anything from this env since it's fully
    // invisible, but the evaluator does not allow for this yet.
    auto inner = std::make_shared<StaticEnv>(nullptr, env.get(), 0);
-    for (auto & from : *inheritFromExprs)
+    for (auto from : *inheritFromExprs)
        from->bindVars(es, env);

    return inner;
@@ -473,7 +462,7 @@ void ExprCall::bindVars(EvalState & es, const std::shared_ptr<const StaticEnv> &
        es.exprEnvs.insert(std::make_pair(this, env));

    fun->bindVars(es, env);
-    for (auto & e : args)
+    for (auto e : args)
        e->bindVars(es, env);
 }

@@ -558,7 +547,7 @@ void ExprConcatStrings::bindVars(EvalState & es, const std::shared_ptr<const Sta
    if (es.debugRepl)
        es.exprEnvs.insert(std::make_pair(this, env));

-    for (auto & i : this->es)
+    for (auto & i : *this->es)
        i.second->bindVars(es, env);
 }

@@ -1,7 +1,3 @@
-// SPDX-FileCopyrightText: 2024 Nix and Lix Authors
-//
-// SPDX-License-Identifier: LGPL-2.1-only
-
 #pragma once
 ///@file

@@ -32,9 +28,9 @@ struct StaticEnv;
 struct AttrName
 {
    Symbol symbol;
-    std::unique_ptr<Expr> expr;
+    Expr * expr;
    AttrName(Symbol s) : symbol(s) {};
-    AttrName(std::unique_ptr<Expr> e) : expr(std::move(e)) {};
+    AttrName(Expr * e) : expr(e) {};
 };

 typedef std::vector<AttrName> AttrPath;
@@ -46,21 +42,12 @@ std::string showAttrPath(const SymbolTable & symbols, const AttrPath & attrPath)

 struct Expr
 {
-protected:
-    Expr(Expr &&) = default;
-    Expr & operator=(Expr &&) = default;
-
-public:
    struct AstSymbols {
        Symbol sub, lessThan, mul, div, or_, findFile, nixPath, body;
    };


-    Expr() = default;
-    Expr(const Expr &) = delete;
-    Expr & operator=(const Expr &) = delete;
    virtual ~Expr() { };
-
    virtual void show(const SymbolTable & symbols, std::ostream & str) const;
    virtual void bindVars(EvalState & es, const std::shared_ptr<const StaticEnv> & env);
    virtual void eval(EvalState & state, Env & env, Value & v);
@@ -148,46 +135,32 @@ struct ExprVar : Expr
 */
 struct ExprInheritFrom : ExprVar
 {
-    ref<Expr> fromExpr;
-
-    ExprInheritFrom(PosIdx pos, Displacement displ, ref<Expr> fromExpr)
-          : ExprVar(pos, {}), fromExpr(fromExpr)
+    ExprInheritFrom(PosIdx pos, Displacement displ): ExprVar(pos, {})
    {
        this->level = 0;
        this->displ = displ;
        this->fromWith = nullptr;
    }

-    void show(SymbolTable const & symbols, std::ostream & str) const override;
-    void bindVars(EvalState & es, const std::shared_ptr<const StaticEnv> & env) override;
+    void bindVars(EvalState & es, const std::shared_ptr<const StaticEnv> & env);
 };

 struct ExprSelect : Expr
 {
    PosIdx pos;
-
-    /** The expression attributes are being selected on. e.g. `foo` in `foo.bar.baz`. */
-    std::unique_ptr<Expr> e;
-
-    /** A default value specified with `or`, if the selected attr doesn't exist.
-     * e.g. `bix` in `foo.bar.baz or bix`
-     */
-    std::unique_ptr<Expr> def;
-
-    /** The path of attributes being selected. e.g. `bar.baz` in `foo.bar.baz.` */
+    Expr * e, * def;
    AttrPath attrPath;
-
-    ExprSelect(const PosIdx & pos, std::unique_ptr<Expr> e, AttrPath attrPath, std::unique_ptr<Expr> def) : pos(pos), e(std::move(e)), def(std::move(def)), attrPath(std::move(attrPath)) { };
-    ExprSelect(const PosIdx & pos, std::unique_ptr<Expr> e, Symbol name) : pos(pos), e(std::move(e)) { attrPath.push_back(AttrName(name)); };
+    ExprSelect(const PosIdx & pos, Expr * e, AttrPath attrPath, Expr * def) : pos(pos), e(e), def(def), attrPath(std::move(attrPath)) { };
+    ExprSelect(const PosIdx & pos, Expr * e, Symbol name) : pos(pos), e(e), def(0) { attrPath.push_back(AttrName(name)); };
    PosIdx getPos() const override { return pos; }
    COMMON_METHODS
 };

