Get rid of lowdown!

`cmark` is a more robust library for constructing Markdown than
`lowdown`. It in particular has the functionality we need to compute the
doc we need to compute. It is also more portable.

For terminal output, there is a new A.I. slop library has the same
license as the C code from lowdown upon which it is based. This keeps
our options open for upstreaming, if we want to do that.

Also, the `builtins.fetchTree` docs are now assembled using the cmark
AST rather than janky string indenting.

.github/workflows/ci.yml

@@ -174,7 +174,7 @@ jobs:
         echo "installer-url=file://$GITHUB_WORKSPACE/out" >> "$GITHUB_OUTPUT"
         TARBALL_PATH="$(find "$GITHUB_WORKSPACE/out" -name 'nix*.tar.xz' -print | head -n 1)"
         echo "tarball-path=file://$TARBALL_PATH" >> "$GITHUB_OUTPUT"
-    - uses: cachix/install-nix-action@0b0e072294b088b73964f1d72dfdac0951439dbd # v31.8.4
+    - uses: cachix/install-nix-action@7ec16f2c061ab07b235a7245e06ed46fe9a1cab6 # v31.8.3
       if: ${{ !matrix.experimental-installer }}
       with:
         install_url: ${{ format('{0}/install', steps.installer-tarball-url.outputs.installer-url) }}

doc/manual/source/command-ref/nix-build.md

@@ -36,7 +36,7 @@ to a temporary location. The tarball must include a single top-level
 directory containing at least a file named `default.nix`.
 
 `nix-build` is essentially a wrapper around
-[`nix-instantiate`](./nix-instantiate.md) (to translate a high-level Nix
+[`nix-instantiate`](nix-instantiate.md) (to translate a high-level Nix
 expression to a low-level [store derivation]) and [`nix-store
 --realise`](@docroot@/command-ref/nix-store/realise.md) (to build the store
 derivation).
@@ -52,8 +52,8 @@ derivation).
 # Options
 
 All options not listed here are passed to
-[`nix-store --realise`](./nix-store/realise.md),
-except for `--arg` and `--attr` / `-A` which are passed to [`nix-instantiate`](./nix-instantiate.md).
+[`nix-store --realise`](nix-store/realise.md),
+except for `--arg` and `--attr` / `-A` which are passed to [`nix-instantiate`](nix-instantiate.md).
 
 - <span id="opt-no-out-link">[`--no-out-link`](#opt-no-out-link)<span>
 

doc/manual/source/command-ref/nix-instantiate.md

@@ -32,7 +32,7 @@ standard input.
 
 - `--add-root` *path*
 
-  See the [corresponding option](./nix-store.md) in `nix-store`.
+  See the [corresponding option](nix-store.md) in `nix-store`.
 
 - `--parse`
 

meson.build

@@ -13,6 +13,7 @@ project(
 )
 
 # Internal Libraries
+subproject('libcmarkcpp')
 subproject('libutil')
 subproject('libstore')
 subproject('libfetchers')

packaging/dev-shell.nix

@@ -130,19 +130,15 @@ pkgs.nixComponents2.nix-util.overrideAttrs (
     havePerl = stdenv.buildPlatform == stdenv.hostPlatform && stdenv.hostPlatform.isUnix;
     ignoreCrossFile = flags: builtins.filter (flag: !(lib.strings.hasInfix "cross-file" flag)) flags;
 
-    availableComponents = lib.filterAttrs (
-      k: v: lib.meta.availableOn pkgs.hostPlatform v
-    ) allComponents;
-
     activeComponents = buildInputsClosureCond isInternal (
-      lib.attrValues (finalAttrs.passthru.config.getComponents availableComponents)
+      lib.attrValues (finalAttrs.passthru.config.getComponents allComponents)
     );
 
     allComponents = lib.filterAttrs (k: v: lib.isDerivation v) pkgs.nixComponents2;
     internalDrvs = byDrvPath (
       # Drop the attr names (not present in buildInputs anyway)
-      lib.attrValues availableComponents
-      ++ lib.concatMap (c: lib.attrValues c.tests or { }) (lib.attrValues availableComponents)
+      lib.attrValues allComponents
+      ++ lib.concatMap (c: lib.attrValues c.tests or { }) (lib.attrValues allComponents)
     );
 
     isInternal =
@@ -191,19 +187,19 @@ pkgs.nixComponents2.nix-util.overrideAttrs (
         );
 
       small =
-        (finalAttrs.finalPackage.withActiveComponents (
-          c:
-          lib.intersectAttrs (lib.genAttrs [
-            "nix-cli"
-            "nix-util-tests"
-            "nix-store-tests"
-            "nix-expr-tests"
-            "nix-fetchers-tests"
-            "nix-flake-tests"
-            "nix-functional-tests"
-            "nix-perl-bindings"
-          ] (_: null)) c
-        )).overrideAttrs
+        (finalAttrs.finalPackage.withActiveComponents (c: {
+          inherit (c)
+            nix-cli
+            nix-util-tests
+            nix-store-tests
+            nix-expr-tests
+            nix-fetchers-tests
+            nix-flake-tests
+            nix-functional-tests
+            # Currently required
+            nix-perl-bindings
+            ;
+        })).overrideAttrs
           (o: {
             mesonFlags = o.mesonFlags ++ [
               # TODO: infer from activeComponents or vice versa

packaging/hydra.nix

@@ -174,24 +174,6 @@ rec {
 
   buildNoTests = forAllSystems (system: nixpkgsFor.${system}.native.nixComponents2.nix-cli);
 
-  # Toggles some settings for better coverage. Windows needs these
-  # library combinations, and Debian build Nix with GNU readline too.
-  buildReadlineNoMarkdown =
-    let
-      components = forAllSystems (
-        system:
-        nixpkgsFor.${system}.native.nixComponents2.overrideScope (
-          self: super: {
-            nix-cmd = super.nix-cmd.override {
-              enableMarkdown = false;
-              readlineFlavor = "readline";
-            };
-          }
-        )
-      );
-    in
-    forAllPackages (pkgName: forAllSystems (system: components.${system}.${pkgName}));
-
   # Perl bindings for various platforms.
   perlBindings = forAllSystems (system: nixpkgsFor.${system}.native.nixComponents2.nix-perl-bindings);
 

src/kaitai-struct-checks/package.nix

@@ -65,6 +65,6 @@ mkMesonDerivation (finalAttrs: {
   '';
 
   meta = {
-    platforms = lib.platforms.unix;
+    platforms = lib.platforms.all;
   };
 })

src/libcmarkcpp/LICENSE.md

@@ -0,0 +1,17 @@
+Copyright (c) 2008, Natacha Porté
+Copyright (c) 2011, Vicent Martí
+Copyright (c) 2014, Xavier Mendez, Devin Torres and the Hoedown authors
+Copyright (c) 2016--2023, Kristaps Dzonsons
+Copyright (c) 2025, Obsidian Systems
+
+Permission to use, copy, modify, and/or distribute this software for any purpose
+with or without fee is hereby granted, provided that the above copyright notice
+and this permission notice appear in all copies.
+
+THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
+REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
+FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
+INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS
+OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
+TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF
+THIS SOFTWARE.

src/libcmarkcpp/README.md

@@ -0,0 +1,36 @@
+# libcmarkcpp
+
+A C++ terminal renderer for CommonMark documents.
+
+## Overview
+
+libcmarkcpp provides a terminal renderer for CommonMark (Markdown) documents using the cmark library. It renders formatted, colored output suitable for display in ANSI-capable terminals.
+
+## Features
+
+- ANSI color styling and text formatting (bold, italic, underline)
+- Intelligent text wrapping and indentation
+- Support for:
+  - Headers with hierarchical styling
+  - Lists (ordered and unordered)
+  - Code blocks (fenced and indented)
+  - Blockquotes
+  - Links with OSC8 hyperlink support
+  - Inline code, bold, and italic
+  - Horizontal rules
+  - Images
+- Terminal width detection and adaptive wrapping
+- Configurable margins, padding, and styling options
+
+## Origin
+
+This library is a C++ port of the terminal renderer from [lowdown](https://github.com/kristapsdz/lowdown) by Kristaps Dzonsons, adapted to work with the [cmark](https://github.com/commonmark/cmark) CommonMark implementation.
+
+## License
+
+ISC License (same as lowdown)
+
+## Dependencies
+
+- cmark >= 0.31.0
+- C++20 compiler

src/libcmarkcpp/include/cmark/cmark-cpp.hh

@@ -0,0 +1,89 @@
+#pragma once
+/**
+ * @file cmark-cpp.hh
+ * @brief C++ wrappers for the cmark CommonMark library
+ */
+
+#include <cmark.h>
+#include <memory>
+#include <string_view>
+#include <cassert>
+
+namespace cmark {
+
+using Node = struct cmark_node;
+using NodeType = cmark_node_type;
+using ListType = cmark_list_type;
+
+using Iter = struct cmark_iter;
+
+struct Deleter
+{
+    void operator()(Node * ptr)
+    {
+        cmark_node_free(ptr);
+    }
+
+    void operator()(Iter * ptr)
+    {
+        cmark_iter_free(ptr);
+    }
+
+    void operator()(char * ptr)
+    {
+        free(ptr);
+    }
+};
+
+template<typename T>
+using UniquePtr = std::unique_ptr<Node, Deleter>;
+
+static inline void parse_document(Node & root, std::string_view s, int options)
+{
+    cmark_parser * parser = cmark_parser_new_with_mem_into_root(options, cmark_get_default_mem_allocator(), &root);
+    cmark_parser_feed(parser, s.data(), s.size());
+    (void) cmark_parser_finish(parser);
+    cmark_parser_free(parser);
+}
+
+static inline UniquePtr<Node> parse_document(std::string_view s, int options)
+{
+    return UniquePtr<Node>{cmark_parse_document(s.data(), s.size(), options)};
+}
+
+static inline std::unique_ptr<char, Deleter> render_commonmark(Node & root, int options, int width)
+{
+    return std::unique_ptr<char, Deleter>{cmark_render_commonmark(&root, options, width)};
+}
+
+static inline std::unique_ptr<char, Deleter> render_xml(Node & root, int options)
+{
+    return std::unique_ptr<char, Deleter>{cmark_render_xml(&root, options)};
+}
+
+static inline UniquePtr<Node> node_new(NodeType type)
+{
+    return UniquePtr<Node>{cmark_node_new(type)};
+}
+
+/**
+ * The parent takes ownership
+ */
+static inline Node & node_append_child(Node & node, UniquePtr<Node> child)
+{
+    auto status = (bool) cmark_node_append_child(&node, &*child);
+    assert(status);
+    return *child.release();
+}
+
+static inline bool node_set_literal(Node & node, const char * content)
+{
+    return (bool) cmark_node_set_literal(&node, content);
+}
+
+static inline bool node_set_list_type(Node & node, ListType type)
+{
+    return (bool) cmark_node_set_list_type(&node, type);
+}
+
+} // namespace cmark

src/libcmarkcpp/include/cmark/cmark-terminal.hh

@@ -0,0 +1,108 @@
+#pragma once
+///@file
+
+#include "cmark-cpp.hh"
+
+#include <string>
+#include <vector>
+#include <memory>
+
+namespace cmark {
+
+/**
+ * Terminal rendering options
+ */
+struct TerminalOptions
+{
+    /** Terminal width in columns */
+    size_t cols = 80;
+
+    /** Content width (0 = auto, max 80 or cols) */
+    size_t width = 0;
+
+    /** Horizontal margin (left padding) */
+    size_t hmargin = 0;
+
+    /** Horizontal padding (additional left padding) */
+    size_t hpadding = 4;
+
+    /** Vertical margin (blank lines before/after) */
+    size_t vmargin = 0;
+
+    /** Center content */
+    bool centre = false;
+
+    /** Disable ANSI escape sequences */
+    bool noAnsi = false;
+
+    /** Disable ANSI colors only */
+    bool noColor = false;
+
+    /** Don't show any link URLs */
+    bool noLink = false;
+
+    /** Don't show relative link URLs */
+    bool noRelLink = false;
+
+    /** Shorten long URLs */
+    bool shortLink = false;
+};
+
+/**
+ * Style attributes for terminal output
+ */
+struct Style
+{
+    bool italic = false;
+    bool strike = false;
+    bool bold = false;
+    bool under = false;
+    size_t bcolour = 0; // Background color (ANSI code)
+    size_t colour = 0;  // Foreground color (ANSI code)
+    int override = 0;   // Override flags
+
+    static constexpr int OVERRIDE_UNDER = 0x01;
+    static constexpr int OVERRIDE_BOLD = 0x02;
+
+    bool hasStyle() const
+    {
+        return colour || bold || italic || under || strike || bcolour || override;
+    }
+};
+
+/**
+ * Terminal renderer for CommonMark documents
+ *
+ * Renders a CMark AST to ANSI terminal output with styling, wrapping,
+ * and proper indentation.
+ */
+class TerminalRenderer
+{
+public:
+    /**
+     * Create a new terminal renderer with the given options
+     */
+    explicit TerminalRenderer(const TerminalOptions & opts = TerminalOptions{});
+
+    ~TerminalRenderer();
+
+    // Non-copyable
+    TerminalRenderer(const TerminalRenderer &) = delete;
+    TerminalRenderer & operator=(const TerminalRenderer &) = delete;
+
+    /**
+     * Render a CMark node tree to a string
+     */
+    std::string render(cmark::Node & root);
+
+private:
+    struct Impl;
+    std::unique_ptr<Impl> impl;
+};
+
+/**
+ * Convenience function to render a CMark document to terminal output
+ */
+std::string renderTerminal(cmark::Node & root, const TerminalOptions & opts = TerminalOptions{});
+
+} // namespace cmark

src/libcmarkcpp/meson.build

@@ -0,0 +1,57 @@
+project(
+  'cmark-cpp',
+  'cpp',
+  version : '0.1',
+  default_options : [
+    'cpp_std=c++20',
+    'warning_level=1',
+  ],
+  meson_version : '>= 1.1',
+  license : 'ISC',
+)
+
+cxx = meson.get_compiler('cpp')
+
+# CMark dependency
+cmark = dependency('libcmark', required : true)
+
+sources = files(
+  'cmark-terminal.cc',
+)
+
+headers = files(
+  'include/cmark/cmark-cpp.hh',
+  'include/cmark/cmark-terminal.hh',
+)
+
+include_dirs = include_directories('include')
+
+libcmarkcpp = library(
+  'cmarkcpp',
+  sources,
+  dependencies : cmark,
+  include_directories : include_dirs,
+  install : true,
+  version : meson.project_version(),
+)
+
+install_headers(headers, subdir : 'cmark')
+
+# Make this available as a dependency for meson projects
+meson.override_dependency(
+  'cmark-cpp',
+  declare_dependency(
+    include_directories : include_dirs,
+    link_with : libcmarkcpp,
+    dependencies : cmark,
+  ),
+)
+
+# Pkg-config file
+pkg = import('pkgconfig')
+pkg.generate(
+  libcmarkcpp,
+  name : 'cmark-cpp',
+  description : 'C++ terminal renderer for CommonMark',
+  url : 'https://github.com/NixOS/nix',
+)

src/libcmd/common-eval-args.cc

@@ -132,7 +132,7 @@ MixEvalArgs::MixEvalArgs()
             fetchers::Attrs extraAttrs;
             if (to.subdir != "")
                 extraAttrs["dir"] = to.subdir;
-            fetchers::overrideRegistry(from.input, to.input, extraAttrs);
+            fetchers::overrideRegistry(fetchSettings, from.input, to.input, extraAttrs);
         }},
         .completer = {[&](AddCompletions & completions, size_t, std::string_view prefix) {
             completeFlakeRef(completions, openStore(), prefix);

src/libcmd/installables.cc

@@ -185,6 +185,7 @@ MixFlakeOptions::MixFlakeOptions()
                     }
 
                     overrideRegistry(
+                        fetchSettings,
                         fetchers::Input::fromAttrs(fetchSettings, {{"type", "indirect"}, {"id", inputName}}),
                         input3->lockedRef.input,
                         extraAttrs);

src/libcmd/markdown.cc

@@ -1,79 +1,38 @@
 #include "nix/cmd/markdown.hh"
 #include "nix/util/environment-variables.hh"
 #include "nix/util/error.hh"
-#include "nix/util/finally.hh"
 #include "nix/util/terminal.hh"
 
-#include "cmd-config-private.hh"
-
-#if HAVE_LOWDOWN
-#  include <sys/queue.h>
-#  include <lowdown.h>
-#endif
+#include <cmark/cmark-cpp.hh>
+#include <cmark/cmark-terminal.hh>
 
 namespace nix {
 
-#if HAVE_LOWDOWN
 static std::string doRenderMarkdownToTerminal(std::string_view markdown)
 {
     int windowWidth = getWindowSize().second;
 
-#  if HAVE_LOWDOWN_1_4
-    struct lowdown_opts_term opts_term{
-        .cols = (size_t) std::max(windowWidth - 5, 60),
-        .hmargin = 0,
-        .vmargin = 0,
-    };
-#  endif
-    struct lowdown_opts opts{
-        .type = LOWDOWN_TERM,
-#  if HAVE_LOWDOWN_1_4
-        .term = opts_term,
-#  endif
-        .maxdepth = 20,
-#  if !HAVE_LOWDOWN_1_4
-        .cols = (size_t) std::max(windowWidth - 5, 60),
-        .hmargin = 0,
-        .vmargin = 0,
-#  endif
-        .feat = LOWDOWN_COMMONMARK | LOWDOWN_FENCED | LOWDOWN_DEFLIST | LOWDOWN_TABLES,
-        .oflags =
-#  if HAVE_LOWDOWN_1_4
-            LOWDOWN_TERM_NORELLINK // To render full links while skipping relative ones
-#  else
-            LOWDOWN_TERM_NOLINK
-#  endif
-    };
+    // Set up terminal rendering options
+    ::cmark::TerminalOptions opts;
+    opts.cols = std::max(windowWidth - 5, 60);
+    opts.hmargin = 0;
+    opts.vmargin = 0;
+    opts.noRelLink = true; // Skip rendering relative links
 
     if (!isTTY())
-        opts.oflags |= LOWDOWN_TERM_NOANSI;
+        opts.noAnsi = true;
 