 struct ExprOpHasAttr : Expr
 {
-    std::unique_ptr<Expr> e;
+    Expr * e;
    AttrPath attrPath;
-    ExprOpHasAttr(std::unique_ptr<Expr> e, AttrPath attrPath) : e(std::move(e)), attrPath(std::move(attrPath)) { };
+    ExprOpHasAttr(Expr * e, AttrPath attrPath) : e(e), attrPath(std::move(attrPath)) { };
    PosIdx getPos() const override { return e->getPos(); }
    COMMON_METHODS
 };
@@ -207,11 +180,11 @@ struct ExprAttrs : Expr
        };

        Kind kind;
-        std::unique_ptr<Expr> e;
+        Expr * e;
        PosIdx pos;
        Displacement displ; // displacement
-        AttrDef(std::unique_ptr<Expr> e, const PosIdx & pos, Kind kind = Kind::Plain)
-            : kind(kind), e(std::move(e)), pos(pos) { };
+        AttrDef(Expr * e, const PosIdx & pos, Kind kind = Kind::Plain)
+            : kind(kind), e(e), pos(pos) { };
        AttrDef() { };

        template<typename T>
@@ -230,12 +203,12 @@ struct ExprAttrs : Expr
    };
    typedef std::map<Symbol, AttrDef> AttrDefs;
    AttrDefs attrs;
-    std::unique_ptr<std::vector<ref<Expr>>> inheritFromExprs;
+    std::unique_ptr<std::vector<Expr *>> inheritFromExprs;
    struct DynamicAttrDef {
-        std::unique_ptr<Expr> nameExpr, valueExpr;
+        Expr * nameExpr, * valueExpr;
        PosIdx pos;
-        DynamicAttrDef(std::unique_ptr<Expr> nameExpr, std::unique_ptr<Expr> valueExpr, const PosIdx & pos)
-            : nameExpr(std::move(nameExpr)), valueExpr(std::move(valueExpr)), pos(pos) { };
+        DynamicAttrDef(Expr * nameExpr, Expr * valueExpr, const PosIdx & pos)
+            : nameExpr(nameExpr), valueExpr(valueExpr), pos(pos) { };
    };
    typedef std::vector<DynamicAttrDef> DynamicAttrDefs;
    DynamicAttrDefs dynamicAttrs;
@@ -252,7 +225,7 @@ struct ExprAttrs : Expr

 struct ExprList : Expr
 {
-    std::vector<std::unique_ptr<Expr>> elems;
+    std::vector<Expr *> elems;
    ExprList() { };
    COMMON_METHODS
    Value * maybeThunk(EvalState & state, Env & env) override;
@@ -267,7 +240,7 @@ struct Formal
 {
    PosIdx pos;
    Symbol name;
-    std::unique_ptr<Expr> def;
+    Expr * def;
 };

 /** Attribute set destructuring in arguments of a lambda, if present */
@@ -284,9 +257,9 @@ struct Formals
        return it != formals.end() && it->name == arg;
    }

-    std::vector<std::reference_wrapper<const Formal>> lexicographicOrder(const SymbolTable & symbols) const
+    std::vector<Formal> lexicographicOrder(const SymbolTable & symbols) const
    {
-        std::vector<std::reference_wrapper<const Formal>> result(formals.begin(), formals.end());
+        std::vector<Formal> result(formals.begin(), formals.end());
        std::sort(result.begin(), result.end(),
            [&] (const Formal & a, const Formal & b) {
                std::string_view sa = symbols[a.name], sb = symbols[b.name];
@@ -310,55 +283,30 @@ struct ExprLambda : Expr
    Symbol arg;
    /** Formals are present when the lambda destructures an attr set as
     * argument, with or without ellipsis */
-    std::unique_ptr<Formals> formals;
-    std::unique_ptr<Expr> body;
-    ExprLambda(PosIdx pos, Symbol arg, std::unique_ptr<Formals> formals, std::unique_ptr<Expr> body)
-        : pos(pos), arg(arg), formals(std::move(formals)), body(std::move(body))
+    Formals * formals;
+    Expr * body;
+    ExprLambda(PosIdx pos, Symbol arg, Formals * formals, Expr * body)
+        : pos(pos), arg(arg), formals(formals), body(body)
    {
    };
-    ExprLambda(PosIdx pos, std::unique_ptr<Formals> formals, std::unique_ptr<Expr> body)
-        : pos(pos), formals(std::move(formals)), body(std::move(body))
+    ExprLambda(PosIdx pos, Formals * formals, Expr * body)
+        : pos(pos), formals(formals), body(body)
    {
    }
    void setName(Symbol name) override;
    std::string showNamePos(const EvalState & state) const;
    inline bool hasFormals() const { return formals != nullptr; }
    PosIdx getPos() const override { return pos; }
-
-    /** Returns the name of the lambda,
-     * or "anonymous lambda" if it doesn't have one.
-     */
-    inline std::string getName(SymbolTable const & symbols) const
-    {
-        if (this->name) {
-            return symbols[this->name];
-        }
-
-        return "anonymous lambda";
-    }
-
-    /** Returns the name of the lambda in single quotes,
-     * or "anonymous lambda" if it doesn't have one.
-     */
-    inline std::string getQuotedName(SymbolTable const & symbols) const
-    {
-        if (this->name) {
-            return concatStrings("'", symbols[this->name], "'");
-        }
-
-        return "anonymous lambda";
-    }
-
    COMMON_METHODS
 };

 struct ExprCall : Expr
 {
-    std::unique_ptr<Expr> fun;
-    std::vector<std::unique_ptr<Expr>> args;
+    Expr * fun;
+    std::vector<Expr *> args;
    PosIdx pos;
-    ExprCall(const PosIdx & pos, std::unique_ptr<Expr> fun, std::vector<std::unique_ptr<Expr>> && args)
-        : fun(std::move(fun)), args(std::move(args)), pos(pos)
+    ExprCall(const PosIdx & pos, Expr * fun, std::vector<Expr *> && args)
+        : fun(fun), args(args), pos(pos)
    { }
    PosIdx getPos() const override { return pos; }
    COMMON_METHODS
@@ -366,19 +314,19 @@ struct ExprCall : Expr

 struct ExprLet : Expr
 {
-    std::unique_ptr<ExprAttrs> attrs;
-    std::unique_ptr<Expr> body;
-    ExprLet(std::unique_ptr<ExprAttrs> attrs, std::unique_ptr<Expr> body) : attrs(std::move(attrs)), body(std::move(body)) { };
+    ExprAttrs * attrs;
+    Expr * body;
+    ExprLet(ExprAttrs * attrs, Expr * body) : attrs(attrs), body(body) { };
    COMMON_METHODS
 };