-    auto doc = lowdown_doc_new(&opts);
+    // Parse the markdown document
+    auto doc = ::cmark::parse_document(markdown, CMARK_OPT_DEFAULT);
     if (!doc)
-        throw Error("cannot allocate Markdown document");
-    Finally freeDoc([&]() { lowdown_doc_free(doc); });
-
-    size_t maxn = 0;
-    auto node = lowdown_doc_parse(doc, &maxn, markdown.data(), markdown.size(), nullptr);
-    if (!node)
         throw Error("cannot parse Markdown document");
-    Finally freeNode([&]() { lowdown_node_free(node); });
 
-    auto renderer = lowdown_term_new(&opts);
-    if (!renderer)
-        throw Error("cannot allocate Markdown renderer");
-    Finally freeRenderer([&]() { lowdown_term_free(renderer); });
-
-    auto buf = lowdown_buf_new(16384);
-    if (!buf)
-        throw Error("cannot allocate Markdown output buffer");
-    Finally freeBuffer([&]() { lowdown_buf_free(buf); });
-
-    int rndr_res = lowdown_term_rndr(buf, renderer, node);
-    if (!rndr_res)
-        throw Error("allocation error while rendering Markdown");
-
-    return std::string(buf->data, buf->size);
+    try {
+        // Render to terminal
+        return ::cmark::renderTerminal(*doc, opts);
+    } catch (const std::exception & e) {
+        throw Error("error rendering Markdown: %s", e.what());
+    }
 }
 
 std::string renderMarkdownToTerminal(std::string_view markdown)
@@ -84,11 +43,4 @@ std::string renderMarkdownToTerminal(std::string_view markdown)
         return doRenderMarkdownToTerminal(markdown);
 }
 
-#else
-std::string renderMarkdownToTerminal(std::string_view markdown)
-{
-    return std::string(markdown);
-}
-#endif
-
 } // namespace nix

src/libcmd/meson.build

@@ -26,25 +26,13 @@ deps_public_maybe_subproject = [
   dependency('nix-expr'),
   dependency('nix-flake'),
   dependency('nix-main'),
+  dependency('cmark-cpp'),
 ]
 subdir('nix-meson-build-support/subprojects')
 
 nlohmann_json = dependency('nlohmann_json', version : '>= 3.9')
 deps_public += nlohmann_json
 
-lowdown = dependency(
-  'lowdown',
-  version : '>= 0.9.0',
-  required : get_option('markdown'),
-)
-deps_private += lowdown
-configdata.set('HAVE_LOWDOWN', lowdown.found().to_int())
-# The API changed slightly around terminal initialization.
-configdata.set(
-  'HAVE_LOWDOWN_1_4',
-  lowdown.version().version_compare('>= 1.4.0').to_int(),
-)
-
 readline_flavor = get_option('readline-flavor')
 if readline_flavor == 'editline'
   editline = dependency('libeditline', 'editline', version : '>=1.14')

src/libcmd/meson.options

@@ -1,11 +1,5 @@
 # vim: filetype=meson
 
-option(
-  'markdown',
-  type : 'feature',
-  description : 'Enable Markdown rendering in the Nix binary (requires lowdown)',
-)
-
 option(
   'readline-flavor',
   type : 'combo',

src/libcmd/package.nix

@@ -11,16 +11,12 @@
   nix-main,
   editline,
   readline,
-  lowdown,
   nlohmann_json,
 
   # Configuration Options
 
   version,
 
-  # Whether to enable Markdown rendering in the Nix binary.
-  enableMarkdown ? !stdenv.hostPlatform.isWindows,
-
   # Which interactive line editor library to use for Nix's repl.
   #
   # Currently supported choices are:
@@ -53,8 +49,7 @@ mkMesonLibrary (finalAttrs: {
 
   buildInputs = [
     ({ inherit editline readline; }.${readlineFlavor})
-  ]
-  ++ lib.optional enableMarkdown lowdown;
+  ];
 
   propagatedBuildInputs = [
     nix-util
@@ -67,7 +62,6 @@ mkMesonLibrary (finalAttrs: {
   ];
 
   mesonFlags = [
-    (lib.mesonEnable "markdown" enableMarkdown)
     (lib.mesonOption "readline-flavor" readlineFlavor)
   ];
 

src/libexpr/meson.build

@@ -24,6 +24,7 @@ deps_public_maybe_subproject = [
   dependency('nix-util'),
   dependency('nix-store'),
   dependency('nix-fetchers'),
+  dependency('cmark-cpp'),
 ]
 subdir('nix-meson-build-support/subprojects')
 subdir('nix-meson-build-support/big-objs')

src/libexpr/primops/fetchTree.cc

@@ -8,6 +8,7 @@
 #include "nix/fetchers/registry.hh"
 #include "nix/fetchers/tarball.hh"
 #include "nix/util/url.hh"
+#include "nix/util/cmark-cpp.hh"
 #include "nix/expr/value-to-json.hh"
 #include "nix/fetchers/fetch-to-store.hh"
 #include "nix/fetchers/input-cache.hh"
@@ -236,7 +237,14 @@ static RegisterPrimOp primop_fetchTree({
     .name = "fetchTree",
     .args = {"input"},
     .doc = []() -> std::string {
-        std::string doc = stripIndentation(R"(
+        using namespace cmark;
+
+        // Stores strings referenced by AST. Deallocate after rendering.
+        std::vector<std::string> textArena;
+
+        auto root = node_new(CMARK_NODE_DOCUMENT);
+
+        auto & before = textArena.emplace_back(stripIndentation(R"(
           Fetch a file system tree or a plain file using one of the supported backends and return an attribute set with:
 
           - the resulting fixed-output [store path](@docroot@/store/store-path.md)
@@ -276,38 +284,45 @@ static RegisterPrimOp primop_fetchTree({
           <!-- TODO: It would be soooo much more predictable to work with (and
           document) if `fetchTree` was a curried call with the first parameter for
           `type` or an attribute like `builtins.fetchTree.git`! -->
-        )");
+        )"));
+        parse_document(*root, before, CMARK_OPT_DEFAULT);
 
-        auto indentString = [](std::string const & str, std::string const & indent) {
-            std::string result;
-            std::istringstream stream(str);
-            std::string line;
-            bool first = true;
-            while (std::getline(stream, line)) {
-                if (!first)
-                    result += "\n";
-                result += indent + line;
-                first = false;
-            }
-            return result;
-        };
+        auto & schemes = node_append_child(*root, node_new(CMARK_NODE_LIST));
 
         for (const auto & [schemeName, scheme] : fetchers::getAllInputSchemes()) {
-            doc += "\n- `" + quoteString(schemeName, '"') + "`\n\n";
-            doc += indentString(scheme->schemeDescription(), "  ");
-            if (!doc.empty() && doc.back() != '\n')
-                doc += "\n";
+            auto & s = node_append_child(schemes, node_new(CMARK_NODE_ITEM));
+            {
+                auto & name_p = node_append_child(s, node_new(CMARK_NODE_PARAGRAPH));
+                auto & name = node_append_child(name_p, node_new(CMARK_NODE_CODE));
+                auto & name_t = textArena.emplace_back(quoteString(schemeName, '"'));
+                node_set_literal(name, name_t.c_str());
+            }
+            parse_document(s, scheme->schemeDescription(), CMARK_OPT_DEFAULT);
 
+            auto & attrs = node_append_child(s, node_new(CMARK_NODE_LIST));
             for (const auto & [attrName, attribute] : scheme->allowedAttrs()) {
-                doc += "\n  - `" + attrName + "` (" + attribute.type + ", "
-                       + (attribute.required ? "required" : "optional") + ")\n\n";
-                doc += indentString(stripIndentation(attribute.doc), "    ");
-                if (!doc.empty() && doc.back() != '\n')
-                    doc += "\n";
+                auto & a = node_append_child(attrs, node_new(CMARK_NODE_ITEM));
+                {
+                    auto & name_info = node_append_child(a, node_new(CMARK_NODE_PARAGRAPH));
+                    {
+                        auto & name = node_append_child(name_info, node_new(CMARK_NODE_CODE));
+                        auto & name_t = textArena.emplace_back(attrName);
+                        node_set_literal(name, name_t.c_str());
+                    }
+                    auto & info = node_append_child(name_info, node_new(CMARK_NODE_TEXT));
+                    auto & header = textArena.emplace_back(
+                        std::string{} + " (" + attribute.type + ", " + (attribute.required ? "required" : "optional")
+                        + ")");
+                    node_set_literal(info, header.c_str());
+                }
+                {
+                    auto & doc = textArena.emplace_back(stripIndentation(attribute.doc));
+                    parse_document(a, doc, CMARK_OPT_DEFAULT);
+                }
             }
         }
 
-        doc += "\n" + stripIndentation(R"(
+        auto & after = textArena.emplace_back(stripIndentation(R"(
           The following input types are still subject to change:
 
           - `"path"`
@@ -352,9 +367,12 @@ static RegisterPrimOp primop_fetchTree({
           >   ```nix
           >   builtins.fetchTree "github:NixOS/nixpkgs/ae2e6b3958682513d28f7d633734571fb18285dd"
           >   ```
-        )");
+        )"));
+        parse_document(*root, after, CMARK_OPT_DEFAULT);
 
-        return doc;
+        auto p = render_commonmark(*root, CMARK_OPT_DEFAULT, 0);
+        assert(p);
+        return {&*p};
     }(),
     .fun = prim_fetchTree,
     .experimentalFeature = Xp::FetchTree,

src/libfetchers/include/nix/fetchers/registry.hh

@@ -13,6 +13,8 @@ namespace nix::fetchers {
 
 struct Registry
 {
+    const Settings & settings;
+
     enum RegistryType {
         Flag = 0,
         User = 1,
@@ -32,8 +34,9 @@ struct Registry
 
     std::vector<Entry> entries;
 
-    Registry(RegistryType type)
-        : type{type}
+    Registry(const Settings & settings, RegistryType type)
+        : settings{settings}
+        , type{type}
     {
     }
 
@@ -56,7 +59,7 @@ Path getUserRegistryPath();
 
 Registries getRegistries(const Settings & settings, Store & store);
 
-void overrideRegistry(const Input & from, const Input & to, const Attrs & extraAttrs);
+void overrideRegistry(const Settings & settings, const Input & from, const Input & to, const Attrs & extraAttrs);
 
 enum class UseRegistries : int {
     No,

src/libfetchers/registry.cc

@@ -14,10 +14,10 @@ std::shared_ptr<Registry> Registry::read(const Settings & settings, const Source
 {
     debug("reading registry '%s'", path);
 
-    auto registry = std::make_shared<Registry>(type);
+    auto registry = std::make_shared<Registry>(settings, type);
 
     if (!path.pathExists())
-        return std::make_shared<Registry>(type);
+        return std::make_shared<Registry>(settings, type);
 
     try {
 
@@ -125,15 +125,15 @@ std::shared_ptr<Registry> getCustomRegistry(const Settings & settings, const Pat
     return customRegistry;
 }
 
-std::shared_ptr<Registry> getFlagRegistry()
+std::shared_ptr<Registry> getFlagRegistry(const Settings & settings)
 {
-    static auto flagRegistry = std::make_shared<Registry>(Registry::Flag);
+    static auto flagRegistry = std::make_shared<Registry>(settings, Registry::Flag);
     return flagRegistry;
 }
 
-void overrideRegistry(const Input & from, const Input & to, const Attrs & extraAttrs)
+void overrideRegistry(const Settings & settings, const Input & from, const Input & to, const Attrs & extraAttrs)
 {
-    getFlagRegistry()->add(from, to, extraAttrs);
+    getFlagRegistry(settings)->add(from, to, extraAttrs);
 }
 
 static std::shared_ptr<Registry> getGlobalRegistry(const Settings & settings, Store & store)
@@ -141,7 +141,7 @@ static std::shared_ptr<Registry> getGlobalRegistry(const Settings & settings, St
     static auto reg = [&]() {
         auto path = settings.flakeRegistry.get();
         if (path == "") {
-            return std::make_shared<Registry>(Registry::Global); // empty registry
+            return std::make_shared<Registry>(settings, Registry::Global); // empty registry
         }
 
         return Registry::read(
@@ -165,7 +165,7 @@ static std::shared_ptr<Registry> getGlobalRegistry(const Settings & settings, St
 Registries getRegistries(const Settings & settings, Store & store)
 {
     Registries registries;
-    registries.push_back(getFlagRegistry());
+    registries.push_back(getFlagRegistry(settings));
     registries.push_back(getUserRegistry(settings));
     registries.push_back(getSystemRegistry(settings));
     registries.push_back(getGlobalRegistry(settings, store));

src/libstore-tests/data/derivation/ca/all_set.json

@@ -4,13 +4,10 @@
   "allowSubstitutes": false,
   "exportReferencesGraph": {
     "refs1": [
-      {
-        "drvPath": "j56sf12rxpcv5swr14vsjn5cwm6bj03h-foo.drv",
-        "output": "out"
-      }
+      "/164j69y6zir9z0339n8pjigg3rckinlr77bxsavzizdaaljb7nh9"
     ],
     "refs2": [
-      "qnml92yh97a6fbrs2m5qg5cqlc8vni58-bar.drv"
+      "/nix/store/qnml92yh97a6fbrs2m5qg5cqlc8vni58-bar.drv"
     ]
   },
   "impureEnvVars": [
@@ -23,36 +20,18 @@
   "outputChecks": {
     "forAllOutputs": {
       "allowedReferences": [
-        {
-          "drvPath": "j56sf12rxpcv5swr14vsjn5cwm6bj03h-foo.drv",
-          "output": "out"
-        }
+        "/164j69y6zir9z0339n8pjigg3rckinlr77bxsavzizdaaljb7nh9"
       ],
       "allowedRequisites": [
-        {
-          "drvPath": "self",
-          "output": "bin"
-        },
-        {
-          "drvPath": "j56sf12rxpcv5swr14vsjn5cwm6bj03h-foo.drv",
-          "output": "dev"
-        }
+        "/0nr45p69vn6izw9446wsh9bng9nndhvn19kpsm4n96a5mycw0s4z",
+        "bin"
       ],
       "disallowedReferences": [
-        {
-          "drvPath": "self",
-          "output": "dev"
-        },
-        {
-          "drvPath": "qnml92yh97a6fbrs2m5qg5cqlc8vni58-bar.drv",
-          "output": "out"
-        }
+        "/0nyw57wm2iicnm9rglvjmbci3ikmcp823czdqdzdcgsnnwqps71g",
+        "dev"
       ],
       "disallowedRequisites": [
-        {
-          "drvPath": "qnml92yh97a6fbrs2m5qg5cqlc8vni58-bar.drv",
-          "output": "dev"
-        }
+        "/07f301yqyz8c6wf6bbbavb2q39j4n8kmcly1s09xadyhgy6x2wr8"
       ],
       "ignoreSelfRefs": true,
       "maxClosureSize": null,

src/libstore-tests/data/derivation/ca/structuredAttrs_all_set.json

@@ -4,13 +4,10 @@
   "allowSubstitutes": false,
   "exportReferencesGraph": {
     "refs1": [
-      {
-        "drvPath": "j56sf12rxpcv5swr14vsjn5cwm6bj03h-foo.drv",
-        "output": "out"
-      }
+      "/164j69y6zir9z0339n8pjigg3rckinlr77bxsavzizdaaljb7nh9"
     ],
     "refs2": [
-      "qnml92yh97a6fbrs2m5qg5cqlc8vni58-bar.drv"
+      "/nix/store/qnml92yh97a6fbrs2m5qg5cqlc8vni58-bar.drv"
     ]
   },
   "impureEnvVars": [
@@ -26,20 +23,11 @@
         "allowedReferences": null,
         "allowedRequisites": null,
         "disallowedReferences": [
-          {
-            "drvPath": "self",
-            "output": "dev"
-          },
-          {
-            "drvPath": "qnml92yh97a6fbrs2m5qg5cqlc8vni58-bar.drv",
-            "output": "out"
-          }
+          "/0nyw57wm2iicnm9rglvjmbci3ikmcp823czdqdzdcgsnnwqps71g",
+          "dev"
         ],
         "disallowedRequisites": [
-          {
-            "drvPath": "qnml92yh97a6fbrs2m5qg5cqlc8vni58-bar.drv",
-            "output": "dev"
-          }
+          "/07f301yqyz8c6wf6bbbavb2q39j4n8kmcly1s09xadyhgy6x2wr8"
         ],
         "ignoreSelfRefs": false,
         "maxClosureSize": null,
@@ -56,20 +44,11 @@
       },
       "out": {
         "allowedReferences": [
-          {
-            "drvPath": "j56sf12rxpcv5swr14vsjn5cwm6bj03h-foo.drv",
-            "output": "out"
-          }
+          "/164j69y6zir9z0339n8pjigg3rckinlr77bxsavzizdaaljb7nh9"
         ],
         "allowedRequisites": [
-          {
-            "drvPath": "self",
-            "output": "bin"
-          },
-          {
-            "drvPath": "j56sf12rxpcv5swr14vsjn5cwm6bj03h-foo.drv",
-            "output": "dev"
-          }
+          "/0nr45p69vn6izw9446wsh9bng9nndhvn19kpsm4n96a5mycw0s4z",
+          "bin"
         ],
         "disallowedReferences": [],
         "disallowedRequisites": [],

src/libstore-tests/data/derivation/ia/all_set.json

@@ -4,10 +4,10 @@
   "allowSubstitutes": false,
   "exportReferencesGraph": {
     "refs1": [
-      "p0hax2lzvjpfc2gwkk62xdglz0fcqfzn-foo"
+      "/nix/store/p0hax2lzvjpfc2gwkk62xdglz0fcqfzn-foo"
     ],
     "refs2": [
-      "vj2i49jm2868j2fmqvxm70vlzmzvgv14-bar.drv"
+      "/nix/store/vj2i49jm2868j2fmqvxm70vlzmzvgv14-bar.drv"
     ]
   },
   "impureEnvVars": [
@@ -20,24 +20,18 @@
   "outputChecks": {
     "forAllOutputs": {
       "allowedReferences": [
-        "p0hax2lzvjpfc2gwkk62xdglz0fcqfzn-foo"
+        "/nix/store/p0hax2lzvjpfc2gwkk62xdglz0fcqfzn-foo"
       ],
       "allowedRequisites": [
-        {
-          "drvPath": "self",
-          "output": "bin"
-        },
-        "z0rjzy29v9k5qa4nqpykrbzirj7sd43v-foo-dev"
+        "/nix/store/z0rjzy29v9k5qa4nqpykrbzirj7sd43v-foo-dev",
+        "bin"
       ],
       "disallowedReferences": [
-        {
-          "drvPath": "self",
-          "output": "dev"
-        },
-        "r5cff30838majxk5mp3ip2diffi8vpaj-bar"
+        "/nix/store/r5cff30838majxk5mp3ip2diffi8vpaj-bar",
+        "dev"
       ],
       "disallowedRequisites": [
-        "9b61w26b4avv870dw0ymb6rw4r1hzpws-bar-dev"
+        "/nix/store/9b61w26b4avv870dw0ymb6rw4r1hzpws-bar-dev"
       ],
       "ignoreSelfRefs": true,
       "maxClosureSize": null,