 struct ExprWith : Expr
 {
    PosIdx pos;
-    std::unique_ptr<Expr> attrs, body;
+    Expr * attrs, * body;
    size_t prevWith;
    ExprWith * parentWith;
-    ExprWith(const PosIdx & pos, std::unique_ptr<Expr> attrs, std::unique_ptr<Expr> body) : pos(pos), attrs(std::move(attrs)), body(std::move(body)) { };
+    ExprWith(const PosIdx & pos, Expr * attrs, Expr * body) : pos(pos), attrs(attrs), body(body) { };
    PosIdx getPos() const override { return pos; }
    COMMON_METHODS
 };
@@ -386,8 +334,8 @@ struct ExprWith : Expr
 struct ExprIf : Expr
 {
    PosIdx pos;
-    std::unique_ptr<Expr> cond, then, else_;
-    ExprIf(const PosIdx & pos, std::unique_ptr<Expr> cond, std::unique_ptr<Expr> then, std::unique_ptr<Expr> else_) : pos(pos), cond(std::move(cond)), then(std::move(then)), else_(std::move(else_)) { };
+    Expr * cond, * then, * else_;
+    ExprIf(const PosIdx & pos, Expr * cond, Expr * then, Expr * else_) : pos(pos), cond(cond), then(then), else_(else_) { };
    PosIdx getPos() const override { return pos; }
    COMMON_METHODS
 };
@@ -395,16 +343,16 @@ struct ExprIf : Expr
 struct ExprAssert : Expr
 {
    PosIdx pos;
-    std::unique_ptr<Expr> cond, body;
-    ExprAssert(const PosIdx & pos, std::unique_ptr<Expr> cond, std::unique_ptr<Expr> body) : pos(pos), cond(std::move(cond)), body(std::move(body)) { };
+    Expr * cond, * body;
+    ExprAssert(const PosIdx & pos, Expr * cond, Expr * body) : pos(pos), cond(cond), body(body) { };
    PosIdx getPos() const override { return pos; }
    COMMON_METHODS
 };

 struct ExprOpNot : Expr
 {
-    std::unique_ptr<Expr> e;
-    ExprOpNot(std::unique_ptr<Expr> e) : e(std::move(e)) { };
+    Expr * e;
+    ExprOpNot(Expr * e) : e(e) { };
    PosIdx getPos() const override { return e->getPos(); }
    COMMON_METHODS
 };
@@ -413,9 +361,9 @@ struct ExprOpNot : Expr
    struct name : Expr \
    { \
        PosIdx pos; \
-        std::unique_ptr<Expr> e1, e2; \
-        name(std::unique_ptr<Expr> e1, std::unique_ptr<Expr> e2) : e1(std::move(e1)), e2(std::move(e2)) { }; \
-        name(const PosIdx & pos, std::unique_ptr<Expr> e1, std::unique_ptr<Expr> e2) : pos(pos), e1(std::move(e1)), e2(std::move(e2)) { }; \
+        Expr * e1, * e2; \
+        name(Expr * e1, Expr * e2) : e1(e1), e2(e2) { }; \
+        name(const PosIdx & pos, Expr * e1, Expr * e2) : pos(pos), e1(e1), e2(e2) { }; \
        void show(const SymbolTable & symbols, std::ostream & str) const override \
        { \
            str << "("; e1->show(symbols, str); str << " " s " "; e2->show(symbols, str); str << ")"; \
@@ -440,9 +388,9 @@ struct ExprConcatStrings : Expr
 {
    PosIdx pos;
    bool forceString;
-    std::vector<std::pair<PosIdx, std::unique_ptr<Expr>>> es;
-    ExprConcatStrings(const PosIdx & pos, bool forceString, std::vector<std::pair<PosIdx, std::unique_ptr<Expr>>> es)
-        : pos(pos), forceString(forceString), es(std::move(es)) { };
+    std::vector<std::pair<PosIdx, Expr *>> * es;
+    ExprConcatStrings(const PosIdx & pos, bool forceString, std::vector<std::pair<PosIdx, Expr *>> * es)
+        : pos(pos), forceString(forceString), es(es) { };
    PosIdx getPos() const override { return pos; }
    COMMON_METHODS
 };
@@ -1,50 +1,61 @@
-// SPDX-FileCopyrightText: 2024 Nix and Lix Authors
-//
-// SPDX-License-Identifier: LGPL-2.1-only
-
 #pragma once
 ///@file

 #include "eval.hh"

-namespace nix::parser {
+namespace nix {

+/**
+ * @note Storing a C-style `char *` and `size_t` allows us to avoid
+ * having to define the special members that using string_view here
+ * would implicitly delete.
+ */
 struct StringToken
 {
-    std::string_view s;
+    const char * p;
+    size_t l;
    bool hasIndentation;
-    operator std::string_view() const { return s; }
+    operator std::string_view() const { return {p, l}; }
 };

-struct State
+struct ParserLocation
+{
+    int first_line, first_column;
+    int last_line, last_column;
+
+    // backup to recover from yyless(0)
+    int stashed_first_column, stashed_last_column;
+
+    void stash() {
+        stashed_first_column = first_column;
+        stashed_last_column = last_column;
+    }
+
+    void unstash() {
+        first_column = stashed_first_column;
+        last_column = stashed_last_column;
+    }
+};
+
+struct ParserState
 {
    SymbolTable & symbols;
    PosTable & positions;
+    Expr * result;
    SourcePath basePath;
    PosTable::Origin origin;
    const Expr::AstSymbols & s;

    void dupAttr(const AttrPath & attrPath, const PosIdx pos, const PosIdx prevPos);
    void dupAttr(Symbol attr, const PosIdx pos, const PosIdx prevPos);
-    void addAttr(ExprAttrs * attrs, AttrPath && attrPath, std::unique_ptr<Expr> e, const PosIdx pos);
-    std::unique_ptr<Formals> validateFormals(std::unique_ptr<Formals> formals, PosIdx pos = noPos, Symbol arg = {});
-    std::unique_ptr<Expr> stripIndentation(const PosIdx pos,
-        std::vector<std::pair<PosIdx, std::variant<std::unique_ptr<Expr>, StringToken>>> && es);
-
-    // lazy positioning means we don't get byte offsets directly, in.position() would work
-    // but also requires line and column (which is expensive)
-    PosIdx at(const auto & in)
-    {
-        return positions.add(origin, in.begin() - in.input().begin());
-    }
-
-    PosIdx atEnd(const auto & in)
-    {
-        return positions.add(origin, in.end() - in.input().begin());
-    }
+    void addAttr(ExprAttrs * attrs, AttrPath && attrPath, Expr * e, const PosIdx pos);
+    Formals * validateFormals(Formals * formals, PosIdx pos = noPos, Symbol arg = {});
+    Expr * stripIndentation(const PosIdx pos,
+        std::vector<std::pair<PosIdx, std::variant<Expr *, StringToken>>> && es);
+    PosIdx at(const ParserLocation & loc);
 };

-inline void State::dupAttr(const AttrPath & attrPath, const PosIdx pos, const PosIdx prevPos)
+inline void ParserState::dupAttr(const AttrPath & attrPath, const PosIdx pos, const PosIdx prevPos)
 {
    throw ParseError({
         .msg = HintFmt("attribute '%1%' already defined at %2%",
@@ -53,7 +64,7 @@ inline void State::dupAttr(const AttrPath & attrPath, const PosIdx pos, const Po
    });
 }

-inline void State::dupAttr(Symbol attr, const PosIdx pos, const PosIdx prevPos)
+inline void ParserState::dupAttr(Symbol attr, const PosIdx pos, const PosIdx prevPos)
 {
    throw ParseError({
        .msg = HintFmt("attribute '%1%' already defined at %2%", symbols[attr], positions[prevPos]),
@@ -61,7 +72,7 @@ inline void State::dupAttr(Symbol attr, const PosIdx pos, const PosIdx prevPos)
    });
 }