src/libstore-tests/data/derivation/ia/structuredAttrs_all_set.json

@@ -4,10 +4,10 @@
   "allowSubstitutes": false,
   "exportReferencesGraph": {
     "refs1": [
-      "p0hax2lzvjpfc2gwkk62xdglz0fcqfzn-foo"
+      "/nix/store/p0hax2lzvjpfc2gwkk62xdglz0fcqfzn-foo"
     ],
     "refs2": [
-      "vj2i49jm2868j2fmqvxm70vlzmzvgv14-bar.drv"
+      "/nix/store/vj2i49jm2868j2fmqvxm70vlzmzvgv14-bar.drv"
     ]
   },
   "impureEnvVars": [
@@ -23,14 +23,11 @@
         "allowedReferences": null,
         "allowedRequisites": null,
         "disallowedReferences": [
-          {
-            "drvPath": "self",
-            "output": "dev"
-          },
-          "r5cff30838majxk5mp3ip2diffi8vpaj-bar"
+          "/nix/store/r5cff30838majxk5mp3ip2diffi8vpaj-bar",
+          "dev"
         ],
         "disallowedRequisites": [
-          "9b61w26b4avv870dw0ymb6rw4r1hzpws-bar-dev"
+          "/nix/store/9b61w26b4avv870dw0ymb6rw4r1hzpws-bar-dev"
         ],
         "ignoreSelfRefs": false,
         "maxClosureSize": null,
@@ -47,14 +44,11 @@
       },
       "out": {
         "allowedReferences": [
-          "p0hax2lzvjpfc2gwkk62xdglz0fcqfzn-foo"
+          "/nix/store/p0hax2lzvjpfc2gwkk62xdglz0fcqfzn-foo"
         ],
         "allowedRequisites": [
-          {
-            "drvPath": "self",
-            "output": "bin"
-          },
-          "z0rjzy29v9k5qa4nqpykrbzirj7sd43v-foo-dev"
+          "/nix/store/z0rjzy29v9k5qa4nqpykrbzirj7sd43v-foo-dev",
+          "bin"
         ],
         "disallowedReferences": [],
         "disallowedRequisites": [],

src/libstore-tests/derivation-advanced-attrs.cc

@@ -3,7 +3,7 @@
 
 #include "nix/util/experimental-features.hh"
 #include "nix/store/derivations.hh"
-#include "nix/store/derived-path.hh"
+#include "nix/store/derivations.hh"
 #include "nix/store/derivation-options.hh"
 #include "nix/store/parsed-derivations.hh"
 #include "nix/util/types.hh"
@@ -17,7 +17,7 @@ namespace nix {
 using namespace nlohmann;
 
 class DerivationAdvancedAttrsTest : public JsonCharacterizationTest<Derivation>,
-                                    public JsonCharacterizationTest<DerivationOptions<SingleDerivedPath>>,
+                                    public JsonCharacterizationTest<DerivationOptions>,
                                     public LibStoreTest
 {
 protected:
@@ -42,8 +42,7 @@ public:
     {
         this->readTest(fileName, [&](auto encoded) {
             auto got = parseDerivation(*this->store, std::move(encoded), "foo", this->mockXpSettings);
-            auto options = derivationOptionsFromStructuredAttrs(
-                *this->store, got.inputDrvs, got.env, get(got.structuredAttrs), true, this->mockXpSettings);
+            DerivationOptions options = DerivationOptions::fromStructuredAttrs(got.env, got.structuredAttrs);
             EXPECT_EQ(options.getRequiredSystemFeatures(got), expectedFeatures);
         });
     }
@@ -52,14 +51,11 @@ public:
      * Helper function to test DerivationOptions parsing and comparison
      */
     void testDerivationOptions(
-        const std::string & fileName,
-        const DerivationOptions<SingleDerivedPath> & expected,
-        const StringSet & expectedSystemFeatures)
+        const std::string & fileName, const DerivationOptions & expected, const StringSet & expectedSystemFeatures)
     {
         this->readTest(fileName, [&](auto encoded) {
             auto got = parseDerivation(*this->store, std::move(encoded), "foo", this->mockXpSettings);
-            auto options = derivationOptionsFromStructuredAttrs(
-                *this->store, got.inputDrvs, got.env, get(got.structuredAttrs), true, this->mockXpSettings);
+            DerivationOptions options = DerivationOptions::fromStructuredAttrs(got.env, got.structuredAttrs);
 
             EXPECT_EQ(options, expected);
             EXPECT_EQ(options.getRequiredSystemFeatures(got), expectedSystemFeatures);
@@ -135,38 +131,22 @@ TEST_ATERM_JSON(advancedAttributes_structuredAttrs_defaults, "advanced-attribute
  * Since these are both repeated and sensative opaque values, it makes
  * sense to give them names in this file.
  */
-static SingleDerivedPath
-    pathFoo = SingleDerivedPath::Opaque{StorePath{"p0hax2lzvjpfc2gwkk62xdglz0fcqfzn-foo"}},
-    pathFooDev = SingleDerivedPath::Opaque{StorePath{"z0rjzy29v9k5qa4nqpykrbzirj7sd43v-foo-dev"}},
-    pathBar = SingleDerivedPath::Opaque{StorePath{"r5cff30838majxk5mp3ip2diffi8vpaj-bar"}},
-    pathBarDev = SingleDerivedPath::Opaque{StorePath{"9b61w26b4avv870dw0ymb6rw4r1hzpws-bar-dev"}},
-    pathBarDrvIA = SingleDerivedPath::Opaque{StorePath{"vj2i49jm2868j2fmqvxm70vlzmzvgv14-bar.drv"}},
-    pathBarDrvCA = SingleDerivedPath::Opaque{StorePath{"qnml92yh97a6fbrs2m5qg5cqlc8vni58-bar.drv"}},
-    placeholderFoo =
-        SingleDerivedPath::Built{
-            .drvPath = makeConstantStorePathRef(StorePath{"j56sf12rxpcv5swr14vsjn5cwm6bj03h-foo.drv"}),
-            .output = "out",
-        },
-    placeholderFooDev =
-        SingleDerivedPath::Built{
-            .drvPath = makeConstantStorePathRef(StorePath{"j56sf12rxpcv5swr14vsjn5cwm6bj03h-foo.drv"}),
-            .output = "dev",
-        },
-    placeholderBar =
-        SingleDerivedPath::Built{
-            .drvPath = makeConstantStorePathRef(StorePath{"qnml92yh97a6fbrs2m5qg5cqlc8vni58-bar.drv"}),
-            .output = "out",
-        },
-    placeholderBarDev = SingleDerivedPath::Built{
-        .drvPath = makeConstantStorePathRef(StorePath{"qnml92yh97a6fbrs2m5qg5cqlc8vni58-bar.drv"}),
-        .output = "dev",
-    };
+static std::string pathFoo = "/nix/store/p0hax2lzvjpfc2gwkk62xdglz0fcqfzn-foo",
+                   pathFooDev = "/nix/store/z0rjzy29v9k5qa4nqpykrbzirj7sd43v-foo-dev",
+                   pathBar = "/nix/store/r5cff30838majxk5mp3ip2diffi8vpaj-bar",
+                   pathBarDev = "/nix/store/9b61w26b4avv870dw0ymb6rw4r1hzpws-bar-dev",
+                   pathBarDrvIA = "/nix/store/vj2i49jm2868j2fmqvxm70vlzmzvgv14-bar.drv",
+                   pathBarDrvCA = "/nix/store/qnml92yh97a6fbrs2m5qg5cqlc8vni58-bar.drv",
+                   placeholderFoo = "/164j69y6zir9z0339n8pjigg3rckinlr77bxsavzizdaaljb7nh9",
+                   placeholderFooDev = "/0nr45p69vn6izw9446wsh9bng9nndhvn19kpsm4n96a5mycw0s4z",
+                   placeholderBar = "/0nyw57wm2iicnm9rglvjmbci3ikmcp823czdqdzdcgsnnwqps71g",
+                   placeholderBarDev = "/07f301yqyz8c6wf6bbbavb2q39j4n8kmcly1s09xadyhgy6x2wr8";
 
-using ExportReferencesMap = decltype(DerivationOptions<SingleDerivedPath>::exportReferencesGraph);
+using ExportReferencesMap = decltype(DerivationOptions::exportReferencesGraph);
 
-static const DerivationOptions<SingleDerivedPath> advancedAttributes_defaults = {
+static const DerivationOptions advancedAttributes_defaults = {
     .outputChecks =
-        DerivationOptions<SingleDerivedPath>::OutputChecks{
+        DerivationOptions::OutputChecks{
             .ignoreSelfRefs = true,
         },
     .unsafeDiscardReferences = {},
@@ -187,8 +167,7 @@ TYPED_TEST(DerivationAdvancedAttrsBothTest, advancedAttributes_defaults)
     this->readTest("advanced-attributes-defaults.drv", [&](auto encoded) {
         auto got = parseDerivation(*this->store, std::move(encoded), "foo", this->mockXpSettings);
 
-        auto options = derivationOptionsFromStructuredAttrs(
-            *this->store, got.inputDrvs, got.env, get(got.structuredAttrs), true, this->mockXpSettings);
+        DerivationOptions options = DerivationOptions::fromStructuredAttrs(got.env, got.structuredAttrs);
 
         EXPECT_TRUE(!got.structuredAttrs);
 
@@ -213,9 +192,9 @@ TEST_F(CaDerivationAdvancedAttrsTest, advancedAttributes_defaults)
 
 TYPED_TEST(DerivationAdvancedAttrsBothTest, advancedAttributes)
 {
-    DerivationOptions<SingleDerivedPath> expected = {
+    DerivationOptions expected = {
         .outputChecks =
-            DerivationOptions<SingleDerivedPath>::OutputChecks{
+            DerivationOptions::OutputChecks{
                 .ignoreSelfRefs = true,
             },
         .unsafeDiscardReferences = {},
@@ -233,13 +212,12 @@ TYPED_TEST(DerivationAdvancedAttrsBothTest, advancedAttributes)
     this->readTest("advanced-attributes.drv", [&](auto encoded) {
         auto got = parseDerivation(*this->store, std::move(encoded), "foo", this->mockXpSettings);
 
-        auto options = derivationOptionsFromStructuredAttrs(
-            *this->store, got.inputDrvs, got.env, get(got.structuredAttrs), true, this->mockXpSettings);
+        DerivationOptions options = DerivationOptions::fromStructuredAttrs(got.env, got.structuredAttrs);
 
         EXPECT_TRUE(!got.structuredAttrs);
 
         // Reset fields that vary between test cases to enable whole-object comparison
-        options.outputChecks = DerivationOptions<SingleDerivedPath>::OutputChecks{.ignoreSelfRefs = true};
+        options.outputChecks = DerivationOptions::OutputChecks{.ignoreSelfRefs = true};
         options.exportReferencesGraph = {};
 
         EXPECT_EQ(options, expected);
@@ -249,14 +227,14 @@ TYPED_TEST(DerivationAdvancedAttrsBothTest, advancedAttributes)
     });
 };
 
-DerivationOptions<SingleDerivedPath> advancedAttributes_ia = {
+DerivationOptions advancedAttributes_ia = {
     .outputChecks =
-        DerivationOptions<SingleDerivedPath>::OutputChecks{
+        DerivationOptions::OutputChecks{
             .ignoreSelfRefs = true,
-            .allowedReferences = std::set<DrvRef<SingleDerivedPath>>{pathFoo},
-            .disallowedReferences = std::set<DrvRef<SingleDerivedPath>>{pathBar, OutputName{"dev"}},
-            .allowedRequisites = std::set<DrvRef<SingleDerivedPath>>{pathFooDev, OutputName{"bin"}},
-            .disallowedRequisites = std::set<DrvRef<SingleDerivedPath>>{pathBarDev},
+            .allowedReferences = StringSet{pathFoo},
+            .disallowedReferences = StringSet{pathBar, "dev"},
+            .allowedRequisites = StringSet{pathFooDev, "bin"},
+            .disallowedRequisites = StringSet{pathBarDev},
         },
     .unsafeDiscardReferences = {},
     .passAsFile = {},
@@ -279,14 +257,14 @@ TEST_F(DerivationAdvancedAttrsTest, advancedAttributes_ia)
     testDerivationOptions("advanced-attributes.drv", advancedAttributes_ia, {"rainbow", "uid-range"});
 };
 
-DerivationOptions<SingleDerivedPath> advancedAttributes_ca = {
+DerivationOptions advancedAttributes_ca = {
     .outputChecks =
-        DerivationOptions<SingleDerivedPath>::OutputChecks{
+        DerivationOptions::OutputChecks{
             .ignoreSelfRefs = true,
-            .allowedReferences = std::set<DrvRef<SingleDerivedPath>>{placeholderFoo},
-            .disallowedReferences = std::set<DrvRef<SingleDerivedPath>>{placeholderBar, OutputName{"dev"}},
-            .allowedRequisites = std::set<DrvRef<SingleDerivedPath>>{placeholderFooDev, OutputName{"bin"}},
-            .disallowedRequisites = std::set<DrvRef<SingleDerivedPath>>{placeholderBarDev},
+            .allowedReferences = StringSet{placeholderFoo},
+            .disallowedReferences = StringSet{placeholderBar, "dev"},
+            .allowedRequisites = StringSet{placeholderFooDev, "bin"},
+            .disallowedRequisites = StringSet{placeholderBarDev},
         },
     .unsafeDiscardReferences = {},
     .passAsFile = {},
@@ -309,8 +287,8 @@ TEST_F(CaDerivationAdvancedAttrsTest, advancedAttributes)
     testDerivationOptions("advanced-attributes.drv", advancedAttributes_ca, {"rainbow", "uid-range", "ca-derivations"});
 };
 
-DerivationOptions<SingleDerivedPath> advancedAttributes_structuredAttrs_defaults = {
-    .outputChecks = std::map<std::string, DerivationOptions<SingleDerivedPath>::OutputChecks>{},
+DerivationOptions advancedAttributes_structuredAttrs_defaults = {
+    .outputChecks = std::map<std::string, DerivationOptions::OutputChecks>{},
     .unsafeDiscardReferences = {},
     .passAsFile = {},
     .exportReferencesGraph = {},
@@ -329,8 +307,7 @@ TYPED_TEST(DerivationAdvancedAttrsBothTest, advancedAttributes_structuredAttrs_d
     this->readTest("advanced-attributes-structured-attrs-defaults.drv", [&](auto encoded) {
         auto got = parseDerivation(*this->store, std::move(encoded), "foo", this->mockXpSettings);
 
-        auto options = derivationOptionsFromStructuredAttrs(
-            *this->store, got.inputDrvs, got.env, get(got.structuredAttrs), true, this->mockXpSettings);
+        DerivationOptions options = DerivationOptions::fromStructuredAttrs(got.env, got.structuredAttrs);
 
         EXPECT_TRUE(got.structuredAttrs);
 
@@ -355,11 +332,11 @@ TEST_F(CaDerivationAdvancedAttrsTest, advancedAttributes_structuredAttrs_default
 
 TYPED_TEST(DerivationAdvancedAttrsBothTest, advancedAttributes_structuredAttrs)
 {
-    DerivationOptions<SingleDerivedPath> expected = {
+    DerivationOptions expected = {
         .outputChecks =
-            std::map<std::string, DerivationOptions<SingleDerivedPath>::OutputChecks>{
+            std::map<std::string, DerivationOptions::OutputChecks>{
                 {"dev",
-                 DerivationOptions<SingleDerivedPath>::OutputChecks{
+                 DerivationOptions::OutputChecks{
                      .maxSize = 789,
                      .maxClosureSize = 5909,
                  }},
@@ -380,8 +357,7 @@ TYPED_TEST(DerivationAdvancedAttrsBothTest, advancedAttributes_structuredAttrs)
     this->readTest("advanced-attributes-structured-attrs.drv", [&](auto encoded) {
         auto got = parseDerivation(*this->store, std::move(encoded), "foo", this->mockXpSettings);
 
-        auto options = derivationOptionsFromStructuredAttrs(
-            *this->store, got.inputDrvs, got.env, get(got.structuredAttrs), true, this->mockXpSettings);
+        DerivationOptions options = DerivationOptions::fromStructuredAttrs(got.env, got.structuredAttrs);
 
         EXPECT_TRUE(got.structuredAttrs);
 
@@ -389,8 +365,7 @@ TYPED_TEST(DerivationAdvancedAttrsBothTest, advancedAttributes_structuredAttrs)
         {
             // Delete all keys but "dev" in options.outputChecks
             auto * outputChecksMapP =
-                std::get_if<std::map<std::string, DerivationOptions<SingleDerivedPath>::OutputChecks>>(
-                    &options.outputChecks);
+                std::get_if<std::map<std::string, DerivationOptions::OutputChecks>>(&options.outputChecks);
             ASSERT_TRUE(outputChecksMapP);
             auto & outputChecksMap = *outputChecksMapP;
             auto devEntry = outputChecksMap.find("dev");
@@ -410,21 +385,21 @@ TYPED_TEST(DerivationAdvancedAttrsBothTest, advancedAttributes_structuredAttrs)
     });
 };
 
-DerivationOptions<SingleDerivedPath> advancedAttributes_structuredAttrs_ia = {
+DerivationOptions advancedAttributes_structuredAttrs_ia = {
     .outputChecks =
-        std::map<std::string, DerivationOptions<SingleDerivedPath>::OutputChecks>{
+        std::map<std::string, DerivationOptions::OutputChecks>{
             {"out",
-             DerivationOptions<SingleDerivedPath>::OutputChecks{
-                 .allowedReferences = std::set<DrvRef<SingleDerivedPath>>{pathFoo},
-                 .allowedRequisites = std::set<DrvRef<SingleDerivedPath>>{pathFooDev, OutputName{"bin"}},
+             DerivationOptions::OutputChecks{
+                 .allowedReferences = StringSet{pathFoo},
+                 .allowedRequisites = StringSet{pathFooDev, "bin"},
              }},
             {"bin",
-             DerivationOptions<SingleDerivedPath>::OutputChecks{
-                 .disallowedReferences = std::set<DrvRef<SingleDerivedPath>>{pathBar, OutputName{"dev"}},
-                 .disallowedRequisites = std::set<DrvRef<SingleDerivedPath>>{pathBarDev},
+             DerivationOptions::OutputChecks{
+                 .disallowedReferences = StringSet{pathBar, "dev"},
+                 .disallowedRequisites = StringSet{pathBarDev},
              }},
             {"dev",
-             DerivationOptions<SingleDerivedPath>::OutputChecks{
+             DerivationOptions::OutputChecks{
                  .maxSize = 789,
                  .maxClosureSize = 5909,
              }},
@@ -452,21 +427,21 @@ TEST_F(DerivationAdvancedAttrsTest, advancedAttributes_structuredAttrs)
         "advanced-attributes-structured-attrs.drv", advancedAttributes_structuredAttrs_ia, {"rainbow", "uid-range"});
 };
 
-DerivationOptions<SingleDerivedPath> advancedAttributes_structuredAttrs_ca = {
+DerivationOptions advancedAttributes_structuredAttrs_ca = {
     .outputChecks =
-        std::map<std::string, DerivationOptions<SingleDerivedPath>::OutputChecks>{
+        std::map<std::string, DerivationOptions::OutputChecks>{
             {"out",
-             DerivationOptions<SingleDerivedPath>::OutputChecks{
-                 .allowedReferences = std::set<DrvRef<SingleDerivedPath>>{placeholderFoo},
-                 .allowedRequisites = std::set<DrvRef<SingleDerivedPath>>{placeholderFooDev, OutputName{"bin"}},
+             DerivationOptions::OutputChecks{
+                 .allowedReferences = StringSet{placeholderFoo},
+                 .allowedRequisites = StringSet{placeholderFooDev, "bin"},
              }},
             {"bin",
-             DerivationOptions<SingleDerivedPath>::OutputChecks{
-                 .disallowedReferences = std::set<DrvRef<SingleDerivedPath>>{placeholderBar, OutputName{"dev"}},
-                 .disallowedRequisites = std::set<DrvRef<SingleDerivedPath>>{placeholderBarDev},
+             DerivationOptions::OutputChecks{
+                 .disallowedReferences = StringSet{placeholderBar, "dev"},
+                 .disallowedRequisites = StringSet{placeholderBarDev},
              }},
             {"dev",
-             DerivationOptions<SingleDerivedPath>::OutputChecks{
+             DerivationOptions::OutputChecks{
                  .maxSize = 789,
                  .maxClosureSize = 5909,
              }},
@@ -496,16 +471,14 @@ TEST_F(CaDerivationAdvancedAttrsTest, advancedAttributes_structuredAttrs)
         {"rainbow", "uid-range", "ca-derivations"});
 };
 
-#define TEST_JSON_OPTIONS(FIXUTURE, VAR, VAR2)                                               \
-    TEST_F(FIXUTURE, DerivationOptions_##VAR##_from_json)                                    \
-    {                                                                                        \
-        this->JsonCharacterizationTest<DerivationOptions<SingleDerivedPath>>::readJsonTest(  \
-            #VAR, advancedAttributes_##VAR2);                                                \
-    }                                                                                        \
-    TEST_F(FIXUTURE, DerivationOptions_##VAR##_to_json)                                      \
-    {                                                                                        \
-        this->JsonCharacterizationTest<DerivationOptions<SingleDerivedPath>>::writeJsonTest( \
-            #VAR, advancedAttributes_##VAR2);                                                \
+#define TEST_JSON_OPTIONS(FIXUTURE, VAR, VAR2)                                                             \
+    TEST_F(FIXUTURE, DerivationOptions_##VAR##_from_json)                                                  \
+    {                                                                                                      \
+        this->JsonCharacterizationTest<DerivationOptions>::readJsonTest(#VAR, advancedAttributes_##VAR2);  \
+    }                                                                                                      \
+    TEST_F(FIXUTURE, DerivationOptions_##VAR##_to_json)                                                    \
+    {                                                                                                      \
+        this->JsonCharacterizationTest<DerivationOptions>::writeJsonTest(#VAR, advancedAttributes_##VAR2); \
     }
 
 TEST_JSON_OPTIONS(DerivationAdvancedAttrsTest, defaults, defaults)

src/libstore/build/derivation-building-goal.cc

@@ -32,6 +32,14 @@ DerivationBuildingGoal::DerivationBuildingGoal(
     , drv{std::make_unique<Derivation>(drv)}
     , buildMode(buildMode)
 {
+    try {
+        drvOptions =
+            std::make_unique<DerivationOptions>(DerivationOptions::fromStructuredAttrs(drv.env, drv.structuredAttrs));
+    } catch (Error & e) {
+        e.addTrace({}, "while parsing derivation '%s'", worker.store.printStorePath(drvPath));
+        throw;
+    }
+
     name = fmt("building derivation '%s'", worker.store.printStorePath(drvPath));
     trace("created");
 
@@ -198,38 +206,6 @@ Goal::Co DerivationBuildingGoal::gaveUpOnSubstitution(bool storeDerivation)
 
 Goal::Co DerivationBuildingGoal::tryToBuild()
 {
-    auto drvOptions = [&] {
-        DerivationOptions<SingleDerivedPath> temp;
-        try {
-            temp =
-                derivationOptionsFromStructuredAttrs(worker.store, drv->inputDrvs, drv->env, get(drv->structuredAttrs));
-        } catch (Error & e) {
-            e.addTrace({}, "while parsing derivation '%s'", worker.store.printStorePath(drvPath));
-            throw;
-        }
-
-        auto res = tryResolve(
-            temp,
-            [&](ref<const SingleDerivedPath> drvPath, const std::string & outputName) -> std::optional<StorePath> {
-                try {
-                    return resolveDerivedPath(
-                        worker.store, SingleDerivedPath::Built{drvPath, outputName}, &worker.evalStore);
-                } catch (Error &) {
-                    return std::nullopt;
-                }
-            });
-
-        /* The derivation must have all of its inputs gotten this point,
-           so the resolution will surely succeed.
-
-           (Actually, we shouldn't even enter this goal until we have a
-           resolved derivation, or derivation with only input addressed
-           transitive inputs, so this should be a no-opt anyways.)
-         */
-        assert(res);
-        return *res;
-    }();
-
     std::map<std::string, InitialOutput> initialOutputs;
 
     /* Recheck at this point. In particular, whereas before we were
@@ -368,13 +344,13 @@ Goal::Co DerivationBuildingGoal::tryToBuild()
         /* Don't do a remote build if the derivation has the attribute
            `preferLocalBuild' set.  Also, check and repair modes are only
            supported for local builds. */
-        bool buildLocally = (buildMode != bmNormal || drvOptions.willBuildLocally(worker.store, *drv))
+        bool buildLocally = (buildMode != bmNormal || drvOptions->willBuildLocally(worker.store, *drv))
                             && settings.maxBuildJobs.get() != 0;
 
         if (buildLocally) {
             useHook = false;
         } else {
-            switch (tryBuildHook(initialOutputs, drvOptions)) {
+            switch (tryBuildHook(initialOutputs)) {
             case rpAccept:
                 /* Yes, it has started doing so.  Wait until we get
                    EOF from the hook. */
@@ -403,7 +379,7 @@ Goal::Co DerivationBuildingGoal::tryToBuild()
 
                 externalBuilder = settings.findExternalDerivationBuilderIfSupported(*drv);
 
-                if (!externalBuilder && !drvOptions.canBuildLocally(worker.store, *drv)) {
+                if (!externalBuilder && !drvOptions->canBuildLocally(worker.store, *drv)) {
                     auto msg =
                         fmt("Cannot build '%s'.\n"
                             "Reason: " ANSI_RED "required system or feature not available" ANSI_NORMAL
@@ -412,7 +388,7 @@ Goal::Co DerivationBuildingGoal::tryToBuild()
                             "Current system: '%s' with features {%s}",
                             Magenta(worker.store.printStorePath(drvPath)),
                             Magenta(drv->platform),
-                            concatStringsSep(", ", drvOptions.getRequiredSystemFeatures(*drv)),
+                            concatStringsSep(", ", drvOptions->getRequiredSystemFeatures(*drv)),
                             Magenta(settings.thisSystem),
                             concatStringsSep<StringSet>(", ", worker.store.Store::config.systemFeatures));
 
@@ -610,7 +586,7 @@ Goal::Co DerivationBuildingGoal::tryToBuild()
             }
 
             try {
-                desugaredEnv = DesugaredEnv::create(worker.store, *drv, drvOptions, inputPaths);
+                desugaredEnv = DesugaredEnv::create(worker.store, *drv, *drvOptions, inputPaths);
             } catch (BuildError & e) {
                 outputLocks.unlock();
                 worker.permanentFailure = true;
@@ -621,7 +597,7 @@ Goal::Co DerivationBuildingGoal::tryToBuild()
                 .drvPath = drvPath,
                 .buildResult = buildResult,
                 .drv = *drv,
-                .drvOptions = drvOptions,
+                .drvOptions = *drvOptions,
                 .inputPaths = inputPaths,
                 .initialOutputs = initialOutputs,
                 .buildMode = buildMode,
@@ -827,8 +803,7 @@ BuildError DerivationBuildingGoal::fixupBuilderFailureErrorMessage(BuilderFailur
     return BuildError{e.status, msg};
 }
 
-HookReply DerivationBuildingGoal::tryBuildHook(
-    const std::map<std::string, InitialOutput> & initialOutputs, const DerivationOptions<StorePath> & drvOptions)
+HookReply DerivationBuildingGoal::tryBuildHook(const std::map<std::string, InitialOutput> & initialOutputs)
 {
 #ifdef _WIN32 // TODO enable build hook on Windows
     return rpDecline;
@@ -845,7 +820,7 @@ HookReply DerivationBuildingGoal::tryBuildHook(
 
         /* Send the request to the hook. */
         worker.hook->sink << "try" << (worker.getNrLocalBuilds() < settings.maxBuildJobs ? 1 : 0) << drv->platform
-                          << worker.store.printStorePath(drvPath) << drvOptions.getRequiredSystemFeatures(*drv);
+                          << worker.store.printStorePath(drvPath) << drvOptions->getRequiredSystemFeatures(*drv);
         worker.hook->sink.flush();
 
         /* Read the first line of input, which should be a word indicating

src/libstore/build/derivation-check.cc

@@ -11,7 +11,7 @@ void checkOutputs(
     Store & store,
     const StorePath & drvPath,
     const decltype(Derivation::outputs) & drvOutputs,
-    const decltype(DerivationOptions<StorePath>::outputChecks) & outputChecks,
+    const decltype(DerivationOptions::outputChecks) & outputChecks,
     const std::map<std::string, ValidPathInfo> & outputs)
 {
     std::map<Path, const ValidPathInfo &> outputsByPath;
@@ -85,7 +85,7 @@ void checkOutputs(
             return std::make_pair(std::move(pathsDone), closureSize);
         };
 
-        auto applyChecks = [&](const DerivationOptions<StorePath>::OutputChecks & checks) {
+        auto applyChecks = [&](const DerivationOptions::OutputChecks & checks) {
             if (checks.maxSize && info.narSize > *checks.maxSize)
                 throw BuildError(
                     BuildResult::Failure::OutputRejected,
@@ -105,33 +105,28 @@ void checkOutputs(
                         *checks.maxClosureSize);
             }
 
-            auto checkRefs = [&](const std::set<DrvRef<StorePath>> & value, bool allowed, bool recursive) {
+            auto checkRefs = [&](const StringSet & value, bool allowed, bool recursive) {
                 /* Parse a list of reference specifiers.  Each element must
                    either be a store path, or the symbolic name of the output
                    of the derivation (such as `out'). */
                 StorePathSet spec;
                 for (auto & i : value) {
-                    std::visit(
-                        overloaded{
-                            [&](const StorePath & path) { spec.insert(path); },
-                            [&](const OutputName & refOutputName) {
-                                if (auto output = get(outputs, refOutputName))
-                                    spec.insert(output->path);
-                                else {
-                                    std::string outputsListing =
-                                        concatMapStringsSep(", ", outputs, [](auto & o) { return o.first; });
-                                    throw BuildError(
-                                        BuildResult::Failure::OutputRejected,
-                                        "derivation '%s' output check for '%s' contains output name '%s',"
-                                        " but this is not a valid output of this derivation."
-                                        " (Valid outputs are [%s].)",
-                                        store.printStorePath(drvPath),
-                                        outputName,
-                                        refOutputName,
-                                        outputsListing);
-                                }
-                            }},
-                        i);
+                    if (store.isStorePath(i))
+                        spec.insert(store.parseStorePath(i));
+                    else if (auto output = get(outputs, i))
+                        spec.insert(output->path);
+                    else {
+                        std::string outputsListing =
+                            concatMapStringsSep(", ", outputs, [](auto & o) { return o.first; });
+                        throw BuildError(
+                            BuildResult::Failure::OutputRejected,
+                            "derivation '%s' output check for '%s' contains an illegal reference specifier '%s',"
+                            " expected store path or output name (one of [%s])",
+                            store.printStorePath(drvPath),
+                            outputName,
+                            i,
+                            outputsListing);
+                    }
                 }
 
                 auto used = recursive ? getClosure(info.path).first : info.references;
@@ -185,8 +180,8 @@ void checkOutputs(
 
         std::visit(
             overloaded{
-                [&](const DerivationOptions<StorePath>::OutputChecks & checks) { applyChecks(checks); },
-                [&](const std::map<std::string, DerivationOptions<StorePath>::OutputChecks> & checksPerOutput) {
+                [&](const DerivationOptions::OutputChecks & checks) { applyChecks(checks); },
+                [&](const std::map<std::string, DerivationOptions::OutputChecks> & checksPerOutput) {
                     if (auto outputChecks = get(checksPerOutput, outputName))
 
                         applyChecks(*outputChecks);

src/libstore/build/derivation-check.hh

@@ -21,7 +21,7 @@ void checkOutputs(
     Store & store,
     const StorePath & drvPath,
     const decltype(Derivation::outputs) & drvOutputs,
-    const decltype(DerivationOptions<StorePath>::outputChecks) & drvOptions,
+    const decltype(DerivationOptions::outputChecks) & drvOptions,
     const std::map<std::string, ValidPathInfo> & outputs);
 
 } // namespace nix

src/libstore/build/derivation-env-desugar.cc

@@ -18,10 +18,7 @@ std::string & DesugaredEnv::atFileEnvPair(std::string_view name, std::string fil
 }
 
 DesugaredEnv DesugaredEnv::create(
-    Store & store,
-    const Derivation & drv,
-    const DerivationOptions<StorePath> & drvOptions,
-    const StorePathSet & inputPaths)
+    Store & store, const Derivation & drv, const DerivationOptions & drvOptions, const StorePathSet & inputPaths)
 {
     DesugaredEnv res;
 
@@ -49,7 +46,7 @@ DesugaredEnv DesugaredEnv::create(
         }
 
         /* Handle exportReferencesGraph(), if set. */
-        for (auto & [fileName, storePaths] : drvOptions.exportReferencesGraph) {
+        for (auto & [fileName, storePaths] : drvOptions.getParsedExportReferencesGraph(store)) {
             /* Write closure info to <fileName>. */
             res.extraFiles.insert_or_assign(
                 fileName, store.makeValidityRegistration(store.exportReferences(storePaths, inputPaths), false, false));

src/libstore/build/derivation-goal.cc

@@ -64,10 +64,9 @@ Goal::Co DerivationGoal::haveDerivation(bool storeDerivation)
 {
     trace("have derivation");
 
-    auto drvOptions = [&]() -> DerivationOptions<SingleDerivedPath> {
+    auto drvOptions = [&]() -> DerivationOptions {
         try {
-            return derivationOptionsFromStructuredAttrs(
-                worker.store, drv->inputDrvs, drv->env, get(drv->structuredAttrs));
+            return DerivationOptions::fromStructuredAttrs(drv->env, drv->structuredAttrs);
         } catch (Error & e) {
             e.addTrace({}, "while parsing derivation '%s'", worker.store.printStorePath(drvPath));
             throw;

src/libstore/derivation-options.cc

@@ -2,18 +2,15 @@
 #include "nix/util/json-utils.hh"
 #include "nix/store/parsed-derivations.hh"
 #include "nix/store/derivations.hh"
-#include "nix/store/derived-path.hh"
 #include "nix/store/store-api.hh"
 #include "nix/util/types.hh"
 #include "nix/util/util.hh"
 #include "nix/store/globals.hh"
-#include "nix/util/variant-wrapper.hh"
 
 #include <optional>
 #include <string>
 #include <variant>
 #include <regex>
-#include <ranges>
 
 namespace nix {
 
@@ -93,38 +90,14 @@ getStringSetAttr(const StringMap & env, const StructuredAttrs * parsed, const st
     return ss ? (std::optional{StringSet{ss->begin(), ss->end()}}) : (std::optional<StringSet>{});
 }
 
-template<typename Inputs>
-using OutputChecks = DerivationOptions<Inputs>::OutputChecks;
+using OutputChecks = DerivationOptions::OutputChecks;
 
-template<typename Inputs>
-using OutputChecksVariant = std::variant<OutputChecks<Inputs>, std::map<std::string, OutputChecks<Inputs>>>;
+using OutputChecksVariant = std::variant<OutputChecks, std::map<std::string, OutputChecks>>;
 
-DerivationOptions<StorePath> derivationOptionsFromStructuredAttrs(
-    const StoreDirConfig & store,
-    const StringMap & env,
-    const StructuredAttrs * parsed,
-    bool shouldWarn,
-    const ExperimentalFeatureSettings & mockXpSettings)
+DerivationOptions DerivationOptions::fromStructuredAttrs(
+    const StringMap & env, const std::optional<StructuredAttrs> & parsed, bool shouldWarn)
 {
-    /* Use the SingleDerivedPath version with empty inputDrvs, then
-       resolve. */
-    DerivedPathMap<StringSet> emptyInputDrvs{};
-    auto singleDerivedPathOptions =
-        derivationOptionsFromStructuredAttrs(store, emptyInputDrvs, env, parsed, shouldWarn, mockXpSettings);
-
-    /* "Resolve" all SingleDerivedPath inputs to StorePath. */
-    auto resolved = tryResolve(
-        singleDerivedPathOptions,
-        [&](ref<const SingleDerivedPath> drvPath, const std::string & outputName) -> std::optional<StorePath> {
-            // there should be nothing to resolve
-            assert(false);
-        });
-
-    /* Since we should never need to call the call back, there should be
-       no way it fails. */
-    assert(resolved);
-
-    return *resolved;
+    return fromStructuredAttrs(env, parsed ? &*parsed : nullptr);
 }
 
 static void flatten(const nlohmann::json & value, StringSet & res)
@@ -138,63 +111,10 @@ static void flatten(const nlohmann::json & value, StringSet & res)
         throw Error("'exportReferencesGraph' value is not an array or a string");
 }
 