-inline void State::addAttr(ExprAttrs * attrs, AttrPath && attrPath, std::unique_ptr<Expr> e, const PosIdx pos)
+inline void ParserState::addAttr(ExprAttrs * attrs, AttrPath && attrPath, Expr * e, const PosIdx pos)
 {
    AttrPath::iterator i;
    // All attrpaths have at least one attr
@@ -73,25 +84,20 @@ inline void State::addAttr(ExprAttrs * attrs, AttrPath && attrPath, std::unique_
            ExprAttrs::AttrDefs::iterator j = attrs->attrs.find(i->symbol);
            if (j != attrs->attrs.end()) {
                if (j->second.kind != ExprAttrs::AttrDef::Kind::Inherited) {
-                    ExprAttrs * attrs2 = dynamic_cast<ExprAttrs *>(j->second.e.get());
-                    if (!attrs2) {
-                        attrPath.erase(i + 1, attrPath.end());
-                        dupAttr(attrPath, pos, j->second.pos);
-                    }
+                    ExprAttrs * attrs2 = dynamic_cast<ExprAttrs *>(j->second.e);
+                    if (!attrs2) dupAttr({attrPath.begin(), i + 1}, pos, j->second.pos);
                    attrs = attrs2;
-                } else {
-                    attrPath.erase(i + 1, attrPath.end());
-                    dupAttr(attrPath, pos, j->second.pos);
-                }
+                } else
+                    dupAttr({attrPath.begin(), i + 1}, pos, j->second.pos);
            } else {
-                auto next = attrs->attrs.emplace(std::piecewise_construct,
-                    std::tuple(i->symbol),
-                    std::tuple(std::make_unique<ExprAttrs>(), pos));
-                attrs = static_cast<ExprAttrs *>(next.first->second.e.get());
+                ExprAttrs * nested = new ExprAttrs;
+                attrs->attrs[i->symbol] = ExprAttrs::AttrDef(nested, pos);
+                attrs = nested;
            }
        } else {
-            auto & next = attrs->dynamicAttrs.emplace_back(std::move(i->expr), std::make_unique<ExprAttrs>(), pos);
-            attrs = static_cast<ExprAttrs *>(next.valueExpr.get());
+            ExprAttrs *nested = new ExprAttrs;
+            attrs->dynamicAttrs.push_back(ExprAttrs::DynamicAttrDef(i->expr, nested, pos));
+            attrs = nested;
        }
    }
    // Expr insertion.
@@ -103,41 +109,41 @@ inline void State::addAttr(ExprAttrs * attrs, AttrPath && attrPath, std::unique_
            // e and the expr pointed by the attr path are two attribute sets,
            // we want to merge them.
            // Otherwise, throw an error.
-            auto * ae = dynamic_cast<ExprAttrs *>(e.get());
-            auto * jAttrs = dynamic_cast<ExprAttrs *>(j->second.e.get());
+            auto ae = dynamic_cast<ExprAttrs *>(e);
+            auto jAttrs = dynamic_cast<ExprAttrs *>(j->second.e);
            if (jAttrs && ae) {
                if (ae->inheritFromExprs && !jAttrs->inheritFromExprs)
-                    jAttrs->inheritFromExprs = std::make_unique<std::vector<ref<Expr>>>();
+                    jAttrs->inheritFromExprs = std::make_unique<std::vector<Expr *>>();
                for (auto & ad : ae->attrs) {
                    auto j2 = jAttrs->attrs.find(ad.first);
                    if (j2 != jAttrs->attrs.end()) // Attr already defined in iAttrs, error.
-                        return dupAttr(ad.first, j2->second.pos, ad.second.pos);
+                        dupAttr(ad.first, j2->second.pos, ad.second.pos);
+                    jAttrs->attrs.emplace(ad.first, ad.second);
                    if (ad.second.kind == ExprAttrs::AttrDef::Kind::InheritedFrom) {
                        auto & sel = dynamic_cast<ExprSelect &>(*ad.second.e);
                        auto & from = dynamic_cast<ExprInheritFrom &>(*sel.e);
                        from.displ += jAttrs->inheritFromExprs->size();
                    }
-                    jAttrs->attrs.emplace(ad.first, std::move(ad.second));
                }
-                std::ranges::move(ae->dynamicAttrs, std::back_inserter(jAttrs->dynamicAttrs));
-                if (ae->inheritFromExprs)
-                    std::ranges::move(*ae->inheritFromExprs, std::back_inserter(*jAttrs->inheritFromExprs));
+                jAttrs->dynamicAttrs.insert(jAttrs->dynamicAttrs.end(), ae->dynamicAttrs.begin(), ae->dynamicAttrs.end());
+                if (ae->inheritFromExprs) {
+                    jAttrs->inheritFromExprs->insert(jAttrs->inheritFromExprs->end(),
+                        ae->inheritFromExprs->begin(), ae->inheritFromExprs->end());
+                }
            } else {
                dupAttr(attrPath, pos, j->second.pos);
            }
        } else {
            // This attr path is not defined. Let's create it.
+            attrs->attrs.emplace(i->symbol, ExprAttrs::AttrDef(e, pos));
            e->setName(i->symbol);
-            attrs->attrs.emplace(std::piecewise_construct,
-                std::tuple(i->symbol),
-                std::tuple(std::move(e), pos));
        }
    } else {
-        attrs->dynamicAttrs.emplace_back(std::move(i->expr), std::move(e), pos);
+        attrs->dynamicAttrs.push_back(ExprAttrs::DynamicAttrDef(i->expr, e, pos));
    }
 }

-inline std::unique_ptr<Formals> State::validateFormals(std::unique_ptr<Formals> formals, PosIdx pos, Symbol arg)
+inline Formals * ParserState::validateFormals(Formals * formals, PosIdx pos, Symbol arg)
 {
    std::sort(formals->formals.begin(), formals->formals.end(),
        [] (const auto & a, const auto & b) {
@@ -166,10 +172,10 @@ inline std::unique_ptr<Formals> State::validateFormals(std::unique_ptr<Formals>
    return formals;
 }

-inline std::unique_ptr<Expr> State::stripIndentation(const PosIdx pos,
-    std::vector<std::pair<PosIdx, std::variant<std::unique_ptr<Expr>, StringToken>>> && es)
+inline Expr * ParserState::stripIndentation(const PosIdx pos,
+    std::vector<std::pair<PosIdx, std::variant<Expr *, StringToken>>> && es)
 {
-    if (es.empty()) return std::make_unique<ExprString>("");
+    if (es.empty()) return new ExprString("");

    /* Figure out the minimum indentation.  Note that by design
       whitespace-only final lines are not taken into account.  (So
@@ -187,11 +193,11 @@ inline std::unique_ptr<Expr> State::stripIndentation(const PosIdx pos,
            }
            continue;
        }
-        for (size_t j = 0; j < str->s.size(); ++j) {
+        for (size_t j = 0; j < str->l; ++j) {
            if (atStartOfLine) {
-                if (str->s[j] == ' ')
+                if (str->p[j] == ' ')
                    curIndent++;
-                else if (str->s[j] == '\n') {
+                else if (str->p[j] == '\n') {
                    /* Empty line, doesn't influence minimum
                       indentation. */
                    curIndent = 0;
@@ -199,7 +205,7 @@ inline std::unique_ptr<Expr> State::stripIndentation(const PosIdx pos,
                    atStartOfLine = false;
                    if (curIndent < minIndent) minIndent = curIndent;
                }
-            } else if (str->s[j] == '\n') {
+            } else if (str->p[j] == '\n') {
                atStartOfLine = true;
                curIndent = 0;
            }
@@ -207,35 +213,35 @@ inline std::unique_ptr<Expr> State::stripIndentation(const PosIdx pos,
    }

    /* Strip spaces from each line. */
-    std::vector<std::pair<PosIdx, std::unique_ptr<Expr>>> es2;
+    auto * es2 = new std::vector<std::pair<PosIdx, Expr *>>;
    atStartOfLine = true;
    size_t curDropped = 0;
    size_t n = es.size();
    auto i = es.begin();
-    const auto trimExpr = [&] (std::unique_ptr<Expr> e) {
+    const auto trimExpr = [&] (Expr * e) {
        atStartOfLine = false;
        curDropped = 0;
-        es2.emplace_back(i->first, std::move(e));
+        es2->emplace_back(i->first, e);
    };
-    const auto trimString = [&] (const StringToken t) {
+    const auto trimString = [&] (const StringToken & t) {
        std::string s2;
-        for (size_t j = 0; j < t.s.size(); ++j) {
+        for (size_t j = 0; j < t.l; ++j) {
            if (atStartOfLine) {
-                if (t.s[j] == ' ') {
+                if (t.p[j] == ' ') {
                    if (curDropped++ >= minIndent)
-                        s2 += t.s[j];
+                        s2 += t.p[j];
                }
-                else if (t.s[j] == '\n') {
+                else if (t.p[j] == '\n') {
                    curDropped = 0;
-                    s2 += t.s[j];
+                    s2 += t.p[j];
                } else {
                    atStartOfLine = false;
                    curDropped = 0;
-                    s2 += t.s[j];
+                    s2 += t.p[j];
                }
            } else {
-                s2 += t.s[j];
-                if (t.s[j] == '\n') atStartOfLine = true;
+                s2 += t.p[j];
+                if (t.p[j] == '\n') atStartOfLine = true;
            }
        }