-DerivationOptions<SingleDerivedPath> derivationOptionsFromStructuredAttrs(
-    const StoreDirConfig & store,
-    const DerivedPathMap<StringSet> & inputDrvs,
-    const StringMap & env,
-    const StructuredAttrs * parsed,
-    bool shouldWarn,
-    const ExperimentalFeatureSettings & mockXpSettings)
+DerivationOptions
+DerivationOptions::fromStructuredAttrs(const StringMap & env, const StructuredAttrs * parsed, bool shouldWarn)
 {
-    DerivationOptions<SingleDerivedPath> defaults = {};
-
-    std::map<std::string, SingleDerivedPath::Built> placeholders;
-    if (mockXpSettings.isEnabled(Xp::CaDerivations)) {
-        /* Initialize placeholder map from inputDrvs */
-        auto initPlaceholders = [&](this const auto & initPlaceholders,
-                                    ref<const SingleDerivedPath> basePath,
-                                    const DerivedPathMap<StringSet>::ChildNode & node) -> void {
-            for (const auto & outputName : node.value) {
-                auto built = SingleDerivedPath::Built{
-                    .drvPath = basePath,
-                    .output = outputName,
-                };
-                placeholders.insert_or_assign(
-                    DownstreamPlaceholder::fromSingleDerivedPathBuilt(built, mockXpSettings).render(),
-                    std::move(built));
-            }
-
-            for (const auto & [outputName, childNode] : node.childMap) {
-                initPlaceholders(
-                    make_ref<const SingleDerivedPath>(SingleDerivedPath::Built{
-                        .drvPath = basePath,
-                        .output = outputName,
-                    }),
-                    childNode);
-            }
-        };
-
-        for (const auto & [drvPath, outputs] : inputDrvs.map) {
-            auto basePath = make_ref<const SingleDerivedPath>(SingleDerivedPath::Opaque{drvPath});
-            initPlaceholders(basePath, outputs);
-        }
-    }
-
-    auto parseSingleDerivedPath = [&](const std::string & pathS) -> SingleDerivedPath {
-        if (auto it = placeholders.find(pathS); it != placeholders.end())
-            return it->second;
-        else
-            return SingleDerivedPath::Opaque{store.toStorePath(pathS).first};
-    };
-
-    auto parseRef = [&](const std::string & pathS) -> DrvRef<SingleDerivedPath> {
-        if (auto it = placeholders.find(pathS); it != placeholders.end())
-            return it->second;
-        if (store.isStorePath(pathS))
-            return SingleDerivedPath::Opaque{store.toStorePath(pathS).first};
-        else
-            return pathS;
-    };
+    DerivationOptions defaults = {};
 
     if (shouldWarn && parsed) {
         auto & structuredAttrs = parsed->structuredAttrs;
@@ -226,14 +146,14 @@ DerivationOptions<SingleDerivedPath> derivationOptionsFromStructuredAttrs(
     }
 
     return {
-        .outputChecks = [&]() -> OutputChecksVariant<SingleDerivedPath> {
+        .outputChecks = [&]() -> OutputChecksVariant {
             if (parsed) {
                 auto & structuredAttrs = parsed->structuredAttrs;
 
-                std::map<std::string, OutputChecks<SingleDerivedPath>> res;
+                std::map<std::string, OutputChecks> res;
                 if (auto * outputChecks = get(structuredAttrs, "outputChecks")) {
                     for (auto & [outputName, output_] : getObject(*outputChecks)) {
-                        OutputChecks<SingleDerivedPath> checks;
+                        OutputChecks checks;
 
                         auto & output = getObject(output_);
 
@@ -243,14 +163,13 @@ DerivationOptions<SingleDerivedPath> derivationOptionsFromStructuredAttrs(
                         if (auto maxClosureSize = get(output, "maxClosureSize"))
                             checks.maxClosureSize = maxClosureSize->get<uint64_t>();
 
-                        auto get_ =
-                            [&](const std::string & name) -> std::optional<std::set<DrvRef<SingleDerivedPath>>> {
+                        auto get_ = [&output = output](const std::string & name) -> std::optional<StringSet> {
                             if (auto i = get(output, name)) {
-                                std::set<DrvRef<SingleDerivedPath>> res;
+                                StringSet res;
                                 for (auto j = i->begin(); j != i->end(); ++j) {
                                     if (!j->is_string())
                                         throw Error("attribute '%s' must be a list of strings", name);
-                                    res.insert(parseRef(j->get<std::string>()));
+                                    res.insert(j->get<std::string>());
                                 }
                                 return res;
                             }
@@ -259,7 +178,7 @@ DerivationOptions<SingleDerivedPath> derivationOptionsFromStructuredAttrs(
 
                         res.insert_or_assign(
                             outputName,
-                            OutputChecks<SingleDerivedPath>{
+                            OutputChecks{
                                 .maxSize = [&]() -> std::optional<uint64_t> {
                                     if (auto maxSize = get(output, "maxSize"))
                                         return maxSize->get<uint64_t>();
@@ -273,32 +192,21 @@ DerivationOptions<SingleDerivedPath> derivationOptionsFromStructuredAttrs(
                                         return std::nullopt;
                                 }(),
                                 .allowedReferences = get_("allowedReferences"),
-                                .disallowedReferences =
-                                    get_("disallowedReferences").value_or(std::set<DrvRef<SingleDerivedPath>>{}),
+                                .disallowedReferences = get_("disallowedReferences").value_or(StringSet{}),
                                 .allowedRequisites = get_("allowedRequisites"),
-                                .disallowedRequisites =
-                                    get_("disallowedRequisites").value_or(std::set<DrvRef<SingleDerivedPath>>{}),
+                                .disallowedRequisites = get_("disallowedRequisites").value_or(StringSet{}),
                             });
                     }
                 }
                 return res;
             } else {
-                auto parseRefSet = [&](const std::optional<StringSet> optionalStringSet)
-                    -> std::optional<std::set<DrvRef<SingleDerivedPath>>> {
-                    if (!optionalStringSet)
-                        return std::nullopt;
-                    auto range = *optionalStringSet | std::views::transform(parseRef);
-                    return std::set<DrvRef<SingleDerivedPath>>(range.begin(), range.end());
-                };
-                return OutputChecks<SingleDerivedPath>{
+                return OutputChecks{
                     // legacy non-structured-attributes case
                     .ignoreSelfRefs = true,
-                    .allowedReferences = parseRefSet(getStringSetAttr(env, parsed, "allowedReferences")),
-                    .disallowedReferences = parseRefSet(getStringSetAttr(env, parsed, "disallowedReferences"))
-                                                .value_or(std::set<DrvRef<SingleDerivedPath>>{}),
-                    .allowedRequisites = parseRefSet(getStringSetAttr(env, parsed, "allowedRequisites")),
-                    .disallowedRequisites = parseRefSet(getStringSetAttr(env, parsed, "disallowedRequisites"))
-                                                .value_or(std::set<DrvRef<SingleDerivedPath>>{}),
+                    .allowedReferences = getStringSetAttr(env, parsed, "allowedReferences"),
+                    .disallowedReferences = getStringSetAttr(env, parsed, "disallowedReferences").value_or(StringSet{}),
+                    .allowedRequisites = getStringSetAttr(env, parsed, "allowedRequisites"),
+                    .disallowedRequisites = getStringSetAttr(env, parsed, "disallowedRequisites").value_or(StringSet{}),
                 };
             }
         }(),
@@ -337,19 +245,16 @@ DerivationOptions<SingleDerivedPath> derivationOptionsFromStructuredAttrs(
             }(),
         .exportReferencesGraph =
             [&] {
-                std::map<std::string, std::set<SingleDerivedPath>> ret;
+                std::map<std::string, StringSet> ret;
 
                 if (parsed) {
                     auto * e = optionalValueAt(parsed->structuredAttrs, "exportReferencesGraph");
                     if (!e || !e->is_object())
                         return ret;
-                    for (auto & [key, storePathsJson] : getObject(*e)) {
+                    for (auto & [key, value] : getObject(*e)) {
                         StringSet ss;
-                        flatten(storePathsJson, ss);
-                        std::set<SingleDerivedPath> storePaths;
-                        for (auto & s : ss)
-                            storePaths.insert(parseSingleDerivedPath(s));
-                        ret.insert_or_assign(key, std::move(storePaths));
+                        flatten(value, ss);
+                        ret.insert_or_assign(key, std::move(ss));
                     }
                 } else {
                     auto s = getOr(env, "exportReferencesGraph", "");
@@ -363,7 +268,7 @@ DerivationOptions<SingleDerivedPath> derivationOptionsFromStructuredAttrs(
                             throw Error("invalid file name '%s' in 'exportReferencesGraph'", fileName);
 
                         auto & storePathS = *i++;
-                        ret.insert_or_assign(std::move(fileName), std::set{parseSingleDerivedPath(storePathS)});
+                        ret.insert_or_assign(std::move(fileName), StringSet{storePathS});
                     }
                 }
                 return ret;
@@ -381,8 +286,28 @@ DerivationOptions<SingleDerivedPath> derivationOptionsFromStructuredAttrs(
     };
 }
 
-template<typename Input>
-StringSet DerivationOptions<Input>::getRequiredSystemFeatures(const BasicDerivation & drv) const
+std::map<std::string, StorePathSet>
+DerivationOptions::getParsedExportReferencesGraph(const StoreDirConfig & store) const
+{
+    std::map<std::string, StorePathSet> res;
+
+    for (auto & [fileName, ss] : exportReferencesGraph) {
+        StorePathSet storePaths;
+        for (auto & storePathS : ss) {
+            if (!store.isInStore(storePathS))
+                throw BuildError(
+                    BuildResult::Failure::InputRejected,
+                    "'exportReferencesGraph' contains a non-store path '%1%'",
+                    storePathS);
+            storePaths.insert(store.toStorePath(storePathS).first);
+        }
+        res.insert_or_assign(fileName, storePaths);
+    }
+
+    return res;
+}
+
+StringSet DerivationOptions::getRequiredSystemFeatures(const BasicDerivation & drv) const
 {
     // FIXME: cache this?
     StringSet res;
@@ -393,8 +318,7 @@ StringSet DerivationOptions<Input>::getRequiredSystemFeatures(const BasicDerivat
     return res;
 }
 
-template<typename Input>
-bool DerivationOptions<Input>::canBuildLocally(Store & localStore, const BasicDerivation & drv) const
+bool DerivationOptions::canBuildLocally(Store & localStore, const BasicDerivation & drv) const
 {
     if (drv.platform != settings.thisSystem.get() && !settings.extraPlatforms.get().count(drv.platform)
         && !drv.isBuiltin())
@@ -410,194 +334,42 @@ bool DerivationOptions<Input>::canBuildLocally(Store & localStore, const BasicDe
     return true;
 }
 
-template<typename Input>
-bool DerivationOptions<Input>::willBuildLocally(Store & localStore, const BasicDerivation & drv) const
+bool DerivationOptions::willBuildLocally(Store & localStore, const BasicDerivation & drv) const
 {
     return preferLocalBuild && canBuildLocally(localStore, drv);
 }
 
-template<typename Input>
-bool DerivationOptions<Input>::substitutesAllowed() const
+bool DerivationOptions::substitutesAllowed() const
 {
     return settings.alwaysAllowSubstitutes ? true : allowSubstitutes;
 }
 
-template<typename Input>
-bool DerivationOptions<Input>::useUidRange(const BasicDerivation & drv) const
+bool DerivationOptions::useUidRange(const BasicDerivation & drv) const
 {
     return getRequiredSystemFeatures(drv).count("uid-range");
 }
 
-std::optional<DerivationOptions<StorePath>> tryResolve(
-    const DerivationOptions<SingleDerivedPath> & drvOptions,
-    std::function<std::optional<StorePath>(ref<const SingleDerivedPath> drvPath, const std::string & outputName)>
-        queryResolutionChain)
-{
-    auto tryResolvePath = [&](const SingleDerivedPath & input) -> std::optional<StorePath> {
-        return std::visit(
-            overloaded{
-                [](const SingleDerivedPath::Opaque & p) -> std::optional<StorePath> { return p.path; },
-                [&](const SingleDerivedPath::Built & p) -> std::optional<StorePath> {
-                    return queryResolutionChain(p.drvPath, p.output);
-                }},
-            input.raw());
-    };
-
-    auto tryResolveRef = [&](const DrvRef<SingleDerivedPath> & ref) -> std::optional<DrvRef<StorePath>> {
-        return std::visit(
-            overloaded{
-                [](const OutputName & outputName) -> std::optional<DrvRef<StorePath>> { return outputName; },
-                [&](const SingleDerivedPath & input) -> std::optional<DrvRef<StorePath>> {
-                    return tryResolvePath(input);
-                }},
-            ref);
-    };
-
-    auto tryResolveRefSet =
-        [&](const std::set<DrvRef<SingleDerivedPath>> & refSet) -> std::optional<std::set<DrvRef<StorePath>>> {
-        std::set<DrvRef<StorePath>> resolvedSet;
-        for (const auto & ref : refSet) {
-            auto resolvedRef = tryResolveRef(ref);
-            if (!resolvedRef)
-                return std::nullopt;
-            resolvedSet.insert(*resolvedRef);
-        }
-        return resolvedSet;
-    };
-
-    // Helper function to try resolving OutputChecks using functional style
-    auto tryResolveOutputChecks = [&](const DerivationOptions<SingleDerivedPath>::OutputChecks & checks)
-        -> std::optional<DerivationOptions<StorePath>::OutputChecks> {
-        std::optional<std::set<DrvRef<StorePath>>> resolvedAllowedReferences;
-        if (checks.allowedReferences) {
-            resolvedAllowedReferences = tryResolveRefSet(*checks.allowedReferences);
-            if (!resolvedAllowedReferences)
-                return std::nullopt;
-        }
-
-        std::optional<std::set<DrvRef<StorePath>>> resolvedAllowedRequisites;
-        if (checks.allowedRequisites) {
-            resolvedAllowedRequisites = tryResolveRefSet(*checks.allowedRequisites);
-            if (!resolvedAllowedRequisites)
-                return std::nullopt;
-        }
-
-        auto resolvedDisallowedReferences = tryResolveRefSet(checks.disallowedReferences);
-        if (!resolvedDisallowedReferences)
-            return std::nullopt;
-
-        auto resolvedDisallowedRequisites = tryResolveRefSet(checks.disallowedRequisites);
-        if (!resolvedDisallowedRequisites)
-            return std::nullopt;
-
-        return DerivationOptions<StorePath>::OutputChecks{
-            .ignoreSelfRefs = checks.ignoreSelfRefs,
-            .maxSize = checks.maxSize,
-            .maxClosureSize = checks.maxClosureSize,
-            .allowedReferences = resolvedAllowedReferences,
-            .disallowedReferences = *resolvedDisallowedReferences,
-            .allowedRequisites = resolvedAllowedRequisites,
-            .disallowedRequisites = *resolvedDisallowedRequisites,
-        };
-    };
-
-    // Helper function to resolve exportReferencesGraph using functional style
-    auto tryResolveExportReferencesGraph = [&](const std::map<std::string, std::set<SingleDerivedPath>> & exportGraph)
-        -> std::optional<std::map<std::string, std::set<StorePath>>> {
-        std::map<std::string, std::set<StorePath>> resolved;
-        for (const auto & [name, inputPaths] : exportGraph) {
-            std::set<StorePath> resolvedPaths;
-            for (const auto & inputPath : inputPaths) {
-                auto resolvedPath = tryResolvePath(inputPath);
-                if (!resolvedPath)
-                    return std::nullopt;
-                resolvedPaths.insert(*resolvedPath);
-            }
-            resolved.emplace(name, std::move(resolvedPaths));
-        }
-        return resolved;
-    };
-
-    // Resolve outputChecks using functional style with std::visit
-    auto resolvedOutputChecks = std::visit(
-        overloaded{
-            [&](const DerivationOptions<SingleDerivedPath>::OutputChecks & checks)
-                -> std::optional<std::variant<
-                    DerivationOptions<StorePath>::OutputChecks,
-                    std::map<std::string, DerivationOptions<StorePath>::OutputChecks>>> {
-                auto resolved = tryResolveOutputChecks(checks);
-                if (!resolved)
-                    return std::nullopt;
-                return std::variant<
-                    DerivationOptions<StorePath>::OutputChecks,
-                    std::map<std::string, DerivationOptions<StorePath>::OutputChecks>>(*resolved);
-            },
-            [&](const std::map<std::string, DerivationOptions<SingleDerivedPath>::OutputChecks> & checksMap)
-                -> std::optional<std::variant<
-                    DerivationOptions<StorePath>::OutputChecks,
-                    std::map<std::string, DerivationOptions<StorePath>::OutputChecks>>> {
-                std::map<std::string, DerivationOptions<StorePath>::OutputChecks> resolvedMap;
-                for (const auto & [outputName, checks] : checksMap) {
-                    auto resolved = tryResolveOutputChecks(checks);
-                    if (!resolved)
-                        return std::nullopt;
-                    resolvedMap.emplace(outputName, *resolved);
-                }
-                return std::variant<
-                    DerivationOptions<StorePath>::OutputChecks,
-                    std::map<std::string, DerivationOptions<StorePath>::OutputChecks>>(resolvedMap);
-            }},
-        drvOptions.outputChecks);
-
-    if (!resolvedOutputChecks)
-        return std::nullopt;
-
-    // Resolve exportReferencesGraph
-    auto resolvedExportGraph = tryResolveExportReferencesGraph(drvOptions.exportReferencesGraph);
-    if (!resolvedExportGraph)
-        return std::nullopt;
-
-    // Return resolved DerivationOptions using designated initializers
-    return DerivationOptions<StorePath>{
-        .outputChecks = *resolvedOutputChecks,
-        .unsafeDiscardReferences = drvOptions.unsafeDiscardReferences,
-        .passAsFile = drvOptions.passAsFile,
-        .exportReferencesGraph = *resolvedExportGraph,
-        .additionalSandboxProfile = drvOptions.additionalSandboxProfile,
-        .noChroot = drvOptions.noChroot,
-        .impureHostDeps = drvOptions.impureHostDeps,
-        .impureEnvVars = drvOptions.impureEnvVars,
-        .allowLocalNetworking = drvOptions.allowLocalNetworking,
-        .requiredSystemFeatures = drvOptions.requiredSystemFeatures,
-        .preferLocalBuild = drvOptions.preferLocalBuild,
-        .allowSubstitutes = drvOptions.allowSubstitutes,
-    };
-}
-
-template struct DerivationOptions<StorePath>;
-template struct DerivationOptions<SingleDerivedPath>;
-
 } // namespace nix
 
 namespace nlohmann {
 
 using namespace nix;
 