@@ -247,17 +253,24 @@ inline std::unique_ptr<Expr> State::stripIndentation(const PosIdx pos,
                s2 = std::string(s2, 0, p + 1);
        }

-        es2.emplace_back(i->first, std::make_unique<ExprString>(std::move(s2)));
+        es2->emplace_back(i->first, new ExprString(std::move(s2)));
    };
    for (; i != es.end(); ++i, --n) {
-        std::visit(overloaded { trimExpr, trimString }, std::move(i->second));
+        std::visit(overloaded { trimExpr, trimString }, i->second);
    }

    /* If this is a single string, then don't do a concatenation. */
-    if (es2.size() == 1 && dynamic_cast<ExprString *>(es2[0].second.get())) {
-        return std::move(es2[0].second);
+    if (es2->size() == 1 && dynamic_cast<ExprString *>((*es2)[0].second)) {
+        auto *const result = (*es2)[0].second;
+        delete es2;
+        return result;
    }
-    return std::make_unique<ExprConcatStrings>(pos, true, std::move(es2));
+    return new ExprConcatStrings(pos, true, es2);
+}
+
+inline PosIdx ParserState::at(const ParserLocation & loc)
+{
+    return positions.add(origin, loc.first_column);
 }

 }
--- a/Show More
+++ b/Show More
Author	SHA1	Message	Date
Jade Lovelace	5bf891b15a	release: 2.90.0 "Vanilla Ice Cream" Release produced with releng/create_release.xsh Change-Id: Ice53891cdeafff04bd6537be66e8cd6b7dd9678c	2024-07-10 08:40:42 -07:00
Raito Bezariusandjade	f72153a510	doc/release-notes: add date for major release Change-Id: I93aab93c069bb3989c3f8d17e0862899e6f76865 Signed-off-by: Raito Bezarius <raito@lix.systems>	2024-07-10 15:35:00 +00:00
Raito Bezarius	8da08ab551	version: finalize 2.90.0 Tested by Raito, pennae and time. It looks in good shape. Change-Id: I32492557361888c28fe40553c699833876a1deab Signed-off-by: Raito Bezarius <raito@lix.systems>	2024-07-10 15:32:19 +02:00
Jade Lovelace	98d0249d5c	releng: fix broken manifest from 2.90-rc1 Well that is embarrassing. I think the proper thing is to just quickly ship a -rc2, so I will open a backport of this. $ curl https://releases.lix.systems/manifest.nix # This file was generated by releng/create_release.xsh in Lix { aarch64-linux = "/nix/store/mrbknq000af7iaqhk53bnpk1fvfrc1xp-lix-2.90.0-rc1"; aarch64-darwin = "/nix/store/z1bdccwsk34iv491aygh0mm1lgpf7yy1-lix-2.90.0-rc1"; x86_64-darwin = "/nix/store/xqvfpdhzck44v6kyhgi9f8v0xybksb6a-lix-2.90.0-rc1"; x86_64-linux = "/nix/store/h2ml0nx4477r84y82jgm8y80jpr72gqw-lix-release-tarballs"; } Change-Id: I9cf007c850c2faf995a3a9d92457517b8501d1a1	2024-06-16 19:06:45 -07:00
				`@@ -1 +0,0 @@`
				`This is a file used by the dev shell shellHook in package.nix to check that this is actually a Lix repo before installing git hooks. Its contents have no meaning.`