-DerivationOptions<SingleDerivedPath> adl_serializer<DerivationOptions<SingleDerivedPath>>::from_json(const json & json_)
+DerivationOptions adl_serializer<DerivationOptions>::from_json(const json & json_)
 {
     auto & json = getObject(json_);
 
     return {
-        .outputChecks = [&]() -> OutputChecksVariant<SingleDerivedPath> {
+        .outputChecks = [&]() -> OutputChecksVariant {
             auto outputChecks = getObject(valueAt(json, "outputChecks"));
 
             auto forAllOutputsOpt = optionalValueAt(outputChecks, "forAllOutputs");
             auto perOutputOpt = optionalValueAt(outputChecks, "perOutput");
 
             if (forAllOutputsOpt && !perOutputOpt) {
-                return static_cast<OutputChecks<SingleDerivedPath>>(*forAllOutputsOpt);
+                return static_cast<OutputChecks>(*forAllOutputsOpt);
             } else if (perOutputOpt && !forAllOutputsOpt) {
-                return static_cast<std::map<std::string, OutputChecks<SingleDerivedPath>>>(*perOutputOpt);
+                return static_cast<std::map<std::string, OutputChecks>>(*perOutputOpt);
             } else {
                 throw Error("Exactly one of 'perOutput' or 'forAllOutputs' is required");
             }
@@ -605,7 +377,7 @@ DerivationOptions<SingleDerivedPath> adl_serializer<DerivationOptions<SingleDeri
 
         .unsafeDiscardReferences = valueAt(json, "unsafeDiscardReferences"),
         .passAsFile = getStringSet(valueAt(json, "passAsFile")),
-        .exportReferencesGraph = valueAt(json, "exportReferencesGraph"),
+        .exportReferencesGraph = getMap<StringSet>(getObject(valueAt(json, "exportReferencesGraph")), getStringSet),
 
         .additionalSandboxProfile = getString(valueAt(json, "additionalSandboxProfile")),
         .noChroot = getBoolean(valueAt(json, "noChroot")),
@@ -619,17 +391,16 @@ DerivationOptions<SingleDerivedPath> adl_serializer<DerivationOptions<SingleDeri
     };
 }
 
-void adl_serializer<DerivationOptions<SingleDerivedPath>>::to_json(
-    json & json, const DerivationOptions<SingleDerivedPath> & o)
+void adl_serializer<DerivationOptions>::to_json(json & json, const DerivationOptions & o)
 {
     json["outputChecks"] = std::visit(
         overloaded{
-            [&](const OutputChecks<SingleDerivedPath> & checks) {
+            [&](const OutputChecks & checks) {
                 nlohmann::json outputChecks;
                 outputChecks["forAllOutputs"] = checks;
                 return outputChecks;
             },
-            [&](const std::map<std::string, OutputChecks<SingleDerivedPath>> & checksPerOutput) {
+            [&](const std::map<std::string, OutputChecks> & checksPerOutput) {
                 nlohmann::json outputChecks;
                 outputChecks["perOutput"] = checksPerOutput;
                 return outputChecks;
@@ -652,7 +423,7 @@ void adl_serializer<DerivationOptions<SingleDerivedPath>>::to_json(
     json["allowSubstitutes"] = o.allowSubstitutes;
 }
 
-OutputChecks<SingleDerivedPath> adl_serializer<OutputChecks<SingleDerivedPath>>::from_json(const json & json_)
+DerivationOptions::OutputChecks adl_serializer<DerivationOptions::OutputChecks>::from_json(const json & json_)
 {
     auto & json = getObject(json_);
 
@@ -660,16 +431,14 @@ OutputChecks<SingleDerivedPath> adl_serializer<OutputChecks<SingleDerivedPath>>:
         .ignoreSelfRefs = getBoolean(valueAt(json, "ignoreSelfRefs")),
         .maxSize = ptrToOwned<uint64_t>(getNullable(valueAt(json, "maxSize"))),
         .maxClosureSize = ptrToOwned<uint64_t>(getNullable(valueAt(json, "maxClosureSize"))),
-        .allowedReferences =
-            ptrToOwned<std::set<DrvRef<SingleDerivedPath>>>(getNullable(valueAt(json, "allowedReferences"))),
-        .disallowedReferences = valueAt(json, "disallowedReferences"),
-        .allowedRequisites =
-            ptrToOwned<std::set<DrvRef<SingleDerivedPath>>>(getNullable(valueAt(json, "allowedRequisites"))),
-        .disallowedRequisites = valueAt(json, "disallowedRequisites"),
+        .allowedReferences = ptrToOwned<StringSet>(getNullable(valueAt(json, "allowedReferences"))),
+        .disallowedReferences = getStringSet(valueAt(json, "disallowedReferences")),
+        .allowedRequisites = ptrToOwned<StringSet>(getNullable(valueAt(json, "allowedRequisites"))),
+        .disallowedRequisites = getStringSet(valueAt(json, "disallowedRequisites")),
     };
 }
 
-void adl_serializer<OutputChecks<SingleDerivedPath>>::to_json(json & json, const OutputChecks<SingleDerivedPath> & c)
+void adl_serializer<DerivationOptions::OutputChecks>::to_json(json & json, const DerivationOptions::OutputChecks & c)
 {
     json["ignoreSelfRefs"] = c.ignoreSelfRefs;
     json["maxSize"] = c.maxSize;

src/libstore/derivations.cc

@@ -13,7 +13,6 @@
 #include <boost/container/small_vector.hpp>
 #include <boost/unordered/concurrent_flat_map.hpp>
 #include <nlohmann/json.hpp>
-#include <optional>
 
 namespace nix {
 
@@ -792,63 +791,71 @@ std::string outputPathName(std::string_view drvName, OutputNameView outputName)
 
 DerivationType BasicDerivation::type() const
 {
+    std::set<std::string_view> inputAddressedOutputs, fixedCAOutputs, floatingCAOutputs, deferredIAOutputs,
+        impureOutputs;
     std::optional<HashAlgorithm> floatingHashAlgo;
-    std::optional<DerivationType> ty;
-
-    auto decide = [&](DerivationType newTy) {
-        if (!ty)
-            ty = newTy;
-        else if (ty.value() != newTy)
-            throw Error("can't mix derivation output types");
-        else if (ty.value() == DerivationType::ContentAddressed{.sandboxed = false, .fixed = true})
-            // FIXME: Experimental feature?
-            throw Error("only one fixed output is allowed for now");
-    };
 
     for (auto & i : outputs) {
         std::visit(
             overloaded{
-                [&](const DerivationOutput::InputAddressed &) {
-                    decide(
-                        DerivationType::InputAddressed{
-                            .deferred = false,
-                        });
-                },
-                [&](const DerivationOutput::CAFixed &) {
-                    decide(
-                        DerivationType::ContentAddressed{
-                            .sandboxed = false,
-                            .fixed = true,
-                        });
-                    if (i.first != "out"sv)
-                        throw Error("single fixed output must be named \"out\"");
-                },
+                [&](const DerivationOutput::InputAddressed &) { inputAddressedOutputs.insert(i.first); },
+                [&](const DerivationOutput::CAFixed &) { fixedCAOutputs.insert(i.first); },
                 [&](const DerivationOutput::CAFloating & dof) {
-                    decide(
-                        DerivationType::ContentAddressed{
-                            .sandboxed = true,
-                            .fixed = false,
-                        });
-                    if (!floatingHashAlgo)
+                    floatingCAOutputs.insert(i.first);
+                    if (!floatingHashAlgo) {
                         floatingHashAlgo = dof.hashAlgo;
-                    else if (*floatingHashAlgo != dof.hashAlgo)
-                        throw Error("all floating outputs must use the same hash algorithm");
+                    } else {
+                        if (*floatingHashAlgo != dof.hashAlgo)
+                            throw Error("all floating outputs must use the same hash algorithm");
+                    }
                 },
-                [&](const DerivationOutput::Deferred &) {
-                    decide(
-                        DerivationType::InputAddressed{
-                            .deferred = true,
-                        });
-                },
-                [&](const DerivationOutput::Impure &) { decide(DerivationType::Impure{}); },
+                [&](const DerivationOutput::Deferred &) { deferredIAOutputs.insert(i.first); },
+                [&](const DerivationOutput::Impure &) { impureOutputs.insert(i.first); },
             },
             i.second.raw);
     }
 
-    if (!ty)
+    if (inputAddressedOutputs.empty() && fixedCAOutputs.empty() && floatingCAOutputs.empty()
+        && deferredIAOutputs.empty() && impureOutputs.empty())
         throw Error("must have at least one output");
 
-    return ty.value();
+    if (!inputAddressedOutputs.empty() && fixedCAOutputs.empty() && floatingCAOutputs.empty()
+        && deferredIAOutputs.empty() && impureOutputs.empty())
+        return DerivationType::InputAddressed{
+            .deferred = false,
+        };
+
+    if (inputAddressedOutputs.empty() && !fixedCAOutputs.empty() && floatingCAOutputs.empty()
+        && deferredIAOutputs.empty() && impureOutputs.empty()) {
+        if (fixedCAOutputs.size() > 1)
+            // FIXME: Experimental feature?
+            throw Error("only one fixed output is allowed for now");
+        if (*fixedCAOutputs.begin() != "out"sv)
+            throw Error("single fixed output must be named \"out\"");
+        return DerivationType::ContentAddressed{
+            .sandboxed = false,
+            .fixed = true,
+        };
+    }
+
+    if (inputAddressedOutputs.empty() && fixedCAOutputs.empty() && !floatingCAOutputs.empty()
+        && deferredIAOutputs.empty() && impureOutputs.empty())
+        return DerivationType::ContentAddressed{
+            .sandboxed = true,
+            .fixed = false,
+        };
+
+    if (inputAddressedOutputs.empty() && fixedCAOutputs.empty() && floatingCAOutputs.empty()
+        && !deferredIAOutputs.empty() && impureOutputs.empty())
+        return DerivationType::InputAddressed{
+            .deferred = true,
+        };
+
+    if (inputAddressedOutputs.empty() && fixedCAOutputs.empty() && floatingCAOutputs.empty()
+        && deferredIAOutputs.empty() && !impureOutputs.empty())
+        return DerivationType::Impure{};
+
+    throw Error("can't mix derivation output types");
 }
 
 DrvHashes drvHashes;

src/libstore/downstream-placeholder.cc

@@ -1,6 +1,5 @@
 #include "nix/store/downstream-placeholder.hh"
 #include "nix/store/derivations.hh"
-#include "nix/util/json-utils.hh"
 
 namespace nix {
 
@@ -50,45 +49,3 @@ DownstreamPlaceholder DownstreamPlaceholder::fromSingleDerivedPathBuilt(
 }
 
 } // namespace nix
-
-namespace nlohmann {
-
-using namespace nix;
-
-template<typename Item>
-DrvRef<Item> adl_serializer<DrvRef<Item>>::from_json(const json & json)
-{
-    // OutputName case: { "drvPath": "self", "output": <output> }
-    if (json.type() == nlohmann::json::value_t::object) {
-        auto & obj = getObject(json);
-        if (auto * drvPath_ = get(obj, "drvPath")) {
-            auto & drvPath = *drvPath_;
-            if (drvPath.type() == nlohmann::json::value_t::string && getString(drvPath) == "self") {
-                return getString(valueAt(obj, "output"));
-            }
-        }
-    }
-
-    // Input case
-    return adl_serializer<Item>::from_json(json);
-}
-
-template<typename Item>
-void adl_serializer<DrvRef<Item>>::to_json(json & json, const DrvRef<Item> & ref)
-{
-    std::visit(
-        overloaded{
-            [&](const OutputName & outputName) {
-                json = nlohmann::json::object();
-                json["drvPath"] = "self";
-                json["output"] = outputName;
-            },
-            [&](const Item & item) { json = item; },
-        },
-        ref);
-}
-
-template struct adl_serializer<nix::DrvRef<StorePath>>;
-template struct adl_serializer<nix::DrvRef<SingleDerivedPath>>;
-
-} // namespace nlohmann

src/libstore/filetransfer.cc

@@ -151,23 +151,15 @@ struct curlFileTransfer : public FileTransfer
             }
         }
 
-        void failEx(std::exception_ptr ex) noexcept
+        void failEx(std::exception_ptr ex)
         {
             assert(!done);
             done = true;
-            try {
-                std::rethrow_exception(ex);
-            } catch (nix::Error & e) {
-                /* Add more context to the error message. */
-                e.addTrace({}, "during %s of '%s'", Uncolored(request.verb()), request.uri.to_string());
-            } catch (...) {
-                /* Can't add more context to the error. */
-            }
             callback.rethrow(ex);
         }
 
         template<class T>
-        void fail(T && e) noexcept
+        void fail(T && e)
         {
             failEx(std::make_exception_ptr(std::forward<T>(e)));
         }
@@ -176,30 +168,32 @@ struct curlFileTransfer : public FileTransfer
         std::shared_ptr<FinishSink> decompressionSink;
         std::optional<StringSink> errorSink;
 
-        std::exception_ptr callbackException;
+        std::exception_ptr writeException;
 
-        size_t writeCallback(void * contents, size_t size, size_t nmemb) noexcept
-        try {
-            size_t realSize = size * nmemb;
-            result.bodySize += realSize;
+        size_t writeCallback(void * contents, size_t size, size_t nmemb)
+        {
+            try {
+                size_t realSize = size * nmemb;
+                result.bodySize += realSize;
 
-            if (!decompressionSink) {
-                decompressionSink = makeDecompressionSink(encoding, finalSink);
-                if (!successfulStatuses.count(getHTTPStatus())) {
-                    // In this case we want to construct a TeeSink, to keep
-                    // the response around (which we figure won't be big
-                    // like an actual download should be) to improve error
-                    // messages.
-                    errorSink = StringSink{};
+                if (!decompressionSink) {
+                    decompressionSink = makeDecompressionSink(encoding, finalSink);
+                    if (!successfulStatuses.count(getHTTPStatus())) {
+                        // In this case we want to construct a TeeSink, to keep
+                        // the response around (which we figure won't be big
+                        // like an actual download should be) to improve error
+                        // messages.
+                        errorSink = StringSink{};
+                    }
                 }
+
+                (*decompressionSink)({(char *) contents, realSize});
+
+                return realSize;
+            } catch (...) {
+                writeException = std::current_exception();
+                return 0;
             }
-
-            (*decompressionSink)({(char *) contents, realSize});
-
-            return realSize;
-        } catch (...) {
-            callbackException = std::current_exception();
-            return 0;
         }
 
         static size_t writeCallbackWrapper(void * contents, size_t size, size_t nmemb, void * userp)
@@ -215,8 +209,8 @@ struct curlFileTransfer : public FileTransfer
                 result.urls.push_back(effectiveUriCStr);
         }
 
-        size_t headerCallback(void * contents, size_t size, size_t nmemb) noexcept
-        try {
+        size_t headerCallback(void * contents, size_t size, size_t nmemb)
+        {
             size_t realSize = size * nmemb;
             std::string line((char *) contents, realSize);
             printMsg(lvlVomit, "got header for '%s': %s", request.uri, trim(line));
@@ -269,15 +263,6 @@ struct curlFileTransfer : public FileTransfer
                 }
             }
             return realSize;
-        } catch (...) {
-#if LIBCURL_VERSION_NUM >= 0x075700
-            /* https://curl.se/libcurl/c/CURLOPT_HEADERFUNCTION.html:
-               You can also abort the transfer by returning CURL_WRITEFUNC_ERROR. */
-            callbackException = std::current_exception();
-            return CURL_WRITEFUNC_ERROR;
-#else
-            return realSize;
-#endif
         }
 
         static size_t headerCallbackWrapper(void * contents, size_t size, size_t nmemb, void * userp)
@@ -285,17 +270,14 @@ struct curlFileTransfer : public FileTransfer
             return ((TransferItem *) userp)->headerCallback(contents, size, nmemb);
         }
 
-        int progressCallback(curl_off_t dltotal, curl_off_t dlnow) noexcept
-        try {
-            act.progress(dlnow, dltotal);
+        int progressCallback(curl_off_t dltotal, curl_off_t dlnow)
+        {
+            try {
+                act.progress(dlnow, dltotal);
+            } catch (nix::Interrupted &) {
+                assert(getInterrupted());
+            }
             return getInterrupted();
-        } catch (nix::Interrupted &) {
-            assert(getInterrupted());
-            return 1;
-        } catch (...) {
-            /* Something unexpected has happened like logger throwing an exception. */
-            callbackException = std::current_exception();
-            return 1;
         }
 
         static int progressCallbackWrapper(
@@ -306,14 +288,11 @@ struct curlFileTransfer : public FileTransfer
             return item.progressCallback(isUpload ? ultotal : dltotal, isUpload ? ulnow : dlnow);
         }
 
-        static int debugCallback(CURL * handle, curl_infotype type, char * data, size_t size, void * userptr) noexcept
-        try {
+        static int debugCallback(CURL * handle, curl_infotype type, char * data, size_t size, void * userptr)
+        {
             if (type == CURLINFO_TEXT)
                 vomit("curl: %s", chomp(std::string(data, size)));
             return 0;
-        } catch (...) {
-            /* Swallow the exception. Nothing left to do. */
-            return 0;
         }
 
         size_t readCallback(char * buffer, size_t size, size_t nitems) noexcept
@@ -323,7 +302,6 @@ struct curlFileTransfer : public FileTransfer
         } catch (EndOfFile &) {
             return 0;
         } catch (...) {
-            callbackException = std::current_exception();
             return CURL_READFUNC_ABORT;
         }
 
@@ -355,7 +333,6 @@ struct curlFileTransfer : public FileTransfer
             }
             return CURL_SEEKFUNC_OK;
         } catch (...) {
-            callbackException = std::current_exception();
             return CURL_SEEKFUNC_FAIL;
         }
 
@@ -499,7 +476,7 @@ struct curlFileTransfer : public FileTransfer
                 try {
                     decompressionSink->finish();
                 } catch (...) {
-                    callbackException = std::current_exception();
+                    writeException = std::current_exception();
                 }
             }
 
@@ -508,8 +485,8 @@ struct curlFileTransfer : public FileTransfer
                 httpStatus = 304;
             }
 
-            if (callbackException)
-                failEx(callbackException);
+            if (writeException)
+                failEx(writeException);
 
             else if (code == CURLE_OK && successfulStatuses.count(httpStatus)) {
                 result.cached = httpStatus == 304;

src/libstore/include/nix/store/build/derivation-builder.hh

@@ -69,7 +69,7 @@ struct DerivationBuilderParams
      *
      * @todo this should be part of `Derivation`.
      */
-    const DerivationOptions<StorePath> & drvOptions;
+    const DerivationOptions & drvOptions;
 
     // The remainder is state held during the build.
 

src/libstore/include/nix/store/build/derivation-building-goal.hh

@@ -52,6 +52,8 @@ private:
      */
     std::unique_ptr<Derivation> drv;
 
+    std::unique_ptr<DerivationOptions> drvOptions;
+
     /**
      * The remainder is state held during the build.
      */
@@ -113,8 +115,7 @@ private:
     /**
      * Is the build hook willing to perform the build?
      */
-    HookReply tryBuildHook(
-        const std::map<std::string, InitialOutput> & initialOutputs, const DerivationOptions<StorePath> & drvOptions);
+    HookReply tryBuildHook(const std::map<std::string, InitialOutput> & initialOutputs);
 
     /**
      * Open a log file and a pipe to it.

src/libstore/include/nix/store/build/derivation-env-desugar.hh

@@ -8,7 +8,6 @@ namespace nix {
 
 class Store;
 struct Derivation;
-template<typename Input>
 struct DerivationOptions;
 
 /**
@@ -78,10 +77,7 @@ struct DesugaredEnv
      * just part of `Derivation`.
      */
     static DesugaredEnv create(
-        Store & store,
-        const Derivation & drv,
-        const DerivationOptions<StorePath> & drvOptions,
-        const StorePathSet & inputPaths);
+        Store & store, const Derivation & drv, const DerivationOptions & drvOptions, const StorePathSet & inputPaths);
 };
 
 } // namespace nix

src/libstore/include/nix/store/derivation-options.hh

@@ -8,8 +8,7 @@
 
 #include "nix/util/types.hh"
 #include "nix/util/json-impls.hh"
-#include "nix/store/store-dir-config.hh"
-#include "nix/store/downstream-placeholder.hh"
+#include "nix/store/path.hh"
 
 namespace nix {
 
@@ -18,9 +17,6 @@ struct StoreDirConfig;
 struct BasicDerivation;
 struct StructuredAttrs;
 
-template<typename V>
-struct DerivedPathMap;
-
 /**
  * This represents all the special options on a `Derivation`.
  *
@@ -38,7 +34,6 @@ struct DerivedPathMap;
  * separately. That would be nice to separate concerns, and not make any
  * environment variable names magical.
  */
-template<typename Input>
 struct DerivationOptions
 {
     struct OutputChecks
@@ -46,15 +41,13 @@ struct DerivationOptions
         bool ignoreSelfRefs = false;
         std::optional<uint64_t> maxSize, maxClosureSize;
 
-        using DrvRef = nix::DrvRef<Input>;
-
         /**
          * env: allowedReferences
          *
          * A value of `nullopt` indicates that the check is skipped.
          * This means that all references are allowed.
          */
-        std::optional<std::set<DrvRef>> allowedReferences;
+        std::optional<StringSet> allowedReferences;
 
         /**
          * env: disallowedReferences
@@ -62,21 +55,21 @@ struct DerivationOptions
          * No needed for `std::optional`, because skipping the check is
          * the same as disallowing the references.
          */
-        std::set<DrvRef> disallowedReferences;
+        StringSet disallowedReferences;
 
         /**
          * env: allowedRequisites
          *
          * See `allowedReferences`
          */
-        std::optional<std::set<DrvRef>> allowedRequisites;
+        std::optional<StringSet> allowedRequisites;
 
         /**
          * env: disallowedRequisites
          *
          * See `disallowedReferences`
          */
-        std::set<DrvRef> disallowedRequisites;
+        StringSet disallowedRequisites;
 
         bool operator==(const OutputChecks &) const = default;
     };
@@ -123,7 +116,23 @@ struct DerivationOptions
      * attributes give to the builder. The set of paths in the original JSON
      * is replaced with a list of `PathInfo` in JSON format.
      */
-    std::map<std::string, std::set<Input>> exportReferencesGraph;
+    std::map<std::string, StringSet> exportReferencesGraph;
+
+    /**
+     * Once a derivations is resolved, the strings in in
+     * `exportReferencesGraph` should all be store paths (with possible
+     * suffix paths, but those are discarded).
+     *
+     * @return The parsed path set for for each key in the map.
+     *
+     * @todo Ideally, `exportReferencesGraph` would just store
+     * `StorePath`s for this, but we can't just do that, because for CA
+     * derivations they is actually in general `DerivedPath`s (via
+     * placeholder strings) until the derivation is resolved and exact
+     * inputs store paths are known. We can use better types for that
+     * too, but that is a longer project.
+     */
+    std::map<std::string, StorePathSet> getParsedExportReferencesGraph(const StoreDirConfig & store) const;
 
     /**
      * env: __sandboxProfile
@@ -176,6 +185,18 @@ struct DerivationOptions
 
     bool operator==(const DerivationOptions &) const = default;
 
+    /**
+     * Parse this information from its legacy encoding as part of the
+     * environment. This should not be used with nice greenfield formats
+     * (e.g. JSON) but is necessary for supporting old formats (e.g.
+     * ATerm).
+     */
+    static DerivationOptions
+    fromStructuredAttrs(const StringMap & env, const StructuredAttrs * parsed, bool shouldWarn = true);
+
+    static DerivationOptions
+    fromStructuredAttrs(const StringMap & env, const std::optional<StructuredAttrs> & parsed, bool shouldWarn = true);
+
     /**
      * @param drv Must be the same derivation we parsed this from. In
      * the future we'll flip things around so a `BasicDerivation` has
@@ -201,49 +222,7 @@ struct DerivationOptions
     bool useUidRange(const BasicDerivation & drv) const;
 };
 
-extern template struct DerivationOptions<StorePath>;
-extern template struct DerivationOptions<SingleDerivedPath>;
-
-struct DerivationOutput;
-
-/**
- * Parse this information from its legacy encoding as part of the
- * environment. This should not be used with nice greenfield formats
- * (e.g. JSON) but is necessary for supporting old formats (e.g.
- * ATerm).
- */
-DerivationOptions<SingleDerivedPath> derivationOptionsFromStructuredAttrs(
-    const StoreDirConfig & store,
-    const DerivedPathMap<StringSet> & inputDrvs,
-    const StringMap & env,
-    const StructuredAttrs * parsed,
-    bool shouldWarn = true,
-    const ExperimentalFeatureSettings & mockXpSettings = experimentalFeatureSettings);
-
-DerivationOptions<StorePath> derivationOptionsFromStructuredAttrs(
-    const StoreDirConfig & store,
-    const StringMap & env,
-    const StructuredAttrs * parsed,
-    bool shouldWarn = true,
-    const ExperimentalFeatureSettings & mockXpSettings = experimentalFeatureSettings);
-
-/**
- * This is the counterpart of `Derivation::tryResolve`. In particular,
- * it takes the same sort of callback, which is used to reolve
- * non-constant deriving paths.
- *
- * We need this function when resolving a derivation, and we will use
- * this as part of that if/when `Derivation` includes
- * `DerivationOptions`
- */
-std::optional<DerivationOptions<StorePath>> tryResolve(
-    const DerivationOptions<SingleDerivedPath> & drvOptions,
-    std::function<std::optional<StorePath>(ref<const SingleDerivedPath> drvPath, const std::string & outputName)>
-        queryResolutionChain);
-
 }; // namespace nix
 
-JSON_IMPL(nix::DerivationOptions<nix::StorePath>);
-JSON_IMPL(nix::DerivationOptions<nix::SingleDerivedPath>);
-JSON_IMPL(nix::DerivationOptions<nix::StorePath>::OutputChecks)
-JSON_IMPL(nix::DerivationOptions<nix::SingleDerivedPath>::OutputChecks)
+JSON_IMPL(DerivationOptions);
+JSON_IMPL(DerivationOptions::OutputChecks)

src/libstore/include/nix/store/downstream-placeholder.hh

@@ -2,23 +2,11 @@
 ///@file
 
 #include "nix/util/hash.hh"
-#include "nix/util/json-impls.hh"
 #include "nix/store/path.hh"
 #include "nix/store/derived-path.hh"
 
 namespace nix {
 
-/**
- * A reference is either to a to-be-registered output (by name),
- * or to an already-registered store object (by `Input`).
- *
- * `Ref<SingleDerivedPath` is a representation of something that can be
- * turned into a placeholder. (Regular own-output placeholder in the
- * first case, `DownstreamPlaceholder` in the second case.)
- */
-template<typename Input>
-using DrvRef = std::variant<OutputName, Input>;
-
 /**
  * Downstream Placeholders are opaque and almost certainly unique values
  * used to allow derivations to refer to store objects which are yet to
@@ -104,17 +92,3 @@ public:
 };
 
 } // namespace nix
-
-namespace nlohmann {
-
-template<typename Item>
-struct adl_serializer<nix::DrvRef<Item>>
-{
-    static nix::DrvRef<Item> from_json(const json & json);
-    static void to_json(json & json, const nix::DrvRef<Item> & t);
-};
-
-extern template struct adl_serializer<nix::DrvRef<nix::StorePath>>;
-extern template struct adl_serializer<nix::DrvRef<nix::SingleDerivedPath>>;
-
-} // namespace nlohmann

src/libstore/include/nix/store/parsed-derivations.hh

@@ -9,7 +9,6 @@
 namespace nix {
 
 class Store;
-template<typename Input>
 struct DerivationOptions;
 struct DerivationOutput;
 
@@ -48,7 +47,7 @@ struct StructuredAttrs
 
     nlohmann::json::object_t prepareStructuredAttrs(
         Store & store,
-        const DerivationOptions<StorePath> & drvOptions,
+        const DerivationOptions & drvOptions,
         const StorePathSet & inputPaths,
         const DerivationOutputs & outputs) const;
 

src/libstore/misc.cc

@@ -225,12 +225,11 @@ MissingPaths Store::queryMissing(const std::vector<DerivedPath> & targets)
                         return;
 
                     auto drv = make_ref<Derivation>(derivationFromPath(drvPath));
-                    DerivationOptions<SingleDerivedPath> drvOptions;
+                    DerivationOptions drvOptions;
                     try {
                         // FIXME: this is a lot of work just to get the value
                         // of `allowSubstitutes`.
-                        drvOptions = derivationOptionsFromStructuredAttrs(
-                            *this, drv->inputDrvs, drv->env, get(drv->structuredAttrs));
+                        drvOptions = DerivationOptions::fromStructuredAttrs(drv->env, drv->structuredAttrs);
                     } catch (Error & e) {
                         e.addTrace({}, "while parsing derivation '%s'", printStorePath(drvPath));
                         throw;

src/libstore/parsed-derivations.cc

@@ -100,7 +100,7 @@ static nlohmann::json pathInfoToJSON(Store & store, const StorePathSet & storePa
 
 nlohmann::json::object_t StructuredAttrs::prepareStructuredAttrs(
     Store & store,
-    const DerivationOptions<StorePath> & drvOptions,
+    const DerivationOptions & drvOptions,
     const StorePathSet & inputPaths,
     const DerivationOutputs & outputs) const
 {
@@ -114,8 +114,8 @@ nlohmann::json::object_t StructuredAttrs::prepareStructuredAttrs(
     json["outputs"] = std::move(outputsJson);
 
     /* Handle exportReferencesGraph. */
-    for (auto & [key, storePaths] : drvOptions.exportReferencesGraph) {
-        json[key] = pathInfoToJSON(store, store.exportReferences(storePaths, inputPaths));
+    for (auto & [key, storePaths] : drvOptions.getParsedExportReferencesGraph(store)) {
+        json[key] = pathInfoToJSON(store, store.exportReferences(storePaths, storePaths));
     }
 
     return json;

src/libutil-c/nix_api_util.cc

@@ -36,7 +36,7 @@ nix_err nix_context_error(nix_c_context * context)
         const char * demangled = abi::__cxa_demangle(typeid(e).name(), 0, 0, &status);
         if (demangled) {
             context->name = demangled;
-            free((void *) demangled);
+            // todo: free(demangled);
         } else {
             context->name = typeid(e).name();
         }

src/libutil/archive.cc

@@ -200,54 +200,54 @@ static void parse(FileSystemObjectSink & sink, Source & source, const CanonPath
     }
 
     else if (type == "directory") {
-        sink.createDirectory(path, [&](FileSystemObjectSink & dirSink, const CanonPath & relDirPath) {
-            std::map<Path, int, CaseInsensitiveCompare> names;
+        sink.createDirectory(path);
 
-            std::string prevName;
+        std::map<Path, int, CaseInsensitiveCompare> names;
 
-            while (1) {
-                auto tag = getString();
+        std::string prevName;
 
-                if (tag == ")")
-                    break;
+        while (1) {
+            auto tag = getString();
 
-                if (tag != "entry")
-                    throw badArchive("expected tag 'entry' or ')', got '%s'", tag);
+            if (tag == ")")
+                break;
 
-                expectTag("(");
+            if (tag != "entry")
+                throw badArchive("expected tag 'entry' or ')', got '%s'", tag);
 
-                expectTag("name");
+            expectTag("(");
 
-                auto name = getString();
-                if (name.empty() || name == "." || name == ".." || name.find('/') != std::string::npos
-                    || name.find((char) 0) != std::string::npos)
-                    throw badArchive("NAR contains invalid file name '%1%'", name);
-                if (name <= prevName)
-                    throw badArchive("NAR directory is not sorted");
-                prevName = name;
-                if (archiveSettings.useCaseHack) {
-                    auto i = names.find(name);
-                    if (i != names.end()) {
-                        debug("case collision between '%1%' and '%2%'", i->first, name);
-                        name += caseHackSuffix;
-                        name += std::to_string(++i->second);
-                        auto j = names.find(name);
-                        if (j != names.end())
-                            throw badArchive(
-                                "NAR contains file name '%s' that collides with case-hacked file name '%s'",
-                                prevName,
-                                j->first);
-                    } else
-                        names[name] = 0;
-                }
+            expectTag("name");
 
-                expectTag("node");
-
-                parse(dirSink, source, relDirPath / name);
-
-                expectTag(")");
+            auto name = getString();
+            if (name.empty() || name == "." || name == ".." || name.find('/') != std::string::npos
+                || name.find((char) 0) != std::string::npos)
+                throw badArchive("NAR contains invalid file name '%1%'", name);
+            if (name <= prevName)
+                throw badArchive("NAR directory is not sorted");
+            prevName = name;
+            if (archiveSettings.useCaseHack) {
+                auto i = names.find(name);
+                if (i != names.end()) {
+                    debug("case collision between '%1%' and '%2%'", i->first, name);
+                    name += caseHackSuffix;
+                    name += std::to_string(++i->second);
+                    auto j = names.find(name);
+                    if (j != names.end())
+                        throw badArchive(
+                            "NAR contains file name '%s' that collides with case-hacked file name '%s'",
+                            prevName,
+                            j->first);
+                } else
+                    names[name] = 0;
             }
-        });
+
+            expectTag("node");
+
+            parse(sink, source, path / name);
+
+            expectTag(")");
+        }
     }
 
     else if (type == "symlink") {

src/libutil/fs-sink.cc

@@ -14,6 +14,44 @@
 
 namespace nix {
 
+void copyRecursive(SourceAccessor & accessor, const CanonPath & from, FileSystemObjectSink & sink, const CanonPath & to)
+{
+    auto stat = accessor.lstat(from);
+
+    switch (stat.type) {
+    case SourceAccessor::tSymlink: {
+        sink.createSymlink(to, accessor.readLink(from));
+        break;
+    }
+
+    case SourceAccessor::tRegular: {
+        sink.createRegularFile(to, [&](CreateRegularFileSink & crf) {
+            if (stat.isExecutable)
+                crf.isExecutable();
+            accessor.readFile(from, crf, [&](uint64_t size) { crf.preallocateContents(size); });
+        });
+        break;
+    }
+
+    case SourceAccessor::tDirectory: {
+        sink.createDirectory(to);
+        for (auto & [name, _] : accessor.readDirectory(from)) {
+            copyRecursive(accessor, from / name, sink, to / name);
+            break;
+        }
+        break;
+    }
+
+    case SourceAccessor::tChar:
+    case SourceAccessor::tBlock:
+    case SourceAccessor::tSocket:
+    case SourceAccessor::tFifo:
+    case SourceAccessor::tUnknown:
+    default:
+        throw Error("file '%1%' has an unsupported type of %2%", from, stat.typeString());
+    }
+}
+
 struct RestoreSinkSettings : Config
 {
     Setting<bool> preallocateContents{
@@ -32,60 +70,11 @@ static std::filesystem::path append(const std::filesystem::path & src, const Can
     return dst;
 }
 
-#ifndef _WIN32
-void RestoreSink::createDirectory(const CanonPath & path, DirectoryCreatedCallback callback)
-{
-    if (path.isRoot()) {
-        createDirectory(path);
-        callback(*this, path);
-        return;
-    }
-
-    createDirectory(path);
-    assert(dirFd); // If that's not true the above call must have thrown an exception.
-
-    RestoreSink dirSink{startFsync};
-    dirSink.dstPath = append(dstPath, path);
-    dirSink.dirFd = ::openat(dirFd.get(), path.rel_c_str(), O_RDONLY | O_DIRECTORY | O_NOFOLLOW | O_CLOEXEC);
-
-    if (!dirSink.dirFd)
-        throw SysError("opening directory '%s'", dirSink.dstPath.string());
-
-    callback(dirSink, CanonPath::root);
-}
-#endif
-
 void RestoreSink::createDirectory(const CanonPath & path)
 {
     auto p = append(dstPath, path);
-
-#ifndef _WIN32
-    if (dirFd) {
-        if (path.isRoot())
-            /* Trying to create a directory that we already have a file descriptor for. */
-            throw Error("path '%s' already exists", p.string());
-
-        if (::mkdirat(dirFd.get(), path.rel_c_str(), 0777) == -1)
-            throw SysError("creating directory '%s'", p.string());
-
-        return;
-    }
-#endif
-
     if (!std::filesystem::create_directory(p))
         throw Error("path '%s' already exists", p.string());
-
-#ifndef _WIN32
-    if (path.isRoot()) {
-        assert(!dirFd); // Handled above
-
-        /* Open directory for further *at operations relative to the sink root
-           directory. */
-        dirFd = open(p.c_str(), O_RDONLY | O_DIRECTORY | O_NOFOLLOW | O_CLOEXEC);
-        if (!dirFd)
-            throw SysError("creating directory '%1%'", p.string());
-    }
-#endif
 };
 
 struct RestoreRegularFile : CreateRegularFileSink
@@ -125,14 +114,7 @@ void RestoreSink::createRegularFile(const CanonPath & path, std::function<void(C
             FILE_ATTRIBUTE_NORMAL,
             NULL)
 #else
-        [&]() {
-            /* O_EXCL together with O_CREAT ensures symbolic links in the last
-              component are not followed. */
-            constexpr int flags = O_CREAT | O_EXCL | O_WRONLY | O_CLOEXEC;
-            if (!dirFd)
-                return ::open(p.c_str(), flags, 0666);
-            return ::openat(dirFd.get(), path.rel_c_str(), flags, 0666);
-        }();
+        open(p.c_str(), O_CREAT | O_EXCL | O_WRONLY | O_CLOEXEC, 0666)
 #endif
         ;
     if (!crf.fd)
@@ -179,13 +161,6 @@ void RestoreRegularFile::operator()(std::string_view data)
 void RestoreSink::createSymlink(const CanonPath & path, const std::string & target)
 {
     auto p = append(dstPath, path);
-#ifndef _WIN32
-    if (dirFd) {
-        if (::symlinkat(requireCString(target), dirFd.get(), path.rel_c_str()) == -1)
-            throw SysError("creating symlink from '%1%' -> '%2%'", p.string(), target);
-        return;
-    }
-#endif
     nix::createSymlink(target, p.string());
 }
 

src/libutil/git.cc

@@ -217,6 +217,29 @@ std::optional<Mode> convertMode(SourceAccessor::Type type)
     }
 }
 
+void restore(FileSystemObjectSink & sink, Source & source, HashAlgorithm hashAlgo, std::function<RestoreHook> hook)
+{
+    parse(sink, CanonPath::root, source, BlobMode::Regular, hashAlgo, [&](CanonPath name, TreeEntry entry) {
+        auto [accessor, from] = hook(entry.hash);
+        auto stat = accessor->lstat(from);
+        auto gotOpt = convertMode(stat.type);
+        if (!gotOpt)
+            throw Error(
+                "file '%s' (git hash %s) has an unsupported type",
+                from,
+                entry.hash.to_string(HashFormat::Base16, false));
+        auto & got = *gotOpt;
+        if (got != entry.mode)
+            throw Error(
+                "git mode of file '%s' (git hash %s) is %o but expected %o",
+                from,
+                entry.hash.to_string(HashFormat::Base16, false),
+                (RawMode) got,
+                (RawMode) entry.mode);
+        copyRecursive(*accessor, from, sink, name);
+    });
+}
+
 void dumpBlobPrefix(uint64_t size, Sink & sink, const ExperimentalFeatureSettings & xpSettings)
 {
     xpSettings.require(Xp::GitHashing);

src/libutil/include/nix/util/cmark-cpp.hh

@@ -0,0 +1,81 @@
+#pragma once
+///@file
+
+#include "types.hh"
+#include "util.hh"
+
+#include <cmark.h>
+
+namespace nix::cmark {
+
+using Node = struct cmark_node;
+using NodeType = cmark_node_type;
+using ListType = cmark_list_type;
+
+using Iter = struct cmark_iter;
+
+struct Deleter
+{
+    void operator()(Node * ptr)
+    {
+        cmark_node_free(ptr);
+    }
+
+    void operator()(Iter * ptr)
+    {
+        cmark_iter_free(ptr);
+    }
+};
+
+template<typename T>
+using UniquePtr = std::unique_ptr<Node, Deleter>;
+
+static inline void parse_document(Node & root, std::string_view s, int options)
+{
+    cmark_parser * parser = cmark_parser_new_with_mem_into_root(options, cmark_get_default_mem_allocator(), &root);
+    cmark_parser_feed(parser, s.data(), s.size());
+    (void) cmark_parser_finish(parser);
+    cmark_parser_free(parser);
+}
+
+static inline UniquePtr<Node> parse_document(std::string_view s, int options)
+{
+    return UniquePtr<Node>{cmark_parse_document(s.data(), s.size(), options)};
+}
+
+static inline std::unique_ptr<char, FreeDeleter> render_commonmark(Node & root, int options, int width)
+{
+    return std::unique_ptr<char, FreeDeleter>{cmark_render_commonmark(&root, options, width)};
+}
+
+static inline std::unique_ptr<char, FreeDeleter> render_xml(Node & root, int options)
+{
+    return std::unique_ptr<char, FreeDeleter>{cmark_render_xml(&root, options)};
+}
+
+static inline UniquePtr<Node> node_new(NodeType type)
+{
+    return UniquePtr<Node>{cmark_node_new(type)};
+}
+
+/**
+ * The parent takes ownership
+ */
+static inline Node & node_append_child(Node & node, UniquePtr<Node> child)
+{
+    auto status = (bool) cmark_node_append_child(&node, &*child);
+    assert(status);
+    return *child.release();
+}
+
+static inline bool node_set_literal(Node & node, const char * content)
+{
+    return (bool) cmark_node_set_literal(&node, content);
+}
+
+static inline bool node_set_list_type(Node & node, ListType type)
+{
+    return (bool) cmark_node_set_list_type(&node, type);
+}
+
+} // namespace nix::cmark

src/libutil/include/nix/util/fs-sink.hh

@@ -36,23 +36,6 @@ struct FileSystemObjectSink
 
     virtual void createDirectory(const CanonPath & path) = 0;
 
-    using DirectoryCreatedCallback = std::function<void(FileSystemObjectSink & dirSink, const CanonPath & dirRelPath)>;
-
-    /**
-     * Create a directory and invoke a callback with a pair of sink + CanonPath
-     * of the created subdirectory relative to dirSink.
-     *
-     * @note This allows for UNIX RestoreSink implementations to implement
-     * *at-style accessors that always keep an open file descriptor for the
-     * freshly created directory. Use this when it's important to disallow any
-     * intermediate path components from being symlinks.
-     */
-    virtual void createDirectory(const CanonPath & path, DirectoryCreatedCallback callback)
-    {
-        createDirectory(path);
-        callback(*this, path);
-    }
-
     /**
      * This function in general is no re-entrant. Only one file can be
      * written at a time.
@@ -99,18 +82,6 @@ struct NullFileSystemObjectSink : FileSystemObjectSink
 struct RestoreSink : FileSystemObjectSink
 {
     std::filesystem::path dstPath;
-#ifndef _WIN32
-    /**
-     * File descriptor for the directory located at dstPath. Used for *at
-     * operations relative to this file descriptor. This sink must *never*
-     * follow intermediate symlinks (starting from dstPath) in case a file
-     * collision is encountered for various reasons like case-insensitivity or
-     * other types on normalization. using appropriate *at system calls and traversing
-     * only one path component at a time ensures that writing is race-free and is
-     * is not susceptible to symlink replacement.
-     */
-    AutoCloseFD dirFd;
-#endif
     bool startFsync = false;
 
     explicit RestoreSink(bool startFsync)
@@ -120,10 +91,6 @@ struct RestoreSink : FileSystemObjectSink
 
     void createDirectory(const CanonPath & path) override;
 
-#ifndef _WIN32
-    void createDirectory(const CanonPath & path, DirectoryCreatedCallback callback) override;
-#endif
-
     void createRegularFile(const CanonPath & path, std::function<void(CreateRegularFileSink &)>) override;
 
     void createSymlink(const CanonPath & path, const std::string & target) override;

src/libutil/include/nix/util/git.hh

@@ -136,6 +136,13 @@ std::optional<Mode> convertMode(SourceAccessor::Type type);
  */
 using RestoreHook = SourcePath(Hash);
 
+/**
+ * Wrapper around `parse` and `RestoreSink`
+ *
+ * @param hashAlgo must be `HashAlgo::SHA1` or `HashAlgo::SHA256` for now.
+ */
+void restore(FileSystemObjectSink & sink, Source & source, HashAlgorithm hashAlgo, std::function<RestoreHook> hook);
+
 /**
  * Dumps a single file to a sink
  *

src/libutil/include/nix/util/meson.build

@@ -17,6 +17,7 @@ headers = files(
   'checked-arithmetic.hh',
   'chunked-vector.hh',
   'closure.hh',
+  'cmark-cpp.hh',
   'comparator.hh',
   'compression.hh',
   'compute-levels.hh',

src/libutil/include/nix/util/strings.hh

@@ -166,10 +166,4 @@ public:
     }
 };
 
-/**
- * Check that the string does not contain any NUL bytes and return c_str().
- * @throws Error if str contains '\0' bytes.
- */
-const char * requireCString(const std::string & str);
-
 } // namespace nix

src/libutil/include/nix/util/util.hh

@@ -242,28 +242,6 @@ std::string stripIndentation(std::string_view s);
  */
 std::pair<std::string_view, std::string_view> getLine(std::string_view s);
 
-/**
- * Get a pointer to the contents of a `std::optional` if it is set, or a
- * null pointer otherise.
- *
- * Const version.
- */
-template<class T>
-const T * get(const std::optional<T> & opt)
-{
-    return opt ? &*opt : nullptr;
-}
-
-/**
- * Non-const counterpart of `const T * get(const std::optional<T>)`.
- * Takes a mutable reference, but returns a mutable pointer.
- */
-template<class T>
-T * get(std::optional<T> & opt)
-{
-    return opt ? &*opt : nullptr;
-}
-
 /**
  * Get a value for the specified key from an associate container.
  */

src/libutil/meson.build

@@ -110,6 +110,9 @@ deps_private += cpuid
 nlohmann_json = dependency('nlohmann_json', version : '>= 3.9')
 deps_public += nlohmann_json
 
+cmark = dependency('libcmark', required : true)
+deps_public += cmark
+
 cxx = meson.get_compiler('cpp')
 
 config_priv_h = configure_file(

src/libutil/package.nix

@@ -5,6 +5,7 @@
 
   boost,
   brotli,
+  cmark,
   libarchive,
   libblake3,
   libcpuid,
@@ -57,6 +58,7 @@ mkMesonLibrary (finalAttrs: {
 
   propagatedBuildInputs = [
     boost
+    cmark
     libarchive
     nlohmann_json
   ];

src/libutil/strings.cc

@@ -5,7 +5,6 @@
 #include "nix/util/strings-inline.hh"
 #include "nix/util/os-string.hh"
 #include "nix/util/error.hh"
-#include "nix/util/util.hh"
 
 namespace nix {
 
@@ -153,14 +152,4 @@ std::string optionalBracket(std::string_view prefix, std::string_view content, s
     return result;
 }
 
-const char * requireCString(const std::string & s)
-{
-    if (std::memchr(s.data(), '\0', s.size())) [[unlikely]] {
-        using namespace std::string_view_literals;
-        auto str = replaceStrings(s, "\0"sv, "␀"sv);
-        throw Error("string '%s' with null (\\0) bytes used where it's not allowed", str);
-    }
-    return s.c_str();
-}
-
 } // namespace nix

src/libutil/url.cc

@@ -327,11 +327,8 @@ Path renderUrlPathEnsureLegal(const std::vector<std::string> & urlPath)
         /* This is only really valid for UNIX. Windows has more restrictions. */
         if (comp.contains('/'))
             throw BadURL("URL path component '%s' contains '/', which is not allowed in file names", comp);
-        if (comp.contains(char(0))) {
-            using namespace std::string_view_literals;
-            auto str = replaceStrings(comp, "\0"sv, "␀"sv);
-            throw BadURL("URL path component '%s' contains NUL byte which is not allowed", str);
-        }
+        if (comp.contains(char(0)))
+            throw BadURL("URL path component '%s' contains NUL byte which is not allowed", comp);
     }
 
     return concatStringsSep("/", urlPath);

src/nix/nix-build/nix-build.cc

@@ -554,9 +554,9 @@ static void main_nix_build(int argc, char ** argv)
         env["NIX_STORE"] = store->storeDir;
         env["NIX_BUILD_CORES"] = fmt("%d", settings.buildCores ? settings.buildCores : settings.getDefaultCores());
 
-        DerivationOptions<StorePath> drvOptions;
+        DerivationOptions drvOptions;
         try {
-            drvOptions = derivationOptionsFromStructuredAttrs(*store, drv.env, get(drv.structuredAttrs));
+            drvOptions = DerivationOptions::fromStructuredAttrs(drv.env, drv.structuredAttrs);
         } catch (Error & e) {
             e.addTrace({}, "while parsing derivation '%s'", store->printStorePath(packageInfo.requireDrvPath()));
             throw;

src/nix/profile-diff-closures.md

@@ -23,6 +23,6 @@ R""(
 
 This command shows the difference between the closures of subsequent
 versions of a profile. See [`nix store
-diff-closures`](./nix3-store-diff-closures.md) for details.
+diff-closures`](nix3-store-diff-closures.md) for details.
 
 )""

src/nix/registry-resolve.md

@@ -1,28 +0,0 @@
-R""(
-
-# Examples
-
-* Resolve the `nixpkgs` and `blender-bin` flakerefs:
-
-  ```console
-  # nix registry resolve nixpkgs blender-bin
-  github:NixOS/nixpkgs/nixpkgs-unstable
-  github:edolstra/nix-warez?dir=blender
-  ```
-
-* Resolve an indirect flakeref with a branch override:
-
-  ```console
-  # nix registry resolve nixpkgs/25.05
-  github:NixOS/nixpkgs/25.05
-  ```
-
-# Description
-
-This command resolves indirect flakerefs (e.g. `nixpkgs`) to direct flakerefs (e.g. `github:NixOS/nixpkgs`) using the flake registries. It looks up each provided flakeref in all available registries (flag, user, system, and global) and returns the resolved direct flakeref on a separate line on standard output. It does not fetch any flakes.
-
-The resolution process may apply multiple redirections if necessary until a direct flakeref is found. If an indirect flakeref cannot be found in any registry, an error will be thrown.
-
-See the [`nix registry` manual page](./nix3-registry.md) for more details on the registry.
-
-)""

src/nix/registry.cc

@@ -202,40 +202,6 @@ struct CmdRegistryPin : RegistryCommand, EvalCommand
     }
 };
 
-struct CmdRegistryResolve : StoreCommand
-{
-    std::vector<std::string> urls;
-
-    std::string description() override
-    {
-        return "resolve flake references using the registry";
-    }
-
-    std::string doc() override
-    {
-        return
-#include "registry-resolve.md"
-            ;
-    }
-
-    CmdRegistryResolve()
-    {
-        expectArgs({
-            .label = "flake-refs",
-            .handler = {&urls},
-        });
-    }
-
-    void run(nix::ref<nix::Store> store) override
-    {
-        for (auto & url : urls) {
-            auto ref = parseFlakeRef(fetchSettings, url);
-            auto resolved = ref.resolve(fetchSettings, *store);
-            logger->cout("%s", resolved.to_string());
-        }
-    }
-};
-
 struct CmdRegistry : NixMultiCommand
 {
     CmdRegistry()
@@ -246,7 +212,6 @@ struct CmdRegistry : NixMultiCommand
                   {"add", []() { return make_ref<CmdRegistryAdd>(); }},
                   {"remove", []() { return make_ref<CmdRegistryRemove>(); }},
                   {"pin", []() { return make_ref<CmdRegistryPin>(); }},
-                  {"resolve", []() { return make_ref<CmdRegistryResolve>(); }},
               })
     {
     }

src/perl/package.nix

@@ -74,9 +74,5 @@ perl.pkgs.toPerlModule (
     ];
 
     strictDeps = false;
-
-    meta = {
-      platforms = lib.platforms.unix;
-    };
   })
 )

tests/functional/check-refs.sh

@@ -64,13 +64,5 @@ fi
 if isDaemonNewer "2.28pre20241225"; then
     # test12 should fail (syntactically invalid).
     expectStderr 1 nix-build -vvv -o "$RESULT" check-refs.nix -A test12 >"$TEST_ROOT/test12.stderr"
-    if isDaemonNewer "2.33pre20251110"; then
-        grepQuiet -F \
-            "output check for 'lib' contains output name 'dev', but this is not a valid output of this derivation. (Valid outputs are [lib, out].)" \
-            < "$TEST_ROOT/test12.stderr"
-    else
-        grepQuiet -F \
-            "output check for 'lib' contains an illegal reference specifier 'dev', expected store path or output name (one of [lib, out])" \
-            < "$TEST_ROOT/test12.stderr"
-    fi
+    grepQuiet -F "output check for 'lib' contains an illegal reference specifier 'dev', expected store path or output name (one of [lib, out])" < "$TEST_ROOT/test12.stderr"
 fi

tests/functional/flakes/flakes.sh

@@ -252,17 +252,15 @@ nix flake lock "$flake3Dir"
 nix flake update --flake "$flake3Dir" --override-flake flake2 nixpkgs
 [[ -n $(git -C "$flake3Dir" diff master || echo failed) ]]
 
-# Test `nix registry` commands.
+# Testing the nix CLI
 nix registry add flake1 flake3
 [[ $(nix registry list | wc -l) == 5 ]]
-[[ $(nix registry resolve flake1) = "git+file://$percentEncodedFlake3Dir" ]]
 nix registry pin flake1
 [[ $(nix registry list | wc -l) == 5 ]]
 nix registry pin flake1 flake3
 [[ $(nix registry list | wc -l) == 5 ]]
 nix registry remove flake1
 [[ $(nix registry list | wc -l) == 4 ]]
-[[ $(nix registry resolve flake1) = "git+file://$flake1Dir" ]]
 
 # Test 'nix registry list' with a disabled global registry.
 nix registry add user-flake1 git+file://"$flake1Dir"

tests/functional/nars.sh

@@ -114,7 +114,7 @@ if (( unicodeTestCode == 1 )); then
     # If the command failed (MacOS or ZFS + normalization), checks that it failed
     # with the expected "already exists" error, and that this is the same
     # behavior as `touch`
-    echo "$unicodeTestOut" | grepQuiet "creating directory '.*/out/â': File exists"
+    echo "$unicodeTestOut" | grepQuiet "path '.*/out/â' already exists"
 
     (( touchFilesCount == 1 ))
 elif (( unicodeTestCode == 0 )); then